# Ford 300 Inline Six



## mayhugh1 (Apr 21, 2021)

I'm plan to try my hand at building George Britnell's 1/5 (approx.) scale Ford Inline Six. This 300 cubic inch workhorse first appeared in the sixties and was used in Ford trucks for a decade. A shorter stroke version was used in passenger vehicles including the first car I was able to purchased new - a 1972 Maverick. In 2000, I rebuilt one of these engines in a '72 F-100 project truck that I used as a daily driver for a dozen years. The drawings purchased from George contain a lot of detail that will add realism to the model and challenge to its build. George documented his own build of this engine several years ago over on the 'other' forum.

After dealing with the pitfalls that can occur when trying to machine a complex crankshaft to fit an already completed crankcase, I decided to tackle it first. The Ford Inline six crankshaft is an interesting-looking 120 degree beast that's been replicated in this model. Its counterweight scheme isn't at all intuitive, but the engineers probably put all the lumps and bumps where they should be. The model's 8" long crank with its twelve tiny .312" journals will be one of the most difficult parts in this build. One of the photos shows a comparison of its SolidWorks model along side the Offy's crankshaft that tested my patience and machining abilities for several weeks last year.

The first step in its construction was to indicate a 9 inch length of 1-1/4" dia. Stressproof in my lathe's 4-jaw chuck so the ends could be center-drilled. Since I didn't have any material on hand, I purchased a length of 'ground and polished' 1144 from Speedy Metals. With the workpiece mounted between centers, I used my lathe's tailstock to zero out the measure of its end-to-end taper so I'd have a metric to track workpiece distortion during its various machining operations.

The workpiece was moved to the mill and clamped horizontally in the vise so a pair of reference flats could be machined on each end. These flats and a v-block were used to relocate the workpiece vertically in the vise so three additional center-drills could be added to each end for offset turning the rod journals.

The rod journals were roughed in using a center-supported four-axis indexing operation on my Tormach. Then with the workpiece set up between centers on the lathe, the rod journals and adjacent web walls were finish machined. The end-to-end taper measured less than .002" with the workpiece set up on centers in all three offset positions. These tapers were rough indicators of the initial mismatch errors in the end-counterbores. The taper measured along the main axis matched them to within a thousandth.

The crankshaft drawing specifies .312" for both main and rod journal diameters. I decided instead to target .328" for the rod journals and .375" for the main journals. The .328" was chosen because I happen to have a corresponding reamer for the rod bores. If a machining issue arises with the rod journals, the rod journal diameters can be reduced as needed to avoid scrapping the part.

The .375" diameter was chosen because of the availability of suitable ball bearings that I want to use for the outside main bearings. My plans include converting George's square bronze bearing design to round bronze bearings within the block and to replace the outer bronze bearings with ball bearings. Since I'm anticipating problems with the main journal machining, they may end up smaller with the inner bearings being machined to fit them.

The the rod journals and their web walls were finished using a Kennametal A2022N00CF02 grooving insert. This .087" wide carbide insert comes already bifurcated, and after a bit of lapping on a fine diamond plate it leaves a brilliant surface finish requiring little or no polishing. It's very important however to perfectly align its cutting edge with the lathe's spindle axis using a dial indicator. - Terry


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## mayhugh1 (Apr 21, 2021)

The journals were turned using side-to-side cutting motions and .005" depths of cut. The depths of these shallow cuts were set while simultaneously moving the carriage and the cross slide in order to achieve the best journal circularities and to reduce the chances of a dig-in due to workpiece deflection. In order to reduce this deflection, the spaces between the rod journal webs were packed with custom ground buttons held in place with lacing cord. All turning operations were done at 80 rpm and feeding was done manually. The finished rod journals wound up with .001" TIRs, and the four workpiece taper measurements remained at their previously measured values indicating a minimum workpiece distortion so far.

The workpiece was returned to the mill where the main journals and inch long ends were roughed in. Back on the lathe and between centers, workpiece deflection was now a major problem even with the rod journal packings. Light thumb pressure on the center of the workpiece easily created a .006" deflection - too much for accurate main journal turning. Some of this deflection was coming from the roughed-in ends which hindsight could have been done later.

I had some 1.250" i.d. seamless tubing on hand that I cut into a number of split pieces in order to stiffen the workpiece during turning. These snapped into place perfectly around the workpiece and were retained with hose clamps. These stiffeners reduced the center deflection to just over .001".

The main journals and their adjacent web walls were then finish turned. The measured TIR's were on the order of .001" with the stiffeners in place. However when they were removed, the workpiece relaxed, and the change in its shape caused two of the TIR's to increase to .004", and one changed to .003". Since the affected journals were still circular to within a thousandth, the increased runout was due to their centers shifting off the crankshaft's main axis. With the semi-finished crankshaft resting on v-blocks, it was apparent that the workpiece distortion had likely occurred sometime after finishing the rod journals and before the main journals were turned.

Next, the weird counterweight shapes were machined into the webs using the 4-axis step indexer still setup on my Tormach. After dealing with the frustrating machining errors on an uninteresting workpiece for so long, it was satisfying to finally see a crankshaft emerge. These operations removed a lot of additional material from the workpiece which added a bit more distortion and another thousandth or so to the main journal runouts. The TIR's of the inner journals were now at .005", .005", .0015", .003" and .0035". These runouts were high enough that if left uncorrected would create difficult fitting problems inside the crankcase, and the final result would most likely be an unsatisfying sloppy fit.

With the off-axis machining operations completed, the end spigots could be safely parted off with the help of a steady rest. I was finally able to measure the runouts with the ends of the crankshaft running in the ball bearings that will eventually be installed in the block. I was hoping the TIR's would improve, but they didn't change measurably.

During my Offy build I came up with a 'scraping' technique that enabled me to reduce the main journal TIR's of that crankshaft by slightly relocating their displaced axes. The journal diameters are reduced in the process, but since work on the crankcase hasn't yet started, this won't be a problem. With the crank resting between centers in the lathe and without any packings or stiffeners, the high areas of the journals were manually rotated back and forth against a razor sharp tool in the tool post. (I continued using the diamond lapped Kennametal carbide insert.) Working carefully while removing a few tenths at a time, the final TIR's were eventually reduced to .002". Progress was monitored with bluing and frequent trips between the lathe and surface plate where the TIR's were measured with the crankshaft running in its ball bearings. The relocated journals received blending polishings with 200g followed by 400g paper to bring them to a common .365"/.366" diameter. All journals then received a final polishing with 600g followed by 1000g paper. - Terry


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## mayhugh1 (Apr 21, 2021)

Although my project write-ups up to this point were done in realtime during the past two months while working on the crankshaft, I didn't make any realtime postings because I wasn't sure I was going to continue the build. The crankshaft looked very 'iffy' to me, and even George had commented about the difficulties he had experienced with its fitting inside his crankcase. If I wasn't happy with the finished part, my plan was to either increase the scale of the engine or to abandon the project completely.

Since I am reasonably satisfied with the final result, and it's likely that I'll be looking at it for the next year, I prettied it up some by masking off the journals and bead blasting the webs to remove the machining marks. Both ends received 1/16" keyways, and they were tapped with 8-32 screws. I've included a number of photos of the finished product. The block machining will probably begin next. - Terry


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## Ghosty (Apr 21, 2021)

Terry, another one I will be watching, You do amazing work and incredible documentation of the build
Cheers
Andrew


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## gbritnell (Apr 22, 2021)

Hi Terry,
It brings joy to my heart watching another one of my designs come to life. Like you I thought about increasing the rod and main journals but I didn't have any problems with the smaller size so continues on. When the day comes to 
make the helical gears for the cam you're welcome to borrow my fixture.


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## awake (Apr 22, 2021)

Incredible work as always! And I have a special fondness for that engine; the first pickup I owned was a beat-to-near-death F100 with a 5-cylinder version of that engine. As in, it had 6 cylinders in it, but only ran on 5! Nevertheless, it hauled many a load of mulch and firewood before I finally sold it for $200 ... which was 4x what I had paid to purchase it!


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## a41capt (Apr 23, 2021)

Wow!  Nice work Terry, and like others in this thread, I too had the pleasure of owning an early 80s F150 with a 300 six.  A great engine, and thank you George for putting the effort into designing the model of this fantastic workhorse.

I’m watching with great interest Terry, the work on your crankshaft is nothing short of beautiful.

John W


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## Tim Wescott (Apr 23, 2021)

awake said:


> Incredible work as always! And I have a special fondness for that engine; the first pickup I owned was a beat-to-near-death F100 with a 5-cylinder version of that engine. As in, it had 6 cylinders in it, but only ran on 5! Nevertheless, it hauled many a load of mulch and firewood before I finally sold it for $200 ... which was 4x what I had paid to purchase it!



Hah!  My dad had a friend who rebuilt engines.  He had a story of an old Hudson that he bought and drove for a while.  It had excessive vibration in the engine that he decided to fix.  When he tore it down, he found a block of wood driven into one of the cylinder bores (and no piston, obviously), which looked like it had suffered from a broken ring.


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## johnmcc69 (Apr 23, 2021)

And after you build the engine.....you'll have to build Georges transmission for it. 

 John


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## splodge (Apr 27, 2021)

Great quality workmanship, will follow this with great interest...

Could I ask you , how I would go about purchasing drawings for this engine ?

Gary


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## mayhugh1 (Apr 27, 2021)

splodge said:


> Great quality workmanship, will follow this with great interest...
> 
> Could I ask you , how I would go about purchasing drawings for this engine ?
> 
> Gary


Contact George Britnell. He posts on this forum and in fact in this thread above.


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## splodge (Apr 27, 2021)

Thanks for the fast reply , I've been on the forum for many years and just quiet !..I follow all your builds , and I'm also a long way into building Ron's, offy 270.

Daft question maybe but how do I contact George Britnell directly ?

I'm still learning after all these years !

Gary


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## The_reach (Apr 27, 2021)

splodge said:


> Thanks for the fast reply , I've been on the forum for many years and just quiet !..I follow all your builds , and I'm also a long way into building Ron's, offy 270.
> 
> Daft question maybe but how do I contact George Britnell directly ?
> 
> ...


Would like to see your offy progress, im collecting materials for a half scale version


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## Scott_M (Apr 27, 2021)

splodge said:


> Daft question maybe but how do I contact George Britnell directly ?



Hi Gary
Just hover over anybody's avatar and then click on "Start a Conversation"  This will start what we used to call a PM  "private message"  directly through the forum.

Scott


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## mayhugh1 (Apr 27, 2021)

splodge said:


> Thanks for the fast reply , I've been on the forum for many years and just quiet !..I follow all your builds , and I'm also a long way into building Ron's, offy 270.
> 
> Daft question maybe but how do I contact George Britnell directly ?
> 
> ...


You can send him a personal e-mail through this forum or he might contact you when he re-visits this thread.


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## mayhugh1 (Apr 27, 2021)

The_reach said:


> Would like to see your offy progress, im collecting materials for a half scale version



There hasn't been any more progress since it was completed.


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## The_reach (Apr 27, 2021)

mayhugh1 said:


> There hasn't been any more progress since it was completed.


Hi mate, was a reply to splodge


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## splodge (Apr 28, 2021)

Thanks for the help folks, I will give it a go !



The_reach said:


> Would like to see your offy progress, im collecting materials for a half scale version


As for my Offy 1/4 scale is a nice size for me to work with, your going to need a large piece of aluminium for the crankcase in half scale !

Haven't any pictures of my progress , but can take pics , if you want to know anything...its a slow build for me but  Rons build instructions are great , I assume you have it also..

Gary


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## Willyb (Apr 28, 2021)

Hi Terry
Great start on your Ford 300 six project.  What are you using for media in your Bead Blaster? Really like the finish your getting. Looking forward to following along with your build.
Cheers
Willy


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## sition (May 2, 2021)

：eek：


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## dnalot (May 2, 2021)

sition said:


> eek



"eek a mouse" one of my favorite musicians.

Mark T


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## propclock (May 2, 2021)

Beautiful work and documentation. I was wondering if the crank distorted any after bead blasting?
I have had some major revelations after the seemingly trivial stress removal from bead blasting. 
Again thank you for all your posts.


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## mayhugh1 (May 2, 2021)

propclock said:


> Beautiful work and documentation. I was wondering if the crank distorted any after bead blasting?
> I have had some major revelations after the seemingly trivial stress removal from bead blasting.
> Again thank you for all your posts.


No, there wasn't any additional distortion that I could measure. For media I'm using glass 'beads' (really ground up glass) purchased from Harbor Freight. A grit wasn't spec'd for the material, but I would guess it started at about 60 and has been getting finer during the past 20 years. - Terry


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## Eccentric (May 2, 2021)

Great new project, looking forward to following along.


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## mayhugh1 (May 7, 2021)

Block construction began with squaring up a 7" long block of 7075 aluminum with a bit of excess stock on all surfaces. This particular alloy is harder than 6061 and should provide additional wear resistance to the splash lubricated camshaft that will spin directly in the block. The 5/16" through-hole for the camshaft was the block's first machining operation.

The usual approach to a hole like this would be to work from both ends of the workpiece. However, I had an extra-long .294" diameter drill and 5/16" reamer and was curious to see how accurately I could place the hole while working from only one end. With the workpiece clamped in a vise and indicated to my mill's vertical axis, the drill had to be gripped in a 5/16" R8 collet to get the needed head room. The hole took half an hour to complete with the table's z-axis used in conjunction with the quill for peck drilling. Measurements show the hole had wondered off vertical with a .001" error on one axis and a .005" error on the other. I could probably have lived with the .005" error but, since the workpiece was oversize, it was re-squared around the hole.

The next operations were performed through what will become the bottom surface of the block. These included the lifter bores, main bearing supports, and the clearances around the crankshaft and rods. These operations began with drilled-through pilot holes for the sleeves and removal of the excess stock on block's bottom surface. This seemingly trivial facing operation was critical because it established the distance between the main bearings and the camshaft which is important for a proper mesh of the timing gears. When completed, and with the crankshaft resting in its outer ball bearings, this distance was within a thousandth of its target value. The complex clearances were machined on the Tormach. 

The workpiece was then flipped over so the bores for the piston sleeves could be machined through the top of the block. Slip-fit sleeves will eventually be sealed in these bores with high-temp Loctite before the excess material on the block's top is finally removed. A 3/4" Woodruff cutter with a turned-down shank was used to machine the undercut spaces for the water jackets. The water jacket shapes are fairly complex and biased toward the port side of the engine. They were designed around the starboard-side head bolt locations to maximize the volume of coolant around the sleeves. Their enlarged shapes allowed me to slightly increase the diameter of the transfer holes that will carry coolant into the head. 

My CAM software wasn't happy with the undercut operations. It only understands full length constant diameter cutters for operations that must keep track of the workpiece, and it refused to generate the needed code below the deck surface. I eventually got around this by lying to the software about the shapes of the cutter and the part and by modifying the tool's approach and retract code by hand. Some previous attempts to trick this CAM software haven't ended well, and so the code was developed on a piece of scrap before being run on the block.

Although most of the block's critical machining has been completed, it's probably only 10% finished. Most of its remaining machining will be cosmetic, and at least half of the remaining workpiece will be turned into chips. - Terry


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## mayhugh1 (May 7, 2021)

More Photos ...


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## pickleford75 (May 7, 2021)

Wow! Beautiful work as always Terry!


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## SmithDoor (May 8, 2021)

mayhugh1 said:


> The journals were turned using side-to-side cutting motions and .005" depths of cut. The depths of these shallow cuts were set while simultaneously moving the carriage and the cross slide in order to achieve the best journal circularities and to reduce the chances of a dig-in due to workpiece deflection. In order to reduce this deflection, the spaces between the rod journal webs were packed with custom ground buttons held in place with lacing cord. All turning operations were done at 80 rpm and feeding was done manually. The finished rod journals wound up with .001" TIRs, and the four workpiece taper measurements remained at their previously measured values indicating a minimum workpiece distortion so far.
> 
> The workpiece was returned to the mill where the main journals and inch long ends were roughed in. Back on the lathe and between centers, workpiece deflection was now a major problem even with the rod journal packings. Light thumb pressure on the center of the workpiece easily created a .006" deflection - too much for accurate main journal turning. Some of this deflection was coming from the roughed-in ends which hindsight could have been done later.
> 
> ...


I saw crank machine from bar stock 144" long and about 8" stoke about 12 cylinder. 
I would hate to machine that one it may take year.

Dave


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## gbritnell (May 8, 2021)

Absolutely gorgeous Terry! What is your plan for the main bearings?


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## Vixen (May 8, 2021)

Terry, More gorgeous high precision work for us to admire. Well done.

Quote: "Measurements show the hole had wondered off vertical with a .001" error on one axis and a .005" error on the other. I could probably have lived with the .005" error but, since the workpiece was oversize, it was re-squared around the hole."

So, how did you measure the hole to determine it had wondered off axis by 0.001" and 0.005"? Then how did you re-jig the workpiece to re-square it around the hole?

Thanks for posting your work

Mike


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## mayhugh1 (May 8, 2021)

Vixen said:


> Terry, More gorgeous high precision work for us to admire. Well done.
> 
> Quote: "Measurements show the hole had wondered off vertical with a .001" error on one axis and a .005" error on the other. I could probably have lived with the .005" error but, since the workpiece was oversize, it was re-squared around the hole."
> 
> ...


Mike,
I inserted a length of .312" drill rod in the hole and measured its height at both ends on both axes using a height gage over a surface plate to get the relative offset errors. I was satisfied with the .001" error, but I shimmed the workpiece in the mill vise to re-face the two surface straddling the .005" error. I then corrected the ends with a long 1" diameter end mill. Since the workpiece still had excess stock all around, I just had to correct my modeling to the new values. - Terry


George,
I plan to use split bronze bearings. There is a picture of them in my model in my very first post. They're similar to what I did in my split crankcase Offy. Instead of milling the oiling slot in the crankcase and drilling up through the bearing to lubricate the crankshaft as you did, my round bearings will be large enough in diameter that I'll mill the slot directly in them. - Terry


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## kvom (May 9, 2021)

Where did you order the 7075?  I've only seen it locally in round rod.


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## mayhugh1 (May 9, 2021)

kvom said:


> Where did you order the 7075?  I've only seen it locally in round rod.


Speedy Metals ...


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## e.picler (May 11, 2021)

Hi Mayhugh!
Congratulations on one more wonderful work. I will follow this project with close interest because I also have the same plans from George.
Beautiful work.

TKS,
Edi


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## mayhugh1 (May 16, 2021)

Although most of the block's machining could be done in a single four-axis setup, I opted to machine it in a vise one face at a time. With this simpler approach, I was able to continue tweaking the block's design while making chips. The already completed machining through the block's top and bottom surfaces left them flat and usable for subsequent work-holding. 

The front and rear faces contain features that wrap around the sides of the block and potentially span two different setups. Machine backlash in addition to tiny errors in tool definitions and vise setups can create significant defects in the surfaces trapped between overlapping operations. In order to eliminate manual cleanup, boundaries need to be defined that avoid splitting complex features across multiple setups. 

My CAM software provides tools for limiting its tool path generation to user-defined areas on the part, but they don't always work as needed, and I wind up spending most of my time with the software trying to convince it to not cross boundaries. On the other hand, its own internal checks to ensure the actual part isn't gouged during machining are very reliable. So, I created a unique model for each setup in which I used SolidWorks to extrude material (in the same shape as the workpiece) over the part's keep-out areas. To the software this additional material is an inviolate feature on the final part. Since it's easier to visualize than explain, I've included a rendering of the model used to machine the front and rear ends.

The front-end was machined with the workpiece gripped vertically in a vise. The operations' depth was chosen so the fillets connecting the gear case to the sides of the block would fall inside only one setup. In my version of the block, the gear case was extended to accommodate the crankshaft's thicker front bearing and a few changes planned for the timing gear. Instead of securing this gear to the camshaft with a setscrew, it will be slotted and attached with SHCS's to a flange on the camshaft to provide a vernier for valve timing. A bolt-in retainer for the front bearing was also added inside the gear case.

Even though the workpiece sat pretty high in the vise, it still had plenty of mass to dampen any surface spoiling vibrations created during milling. Just to be sure, though, a pair of 4-5-6 blocks were clamped to it.

The rear-end machining setup was similar. The rear of the block was also extended to accommodate the thicker rear bearing and its retainer. The front and rear o-ring shaft seals in the original design were omitted since the outer bearings are being replaced with sealed ball bearings. The extra space inside the bell housing will be filled with a faux torque converter that I plan to add for a bit more angular momentum. I also hope to investigate using an electric starter. - Terry


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## Scott_M (May 16, 2021)

Hi Terry
Gorgeous as always !! Your fits and finishes are always a treat to see.
You have become very proficient at lying to sprutcam  . I am still using version 7 and know all too well what you mean.

I still think the best part of your builds is your documentation, photography and willingness to share it all with us. And sometimes "Warts and all" but there is always an in depth resolution on how the "Wart" was dealt with.  Outstanding

Thanks again

Scott


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## kuhncw (May 16, 2021)

Terry,

Very nice work as always.  Thanks for explaining your CNC machining sequences.

Chuck


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## kuhncw (May 16, 2021)

Terry,
Which surfaces or features are you using to locate the part when you flip it end for end?

Chuck


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## mayhugh1 (May 16, 2021)

Chuck, I used the same corner of the workpiece for both ends. The ends of the workpiece match to within a thousandth even over the 7" length.
 -Terry


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## kuhncw (May 16, 2021)

Thank you, Terry.

Chuck


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## gbritnell (May 17, 2021)

Hi Terry,
If you don't mind I would like to incorporate your changes into a modified version of the engine. I would still keep the original set but could notify potential builders of your changes. Please contact me at my email address so we can discuss it further without having to go through the forum chat.
gbritnell


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## Foketry (May 18, 2021)

mayhugh1 said:


> More Photos ...View attachment 125241
> View attachment 125242
> View attachment 125243
> View attachment 125244



what kind of end mill did you use to get a mirror surface with no machining marks ?
it seems to me a large diameter tool


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## mayhugh1 (May 18, 2021)

Hi Foketry,
I used a Glacern FM45-300 face mill @ 3000rpm/20ipm.

Terry


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## mayhugh1 (May 23, 2021)

The sides of the block were machined next. The features on them are very similar to those on the full-size block, and the realism they add make this engine much more than just another runner. George's attention to detail is especially remarkable since he planned to manually machine the entire engine.

I tweaked the design and placement of some of the features in George's original design in order to limit the number and sizes of the end mills needed to machine it. The radii of the fillets were limited to a minimum of 3/32" to avoid the difficulties and surface finish issues sometimes encountered with tiny long stick-out cutters running on a 5k rpm mill.

Waterline roughing operations with .040" vertical steps were used on both sides of the block. These operations were compiled for 1/2" and 1/4" diameter end mills to leave .007" radial and axial excess stocks for finishing. The final finishing operations were also waterline, but rather than fixed steps they were compiled for .0003" maximum scallop heights using 1/4" and 3/16" ball cutters. The sides' few truly flat surfaces were finally finished using a 3/16" end mill.

Even with my tweaking, simulation results showed spaces between several port-side filleted features that would have required a long reach 1/16" end mill to entirely machine finish. These were manually filed down later using a tiny spherical carbide burr in a hand-held pin vise. The block's total six-sided machining time on my Tormach came out to some 27 hours making it the most complex part I've machined to date.

A fixture plate drilled with the block's bottom hole pattern was also machined. This plate will eventually be used to hold the workpiece for the oil pan while it's being machined. It's also needed to support the block while drilling the angled holes for the dipstick and distributor. The bore for the distributor is especially critical since it will establish the mesh for a custom machined 72 pitch/14 tooth 45 degree helical gear set used to drive the distributor from the camshaft. The distributor bore won't be done until these gears have been machined and are in hand so their center-to-center distance can be verified. The less critical dipstick hole, however, was drilled as a warm-up exercise for the distributor bore. Both holes are to be drilled at 60.43 degree angles, and each is referenced to the camshaft bore.

The angle plate setup used to drill the 3/32" dipstick hole is shown in one of the photos. This same setup will be used later for the distributor bore. After carefully establishing the exact drilling angle, measurements on the exit point of the resulting hole showed the actual angle had ended up 0.4 degrees too shallow. If this had been the distributor bore, the resulting .010" mesh error would have been enough to bind the gears, and the block would have become scrap.

After several hours of detective work, I concluded that regardless of the beefy appearance of my ten pound angle plate, it lacked the rigidity needed to hold the setup angle during the drilling of the tiny dipstick hole. A shimmed support block under the front edge of the movable plate should hopefully eliminate the problem for the distributor bore.

Bead blasting using generic glass media from Harbor Freight hid the machining marks and allowed me to see the places that needed manual touch-up. It also gave the block's exterior a nice cast metal looking finish. Only two operations remain. In addition to the scary distributor bore, the top surface will be faced to remove its excess stock once the liners are installed. - Terry


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## stevehuckss396 (May 23, 2021)

That is absolutely beautiful. Great job sir!


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## kuhncw (May 23, 2021)

That is an amazing piece of work, Terry.

Please remind me which CAM software package you use.

Chuck


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## mayhugh1 (May 23, 2021)

kuhncw said:


> That is an amazing piece of work, Terry.
> 
> Please remind me which CAM software package you use.
> 
> Chuck


Chuck,
I use Sprutcam, a Russian product marketed by Tormach. My version SC-7 is a dozen years old, but it has some continuous 4-axis capabilities that I've used to machine camshafts and crankshafts. When I purchased mine it was a tenth the cost of packages with similar capabilities. Unfortunately the user manual left a lot to be desired, and since I learned CAM using this software my learning curve was steep. I don't know how more modern packages compare, but so long as I can keep an XT computer running I plan to stick with this one. - Terry


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## kuhncw (May 23, 2021)

Thanks, Terry.

Chuck


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## gbritnell (May 24, 2021)

Wow,  gorgeous!


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## harborfreight8x12 (May 24, 2021)

Beautiful work.  I especially liked the wood hold-downs, I learned something.


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## 58tux (May 24, 2021)

Terry. Just out of curiosity how long did it take to machine the side of the block and how many lines of code did it take?

Rich


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## mayhugh1 (May 24, 2021)

58tux said:


> Terry. Just out of curiosity how long did it take to machine the side of the block and how many lines of code did it take?
> 
> Rich


Rich,
The most complex side, the port side, was done in seven individual steps using seven different g-code programs totaling 165k lines in just under 9 hours. On complex parts I usually break up the CAM into separate steps so I can run them over a number of days to limit the heat rise in the shop from the mill especially this time of year here in Texas. There is also a problem with the limited resources in my computer. Memory leaks are an issue with this CAM software, and I found that I had to quit and restart the application after each compile of the complex finishing programs to keep the application from hanging. - Terry


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## Eccentric (May 24, 2021)

Awesome as always Terry.  How do you keep from getting oily finger prints on your beautiful bead blasted surfaces?


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## Vixen (May 24, 2021)

Terry,

You seem happy with your Russian, Sprutcam Ver 7 software. We know there are newer versions available, but if SC-7 does everything you want it to do and can do it on an old 32 bit PC, so why change?  I am looking for a better 2D CAM software program than the ones I currently use. Will SC-7 accept 2D drawings and do acceptable 2D CAM, or must it have 3D models.

Mike


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## mayhugh1 (May 24, 2021)

Mike,
The Sprutcam software will handle 2D with special 2D modes which are much simpler than the 3D operations that I use. I've never used them because of the way I learned to use the tool. In my mind it was just easier to stick with 3D for everything which isn't necessarily the best way to use the software. For instance, to round off an edge, I'll use a ball endmill and multiple passes in a 3D operation to get a similar result to what a 2D user would achieve with a single pass and a corner-rounding endmill.
I never continued upgrading the software for a couple reasons. First, the 5-D operations they began adding were beyond the capability of my Tormach, and so my benefit to cost was minimal. The biggest problem, though, were with imperial units. Most of Sprutcam's users use metric units, and every new release seemed to have some problem with imperial units that took even more releases to fix. My understanding is that the company is in a warehouse park and is surrounded by customers who give rapid feedback about bugs. The company seems to be very responsive to them, but less so with the few of us over here that had inch problems. I remember one release in particular that was so bad that it essentially shut me down. I complained loudly about it directly to them and through Tormach and they made a quick release to solve the problem. But, being millimeter people and I guess not knowing better at the time, they did it by adding a choice to use fractional inches! - Terry


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## Vixen (May 24, 2021)

Terry,
Thanks for the thorough explanation. I had an idea of downloading an older SC-7 version for the same reason as you. My requirements are 2D CAM, 32 bit machine and imperial units. So SC-7 appears to tick most of those boxes. What 2D drawing formats will it accept .DWG, .DXF ?.
Fractional inches, your joking ?????  When was the last time enyone used 49/64"
Mike
Sorry for the sidetrack


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## mayhugh1 (May 24, 2021)

Vixen said:


> Terry,
> Thanks for the thorough explanation. I had an idea of downloading an older SC-7 version for the same reason as you. My requirements are 2D CAM, 32 bit machine and imperial units. So SC-7 appears to tick most of those boxes. What 2D drawing formats will it accept .DWG, .DXF ?.
> Fractional inches, your joking ?????  When was the last time enyone used 49/64"
> Mike
> Sorry for the sidetrack


Mike,
It will import igs, iges, stl, wrl, ps, eps, dxf, .3dm, as well Solidworks sldasm,asm, and sldprt.

Terry


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## kvom (May 25, 2021)

> I'll use a ball endmill and multiple passes in a 3D operation to get a similar result to what a 2D user would achieve with a single pass and a corner-rounding endmill.



Likely for the better as corner rounding mills don't give a 90 degree radius.

As for the metric/inch issues, you could certainly generate the CAD model in metric.  Then a newer version of Sprutcam and a faster computer could be used.  The mill won't care.


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## Scott_M (May 25, 2021)

For the record I am running SprutCam7 on a 64 bit windows 10 machine. It seems to work just fine.

Scott


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## propclock (May 25, 2021)

I always appreciate your beautiful work and and your  explanations of problems and solutions.
 I have just 1 question, You use a lot of ball end mills. Do you have a favorite suppler / brand?
Thank you.


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## ddmckee54 (May 25, 2021)

Terry:

Did you do any hand finishing before you bead blasted the part, or was it basically straight from the mill to the bead blaster?

At this scale, the bead blasted finish looks remarkably like a cast part.  I think you said you are using glass beads that you got from HF several years ago?

Don


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## Mike Henry (May 25, 2021)

Terry,

I found that SC got much more user friendly around version 10 or so and has been getting better since.  Or maybe I just learned to think more like they do.

Beautiful work on the Ford engine model - very inspirational.

Mike


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## mayhugh1 (May 25, 2021)

propclock said:


> I always appreciate your beautiful work and and your  explanations of problems and solutions.
> I have just 1 question, You use a lot of ball end mills. Do you have a favorite suppler / brand?
> Thank you.



I use Atrax end mills from MSC.

Scott,
Did you have to upgrade your SC dongle for the current version of Windows or did the one you ran on XP continue to run with no changes?
My Solidworks 2010 won't even work on 64 bit Win7 and has been the main reason I continue with XP. I'm really surprised but glad to hear SC7 can run on current values of Windows.


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## mayhugh1 (May 25, 2021)

ddmckee54 said:


> Terry:
> 
> Did you do any hand finishing before you bead blasted the part, or was it basically straight from the mill to the bead blaster?
> 
> ...


Except for a couple areas between some too-close fillets that would have required a 1/16" end mill, the part went directly off the mill and into the bead blaster. - Terry


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## Scott_M (May 25, 2021)

Hi Terry
It is the one I got with the original software back in the XP days. But the dongle only works with the original "Demo" disk I got from Tormach.
When I built my new computer I downloaded a legacy version of SC7 and my dongle would not work. I had to find my original disk that came with the mill and that was way back in 2007. I did find it and it installed on Win 10 without issue and the dongle was recognized.

Scott


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## mayhugh1 (May 25, 2021)

Scott,
I'm not sure I follow you. When you say 'demo disk' are you talking about the install disk you purchased from Tormach when you upgraded to SC-7? This one would have had a copy of SC7 and a small program that might have updated your dongle (which I think also contains a unique user i.d.) to use it with the new SC-7. 

Have you ever tried to install a legacy copy of SC7 on another computer since then in order to see if it was your dongle that got changed in the process? - Terry


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## Basil (May 26, 2021)

Beautiful work Terry. The bead blasted finish looks awesome. I have found the finish get dirty quickly even when being careful. Have you found anything that seals up the surface to stop this happening?


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## mayhugh1 (May 26, 2021)

Basil said:


> Beautiful work Terry. The bead blasted finish looks awesome. I have found the finish get dirty quickly even when being careful. Have you found anything that seals up the surface to stop this happening?


I brush scrub the part with water and dish soap right after bead blasting and then thoroughly blow dry it with compressed air while holding it in a paper towel. I then let it sit for a day before I touch it. - Terry


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## Scott_M (May 26, 2021)

Hi Terry


mayhugh1 said:


> Scott,
> I'm not sure I follow you. When you say 'demo disk' are you talking about the install disk you purchased from Tormach when you upgraded to SC-7? This one would have had a copy of SC7 and a small program that might have updated your dongle (which I think also contains a unique user i.d.) to use it with the new SC-7.
> 
> Have you ever tried to install a legacy copy of SC7 on another computer since then in order to see if it was your dongle that got changed in the process? - Terry



They used to hand these out at events, I got this one at a "CNC Workshop" in Michigan in 2010. 
This is the only version my dongle will activate.
I am pretty sure the dongle is version specific and not keyed or ID'd to my computer. I have installed it on each new computer over the years. But it will only work with this install disk.
After looking at the demo version I decided to buy it. They sent me the dongle, I plugged it in and it unlocked the "demo" version. As far as I know the dongle has not been written too. I have not installed any such program or manually updated it. As far as I know. I hope that explains it.
Scott


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## mayhugh1 (May 26, 2021)

Scott_M said:


> Hi Terry
> 
> 
> They used to hand these out at events, I got this one at a "CNC Workshop" in Michigan in 2010.
> ...


It sounds like SC-7 was your first version then. I started out with SC-4 which was initially distributed by Alibre for Tormavh, and then I worked my way up over the years. Each time I upgraded to a new version, I had to run a small program that Tormach sent me to read my dongle and it created a file that that I had to send back to Tormach. They then sent me back a license file that I had to install myself in a directory created by the new SC version that I downloaded from zsprutcam and installed myself. On my very latest version, SC-7, instead of going thru the license install myself, after they received my dongle info, they sent me an install disk that did all this automatically. I've been afraid that if I tried to install the software on a Windows platform later than XP, the driver for the dongle would be different and it would get modified and screwed-up in the process somehow. But, your experience suggests it might not. - Terry


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## Scott_M (May 26, 2021)

Yes, 7 was my first version.
Tormach is very good to their legacy users like you and I. My machine is SN#225 and I think your # is lower than mine. I think if something went wrong trying to install it on a new OS, Tormach would take care of it somehow.

Scott


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## mayhugh1 (May 26, 2021)

Scott_M said:


> Yes, 7 was my first version.
> Tormach is very good to their legacy users like you and I. My machine is SN#225 and I think your # is lower than mine. I think if something went wrong trying to install it on a new OS, Tormach would take care of it somehow.
> 
> Scott


I think your right!


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## burkLane (May 27, 2021)

mayhugh1 said:


> I think your right!


While they don't support old versions of software with help. I would expect Jacob @ tormach to help get the older version up and running for you.  I have also noticed in past they work out upgrade deals if you want to move to current version. Still not cheap I bet.  Anyway the current sprutcam mill post still has your name on it as a contributing author.  Anyway your craftsmanship and detailed writeups make for some of the best reading, thanks for taking the time.


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## e.picler (May 27, 2021)

Terry,
This is really outstanding work. Congratulations!!!!
I also use Sprut Cam for my projects. I'm using the SC12
What strategy do you use for the 3D machining? Are you using Rough/Finish Water Line or you use 3D machining?

Tks,
Edi


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## Mike Henry (May 27, 2021)

mayhugh1 said:


> It sounds like SC-7 was your first version then. I started out with SC-4 which was initially distributed by Alibre for Tormavh, and then I worked my way up over the years. Each time I upgraded to a new version, I had to run a small program that Tormach sent me to read my dongle and it created a file that that I had to send back to Tormach. They then sent me back a license file that I had to install myself in a directory created by the new SC version that I downloaded from zsprutcam and installed myself. On my very latest version, SC-7, instead of going thru the license install myself, after they received my dongle info, they sent me an install disk that did all this automatically. I've been afraid that if I tried to install the software on a Windows platform later than XP, the driver for the dongle would be different and it would get modified and screwed-up in the process somehow. But, your experience suggests it might not. - Terry



FWIW, I've run SC 8, 9, 10, 11, and 12 on my Win 7 system with no special problems.  I'm about to switch to a new Win 10 system and will try SC 14 on that.  One advantage to SC is that you can usually run multiple versions on the same system.  A few versions back they started using the same HASP key with each no version.


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## mayhugh1 (May 27, 2021)

e.picler said:


> Terry,
> This is really outstanding work. Congratulations!!!!
> I also use Sprut Cam for my projects. I'm using the SC12
> What strategy do you use for the 3D machining? Are you using Rough/Finish Water Line or you use 3D machining?
> ...


I typically use waterline roughing and finishing operations followed by what they call 'rest' machining. I also use their flatline finishing. I also frequently use their 2-d contouring operation with a spiraling curve when I want a steep wall with minimum machining marks. - Terry


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## mayhugh1 (Jun 1, 2021)

A block of 6061 was squared up for the oil pan's workpiece. Some changes were made to the original pan design to accommodate the outer round bearings. When used with a .015" thick mounting gasket, the new pan will provide the additional 180 degrees of metal-to-metal contact needed to support each outer bearing.

The front and rear ends were machined using essentially the same operations used on the ends of the block. Again, 4-5-6 blocks were used to help stabilize the portion of the workpiece sticking above the vise, and a paper towel bib kept them free of the sticky coolant. After finishing its ends, the workpiece was repositioned so the pan's interior could be hogged out and its drafted walls finished. My modeling showed uncomfortably close clearances between the heads of the rod bolts and the inside corners of the pan, and so I added an array of clearance notches. Rather than use a magnetic drain plug, the floor of the pan was bored with a shallow hole for an epoxied magnet.

The pan's mounting holes were initially drilled undersize and tapped for screws that attached it to the fixture plate made earlier. When the machining was completed, the holes were opened up for the pan bolts.

With the workpiece attached to the fixture plate and its interior packed with modeling clay, the assembly was clamped in the vise for access to the pan's bottom surfaces. At first glance the pan looks fairly simple, but two of its three bottom surface aren't flat, and the sides have three degree draft angles. After being roughed in, the bottom was finished using a waterline operation and a long reach 3/8" ball end mill. The tool path steps were compiled for .0003" high scallops which blended into the surface after bead blasting.

After attaching the workpiece, the sides of the fixture plate should have been skimmed to insure the sides of the workpiece would be truly parallel to the jaws of the vise. I forgot to do this, and the pan's machined sides wound up diagonally offset from the already machined ends by .004" and had to be manually blended.

The full-size engine's oil pan was drawn steel and factory painted either black or Ford Blue. A similar shade of blue is available in Gun Kote that I'll likely use on some of the model's parts when their machining is completed. - Terry


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## mayhugh1 (Jun 1, 2021)

More Photos ...


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## ajoeiam (Jun 1, 2021)

mayhugh1 said:


> More Photos ...
> 
> 
> 
> ...


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## doug tyler (Jun 1, 2021)

My goodness, that's spiffy!!!


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## mayhugh1 (Jun 8, 2021)

The tappets in Ford's inline six are accessed through a recess cast into the starboard side of the block just above the camshaft. They're located behind a tappet cover that fully encloses them and is hopefully leakproof. Simulated stiffeners on the cover's outside surface are a nice cosmetic touch, and the rear face has a sealing lip around its periphery.

Machining began with the cosmetic detail on the cover's outside face. This was machined into the top surface of a .185" thick aluminum workpiece while clamped in the vise on tall parallels. After band sawing the semi-finished cover free, it was flipped over and temporarily glued to a piece of MDF using a quick setting Devcon Epoxy Gel. The workpiece was indicated with the MDF clamped in the vise while the epoxy cured. After all the machining was finished, the part was released with a half hour bake in a 300F oven.

There's a possibility of interference between the cover and the distributor, and so the lower edge of the cover was relieved just above the distributor's mounting boss. This may have to be revisited after the distributor is machined and its bore in the case is finally drilled.

The cosmetic detail on the front face of the timing cover is another nice touch. Changes were required to the timing cover to accommodate earlier modifications made to the front ends of the block and oil pan for the front ballbearing. Hopefully, oil will find its way into the timing gears through a small hole drilled between them through the front of the block. The front pulley's hub will be grooved for a rotating 0-ring seal to prevent oil from leaking around the shaft. Both covers were bead blasted in preparation for painting. - Terry


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## Basil (Jun 8, 2021)

Hi Terry, On the timing cover are you gluing the aluminum to the MDF and holding the MDF in the vice for the full operation? 
Cheers
Mike


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## mayhugh1 (Jun 8, 2021)

Basil said:


> Hi Terry, On the timing cover are you gluing the aluminum to the MDF and holding the MDF in the vice for the full operation?
> Cheers
> Mike


Mike,
Yes, the workpiece was on the MDF for the entire machining of the cover since the rear face was flat and didn't have to be machined. - Terry


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## Sprocket (Jun 9, 2021)

I'm sure I missed it somewhere, but what are you using for blast media?
Thanks,
Doug


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## mayhugh1 (Jun 9, 2021)

Sprocket said:


> I'm sure I missed it somewhere, but what are you using for blast media?
> Thanks,
> Doug


Glass beads from Harbor Freight


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## mayhugh1 (Jun 14, 2021)

It's not a good idea to finish all the fun stuff at the front end of a long build, so I decided to work on the mundane cylinder liners. After lapping, they'll be installed in the block with .004" (diameter) slip fits and sealed with Loctite. When machining the water jackets earlier, generous top and bottom sealing rings were left behind for Loctite, and hopefully coolant leaks won't be an issue.

The first step in construction was to machine a Delrin plug gage that was trial-fitted in each cylinder location to verify the liners' dimensions. With those dimensions in hand, eight 2" long starting blanks were band-sawed from a 1" diameter Stressproof rod. Each workpiece included a 3/4" holding spigot. One of the two extra cylinders will be completely finished and used later for the piston ring light tests.

The liners' 3/4" bores were initially opened up to about .65" with two drilling operations. Their o.d.'s including the top sealing lips were then turned and finished. A grooving tool turned a sharp inside corner and a slight undercut immediately below the lip. Stressproof is a joy to turn with its beautiful surface finishes so easily obtained with little effort.

However, boring Stressproof is an entirely different matter. Its 2X hardness demands a very rigid boring bar setup for acceptable results. I was finally able to get nice surface finishes using a 1/2" bar with a 1.5" stick-out and high rake CCGT inserts designed for aluminum. Chip evacuation was a major problem however. The boring had to be split into three separate operations with the workpiece being removed after each so chips could be unpacked from both the workpiece and collet.

A final operation using a fresh insert removed the last .020" from each bore. Since the piston rings aren't yet machined, the exact bore diameter wasn't important. In order to minimize the lapping effort, however, I was keen on starting out with all the bores nicely finished and as close as possible to an identical diameter.

After parting off the tooling spigots, the parts were marked with unique numbers in preparation for lapping. A worksheet containing a running history of the top and bottom bore measurements was set up so the lapping progress could be tracked for each liner. Although the starting diameters were within a thousandth of one another, each liner had a slight taper running in the wrong direction. 

An Acro barrel lap and 280g Cloverleaf grinding grease was used for all but the final lapping steps. The final pass used 600g grease and removed a negligible amount of metal. A silicone pipe cap was slit open and wrapped around each liner so it could be safely gripped in one hand while the lap was spun by a battery powered drill in my other hand. Drill speed was 200-300 rpm while the part was oscillated over the lap at about 1 Hz.

Bore measurements were made using an inexpensive dial bore gage that had a repeatable resolution on the order of a tenth. After zeroing the gage on an arbitrarily selected liner, plus/minus deviations were recorded after each minute or so of lapping. The liners were thoroughly cleaned with kerosene (the smelly part of the messy process) before being measured.

The tapers were slowly removed by dwelling in the tight end of each liner. After the tapers were removed, all seven liners were carefully brought to the same diameter within the measurement resolution of the gage. Total lapping time worked out to be about four hours with about a thousandth removed from each liner.

The liners were installed with Loctite 620 and the block assembly set aside to cure overnight in my 130F welding rod oven. After an additional 24 hours, the excess uncured adhesive was washed off the liners' exterior walls by pumping solvent into the drilled inlet for the water pump with a syringe.

Before finally facing the deck, I looked at my options for compression ratio. The combustion chamber's shape is fairly complex, but SolidWorks was able to compute its volume. Modeling showed the compression ratio to be 5.7 with no head gasket and 5.4 with a .010" head gasket. I plan to use a .020" head gasket and would like to wind up with a c.r. closer to seven, and so I'll likely increase the heights of the pistons as needed. - Terry


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## propclock (Jun 15, 2021)

Thanks again for sharing . Beautiful.


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## e.picler (Jun 15, 2021)

Hi Terry! Congratulations again!
What component are you using for lapping?

Tks,
Edi


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## Willyb (Jun 15, 2021)

Hi Terry
Wanted to say that I'm very impressed with your project and your attention to detail is just amazing. Thank you for allowing us to follow along with your progress of this project.  Thanks again
Willy


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## petertha (Jun 15, 2021)

mayhugh1 said:


> A Diacro barrel lap and 280g Cloverleaf grinding grease was used....



Is this just a typo and you mean Acro brand lap? 

Re the insert, I've noticed the exact same thing about my CCMTs - sometimes my uncoated 'for aluminum' inserts cut with more uniform surface finish & seem to hold DOC better. They are also Korloy (or so says the Ebay/AliExpress label). I wasn't quite sure if it was absence of typical gold coating for steel alloy or sharper nose radius or maybe rake related to boring specifically. The uncoated don't seem to degrade noticeably faster but are a bit more prone to chipping if you push them as would be expected. I recently bought some 'for stainless' inserts with black coating & selected a smaller radius than normal. I'll get the specs if you are interested. They seem to behave nice on stainless from what I recall making my valves. But now I will give it a go on 1144SP. Part of the mystery is you never really know what you're getting (at least the dark alleys I've been shopping). And probably machine & tool rigidity factors too.


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## mayhugh1 (Jun 15, 2021)

petertha said:


> Is this just a typo and you mean Acro brand lap?
> 
> Re the insert, I've noticed the exact same thing about my CCMTs - sometimes my uncoated 'for aluminum' inserts cut with more uniform surface finish & seem to hold DOC better. They are also Korloy (or so says the Ebay/AliExpress label). I wasn't quite sure if it was absence of typical gold coating for steel alloy or sharper nose radius or maybe rake related to boring specifically. The uncoated don't seem to degrade noticeably faster but are a bit more prone to chipping if you push them as would be expected. I recently bought some 'for stainless' inserts with black coating & selected a smaller radius than normal. I'll get the specs if you are interested. They seem to behave nice on stainless from what I recall making my valves. But now I will give it a go on 1144SP. Part of the mystery is you never really know what you're getting (at least the dark alleys I've been shopping). And probably machine & tool rigidity factors too.


Thanks, you're right. I've corrected it to Acro. 
Those high rake Korloy inserts produce beautiful surface finishes, but they wear quickly on ferrous metals. When I absolutely need to use them on stainless or a tough steel, I'll save the dulled carcass for a later aluminum roughing operation. - Terry


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## mayhugh1 (Jun 15, 2021)

e.picler said:


> Hi Terry! Congratulations again!
> What component are you using for lapping?
> 
> Tks,
> Edi


I'm using an Acro barrel lap and Cloverleaf lapping grease. - Terry


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## mayhugh1 (Jun 25, 2021)

A lot of full-size detail was included on the model's head making it an interesting mini-project of its own. For completeness, George even designed his own 8-40 threaded spark plugs. Fouling became an ongoing issue however, and he recommended I try something larger. I had good results with the Viper VR-1's in my Merlin, and the changes required to fit them in this head were relatively minor. Turning down the end of a 6 mm socket for use as an installation tool minimized the necessary modifications, but the plug depths inside the combustion chambers did have to be corrected.

George machined his head from cast iron and used integral valve seats. Cutting seats directly into a head after it's accumulated tens of hours of machining time seemed too risky to me. Since I also don't like machining cast iron, I elected to use 7075 aluminum and to install pre-tested bronze valve cages.

Machining began with the outside perimeter of the head as well as the drilling and reaming of the numerous holes through its bottom surface. Three coolant passages also run lengthwise through the head and were drilled using Gurling deep hole drills. These small passages were machined by drilling half-way through each end of the workpiece.

The model's coolant system is very similar to the one in the full-size engine. The water pump drives coolant into the front of the block so it can flow sequentially through the water jackets surrounding the cylinders. At the rear of the block, it crosses the head gasket and returns through three lengthwise head passages to the front of the engine and back into the radiator.

The larger two of these passages run through the port side of the head just above the spark plugs and theoretically account for 70% of the return volume. The remaining 30% is handled by a smaller .112" diameter passage that must be snaked through a number of obstacles inside the starboard side of the head.

Looking into the ends of the drilled-through holes, the hole pairs making up the two larger port-side passages appeared to be dead straight and to meet up as expected. However, both holes making up the smaller starboard-side passage appeared to curve downward toward the face that will eventually contain the combustion chambers. The two holes appeared to meet as expected, but their curved trajectories were worrisome since this passage passes within .037" of the yet to be machined combustion chambers.

Next to be machined were the intricate surfaces around the spark plug wells which required a lot of port-side machining time. Since the plugs screw into the head at 39 degree angles, they needed their own machining setup. The bores were drilled and threaded and their mounting surfaces finished in a separate angle block setup to minimize plug leaks.

The pent roof combustion chambers were machined next. It was during this operation that I discovered the troublesome coolant passage had indeed wondered into the space reserved for three of the six combustion chambers. Looking at the depths of the resulting grooves, it was clear the passage had wondered off some .050" from its intended trajectory.

Normally, I'd have scrapped the part and started over. But, I couldn't come up with a drilling technique that I could be sure wouldn't have the same problem. The first inch of those holes were drilled with an almost new jobber length drill and then completed with a brand new (and expensive) Gurling drill designed especially for deep holes. Peck drilling (.1" pecks) was used along with plenty of WD-40 and compressed air for chip control. In addition, the workpiece had been well supported and indicated to the quill.

After a couple days of rationalizing, I managed to convince myself that tiny passage probably wouldn't have flowed its full share of return coolant. And, compared with cast iron, aluminum's 5X thermal conductivity might make up for not having the passage at all.

I eventually decided to continue on with the current workpiece. Two lengths of snug-fitting drill rod augmented with high temperature Loctite were pressed into each end of the wonky passage in order to fill it and to seal the three affected combustion chambers. After a couple days cure, the surfaces inside the combustion chambers were re-machined to blend in the filler rod.

The top-side of the head was machined next and wound up being its own significant project. Although it turned out well, I caught myself not necessarily dreading another error that might force me to scrap the part and start over.

The front end of the block included a raised boss for the coolant return fitting and was machined next. An o-ring'd 90 degree elbow was designed at the same time to insure compatibility, but it will be machined later.

The intake and exhaust manifolds will eventually attached to the head's starboard side. Their ports will be drilled after the valve cages are installed. - Terry


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## mayhugh1 (Jun 25, 2021)

More Photos ...


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## gbritnell (Jun 25, 2021)

Terry,
An absolute thing of beauty! You did the head proud! When making complex parts I always start to pucker when I have many hours spent and get to the final operations knowing that at any minute disaster could happen. 
gbritnell


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## johnmcc69 (Jun 25, 2021)

Incredible detail all around!
Hats off to both of you & George for your wonderful design & build skills!

John


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## Willyb (Jun 26, 2021)

Absolutely amazing work Terry. It's going to be a winner. 
Cheers
Willy


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## kvom (Jun 26, 2021)

Do you put screws in the threaded holes before bead blasting?


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## propclock (Jun 26, 2021)

That is beautiful. It needs a clear lexan valve cover IMO. 
Thanks as always for sharing .


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## mayhugh1 (Jun 26, 2021)

kvom said:


> Do you put screws in the threaded holes before bead blasting?


Yes, and silicone plugs in the coolant passages also. - Terry


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## mayhugh1 (Jul 1, 2021)

The model's rocker cover is pretty similar to the drawn steel original but was machined from a block of 6061 aluminum. A significant difference between them is the original cover attached to the head with seven hex bolts around its perimeter, while the model's cover will be held down with three centrally located studs.

I'd been looking forward to the rocker cover because it was a perfect opportunity to use a new-to-me engraving operation in my CAM software. I've engraved lots of parts using a general purpose 2-d contouring operation to guide a v-cutter over simple stroke fonts. But Sprutcam has a dedicated operation capable of raising or lowering any Windows font using a variety of wall styles.

I hoped to machine the 'powered by Ford' logo that I remembered being in the top of my project truck's rocker cover. But after spending hours working around the cover's filler cap and mounting holes with different fonts, sizes, and spacings, I settled on just 'Ford'.

After a few practice engravings, the cover's exterior machining was pretty straight forward, although its curvy exterior left me with a work-holding problem for the machining of its interior. A wood form, band-sawed with a matching contour, helped spread the clamping forces over the cover's thin (.063") walls. Internal notches were added to the starboard inside edge for additional clearance to the ends of the rocker arms. A pair of 3/64" dowel pins were also added to the head to positively locate the cover.

The cover was painted with Gun Kote's metallic blue - a shade somewhere in between Ford's light and dark blues. Gun Kote is a durable bake-on (325F) resin-based coating that's resistant to gas, oil, and most solvents around my shop. I've used it on small areas on some of my other model engines. With a typical air brushed thickness less than .0005", it typically isn't necessary to mask off tapped holes (except spark plug bores). I only recently discovered the Kote has become available in colors other than black, gray and drab olive.

I originally planned to paint only the rocker cover and then bead blast it away if I didn't like the result. After a few days I was still happy with the cover, and the novelty of a realistically colored engine grew on me, and so I painted the whole thing. - Terry


----------



## petertha (Jul 1, 2021)

_The cover was painted with Gun Kote's metallic blue - a shade somewhere in between Ford's light and dark blues. Gun Kote is a durable bake-on (325F) resin-based coating that's resistant to gas, oil, and most solvents around my shop.  _

Aw, Terry you nailed it. Looks so good! 
I've never used the product but been eyeing it. Just to confirm, did you use the rattle can? And pretty much followed the heat temp/time guidelines?






						Bake-On Aerosol Paints | Paint Finishes at Brownells
					

Brownells is your source for Bake-On Aerosol Paints,Paint Finishes at Brownells parts and accessories. Shop our vast selection and save!



					www.brownells.com


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## mayhugh1 (Jul 1, 2021)

petertha said:


> _The cover was painted with Gun Kote's metallic blue - a shade somewhere in between Ford's light and dark blues. Gun Kote is a durable bake-on (325F) resin-based coating that's resistant to gas, oil, and most solvents around my shop.  _
> 
> Aw, Terry you nailed it. Looks so good!
> I've never used the product but been eyeing it. Just to confirm, did you use the rattle can? And pretty much followed the heat temp/time guidelines?
> ...


Peter,
I've used the rattle can version in the past but have since switched to air brushing. The coating thickness is more easily controlled, runs are less of a problem, and the cans sometime 'spit' out paint and ruin the finish. There are also only a few colors available in rattle can and they're hard to find. I haven't been able to get it (the rattle can version) from Eastwood for a long time now. The manufacturer recommends Alodining aluminum if bead blasting isn't possible, but I've never used it with Alodine. I follow the baking recommendations on their label- one full hour at 325F. I've never had a problem with it chipping or lifting, and it's certainly seen it share of gasoline, oil, and Wd-40 around my shop. A few parts on my motorcycle still look as good as they did when they were painted in 2000. Gun Kote is now also available thru Amazon:



			Amazon.com : gun kote 2500
		


Terry


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## Jones (Jul 1, 2021)

Wow! That before and after blasting pics of the valve cover lettering really show how much of a difference that process makes to the appearance of the parts.

I am following along very closely as I'm currently part way through building a CNC router and have aspirations to use it to make some cool engine parts. You're doing an amazing job on the engine!

Have you thought about maybe sanding the paint off the FORD lettering on a flat surface? Just a thought, could look pretty nice. I remember doing it to a Mazda I used to have.


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## petertha (Jul 2, 2021)

Terry, are you reducing the Gun Kote or straight out of the airbrush?

Your Amazon link had 2500 in it - is this (KG) the parent company do you happen to know?





						KG Industries Products - 4GT.com
					






					www.4gt.ca


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## mayhugh1 (Jul 2, 2021)

petertha said:


> Terry, are you reducing the Gun Kote or straight out of the airbrush?
> 
> Your Amazon link had 2500 in it - is this (KG) the parent company do you happen to know?
> 
> ...


It comes pre-thinned for spraying, and that's the way I've been using it. I think KG is the parent company, and I'm fairly sure they used to re-label their product for Eastwood. Google 'Gun Kote'


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## a41capt (Jul 2, 2021)

mayhugh1 said:


> The model's rocker cover is pretty similar to the drawn steel original but was machined from a block of 6061 aluminum. A significant difference between them is the original cover attached to the head with seven hex bolts around its perimeter, while the model's cover will be held down with three centrally located studs.
> 
> I'd been looking forward to the rocker cover because it was a perfect opportunity to use a new-to-me engraving operation in my CAM software. I've engraved lots of parts using a general purpose 2-d contouring operation to guide a v-cutter over simple stroke fonts. But Sprutcam has a dedicated operation capable of raising or lowering any Windows font using a variety of wall styles.
> 
> ...


Man, I’m REALLY looking forward to your video of it running. That’s downright fantastic looking!


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## mayhugh1 (Jul 10, 2021)

The poly lock rockers in the model's valve train are a deviation from the single shaft rocker assembly used in the actual engine. Scaling probably squeezed out the shaft supports, and the cover's hold-down studs wound up in their place.

I'm looking forward to machining the rocker arm bodies, but each one requires another five nuisance parts to function. These tiny parts not only require careful machining and multiple setups, but they're the kinds of parts that tend to go missing in the shop. I decided to tackle them first and save the rocker arms as carrots to help get me through the miserable parts.

For starters, the rocker posts were machined from 3/16" drill rod. Each end was drilled and tapped for 2-56 Loctited studs and a hex was machined around their bottom ends. The hold-down studs for the rocker cover are similar and were machined using the same setups.

The rocker shafts were machined from the same rod stock. The first operation was a radial thru-hole for the post. After several tries, I had a production setup on the mill that consistently drilled and reamed the hole through the part's center. A center-drilled milled flat was necessary to start the hole. This flat also became the final contact surface for the poly-lock nut.

After parting off the semi-finished shafts, their ends were finished with a v-drill and blued. These cosmetic touches seemed like a good idea at the time, but they added a lot of extra work for little improvement in appearance.

The poly lock nuts were machined and cold blued to look like the after-market nuts I've seen on full-size engines. The rocker arms rotate on the rocker shafts which are located the rocker studs. Lash is adjusted by turning the nut against the flat on the rocker shaft which sets the clearance of the rocker to the end of the valve stem. The 'poly lock' moniker comes from the grub screw in the top of the nut that locks in this adjustment.

After being drilled and reamed for their shafts, the rocker arm rollers were parted from a length of 5/32" drill rod. The shafts will be modified 1/16" dowel pins once the final lengths are determined - Terry


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## dsage (Jul 11, 2021)

x10  ??

Wonderful work - as usual. Thanks


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## mayhugh1 (Jul 11, 2021)

dsage said:


> x10  ??
> 
> Wonderful work - as usual. Thanks


I meant 'x10 magnification' ...


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## mayhugh1 (Jul 17, 2021)

The clearance slots added to the inside of the valve cover allowed some freedom to modify the rocker arm design. My goal was to end up with realistic looking rockers that could be machined in cookie sheet batches. Since there's no top end oil source, I used 7075 for its hardness and wear resistance. Three batches of six rockers were started with the hope of winding up with some spares that could be used to experiment with colored final finishes.

The full shapes of all six rocker bodies, down to their approximate half thicknesses, were machined through the top face of the workpiece. Using a syringe, the troughs left around them were filled with Devcon (flowable) 5-minute epoxy. After an overnight cure, the adhesive kept the parts temporarily attached to the workpiece while their machining was completed through the opposite face of the workpiece. The parts were easily removed after an hour bake at 325F. Stubborn bits of adhesive were easily scraped off the still-hot parts using a sliver of wood.

Machine backlash, tool measurement errors, and edge finder inconsistencies invariably combine to leave seams between oppositely faced machining operations that can add a lot of work to tiny parts. Extra care was taken when setting the work offsets, and the same workpiece corner was used for each pair of operations. I got lucky, and the rockers' seams were on the order of only a thousandth and vanished with bead blasting.

Once freed from their workpieces, the parts were clamped one at a time in a shop-made fixture for the three remaining secondary operations: 1) a hemispherical cavity for the pushrod, 2) a clearance slot for the poly-lock nut, and 3) a clearance notch for the roller.
In order to hold onto the completed rocker arms during bead blasting, I made up some 'lollipop' sticks to protect the two shaft bores from the glass grit. I originally planned to gold anodize the finished parts, but reconsidered after thinking about the problems I'd have to overcome in getting reliable electrical connections to the parts without affecting their finished bores.

Instead, I decided to Alodine them which I hoped would leave leave a similar colored finish. Alodine is used on aluminum as a paint primer or, by itself, as a salt-spray resistant coating. The 'good stuff' is hard to find nowadays because of its chromium health risk, but I was able to purchase a reasonable facsimile from Amazon:






						Amazon.com: Henkel - Alodine 1201 Light Metals Conversion Coating / Bonderite M-CR, Quart : Automotive
					

Buy Henkel - Alodine 1201 Light Metals Conversion Coating / Bonderite M-CR, Quart on Amazon.com ✓ FREE SHIPPING on qualified orders



					www.amazon.com
				




After bead blasting, the lollipop'd rocker arms were dipped in NaOH (drain cleaner) for a fifteen second final cleaning, rinsed in water, and then immediately immersed in the Alodine. The 6061 parts I've coated in the past turned golden bronze in just a few minutes, but the zinc in 7075 greatly slowed the process, and the parts came out gray-green. One of the photos shows the colors obtained on test parts after a half hour and two hours in Alodine. I'd have been happier with the half hour test color, but my batch results were inconsistent, and I had to settle for 'army green'. - Terry


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## Eccentric (Jul 17, 2021)

Looks great Terry, 

yep, Alodine 1201 is the same stuff we use in the experimental aircraft community. I get mine here:








						Bonderite M-Cr 1201 Aero (Formerly Alodine 1201) | Aircraft Spruce
					

Bonderite M-Cr 1201 Aero (Formerly Alodine 1201) After precleaning with BONDERITE C-IC 33 AERO, rinse with water. Apply Alodine without dilution by brushing or swabbing with sponge. Rinse with water and surface is ready for paint. This is a




					www.aircraftspruce.com
				




I use alumiprep to remove all aluminim oxide prior to treatment, but this might also impact your nicely finished bores.


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## Vietti (Jul 17, 2021)

How did you protect the bores?

John


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## mayhugh1 (Jul 17, 2021)

Vietti said:


> How did you protect the bores?
> 
> John


See the fifth photo from the top...


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## joerom (Jul 17, 2021)

It seems a shame to put paint on all that beautiful work...That is incredible......................


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## mayhugh1 (Jul 18, 2021)

joerom said:


> It seems a shame to put paint on all that beautiful work...That is incredible......................


Alodine really isn't a paint. Think of it more as being a chemical stain or metal dye.


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## mayhugh1 (Jul 24, 2021)

The drawings call for machining the valve seats directly into the head. This isn't something I normally do, and I didn't want my first attempt to be on a head with so much machining time. Another consideration was that the seats which sit below the surface of the head are so close to the edges of the combustion chambers that none of my seat cutters will fit.

Converting the head to use valve cages wasn't difficult, but did create extra work. Before installing the cages, their seats were manually cut using a piloted seat cutter and then leak checked. Since the intakes are larger than the exhausts, two different size cages were needed. All were machined from 544 phosphorous bronze.

The cages were turned .0015" under their bores in the head for slip fits augmented with 620 Loctite. Five separate operations in a single lathe setup were used to machine their interiors. To begin, a 3/16" 60 degree carbide v-mill was plunged into the end of the blank to rough out the cage's interior and spot drill its guide bore. The guide bore was drilled and reamed after facing the cage to its final length. Finally, a tiny boring bar was used to finish the cage's i.d. and sculpt a filleted port transition

For seat cutters I typically use piloted 45 degree chamber reamers available from Brownells. A shop-made pilot was required to accommodate the tiny valve stem diameters (.093", increased from .078"). The cutter's final TIR measured .0007", but trial seats cut into a few scrap cages appeared to be perfectly uniform under a microscope.

A pair of leak-check valves was then machined to test the cages before they were installed. These test valves were turned using a portion of the code developed for the actual valves which will be turned later on my little Wabeco CNC lathe. Although dimensions can be challenging, it's not at all difficult to turn a valve's key features precisely concentric and end up with brilliantly polished seating surfaces that don't leak. It's been my experience that pristine valves directly off a lathe seldom if ever leak.

The seats, however, are another matter. Even on a lathe, it's more difficult than one might expect to drill a guide bore precisely concentric with a turned seat. A piloted manual seat cutter solves this problem, but it can leave microscopic scratches behind that affect the seal.

These scratches can be easily polished away without lapping the seats to their valves. Typical automotive lapping compounds are too coarse, and they embed into the bronze alloys typically used for model engine valve seats. Combined with poor lapping techniques, an otherwise perfect valve can be quickly destroyed.

After installation, the valves will be checked by pulling vacuums behind them through their associated ports and measuring their leak-down times. I consider a 10-15 second leak-down time measured from 25 inHg to 15 inHg on a Mityvac to be a 'pass'. 

The standalone cages were tested with a Mityvac drawing a vacuum through the rear of the cage with the test valve held in place with thumb pressure. A tiny flat milled along the length of the test valve's stem provided the evacuation path.

The measured leak-down times on the uncut seats of valves directly off the lathe were on the order of five seconds which might be good enough to get a multi-cylinder engine started. (Seat seals typically improve in a running engine due the explosive forming effects of combustion.) After cutting a .005" to .007" wide seat with the seat cutter, the leak-down times improved to 10-15 seconds. Only the weight of the cutter was used to apply the cutting force, and the cutter was blown free of chips and lubed with WD-40 before each use.

The leak-down times were typically extended to 25-30 seconds by polishing the seats for 10-15 seconds with extra-fine Timesaver. The Timesaver was mixed with oil and applied using a felt bob rotated by hand. A final 10 second polishing with red rouge on a second felt bob typically extended the time another 5-10 seconds. The final leak-downs ranged from 30-45 seconds. Considering the much smaller volumes of these cages, these leak-down times were comparable to some of my previously best results. - Terry


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## mayhugh1 (Jul 30, 2021)

After the Loctite was allowed to cure for a few days, the intake and exhaust ports on the starboard side of the head were drilled and reamed. I tried to not raise burrs inside the cages that might later break free and wind up in the seats, but I ended up with a few anyway. Working through the mouths of the cages with a rifling file would have risked damage to the seats, so I removed them through the ports with a dental pick. The leak-down measurements were repeated to verify the cages hadn't been distorted by drilling nor a seat scratched by the chips. With the test valve in place, the guides were capped and the vacuums pulled through the ports.

I've never cared for the full-size engine's manifold arrangement. The alternating side-by-side intake and exhaust manifold flanges share several of the same mounting bolts. The head bolt clamping forces are divided between the flanges so long as they're exactly the same thickness. When I rebuilt my truck engine, I replaced a leaky cast iron exhaust manifold with a new tubular header but could never get it entirely leak free.

Even with a gasket it will be asking a lot from the model's 2-56 manifold bolts to seal both manifolds, and so a set of thin-wall steel port liners was machined and Loctited inside the ports. The outside ends will slip inside the manifolds and hopefully reduce their tendency to leak. The inside ends were shaped with a Dremel grinder for smooth transitions into the cages. As a bonus, the cages are positively locked inside the head.

Using the spring parameters provided in one of the drawings, I estimated the spring rate to be 8.5 lbs/in and the seat force to be about 1.25 pounds. I attempted to duplicate the seat pressures with a set of springs wound with some .024" diameter stainless steel wire (saltwater fishing leader) that I had on hand. Six active turns around a .190" mandrel resulted in a spring with a .275" o.d. and a .6" length. The wound springs were normalized at 400F for an hour before being tumbled overnight in walnut shells and red rouge. The measured spring rate was 4.5 lbs/in, and the estimated seat force was 1.2 lbs.

A set of spring retainers were machined from 12L14 and cold blued. Commercial e-clips, used as valve locks, will establish the final spring heights and seat pressures. I also added a set of spring cups to keep the springs centered around the guides.

I used my current assembly model to machine a first article valve to verify the seat pressure and to check for clearances and proper operation with the finished valve train components. Minor adjustments to the stem's length and lock groove location were noted for the production valves. The actual seat force measured 1.4 lbs, and yet another leak-down measurement taken. The next step is to machine all the valves and wrap up the head assembly. - Terry


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## Vietti (Jul 30, 2021)

Wonderful work as usual!

I bought one of those muzzle crowning chamfer tools from Brownells.  My valve cages are 1/2" od and 7/16 id.  When I try to use the the tool, holding both the cage and tool in my hands I get a lot of chatter and gnarly looking seats.  What is the recommended method to prevent this?

Thanks, John


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## mayhugh1 (Jul 30, 2021)

Vietti said:


> Wonderful work as usual!
> 
> I bought one of those muzzle crowning chamfer tools from Brownells.  My valve cages are 1/2" od and 7/16 id.  When I try to use the the tool, holding both the cage and tool in my hands I get a lot of chatter and gnarly looking seats.  What is the recommended method to prevent this?
> 
> Thanks, John


I hold the cage, mouth up, in my left hand and then insert the cutter into the cage with my right hand. I just let the weight of the cutter exert all the cutting force while I spin the cutter with my right hand. I use a cutting lubricant, usually cutting oil. This time I used WD-40 which I don't think worked quite as well. It's important to blow the chips out of the cutter's flutes before each use so a chip doesn't get wedged between the cutter and cage and gouge the seat. 

 Don't push on the cutter, you're just trying to put a very tiny seat on the inside edge of the seat. You may be pressing too hard and causing the cutter to dig in. - Terry


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## Vietti (Jul 31, 2021)

Thanks, I'll try that, really like the concept!  John


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## mayhugh1 (Jul 31, 2021)

Vietti said:


> Thanks, I'll try that, really like the concept!  John


I like to think of it as a pressure equalization. When you first start out, the cutter is resting on the 90 degree corner of the cage. Although the cutter weighs only a few ounces, the pressure (lbs per sq inch) is very high. The cutter is driven by gravity into the cage and shears metal away to form a uniform seat as you spin the cutter with your fingers without applying any force (or pressure) of your own. The width of the resulting seat is dependent upon a couple metallurgical properties of the metal which for 544 bronze happens to come out to .005" to .007". This seat width is the point where the resulting pressure of the cage pushing back on the cutter equals that of the cutter acting under gravity alone. The cutter stops shearing metal from the seat under  gravity alone, and this is where I stop.

You can make a wider seat if for some reason you think you have to, but it will be you to continue applying the required additional uniform pressure while spinning the cutter. If you slip up, you may go too deep and things can get difficult if you can't judge the correct force before you end up with a uniformly wider seat. If, as you try to even things out, you gouge it again in a different spot, you'll pretty soon start to feel what seems to be a 'rough' surface.

Although many feel that .005" just isn't wide enough especially compared with the seat on a full size valve, it is wide enough to seal, and the area containing the cutter scratches you can polish out for perfection is small. Once inside a running engine this pressure equalization thing starts all over again. This time the valve is beaten into the seat by the explosive forces of combustion. The area of the seat again starts to widen until the pressures are finally again equalized. However, it's now the high temperature metallurgical properties of the metal that become important in determining the final width of the seat. It's for this reason I use phosphor bronze whose properties are specified at combustion type temperatures. More commonly available (and softer) bearing bronze isn't specified for use at high temperatures although it's sometimes used. If, over time, the lash clearances continue to increase, the valve could be receding because of a wrong choice for the seat material. - Terry


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## CFLBob (Jul 31, 2021)

mayhugh1 said:


> which for 544 bronze happens to be .005" to .005"


???

.005 to .006"?


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## mayhugh1 (Jul 31, 2021)

CFLBob said:


> ???
> 
> .005 to .006"?


oops... I meant .005" to .007". I edited my original post. I guess people are actually reading my texts after all. Thanks. - Terry


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## Vietti (Jul 31, 2021)

Terry,
I think part of my problem is I used 303 or soft brass for the cages, cutter may dig in more than with your 544.  This is a hit and miss engine and the plans show the valve seating on the aluminum head casting so I may be slightly better off than that.

Thanks for the help!  John


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## stevehuckss396 (Aug 1, 2021)

Oh believe me, we are reading your posts. I read and enjoy every single time you post and also enjoy every picture. I should probably chime in more but, don't take it as a sign that I no interest because that is far from reality.  Keep up the the high quality posts. Believe me when I tell you that they are read and highly appreciated.


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## geo (Aug 1, 2021)

Ditto Steve Hucks it’s a bit above my pay grade to reply Terry.
An article you wrote on gear manufacture saved me lot of frustration with the Howell v twin your work is much appreciated.


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## gbritnell (Aug 2, 2021)

Hi Terry,
For me your posts are like a great book. I just can't wait to read further to see what's going to happen! I think the running changes you're making really compliment the engine.
gbritnell


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## a41capt (Aug 2, 2021)

Me too, especially these past two weeks while stuck in bed with Covid!

John W


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## mayhugh1 (Aug 3, 2021)

The valves were machined from 3/8" diameter 303 stainless on my little Wabeco CNC lathe without using the tailstock. For coding purposes, they were divided into five overlapping zones, each about .2 inches long. Five g-code programs, each capable of fully machining a valve inside just one of the zones were compiled and combined into a single operation. Machining began at the stem end and, with less than .2 inch stick-out, part deflection wasn't an issue. Since it wasn't necessary to reposition the workpiece in the chuck during machining, all the valve's features came out precisely concentric. A small downside to this technique was the numerous non-cutting movements at the zone boundaries more than doubled the valve's machining time. But, the 20 minute operations ran hands-off, and the long unwieldy stems came out virtually perfect.

Excess stocks of .001" were left on the stems for final polishing with 600g paper. A spare valve cage repurposed as a go-no-go gage verified the final fits while the parts were still on the lathe. The stem's upper end has to pass through its guide during assembly, but during operation there's no contact. This portion of the stem was turned three thousandths under for a later helpful clearance inside a shop-made collet. This collet was used to hold the valve for two secondary operations: 1) facing the valve's head after band sawing the valve free of the workpiece, and 2) turning the stem's lock groove.

Leak-down measurements were repeated one last time on the fully assembled valve train. Vacuums were pulled through the port liners, but stoppering the valve stem leakages with the springs installed wasn't practical. The dry stem leak-down times were on the order of 15 seconds, but with oil dropper'd on them through the springs they typically improved to 20-30 seconds. - Terry


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## ajoeiam (Aug 4, 2021)

mayhugh1 said:


> The valves were machined from 3/8" diameter 303 stainless on my little Wabeco CNC lathe without using the tailstock. For coding purposes, they were divided into five overlapping zones, each about .2 inches long. Five g-code programs, each capable of fully machining a valve inside just one of the zones were compiled and combined into a single operation. Machining began at the stem end and, with less than .2 inch stick-out, part deflection wasn't an issue. Since it wasn't necessary to reposition the workpiece in the chuck during machining, all the valve's features came out precisely concentric. A small downside to this technique was the numerous non-cutting movements at the zone boundaries more than doubled the valve's machining time. But, the 20 minute operations ran hands-off, and the long unwieldy stems came out virtually perfect.
> 
> Excess stocks of .001" were left on the stems for final polishing with 600g paper. A spare valve cage repurposed as a go-no-go gage verified the final fits while the parts were still on the lathe. The stem's upper end has to pass through its guide during assembly, but during operation there's no contact. This portion of the stem was turned three thousandths under for a later helpful clearance inside a shop-made collet. This collet was used to hold the valve for two secondary operations: 1) facing the valve's head after band sawing the valve free of the workpiece, and 2) turning the stem's lock groove.
> 
> ...



Hmmmmmmmmmm - - - - I 'like' the way you work!!


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## CFLBob (Aug 4, 2021)

I'm curious about why the valves change diameter, but I love the way you did it.  

I built a CNC lathe for threading back at the end of '18 and haven't used it for much.  I think I want to copy your approach!


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## ozzie46 (Aug 4, 2021)

Looks fantastic as always Terry.

Ron


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## stevehuckss396 (Aug 4, 2021)

The diameter change is the part of the stem that is in the valve cage. Reducing the stem in that area allows more room for fuel to flow into the cylinder.


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## propclock (Aug 8, 2021)

Thank You. Just Thank You. Somehow  I missed page 7  previously.
It made for a wonderful Sunday morning read. 
I think valve seats are the biggest hurdle for the beginner  .


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## mayhugh1 (Aug 13, 2021)

While continuing to procrastinate over the 90 degree helical gear set needed in the block for the distributor, I decided to start work on the manifolds. Since I also haven't yet decided between the stock cast iron (looking) exhaust manifold and a nostalgic (for me) tubular header, the easier to make intake manifold was tackled first.

Work began with the .020" Teflon flange gasket. Its design was derived from the manifold's CAM model and used to sanity check the protruding ports and flange mounting hole locations on the head. A 6061 workpiece was then prepared with plenty of excess stock around what would become the finished manifold. After planning its location inside the workpiece, the manifold's port passages were pre-drilled and reamed. The much longer passage connecting the runners to the carburetor mount had to be drilled through the entire seven inch workpiece. Its ends were sealed with Loctited aluminum plugs that were also pinned for good measure. The pins and plugs were blended invisibly into the manifold during its machining.

The workpiece was then moved to the Tormach where the manifold began to take shape as it was machined through the two opposite faces of the workpiece. The trough left around the semi-finished part after working through the first face was filled with Devcon 5 minute epoxy. Self-sticking (red) paper labels were used to keep the epoxy out of the exposed passages. The operations through the opposite face of the workpiece left the nearly finished manifold attached to the workpiece by only the epoxy.

The workpiece (and epoxy) at the flange end of the manifold were machined away before drilling the flange mounting holes. The engine's split manifold design requires truly flat mounting surfaces under the heads of the 2-56 SHCS's that will secure the manifold to the block. Half of these bolts pass through generous fillets left around the runners for a more realistic 'casting' look. The difficult access to these fillets required a tiny shop-made piloted counterbore to create the flats. Machined and hardened from drill rod, the tool was slotted and manually used with a screwdriver.

After completing the counterbores, the mounting flanges were finish machined, and the manifold's fit over the head's port liners could be finally verified. Remarkably, all the mounting hole locations lined up perfectly, and the snug sliding fit probably wouldn't even need the gasket. After a 275F oven bake, the epoxy released the finished manifold from the remaining workpiece.

After temporarily plugging the ports with rubber stoppers, the manifold's surface was glass beaded. Although I'm pretty sure Ford painted the original cast iron manifolds, I'll probably leave leave my 'after market' aluminum version unpainted. - Terry


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## CFLBob (Aug 13, 2021)

Beautiful work, as always.  

When you've got a minute, I've got to say I've never seen the use of epoxy like you're doing here.  What does that do?  Does it add strength to help it resist the machining forces from the other side, or is it cosmetic?


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## kvom (Aug 13, 2021)

CFLBob said:


> Beautiful work, as always.
> 
> When you've got a minute, I've got to say I've never seen the use of epoxy like you're doing here.  What does that do?  Does it add strength to help it resist the machining forces from the other side, or is it cosmetic?



I've leaned this from Terry;  allows all the surrounding bottom stock to milled away while holding the finished part, which would otherwise remain unsupported.  Then the part is released by heating,


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## mayhugh1 (Aug 13, 2021)

CFLBob said:


> Beautiful work, as always.
> 
> When you've got a minute, I've got to say I've never seen the use of epoxy like you're doing here.  What does that do?  Does it add strength to help it resist the machining forces from the other side, or is it cosmetic?


Bob,
It's just like kvom said. The Devcon keeps the already machined side of the part connected to the workpiece so the other side can also be machined free of it while still being held in place. A strong epoxy is needed, but also one that gives up at a reasonable temperature. JB Weld continues to hold on at temperatures that are too high to be useful and isn't useful in this application. Devcon 5 minute epoxy used to give up at a much lower temperature, and I could get it to release with a heat gun. I think they changed their recipe a few years ago, and now an oven bake is needed. I may try one of the high temp glue sticks. The low temp stuff might melt under the heat of some machining operations without sufficient coolant. - Terry


----------



## CFLBob (Aug 13, 2021)

mayhugh1 said:


> Bob,
> It's just like kvom said. The Devcon keeps the already machined side of the part connected to the workpiece so the other side can also be machined free of it while still being held in place. A strong epoxy is needed, but also one that gives up at a reasonable temperature. JB Weld continues to hold on at temperatures that are too high to be useful and isn't useful in this application. Devcon 5 minute epoxy used to give up at a much lower temperature, and I could get it to release with a heat gun. I think they changed their recipe a few years ago, and now an oven bake is needed. I may try one of the high temp glue sticks. The low temp stuff might melt under the heat of some machining operations without sufficient coolant. - Terry



Thanks Terry and kvom.  I didn't have a good mental picture of what was being cut away and what would happen to it.  I see you're cutting away all the aluminum holding those branches of manifold in place and I can imagine those pieces moving enough to get some irregular marks on the pieces.  Or worse.


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## Steamchick (Aug 14, 2021)

Clever! Sounds a bit like "lost-wax" casting work, but in a machining context. New to me, but I'm sure I'll find a use for this process. You can buy hot melt resin - a friend has some for pipe bending - that may work and be re-usable, being hot-melt. Or lead can be used I guess?
K2


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## mayhugh1 (Aug 22, 2021)

I decided on a stock-looking exhaust manifold rather than fabricating a tubular header. Although the full-size castings evolved over their production life, there were two basic varieties of exhaust manifolds used on the Ford 300. George's design is based upon the most common one which used a 2" exhaust flange exiting the heat riser at about 45 degrees. A less common heavy-duty version was used on one-ton trucks and had a 2-1/2" exhaust flange pointing nearly straight down. The heavy duty manifold was popular among performance enthusiasts not only for its freer flow but its better compatibility with aftermarket turbochargers.

My scaled-down manifold is based upon the heavy-duty version although I took liberties with its design to keep its machining reasonable. If accurately scaled, the tiny cutters required for its cooling ribs would have required an inordinate amount of machining time. I also left the exhaust flange as an add-on.

Work began with the preparation of a suitable 6061 workpiece. After planning its location inside the oversize workpiece, the manifold's numerous internal passages were drilled and reamed through the outside faces of the workpiece. Plunged ball cutters were used to blend the 90 degree corners for a smooth exhaust flow.

Precisely cut aluminum plugs inserted through the faces of the workpiece sealed the passages at what will eventually become the exterior surfaces of the manifold. These aluminum plugs were bonded with high temperature 620 Loctite and cross-pinned for good measure with TIG rod. The aluminum plugs and pins should be invisibly blended into the surfaces of the manifold during its machining. 
In Loctite jargon, aluminum is an inactive metal, and so primer was used on both the plugs and pins. Unlike paint, Loctite bonds only to bare metal, and its primers are just copper salts suspended in a volatile solvent. These primers are intended to leave metal ions on the bare surface of at least one of the metals in a bonded pair in order to kick-off the curing process in a timely manner.

The next step will be to finally begin the manifold's machining. - Terry


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## a41capt (Aug 22, 2021)

mayhugh1 said:


> I decided on a stock-looking exhaust manifold rather than fabricating a tubular header. Although the full-size castings evolved over their production life, there were two basic varieties of exhaust manifolds used on the Ford 300. George's design is based upon the most common one which used a 2" exhaust flange exiting the heat riser at about 45 degrees. A less common heavy-duty version was used on one-ton trucks and had a 2-1/2" exhaust flange pointing nearly straight down. The heavy duty manifold was popular among performance enthusiasts not only for its freer flow but its better compatibility with aftermarket turbochargers.
> 
> My scaled-down manifold is based upon the heavy-duty version although I took liberties with its design to keep its machining reasonable. If accurately scaled, the tiny cutters required for its cooling ribs would have required an inordinate amount of machining time. I also left the exhaust flange as an add-on.
> 
> ...


Boy, that’s gonna leave one hell of a mountain of swarf!  I can’t wait to see the finished manifold, your CAD drawing looks amazing.

John W


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## Thommo (Aug 23, 2021)

G’day from Oz. I must say Mayhugh1, I’m loving this project. When I was a kid, iE 7, my Mum, Dad and I traveled around Australia in an F100 and caravan. The F100 had a 300ci 6 cylinder and a four speed box. That beast was loaded up with everything that we owned in a big cage that went up and over the cab. We traveled a lot of miles in the old girl from 1974-1980 and she didn’t miss a beat. Imho those engines were some of the very best made by Ford. I’m really looking forward to seeing and hearing your engine when she finally fires up. Fantastic work!


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## kvom (Aug 23, 2021)

What material(s) for the pins and plugs?


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## mayhugh1 (Aug 23, 2021)

kvom said:


> What material(s) for the pins and plugs?


Aluminum...


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## mayhugh1 (Aug 30, 2021)

The exhaust manifold's machining steps were similar to those used on the intake manifold. Differences in its size and shape, though, made things a little more challenging and at times confusing. As the exhaust manifold took shape, it would have become more and more difficult to fixture it as a standalone part. So, unlike the intake manifold, all its machining was done through five faces of the workpiece. The manifold wasn't released from the workpiece until all its machining was completed.

The manifold's ribbed outer surface was machined first. Since the top surfaces of all six runners were also accessible in the same setup, they were machined as well. A long stick-out 1/4" end mill was used for roughing, but the filleted surfaces were finished with smaller diameter ball mills. Special long reach 1/16" cutters running on a high speed 5-axis machine would have been needed to finish a faithfully scaled manifold. Mine was designed around an 1/8" ball cutter running on a Tormach.

Chatter from the long roughing tool was so annoying that I'd normally have left the shop while it was running. As luck would have it though, my Micro-drop coolant dispenser died shortly after starting, and I had to manually spray coolant and blow away chips during the entire two hour run. Fortunately, surface finish wasn't an issue since the operation was set up to leave .007" excess stock for the finishing tools. Total machining time through the first face of the workpiece was about five hours.

The trough left around the semifinished part in the first setup was filled with Devcon 5 minute epoxy in order to keep the part safely suspended inside the workpiece for the rest of its machining. The runners were designed so the counterbore locations needed for the mounting bolt heads would be accessible in this same setup so the special tool used on the intake manifold wouldn't be needed. Their exact depth was critical for the shared mounting bolt scheme used by Ford to attach the manifolds to the head. These were plunge milled once the epoxy had cured.

The manifold's much simpler rear surface was machined in the second setup. This step left the semi-finished manifold securely suspended inside the workpiece by only the epoxy. The mounting flanges and bolt holes were completed in the third setup.

The filleted surfaces immediately below the runners were machined through the fourth face of the workpiece using a long reach ball cutter. This simple finishing operation was done on my Enco mill so I could continually adjust the tool's feed rate and minimize chatter. A portion of the workpiece had to be milled away in order to get the spindle as close as possible to the runners for minimum tool stick-out.

The heat riser cavity was opened up in the fifth and final setup. Another chunk of workpiece had to removed for its access. A mounting recess, machined for the add-on exhaust pipe flange, was shaped to avoid any awkward intersections with the embedded pins and plugs in this rather busy area. The manifold's total machining time worked out to about ten hours.

During the original preparation of the workpiece, I decided on aluminum pins to backup the Loctite'd plugs used to block off the ends of the numerous internal passages. After noticing a black spot that showed up during the heat riser's machining, I thought one of the pins had not been inserted far enough. The spot turned out to be a steel pin that had been mistakenly used in this particular location.

A trial fit of both manifolds to the head without the use of the flange gasket showed the mounting screws shared between them appeared clamp both flanges equally. The flange thicknesses may be fine tuned later after more careful measurements. Both water and compressed air were used to sanity check the continuity of the exhaust passages through the heat riser.

The extended exhaust pipe flange was machined from 12L14 and permanently attached to the bottom of the heat riser. In addition to a pair of mounting screws, the mating surfaces were coated with Loctite 620 for a sealed bond which should stand up to the engine's exhaust heat.

After temporarily plugging all its openings, the entire manifold assembly was glass beaded to give its surface a cast iron appearance. However, the aluminum's natural color is wrong for an iron manifold. I have some POR-15 dark gray paint intended for exhaust manifolds, but it's gotten pretty thick over the years. I've ordered the special solvent this paint requires, and after some testing I may air brush the manifold with it.- Terry


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## mayhugh1 (Aug 30, 2021)

More Photos ...


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## gbritnell (Aug 30, 2021)

Just another Wow from me. Great work Mr. Mayhugh!


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## CFLBob (Aug 30, 2021)

Just gorgeous work.  

You're convincing me I need a bead blaster.


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## danallen (Aug 31, 2021)

CFLBob said:


> Just gorgeous work.
> 
> You're convincing me I need a bead blaster.
> [/QUOTE/]
> And a well equipped Tormach.


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## kvom (Aug 31, 2021)

No one will peer underneath the manifold to see that pin.


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## awake (Sep 1, 2021)

kvom said:


> No one will peer underneath the manifold to see that pin.



Are you saying that Mayhugh's work is peerless?

(I agree!)


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## cwelkie (Sep 1, 2021)

Phenomenal result from very thoughtful setups!


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## minh-thanh (Sep 3, 2021)

*mayhugh1 !*

  PERFECT !
 There will be one more masterpiece
I have a question about pictures of your projects .
Did you post it directly on the forum or was it quoted from another source ?


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## mayhugh1 (Sep 3, 2021)

minh-thanh said:


> *mayhugh1 !*
> 
> PERFECT !
> There will be one more masterpiece
> ...


Hi minh-thanh,
I upload all my project photos using HMEM's photo posting/storage service. I find this technique most convenient and 'safe' for my usage. I don't cross-post into other forums, and so storing my photos this way will let them live as long as the posts. - Terry


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## minh-thanh (Sep 3, 2021)

*Mayhugh1 !*


mayhugh1 said:


> so storing my photos this way will let them live as long as the posts. - Terry



Thank you very much !


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## ddmckee54 (Sep 3, 2021)

Terry:

I hate to do this, but I've got a question for you from a couple of posts back - when you were maching the manifold backside I believe.  In image 191.jpg you've got something inserted into the exhaust openings.  I assume this was done to keep the crap out of the openings?  Or was there a different reason, and what were they?  It's not important, I'm just curious since I haven't been able to figure out what they were.

Don


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## mayhugh1 (Sep 3, 2021)

ddmckee54 said:


> Terry:
> 
> I hate to do this, but I've got a question for you from a couple of posts back - when you were maching the manifold backside I believe.  In image 191.jpg you've got something inserted into the exhaust openings.  I assume this was done to keep the crap out of the openings?  Or was there a different reason, and what were they?  It's not important, I'm just curious since I haven't been able to figure out what they were.
> 
> Don


Don,
You're right. They're silicone plugs to keep the chips out of the internal passage during machining. I bought them from Amazon:






						Amazon.com: 350pc Ultra Precision High Temp Silicone Rubber Plug & Cap Kit Powder Coating Custom Paint Supplies : Automotive
					

Buy 350pc Ultra Precision High Temp Silicone Rubber Plug & Cap Kit Powder Coating Custom Paint Supplies: Sealants - Amazon.com ✓ FREE DELIVERY possible on eligible purchases



					www.amazon.com
				





They've turned out to be one of the handiest items to have around my shop. _Terry


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## jlchapman (Sep 4, 2021)

Terry,  
Your work on this engine is awesome.  I'm really interested in trying your epoxy method of holding parts while machining the part.  What do you use for an oven?  Can I use a convection toaster oven?

Jerry


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## mayhugh1 (Sep 4, 2021)

jlchapman said:


> Terry,
> Your work on this engine is awesome.  I'm really interested in trying your epoxy method of holding parts while machining the part.  What do you use for an oven?  Can I use a convection toaster oven?
> 
> Jerry


Jerry,
I use my small heat treat oven, but a little toaster oven should be fine. There is a bit of odor and so my wife wouldn't allow it in our kitchen oven. I used to use a heat gun, but I think they changed the formulation of their epoxy a few years ago and an oven seems to work best now. You need to wear gloves and remove the part while still hot or the epoxy will tend to re-seize as it cools. - Terry


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## kvom (Sep 6, 2021)

mayhugh1 said:


> remove the part while still hot or the epoxy will tend to re-seize as it cools.



That explains why I've never gotten it to release cleanly.


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## awake (Sep 7, 2021)

mayhugh1 said:


> Jerry,
> I use my small heat treat oven, but a little toaster oven should be fine. There is a bit of odor and so my wife wouldn't allow it in our kitchen oven. I used to use a heat gun, but I think they changed the formulation of their epoxy a few years ago and an oven seems to work best now. You need to wear gloves and remove the part while still hot or the epoxy will tend to re-seize as it cools. - Terry



So what you're saying is ... no half-baked approach will work.


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## mayhugh1 (Sep 10, 2021)

I've been getting up to speed on helical gear machining since my last post, and so I don't have much show & tell. I've finally gotten serious about the helical gear set needed to drive the mid-engine'd distributor from the camshaft. These .303" diameter gears aren't commercially available, and with 14 teeth @ 72 DP and a 45 degree helix, they're on the edge of what's practical to machine in a home shop. George recognized their difficulty early on and made sure he could make them before completing the design of the engine.

Most of my recent 'shop time' was spent studying related gear posts which began showing up some seven years ago when Chuck Fellows published his design for a fixture he used to machine helical gears on his lathe. Chuck and I were members of a local metalworking club, and I got to watch his progress first hand. Although we had lots of discussion about tooth profiles, I never tried to machine any of my own. 

Rather than duplicate Chuck's fixture which George used in a mill setup, I'm planning to machine mine using a 4-axis setup on my Tormach. I've been in contact with George about these gears, and his generous advice has been invaluable.

In order to set my rotary table 45 degrees nose up under the Tormach's spindle, clearance limitations forced me to align it with the mill's x-axis. I had hoped to use the y-axis instead which would have allowed me to avoid the machining needed to adapt my tilting angle table. Hoisting that 60 lb rotary onto the mill's table isn't something to be taken lightly, and the final setup require planning, some trial and error, and a couple Ibuprofens. 

During study breaks I was able to tie up a few loose ends. A three-bolt exhaust pipe flange was made to match the output of the exhaust manifold. It was machined from a piece of 303 stainless flat bar that was temporarily epoxied to a piece of MDF. The flange was brazed to a simple exhaust pipe bent from 3/8" diameter 304 stainless tubing. Two flanges were made so I'd later have the option of an alternate exhaust.

The exhaust manifold was airbrushed with POR-15 high temperature (1200F) paint. By greatly thinning the paint down using the manufacturer's special thinner, I was able to spray a very light coat that changed the manifold's color without leveling its glass-beaded textured surface. This paint requires a 24 hour room temperature drying time followed by a 300F bake and cool down cycle in order to complete its cure.

The intake manifold was similarly airbrushed with light gray Gun Kote. This gasoline resistant coating requires a similar cure but offers much less heat resistance. - Terry


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## gbritnell (Sep 11, 2021)

Terry,
The colors on your engine sure do enhance the look of it!


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## mayhugh1 (Sep 11, 2021)

gbritnell said:


> Terry,
> The colors on your engine sure do enhance the look of it!


George,
Thanks. I've long wondered about adding color to an engine but so far have only experimented with the display stands. This one seemed like a good candidate for full paint since I still clearly remember Ford's full-size engine. I'm not yet sure how I feel about painting, though. Their shiny machined surfaces always seemed to say 'hey, this was made with care by a machinist," Painted, they seem to say "this is a Toyan RC model from China." - Terry


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## L98fiero (Sep 12, 2021)

mayhugh1 said:


> George,
> Thanks. I've long wondered about adding color to an engine but so far have only experimented with the display stands. This one seemed like a good candidate for full paint since I still clearly remember Ford's full-size engine. I'm not yet sure how I feel about painting, though. Their shiny machined surfaces always seemed to say 'hey, this was made with care by a machinist," Painted, they seem to say "this is a Toyan RC model from China." - Terry


I'm pretty sure no one will ever mistake your engine for a Chinese 'production' model.


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## Auzzie53 (Sep 13, 2021)

man that is one beautiful piece of work well done


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## mayhugh1 (Sep 20, 2021)

Specialized equipment and manufacturing processes are used to commercially manufacture precision helical gears. Reasonable facsimiles, though, can be made using equipment in a typical machine shop. Two things are required. The first is a method to coordinate the moves of the cutter along and around the axis of the gear blank, and the second is a suitable cutter.

Coordinated cutter moves are what CNC is all about, and so I used my Tormach to handle the first requirement. Since I don't have a right angle spindle drive and want to use a circular cutter, the rotary had to be mounted nose-up under the spindle at an angle to the table equal to the helix angle.

Several years ago on this forum, Chuck Fellows published his design of a fixture that enables helical gears to be machined on a lathe or mill without the need for CNC or even a rotary. George Britnell later published a Youtube video demonstrating the machining of the gears for this engine using his version of Chuck's fixture.

Chuck used commercial spur cutters to make his helical gears, and this spawned discussions about tooth profiles. A spur gear cutter is designed to cut an accurate (although not necessarily perfect) profile for teeth that are square to the face of the cutter, but this isn't how helical teeth mate. The mismatch increases with the angle of the helix as well as the cutter-to-blank diameter ratio. It soon came to light that it's common shop practice to cut one-off helical gears using conventional involute cutters designed for a somewhat higher tooth count than specified for the helical gear. (For the same DP, the pitch diameter of a helical gear is greater than the pitch diameter of a spur gear by a factor equal to 1/cos(A) where A is the helix angle.) A common multiplier for the tooth count is 1/[cos(A)]^3. For example, to cut a 14 tooth 72DP 45 degree helical gear, a 72DP spur gear cutter intended for 40 teeth would be used.

One way to visualize a helical gear is to imagine many identical spur gears cut from thin sheets of metal and bonded together so each successive layer rotates slightly beyond the one behind it. Solidworks has a modeling feature capable of handling this, and the first photo contains 3-d models and specifications for the gears to be machined. A pair of these gears is needed to connect the engine's camshaft to the distributor.

Even though these particular gears are lightly loaded, and neither wear nor noise are concerns, they aren't necessarily good choices for a first machining attempt. There are lots of potential errors in setup and machining that can quickly add up on a .303" o.d. gear with .030" teeth.

The block's angled boss for the distributor was designed assuming the distributor's driveshaft will pass by the camshaft with the gears' theoretically correct angle and spacing. Even though the angled (and blind) distributor bore hasn't yet been done on the otherwise finished block, a small error in the theoretical .275" gear-to-gear spacing should also be tolerable.

Neither 72 DP cutters (nor the gears they cut) seem to be commercially available, and so the cutter had to be shop made. The drawing package for the engine doesn't currently include how-to information on the machining of these gears, and so I decided to try my hand at making a cosine cutter. Using data intended for 14-1/2 degree PA button cutters, I came up with the cutter profile shown in the second drawing. The tables in Ivan Law's bible are incomplete for some reason, and so I've included a table I lifted from the online Nov. 2015 issue of the Home Metal Shop Newsletter. This profile was manually machined on the end of a piece of 3/8" drill rod using a Nicole profiling insert. After gashing it to obtain four teeth with a bit of back relief, the cutter was hardened and tempered at 300F.

I've included a rendering of the cutter's profile projected onto the cutting plane of the helical gear model. The fit is reasonable, but the gear's involute contact line that will shared with its mate is questionable. This profile was then used to create CAD models of the gears I might expect to see using this cutter. The accuracy of these results are limited by the fact that I assumed a zero thickness 2-d cutter to create them. I was never able to figure out how to take into account the finite diameter of an actual circular cutter.

I've also included photos of the actual cutter that eventually machined over a dozen brass and steel gears. Due to a rookie mistake that resulted in my worksheet having the profiler's in-feed moves called out as radii while my lathe's DRO was set in diameter mode, my first cutter was devilishly misshaped. Since helical gear machining was a brand new experience for me, I spent days looking in the wrong places for what was wrong. My correspondences with George were very helpful and, in fact, he offered to let me borrow his fixture and cutter, but by this time I was obsessed with doing it myself. Most of my modeling efforts were done while troubleshooting this cutter problem.

My next post will include information about the actual gear machining process and its final results. - Terry


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## gbritnell (Sep 20, 2021)

Hi Terry,
I'm glad to see things are sorting themselves out regarding the helical gear making. I took your suggestion and included a drawing of the required cutter in the drawing set. This will help anyone wanting to build one of these. LOL. I doubt there's not many who would want to tackle a project like this.
gbritnell


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## a41capt (Sep 20, 2021)

Excellent explanation of the math employed in designing your cutter Terry.  Way beyond my capability for sure, but wonderfully illustrated, thanks for the education

So looking forward to hearing it run!

John W


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## mayhugh1 (Sep 22, 2021)

Although just two .250" long gears are needed, several .4" long brass and 12L14 steel blanks were prepared. The longer blanks nearly doubled the machining time, but the longer spares might be more useful in some future project.

In order to set up the work offsets, I made the alignment tool George came up with for use with Chuck's helical fixture. It looks deceptively simple, but it took a couple tries to get one indicating true on a surface plate. The tool was installed on the rotary's mandrel and after indicating the two arms parallel to the mill's table, the rotary's DRO was zero'd. An edge finder was then used to indicate the spindle to the center of one of the arms so the X DRO could be zero'd. The edge finder was then replaced with the cutter which was visually aligned with the pointed end of one of the arms so the Z DRO could be zero'd. Finally, the alignment tool was replaced with a gear blank. After positioning the cutter at X=0, Z=0, it was touched off to the blank's outside surface, and the Y DRO zero'd.

An end point for the cutting passes was then chosen. With the work offsets completed and the rotary pointing up at 45 degrees, equal moves along the X and Z axes keep the cutter properly aligned to the blank. With cutting taking place on the front side of the blank, the cutter will travel upward at a 45 degree trajectory while the rotary turns CCW. In my particular setup, a suitable end point where the cutter just clears the blank turned out to be X=.250, Z=.250. For convenience, the cutter was moved to this location and the X and Z DRO's zero'd for the last time. A suitable starting point for the cutting operation turned out to be X=-.450, Z=-.450.

Between my particular start and stop points, the cutter will travel a total distance of .450" x 1.414 = .6363" along the .400" long blank. One last parameter needed for coding is the gear's lead which is the length over which one full rotation of the gear's helix will occur. Lead is a function of the circumference of the gear's pitch circle and helix angle. It's calculated as L = [pi * N]/[DP * sin(A)] where N is the number of teeth and A is the angle of the helix. For this particular gear, L = .8639". Therefore, in my setup, the cutter's .6363" travel will require a simultaneous rotary movement of 360 x (.6363/.8639) = 265.196 degrees.

A full listing of the g-code is included. Since I was a newbie with the helical gear making process and still troubleshooting my cutter debacle, I didn't attempt a universal program with parameters. I did include plenty of comments. With the machine in incremental mode (G91) and a starting point at (X-.450, Z-.450, Y-.015, A0), the single line of code that does the actual cutting is simply:

G1 X.450 Z.450 A-265.196

During testing, I found it best to machine the .030" teeth in two .015" passes. For reasons I still don't understand, there was a lot more noise and vibration while cutting the brass gears compared with the steel gears which machined dead quiet.

Due to burrs raised by the cutter, the resulting o.d.'s of both gear types consistently came out .007" greater than the starting diameters of their blanks. They were finished on a lathe by re-facing their ends and skimming their diameters back to their blanks' original values. This, of course, left yet another tiny burr on the inside edge of each tooth. These were manually cleaned off using a cobbled-up de-burring tool fashioned from a Nicole .040" diameter profiling insert. Drawing this tool just once through the space between each pair of teeth removed these tiny burrs without significantly affecting the tooth profiles.

The tooth profiles on the finished gears are different from that predicted by my cosine gear model. The difference is probably at least partially related to the non-zero diameter of the actual cutter. The final parts certainly look like helical gears and they do mesh smoothly, but I don't expect a true involute contact line.

One last sanity check is the measurement of the axial spacing between a pair of freely turning 90 degree meshed gears adjusted for minimum backlash. The theoretical number is .275" which is the pitch diameter. The measured spacing of the four gears in my first batch ranged between .276" and .277". After some thought, I decided it would be smart to have a few more options to choose from in case the still-to-be-done drilling operation for the distributor driveshaft bore veers off its course. The diameters of two more batches of blanks were tweaked plus and minus .0015", and I wound up with two more batches of gears with spacings ranging between .271" and .273" and between .280" and .281".

The little shop-made cutter held up much better than I expected - so much better in fact that I don't believe I'll be buying any more expensive commercial cutters. - Terry


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## propclock (Sep 22, 2021)

Simply fantastic! thanks for posting.


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## Thommo (Sep 22, 2021)

I have to say Mayhugh1, every time I look at one of your posts, I immediately realise just how inadequate my machining skills are in comparison to yours lol. A fantastic job you are doing. Can’t wait to hear it running.


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## Scott_M (Sep 23, 2021)

Hi Terry
More often than not my first comment to myself ( out loud ) is usually " wow " when I read your posts 
They really look great !!
Thanks for sharing.

If you get bored or need a diversion a nice torture test of a set of those gears would tell you a lot about  " uses"  in upcoming projects.


Scott


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## kvom (Sep 23, 2021)

Since rotary tables like this use a worm gear to drive, I was wondering initially if reversing the rotation would induce too much backlash.  It appears that the forward rotation for the next tooth does take up any that the reversing might cause.


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## gbritnell (Sep 23, 2021)

Wonderful results Terry! I'm guessing the reason that the cutters made more noise cutting the brass blank compared to the 12L blank is the same reason that it takes a sharper reamer to cut a nice hole in the respective metals. You would think it would be just the opposite but it's not.  Possibly the reason that the profile didn't quite match your model is for the fact that in creating the cutter with the adjusted profile it was meant for a standard diameter involute cutter and not one based on a .375 O.D.
All things being said they look great? I also made a small right angle fixture for checking the gear mesh.  It's much easier doing it out in the open.
Since I made my first specialty cutter many years ago I've never looked back.
gbritnell


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## CFLBob (Sep 23, 2021)

I have an odd question.  The machining is light years from where my skills are, but I think I understand your derivation. 

My question concerns your Gcode 


mayhugh1 said:


> G1 X.450 Z.450 A-265.196



The photo of the Gcode printed out says F6 for brass and F4 for steel

What interpreter are you using?  I'm still using Mach 3, and have done some cutting on the rotary table.  What I note is that (at least in the configuration I'm using) that F6 would be interpreted as 6 inches per minute for X and Z but 6 *degrees*/minute for A.  That's over 44 minutes for one spiral pass; 10-1/2 hours per gear.  Is that real?  

I'm pretty sure that my uses have been in absolute mode, but I don't see that making a big difference.


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## mayhugh1 (Sep 23, 2021)

CFLBob said:


> I have an odd question.  The machining is light years from where my skills are, but I think I understand your derivation.
> 
> My question concerns your Gcode
> 
> ...



I'm also using mach3. G1 uses the F parameter only for linear moves. The rotary's movement is done using degrees. You need to insure your rotary is capable of rotating fast enough to honor the coordinated move, however. Mine will spin 360 degrees in 23 seconds and so there was no problem. - Terry


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## mayhugh1 (Sep 23, 2021)

kvom said:


> Since rotary tables like this use a worm gear to drive, I was wondering initially if reversing the rotation would induce too much backlash.  It appears that the forward rotation for the next tooth does take up any that the reversing might cause.


kvom,
It's been a while since I measured its backlash, but I remember it being less than a thousandth of an inch on the outside of the 8" diameter table or less than .01deg. The gears are heavily preloaded in these Tormach rotaries for continuous 4 axis machining. You have to lube them before every use, though. - Terry


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## kvom (Sep 24, 2021)

In thinking about this procedure as well as the fact that my rotary table+chuck weighs as much as I can lift, being able to machine the gear without the rotab tilted would be nice.  Since the goal is to be able to keep the tool parallel to the groove at all time, it seems to me that tilting the spindle would accomplish this.  Since my mill allows rotating the head around the Y axis, having the work piece oriented in +X should work.  Each cut would be a coordinated move in -X and +A. 

Not many CNC mills have a rotating head so this idea likely isn't that useful.


----------



## pileskis (Sep 24, 2021)

Terry- I wonder if you took a video of the gears being cut?
That would be interesting to see.

Thanks, Sid


----------



## mayhugh1 (Sep 24, 2021)

pileskis said:


> Terry- I wonder if you took a video of the gears being cut?
> That would be interesting to see.
> 
> Thanks, Sid


Sorry, I didn't. It ran so slow that you'd likely have dozed off. - Terry


----------



## mayhugh1 (Sep 24, 2021)

kvom said:


> In thinking about this procedure as well as the fact that my rotary table+chuck weighs as much as I can lift, being able to machine the gear without the rotab tilted would be nice.  Since the goal is to be able to keep the tool parallel to the groove at all time, it seems to me that tilting the spindle would accomplish this.  Since my mill allows rotating the head around the Y axis, having the work piece oriented in +X should work.  Each cut would be a coordinated move in -X and +A.
> 
> Not many CNC mills have a rotating head so this idea likely isn't that useful.


That sounds like it would work. Another approach would be a right angle drive attachment for the spindle. Chuck built one for his mill out of a set of gears from a right angle grinder. It its purpose was mainly low speed gear machining, it  wouldn't have to be that precise. - Terry


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## CFLBob (Sep 24, 2021)

mayhugh1 said:


> I'm also using mach3. G1 uses the F parameter only for linear moves. The rotary's movement is done using degrees. You need to insure your rotary is capable of rotating fast enough to honor the coordinated move, however. Mine will spin 360 degrees in 23 seconds and so there was no problem. - Terry



Terry,

Sorry it took me until today to be able to get to my rotary table and double check, but there's something funny here.  I did this all from the immediate interface (command line) in Mach 3.  I had my rotary axis, A=0.000.

I set F10, and that appeared in the feed rate box.

G1 A90.  If F10 is degrees/min, that should take nine minutes and I should visually see 90 degree movement.  I stopped it after 1 minute when it had gone 10 degrees.   I told it to go back to the starting point, A0.00.

I set F360 at the command line and, again, 360 appeared where it should have.  

G1 A90 should take 15 seconds, 1/4 of a minute for 1/4 of a circle.  And it does.   

So there's some setting that I don't know that's making either yours ignore the F parameter for angles or making mine use it.  Or use them differently.  If I had to choose, I'd rather mine worked closer to the way yours does.  You're able to do coordinated moves between the rotation and the linear axes.

The few times I've used the rotary table under CNC control, it hasn't required coordinated motion between the axes.  I could increase the feed rate to like F720 (2.0 RPM), set the table to whatever angle I needed, set F back to whatever it was before and do whatever X, Y, Z movements I needed, .  

No need to answer unless you happen to know why off hand.  I'll be reading and trying to understand.  Just thought I'd close the loop on this.  


Bob


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## mayhugh1 (Sep 24, 2021)

CFLBob said:


> Terry,
> 
> Sorry it took me until today to be able to get to my rotary table and double check, but there's something funny here.  I did this all from the immediate interface (command line) in Mach 3.  I had my rotary axis, A=0.000.
> 
> ...


Bob,
Make sure in your General Configurations pull-down menu that your units for the A axis is set for angular. In the toolpath set up pull-down menu make sure 'use radius for feedrate' or 'use diameter for feedrate' (depending upon the version of mach) is checked. Also in the upper left hand corner of the settings screen, enter the radius of the part that's in your chuck. Due to a mach3 bug, a zero in this parameter can cause havoc. - Terry

p.s. mach always honors the maximum motor rates allowed in the setup for all the axes, and so the feedrate parameter F should be considered the max feedrate you'll get for a coordinated move if one of your axes can't keep up.


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## mayhugh1 (Oct 4, 2021)

For best visibility while aligning the cutter in my helical gear machining setup, I machined the gears with an opposite handedness compared with those in the full-size engine. The downside of doing this was a reversed direction of the rotor inside the distributor and a backwards order for the plug wires coming out of the cap. A small upside is that the axial thrust created by the driven gear will tend to pull the tiny distributor into the engine rather than push it out.

Fixturing an operation to bore the distributor's mounting hole in the block was a lot easier and much less risky than I had been imagining. After squaring the block on an angle plate, I realized the bore could be accurately located using a driving gear on the end of a rod in the camshaft bore and a driven gear on the end of a dummy shaft in the spindle. The final result was a smoothly meshed gear set with near zero backlash.

The distributor body was machined from 6061 and the distributor shaft from 303 stainless. I replaced the bronze bushings for the distributor shaft with sealed ball bearings to avoid having to manually oil them later. The shaft's long skinny end was turned without using the tailstock similarly to the valves (in a previous post) using short overlapping segments turned one at a time.

A rather sketchy fixture was used to drill a 3/64" hole simultaneously though the assembled gear and distributor shaft for a pin to lock the two together with zero thrust clearance. The pin will be Loctite'd at final assembly but will remain loose for fit testing partial assemblies.

The distributor uses a shuttered type Hall trigger. A machined steel cylinder with six openings rotates between a magnet and a Hall device to provide timed trigger pulses to a CDI. An alternative would be to use six magnets, but this can become tricky inside a tiny distributor where the individual fields of the magnets can interact and reduce the sizes of the flux pulses seen by the Hall device.

A shuttered trigger disk has its own limitations. Even at the ON location in front of an open window, much of the magnet's flux will be shunted away from the Hall device by the low permeability return path offered by the disk. The disk's permeability can be reduced and the flux pulses seen by the device increased by judiciously machining material from the disk. However, if too much is removed, the disk can become saturated and allow flux to pass through even a closed window. Some trial and error is usually required to obtain reliable operation that's also dependent upon the particular Hall device, magnet, and the spacing between them.

The trigger disk was machined from 12L14. It's best to use a soft steel alloy for the disk since hard alloys tends tend to acquire and retain magnetism. I modified the disk design to avoid the angled grub screw suggested in the plans to lock it to the distributor shaft. Instead, the trigger disk attaches to a flange on the distributor shaft with three 0-80 SHCS's. The bolt holes are slotted to allow the disk to be rotated on the shaft for proper timing before being tightened down.

A 1/8" x .100" neodymium magnet was epoxied into a machined aluminum holder that attaches to the floor of the distributor body with stainless steel screws. Hall devices tend to go obsolete very quickly making it difficult to recommend a specific part number. I plan to use up some mystery parts from my junk box on which I've run my preliminary tests. They appear to be marked '738S06L', but I have no idea what the actual part number is or who the manufacturer was. - Terry


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## cwelkie (Oct 4, 2021)

Very thoughtful solution and excellent description using a shutter trigger with a hall effect sensor.


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## Thommo (Oct 5, 2021)

Mayhugh, your skill set is truly excellent. I wish that I was 1/2 the machinist that you are fella


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## a41capt (Oct 5, 2021)

Thommo said:


> Mayhugh, your skill set is truly excellent. I wish that I was 1/2 the machinist that you are fella


AMEN!  That goes double for me!!!


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## mayhugh1 (Oct 10, 2021)

Hall sensor mounts were machined from 6061, bead blasted, and painted with black Gun Kote. A length of 32 AWG Futaba servo cable was soldered to each sensor and the assembly epoxied into a cavity machined into the front side of the mount. A 3/64" hole was drilled into the top of the mount for a pin that will later be used to locate the distributor cap. Soldering the sensors and connectors to the tiny cable required a lot of patience, and after coming up with a process I made three more using the remainder of the mysterious Hall sensors in my junk box.

I've standardized on a male Futaba J-type connector soldered on the ends of the sensor cables in my engines. I've always used the same Maxx brand connector that's been readily available from a local hobby store. Since they no longer carry them, I ordered a kit of compatible Apex connectors from Amazon. The first thing I noticed was the gold flashing on the Apex pins was considerably lighter than what I was accustomed to seeing on the Maxx pins. Also, the plastic tangs used to lock the pins inside the connector shells were iffy, and the resulting connections were unreliable. I ultimately trashed the Apex parts.

The Maxx connectors were difficult to find, but I was eventually able to order them directly from the source (MPI). While waiting for them to arrive, I decided I wasn't happy with the just completed 'fat' mounts, and so I machined a redesigned set of four. Since I didn't have any more mystery sensors, I used the Optek OH090U's that had given me so much grief during my Merlin build. Although a bit larger in size, they worked well with the distributor's trigger disk. A day after the Maxx connectors arrived, I had eight tested sensor assemblies - many more than I hope to ever need. A nice feature of George's distributor is that the Hall device is safely located outside the distributor rather than being inside underneath a lightning storm.

Also while waiting on the Maxx connectors, I machined a hold-down fork to lock the distributor to the block. This tiny part was machined from a bit of 303 stainless bar stock epoxied down to a piece of MDF. A screw through its mounting hole helped secure it to the MDF during the final operation that cut it free from its workpiece. - Terry


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## ajoeiam (Oct 10, 2021)

mayhugh1 said:


> Hall sensor mounts were machined from 6061, bead blasted, and painted with black Gun Kote. A length of 32 AWG Futaba servo cable was soldered to each sensor and the assembly epoxied into a cavity machined into the front side of the mount. A 3/64" hole was drilled into the top of the mount for a pin that will later be used to locate the distributor cap. Soldering the sensors and connectors to the tiny cable required a lot of patience, and after coming up with a process I made three more using the remainder of the mysterious Hall sensors in my junk box.
> 
> I've standardized on a male Futaba J-type connector soldered on the ends of the sensor cables in my engines. I've always used the same Maxx brand connector that's been readily available from a local hobby store. Since they no longer carry them, I ordered a kit of compatible Apex connectors from Amazon. The first thing I noticed was the gold flashing on the Apex pins was considerably lighter than what I was accustomed to seeing on the Maxx pins. Also, the plastic tangs used to lock the pins inside the connector shells were iffy, and the resulting connections were unreliable. I ultimately trashed the Apex parts.
> 
> ...



I greatly appreciate the detail you offer in your build process.
Such really helps prime my design fu AND stimulates me!

Thank you very much!!!


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## a41capt (Oct 10, 2021)

Tiny, tiny, tiny work!!! Most excellent.

I’d have trouble putting the distributor clamp in place, never mind machining it!  Thanks for sharing Terry.

John W


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## petertha (Oct 10, 2021)

Terry, this is a good place to buy leads, pins, plug ends, connectors, kits for DIY & picky RC modelers. I've made many custom leads & harnesses over the years but you may find some other standardized plugs & accessories of interest. I've had their crimpers for many years but I'm told there are decent alternatives if yo stick with reputable tool suppliers.





						Hansen Hobbies - Home
					

Hansen Hobbies - Electronics for Radio Controlled Aircarft



					www.hansenhobbies.com
				








						Hansen Hobbies - Products
					

Hansen Hobbies - Electronics for Radio Controlled Aircarft



					www.hansenhobbies.com
				




Not all braided wire, pins & housings are created equal as you've discovered. It may not make a difference to your particular application but good to know what you're getting anyways. Unfortunately the hobby situation is just getting worse. Some of the Ebay/Ali stuff is OK & some of it is crap. There is no way to distinguish quality from a picture. To make matters worse, there is a lot of disregard (or lack of understanding) for plug standardization one could previously count on. You might see JST or Molex thrown out that have no dimensional equivalent to documented standards or available in a reputable electrical supplier catalog. Its not all bad news, some new plug formats have also emerged, but it takes a lot of digging shed light. Sorry for the tangent, this is a thing for me LoL.


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## mayhugh1 (Oct 10, 2021)

petertha said:


> Terry, this is a good place to buy leads, pins, plug ends, connectors, kits for DIY & picky RC modelers. I've made many custom leads & harnesses over the years but you may find some other standardized plugs & accessories of interest. I've had their crimpers for many years but I'm told there are decent alternatives if yo stick with reputable tool suppliers.
> 
> 
> 
> ...


Thanks for the tip. Their 28 gage servo cable looks good also. The 32 gage I used is tough to work with. - Terry


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## petertha (Oct 10, 2021)

Forgot to mention, they sell the plug housings in many other variations like 1x4, 1x2, 4x4 etc. (standard RC plug would be called 1x3). Not sure you have a requirement but something to know about. Potentially neater way to bundle different cable count combinations for other electrical do-dads but using the exact same male/female pins you already have. I found crimping these is a bit fiddly when you first start out, but like most things, gets better with practice.


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## CFLBob (Oct 10, 2021)

mayhugh1 said:


> Thanks for the tip. Their 28 gage servo cable looks good also. The 32 gage I used is tough to work with. - Terry



With 40 plus years in industrial electronics manufacturing, we called anything finer than about 30 ga. "frog hair".


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## mayhugh1 (Oct 10, 2021)

Bob,
Did you ever resolve your rotary's slow speed problem?
Terry


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## CFLBob (Oct 10, 2021)

mayhugh1 said:


> Bob,
> Did you ever resolve your rotary's slow speed problem?
> Terry



I haven't tested it.  I've been working on the camshaft on the lathe, and some other stuff.  I copied off your recommendations to look at next time I have that computer on.


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## mayhugh1 (Oct 17, 2021)

I happened across an NOS distributor cap left over from my '72 project truck. I noticed the direction of the cylinder numbers on its top agreed with the rotor direction I'm expecting for my model's distributor. It was pure serendipity, but I ended up cutting my helical gears in the same direction as those in the full-size engine after all.

The model's distributor cap was machined from black Delrin. I don't normally use black Delrin for ignition parts since its color is a result of carbon added to the material which can affect its electrical properties. Natural Delrin has excellent electrical characteristics, but manufacturers don't specify them for the black material. The original Ford cap was black, and since other builders have been getting away with using it in their ignitions, I decided to give it a try.

After machining the cap's top surface, brass inserts were pressed into the high voltage towers. These inserts were drilled to accept some gold connector pins from my electronics scrap collection. The pins were soldered to the ends of the plug wires and will later be covered with rubber boots fashioned from automotive vacuum fittings. A small through-hole allow trapped air to escape during the pressing operations. Machining the cap's i.d. exposed the ends of the embedded inserts which will wind up in very close proximity to the tip of the rotor electrode.

The cap is secured to the distributor body with a pair of spring clips similar to those used in the full-size distributor. These simple looking parts took on a build life of their own. Because of the cap's convex top surface, it was necessary to machine recesses into the sides of the cap for the clips to snap into. Similar recesses were added to the bottom of the distributor.

The starting material for the spring clips was a piece of bandsaw blade. The .030" blade was somewhat thicker than I wanted, but my only other on-hand choice was some .010" spring steel that proved to be too flimsy. After annealing the blade, the clips were formed from a thin strip cut from it. The finished clips were brought to red heat with a torch, quenched in oil, and tempered at 500F. After the shop gremlins made off with their share, I turned the rest of the material into spares.

The rotor was the final part of the distributor and was machined from white Delrin. A grub screw will secure it to the distributor shaft once the distributor is timed. A slot was milled into the top of the rotor for a brass electrode that was secured with a pair of 0-80 flat head screws. The tip of the rotor extends beyond the Delrin to prevent burning of the plastic, and its final length was determined by trial-and-error for near zero clearance with the tower electrodes. A strip of .005" phosphor bronze provides a rotating contact with the cap's center button.

The final assembly was bench tested using a bank of six plugs and a CDI module and functioned as expected. The boots will be added during final assembly. The next steps will include work on the camshaft. - Terry


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## doc1955 (Oct 18, 2021)

All I can say is you do some amazing work. I really like the way that distributor looks but than again I like the way the whole build looks totally amazing!!


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## mayhugh1 (Oct 26, 2021)

The helical drive gear in the center of the full-size camshaft was most likely machined using a specialized hob. George came up with a clever solution for the model that requires only a lathe and mill. The camshaft was divided into two halves with machined end tenons fitted together inside the gear. The Loctited assembly was then cured in a simple v-groove fixture.

The tenons were tackled first. I started with two lengths of 5/16" drill rod cut longer than needed for the assembled camshaft so the extra stock could be used for a second chance at a good fit. I got lucky on my first attempt which wound up with a snug fit that rolled flat over a surface plate. Since the tenons were also used to reference the starting orientations for the lobe machining operations, Loctiting was left until the very end.

The intake and exhaust lobe profiles are identical, and so 4-axis g-code was compiled for a single lobe and run twelve times in as many setups. Minimum workpiece stick-out required a new setup for each lobe operation. A brass end-cap temporarily fit to the end tenon and center-drilled for the mill's tailstock stabilized the workpiece for the longer stick-outs. A 10-32 cup set screw tightened against the tenon's flat surface (through a protective pad) held the cap in place so its milled flat top surface could be used to indicate the starting angle for each lobe.

I usually find camshafts confusing parts to machine. This one required working from its center toward its two ends which meant, for machining purposes, the lobes on the two halves rotate in opposite directions. In addition, my CAD, CAM, and controller software all indicate 4th axis rotation angles in different ways. My particular mill's 4th axis also happens to be wired in reverse - something I should have corrected long ago instead of adding G51 A-1 to my coding.

The mental gymnastics got the best of me, and so my heavily rehearsed machining steps eventually included color-coded workpieces and worksheets. In order to reduce the chances of setup errors, the lobe boundaries were 'scratched' into the workpiece ahead of time on a lathe and picked up on the mill with a spindle microscope. (Of course, the 'scratches' really had two 'sides' which were reversed under the microscope.)

The g-code included pair of roughing operations spaced 180 degrees apart that prepared the lobe for its finishing step - a continuous 4-axis rotary operation. Each lobe required about 5 minutes of setup time and some 15 minutes of machining using a conventional 1/8" cylindrical end mill. Tiny step-overs minimized the ridges left by the end mill's relieved cutting edges. The residual machining marks were easily 'shoe-shined' away with 800 grit paper. For cosmetic purposes, the material between lobe pairs was then carefully removed from both camshaft halves using a thin parting tool.

In the original drawing, the 60 tooth timing gear is attached with a pair of set screws. I added a flange to the front end of the camshaft to which the gear will attach with four SHCS's. Machined slots in the gear will allow the camshaft to be timed to the crankshaft before the screws are tightened. The flange was a separately machined part that was Loctited to the camshaft. - Terry


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## CFLBob (Oct 26, 2021)

Are those tenons semi-circular so that when they're in the right place they'll create a small cylinder with the gear bored to that diameter?  

They appear to be that way.  I guess the alternative would be flats with matching slots machined in the gear.


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## mayhugh1 (Oct 26, 2021)

CFLBob said:


> Are those tenons semi-circular so that when they're in the right place they'll create a small cylinder with the gear bored to that diameter?
> 
> They appear to be that way.  I guess the alternative would be flats with matching slots machined in the gear.


You're correct. When fitted together they completely fill the bore through the gear. I could see it also as a way to construct a built-up crankshaft. - Terry


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## awake (Oct 26, 2021)

Terry, what sort of bearing does the camshaft ride on? Is it just steel (camshaft) on aluminum (case), or is there something else in there? (bronze insert??)

By the way - marvelous work, as always!!!


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## mayhugh1 (Oct 26, 2021)

awake said:


> Terry, what sort of bearing does the camshaft ride on? Is it just steel (camshaft) on aluminum (case), or is there something else in there? (bronze insert??)
> 
> By the way - marvelous work, as always!!!


No bearings. Just polished drill rod turning in reamed 7075 block. Being open to the crankcase it should get plenty of oil due to windage. - Terry


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## awake (Oct 26, 2021)

I have seen many designs that run steel in aluminum with lubrication, so thought that might be what you were doing. Again, marvelous work!!


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## stanstocker (Oct 27, 2021)

Wow.  Just plain Wow!  I read your posts, admire your photos, and keep hearing in the back of my head the haunting refrain from Wayne's World - "We're not worthy!"  You play at an entirely different level and I'm very grateful to you for sharing all your knowledge.


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## mayhugh1 (Nov 1, 2021)

With the massive rotary still set up on the mill, it was a good time to machine the timing gears. These 48 DP gears were machined from 1144 and are very similar to those made for the Offy. I may have gone overboard with the timing gear's cosmetics, but I didn't want just another plain disk. The spacing between the block's already machined crank and camshaft bores was laid out for a pair of error-free gears, and so great care and a 4-jaw chuck were used in their machining. After finishing the timing gear, its machining was checked by measuring its pitch diameter spacing with a known good (spare) 60 tooth Offy gear.

Although the bronze main bearings haven't yet been machined, the crank was temporarily installed in its two outer ballbearings. The 30 tooth crankshaft gear meshed smoothly with the 60 tooth timing gear inside the block with no tight spots and just a touch of backlash. The crank gear was then broached for a 1/16" key to match the slot machined much earlier on the front of the crankshaft.

I modified the design of the carrier for the front oil seal to include a mounting flange for the crankshaft pulley. This carrier, machined from 12L14, was keyed to the crankshaft and spins inside an o-ring fitted in the neck of the timing cover.

The crankshaft pulley was machined from 12L14 and attached to the flange with four SHCS's. Its runout was minimized by a snug fit between its bore and the crankshaft. The pulley was marked with a tiny divot adjacent to the crankshaft key so it can be mounted to the crankshaft with a consistent orientation. Later, once the engine is timed, the pulley's outer rim will be scribed with the number one cylinder's TDC. The pointer added to the timing cover will be used to set and indicate ignition timing.

A hex bolt screwed into the nose of the crankshaft completed the crankshaft assembly. A center boss on the rear of its washer bottoms on the nose of the crankshaft and the washer limits the forward travel of the crankshaft components. The backside of the washer was counterbored for clearance around the heads of the pulley's mounting bolts. The pulley, washer, and hex bolt were bead blasted and cold blued.

The drag on the crankshaft created by the seal will hide any tight spots during the fitting of the main bearings, and so the o-ring will be removed during that step. The final machining operation on the timing cover was a shallow bore for a pressed-in bronze button to limit the forward travel of the camshaft. A .010" Teflon timing cover gasket completed the internals associated with the crankshaft's front end. - Terry


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## Eccentric (Nov 4, 2021)

Phenomenal, absolutely beautiful Terry. I especially like the way your camshaft gear came out; the way the lightning holes blend so well into the gear ring and the center spigot is wonderful.


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## mayhugh1 (Nov 8, 2021)

The water pump is another one of the model's very realistic parts. As a Solidworks rendering it could easily be mistaken for the real thing. It wasn't until I was well into its machining that I was struck by just how tiny it actually is.

I didn't want to muck with the pump's design, but earlier changes made to the block to accommodate crankshaft and timing gear modifications required an increase in the length of the pump's body and impeller. I also adjusted its filleting to limit the diameter of the smallest finishing cutter to 1/8".

Construction began on a one inch length of 2" diameter aluminum starting workpiece. After truing it, pockets for a pair of ball bearings and an o-ring seal were machined through what would eventually become the front of the pump. The workpiece was then flipped around in a set-true chuck where the rear was bored for an inlet plenum behind the impeller. A mounting boss was also added to locate the pump to the block.

The workpiece was then moved to the mill where the pump's four mounting holes were drilled and temporarily tapped. All features reachable through the rear face of the workpiece could then be machined. A fixture plate attached to the rear face of the workpiece allowed the remainder of the pump to be machined through its front face. The fixture'd pump was then repositioned so the coolant passage through the pump's angled neck could be drilled. A final operation reamed out the tapped holes for clearances around the pump's 1-72 mounting screws.

Some already on-hand 3/16" i.d. ball bearings established the diameter of the impeller shaft. After pressing on a bronze disk and truing it to the shaft, the impeller's seven blades were machined using a 1/16" end mill.

An included diagram shows the pump's exploded assembly which includes a silicone greased o-ring seal and a pair of ball bearings with their associated spacers. A mounting flange for the drive pulley is secured to the shaft with a grub screw which holds the assembly together. A flat was machined on the shaft for the grub screw.

An aluminum drive pulley and Teflon gasket will complete the pump assembly. The pump will be painted to match the block after the coolant outlet is machined. The pulleys will be be air-brushed flat black Gun Kote. - Terry


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## CFLBob (Nov 8, 2021)

mayhugh1 said:


> It wasn't until I was well into its machining that I was struck by just how tiny it actually is.



How tiny is it? I was trying to extrapolate from those fillets around the base being 1/8" diameter and it seems to be coming up to 3/4" tall.  Maybe 1" tall.


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## mayhugh1 (Nov 8, 2021)

I took this photo but forgot to include it.


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## Steamchick (Nov 9, 2021)

Beautiful work! But the problems of scale make me wonder how successful it will be at moving adequate coolant in reality? I'm sure you'll have used very fine clearances between the rotor and housing..  How much clearance is there?
K2


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## propclock (Nov 9, 2021)

Always inspiring and intimidating. Thank you for your posts.
Where do you get the 2" match sticks?


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## GreenTwin (Nov 9, 2021)

Fantastic build thread.
I will have to go back and read it from the beginning.

.


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## mayhugh1 (Nov 9, 2021)

Steamchick said:


> Beautiful work! But the problems of scale make me wonder how successful it will be at moving adequate coolant in reality? I'm sure you'll have used very fine clearances between the rotor and housing..  How much clearance is there?
> K2


This particular 'pump' is really a circulator. Although coolant enters the block from the radiator through the pump, gravity has more effect on the flow than the pump. The pump's impeller sticks inside the block and really just helps to circulate the coolant between the block and the outlet located in the head. I agree that the coolant system systems don't scale very well. Thermo-siphoning is probably a major component of the coolant system in these models. To answer the question you didn't mean to ask, the impeller rides against the face of the locating boss on the rear of the pump with essentially zero clearance. It will be lubricated by the coolant and so I wouldn't expect any wear. - Terry


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## e.picler (Nov 9, 2021)

Congratulation Terry!
This is really wonderful work.

Did you machine the Camshaft using CNC or did you machine it manually?

Thanks,
Edi


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## Steamchick (Nov 9, 2021)

Thanks Terry. I asked because a friend at my Club has a 3 cylinder side-valve engine that runs for 5 - 10 mins on petrol, and while his water pump is about the same size as yours, his "scale-looking" cooling system cannot cope with any longer, idling, without boiling! It needs a radiator bigger than the engine, and "larger than scale" water pipes. He uses 2mm bras tube. The pump does work well, his runs at above engine speed, belt driven. I think about 3/8" dia rotor. But his is made from non-metal (clear window one side), and is stand-alone, unlike your conventional packaging. I'll try and find a picture....
K2


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## mayhugh1 (Nov 9, 2021)

e.picler said:


> Congratulation Terry!
> This is really wonderful work.
> 
> Did you machine the Camshaft using CNC or did you machine it manually?
> ...


It was done with CNC, one lobe at a time, with each lobe positioned for minimum stick-out before starting (12 setups). - Terry


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## mayhugh1 (Nov 12, 2021)

The water pump pulley was turned and trial assembled on the engine to verify its alignment with the crankshaft pulley. A 1/10" thick o-ring will eventually be used for the belt, but the fit was checked with an on-hand -038 o-ring. The pulley will be painted later along with the fan and spacer block after they're fabricated.

Coolant will eventually flow from the engine to the radiator's upper tank through a thermostat housing attached to the front of the block. Although there's really no thermostat, the housing was a significant machining project. I was able to come up with a bulbous design reminiscent of the full-size casting that I was machinable through only two workpiece faces. It was completed in three setups similar to those used for the water pump.

Construction began by squaring up a small block of aluminum. A single corner was used as the machining reference for all three setups in order to minimize registration errors. The bottom face of the housing was machined first and included a groove for an o-ring seal to the block. Holes for the housing's mounting screws were drilled and temporarily tapped for use later with a fixture plate. All of the housing's features that were accessible through the bottom face of the workpiece were then machined.

The workpiece was then flipped over and attached to a fixture plate where the rest of the machining was completed through the top face of the workpiece. The nozzle was drilled through and reamed in the third setup. Before painting the housing, a steel ferrule that added a hose sealing barb was turned and pressed into the end of the nozzle. A similar ferrule was added to the water pump's inlet nozzle.

The water pump and thermostat housing were bead blasted and air-brushed with blue Gun Kote to match the block. I'm finally getting the hang of air brushing. The trick to painting these small model parts seems to be to keep a high air-to-paint flow to minimize the paint particle size. Spraying many barely perceptible light coats on a glass-beaded metal surface allows the sheen to be fine tuned between satin and gloss. This technique seems to work well with Gun Kote which remains tacky until its heat cure. I'm not sure however it would work with more conventional solvent-based paints. - Terry


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## Steamchick (Nov 13, 2021)

Mayhugh: Top class work! Love it!
K2


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## ajoeiam (Nov 13, 2021)

mayhugh1 said:


> snip
> 
> The water pump and thermostat housing were bead blasted and air-brushed with blue Gun Kote to match the block. I'm finally getting the hang of air brushing. The trick to painting these small model parts seems to be to keep a high air-to-paint flow to minimize the paint particle size. Spraying many barely perceptible light coats on a glass-beaded metal surface allows the sheen to be fine tuned between satin and gloss. This technique seems to work well with Gun Kote which remains tacky until its heat cure. I'm not sure however it would work with more conventional solvent-based paints. - Terry



Hmmmmm - - - - this 'Gun Kote' - - - - what type of paint is it?
(2 part epoxy or ????) 

You're not using any type of primer for a base coat - - - yes?

Finishing - - - - something that I have done very very little and likely know even less about!


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## mayhugh1 (Nov 13, 2021)

ajoeiam said:


> Hmmmmm - - - - this 'Gun Kote' - - - - what type of paint is it?
> (2 part epoxy or ????)
> 
> You're not using any type of primer for a base coat - - - yes?
> ...


Google 'Gun Kote' and you'll get more information than you'll need. No primer - relatively impervious 300F baked-on finish. - Terry


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## mayhugh1 (Nov 16, 2021)

The Ford 300's utilitarian fan was another of the engine's distinguishing features. Although anemic by today's standards, it pulled enough 100F Texas summer air through my truck's radiator to prevent over-heating in our congested traffic. George's design absolutely nailed its look, and his method for making it closely paralleled Ford's.

Construction began with the shearing of a stack of 1"x3" blade blanks from .030" soft aluminum. I needed only two, but I was prepared for a learning curve, and it was just as easy to make a dozen. The blanks were stacked and simultaneously drilled through for hub mounting hardware. After attaching it to a sacrificial plate, the entire stack was milled with the blade's periphery. The stack's screw-down end tabs were sanded away later.

The blades on the full-size fan had beaded stiffeners, and so a pair of aluminum press dies were machined to duplicate them. This was when I discovered that I should have rotated the mounting screw hole pattern 45 degrees so the beads wouldn't pass through the screws. However, rotating the pattern would have moved the beads into the fan's rivets, and so the beads were shortened to keep them out of the hub area.

After pressing in the beads, the blades were pitched by gripping them between a pair of wood blocks and slightly twisting. A machined mandrel was used to set the four aluminum rivets that permanently joined them together.

It was difficult to get an acceptable Gun Kote surface finish on the completed fan assembly. The thinly stretched metal tended to move around during the 300F heat cure, and the paint wrinkled. Top-coating the Gun Kote with an automotive engine paint greatly improved the finish.

Finally, the fan was attached to the water pump through a machined stainless steel spacer. - Terry


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## gbritnell (Nov 16, 2021)

Outstanding work as usual Terry! Looking at the paint on your engine makes me want to tear mine apart and add some color!  
gbritnell


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## cwelkie (Nov 16, 2021)

Inspiring result Terry.  You certainly do have the painting down pat ... on top of all your other capabilities!
Charlie


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## abby (Nov 16, 2021)

Gun Kote doesn't appear to be readily available in the UK , it is out of stock at Amazon and no one else seems to supply it !


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## a41capt (Nov 16, 2021)

As your build moves along, my nostalgia increases. The more work you do, the more I miss my 1981 F-150, it’s reliable 300, and the many fishing trips and drives it took me on.

Exquisite work Terry, thanks for sharing!

John W


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## abby (Nov 16, 2021)

Love this build ! few tears ago my bro and I fitted this engine into his 2 door mk3 Cortina. Had to cut a bit off the sump to get it to fit nicely.
The result was hair raising ...............void bushes lasted a day lol.
Unfortunately Gun Kote doesn't appear to be readily available in the UK , I have been searching for a hard wearing black finish for my loco wheels without any success.
The rims are steel and the main casting is brass which is bead blasted and etch primed before finish coat .
Can anyone recommend a hard wearing finish like a gun coating that is available here in the UK ?
Dan.


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## mayhugh1 (Nov 16, 2021)

abby said:


> Gun Kote doesn't appear to be readily available in the UK , it is out of stock at Amazon and no one else seems to supply it !


Here is the link I used to order flat black Gun Kote a few weeks ago ;






						Amazon.com: KG Industries - 2400 Series GunKote - Baked - 4 oz Bottle (2401F: Flat Black) : Sports & Outdoors
					

Buy KG Industries - 2400 Series GunKote - Baked - 4 oz Bottle (2401F: Flat Black): Gunsmithing Tools - Amazon.com ✓ FREE DELIVERY possible on eligible purchases



					www.amazon.com
				




Terry


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## kvom (Nov 17, 2021)

Have you considered powder coating?


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## mayhugh1 (Nov 17, 2021)

kvom said:


> Have you considered powder coating?


Kvom,
I think powder coat would be too thick and tenacious for an application like this where tiny machined parts need to be precision fitted. Gun Kote can be laid down in a very thin layer and bead blasted away if the need arises. - Terry


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## abby (Nov 17, 2021)

Thanks for the link but like I said "currently unavailable".
Powder coating on a scale model would obliterate fine detail unfortunately , I guess I will have to stick with 2 pack acrylic !
Dan.


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## CFLBob (Nov 17, 2021)

abby said:


> Thanks for the link but like I said "currently unavailable".
> Powder coating on a scale model would obliterate fine detail unfortunately , I guess I will have to stick with 2 pack acrylic !
> Dan.



Interesting - to me that link says five in stock and delivery next Friday, the 26th.  Or I can get it this Friday, the 19th, if I want to pay more for shipping.  

Brownells has a bottle twice the size for $30 instead of $20.  Twice the quantity for 1-1/2 the price is good if you're going to use it.  The flat black isn't showing being on back order or out of stock, either. 






						GUN-KOTE OVEN CURE GUN FINISH MATTE DARK EARTH 8OZ  : BROWNELLS GUN-KOTE™ OVEN CURE, GUN FINISH | Brownells
					

GUN-KOTE OVEN CURE GUN FINISH MATTE DARK EARTH 8OZ The world-famous, ultra-thin, friction-reducing coating that lasts and lasts can now be applied to ...



					www.brownells.com
				




But Terry, that beautiful blue doesn't show up on Brownells as Gun Kote.  Where is that from?


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## Rustkolector (Nov 17, 2021)

I am another long time fan of Gun Kote 2400 baked on finish and have used it on all my engines. Great procduct especially for close fitting parts. Adhesion to aluminum and brass is excellent.  I have always ordered the 8 oz size cans directly from KG Industries. Fast service. I believe they have a Gun Kote source located in Germany. I suggest contacting KG Coatings for information. 
Jeff


			https://shop.kgcoatings.com/kg/customer-support/


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## mayhugh1 (Nov 17, 2021)

CFLBob said:


> Interesting - to me that link says five in stock and delivery next Friday, the 26th.  Or I can get it this Friday, the 19th, if I want to pay more for shipping.
> 
> Brownells has a bottle twice the size for $30 instead of $20.  Twice the quantity for 1-1/2 the price is good if you're going to use it.  The flat black isn't showing being on back order or out of stock, either.
> 
> ...


Brownells carries only a few colors. Search for 'Gun Kote 2400' on Amazon. - Terry


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## Vixen (Nov 17, 2021)

"Gun Kote" always shows as 'currently unavailable' in the UK. 
Our over-strict gun laws make it difficult for us to buy any firearm related materials. They probably think that someone buying "Gun **** " is about to go on a terrorist shooting/ killing spree. If they renamed it "Metal Kote" or something similar, importing to the stuff, into the UK, would be so much easier.


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## Doug Burkart (Nov 18, 2021)

Cerakote ceramic coating is very similar to Gunkote. It also has two formulas, air cured and oven cured.


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## Vixen (Nov 22, 2021)

Thanks Doug,
The 'Cerakote' name must be politically correct, as opposed to 'Gun**** ' and is readily available in the UK from their distribute, Cerakote UK Ltd.
They offer small 118 ml (4 oz ) tester size jars.
Mike


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## mayhugh1 (Nov 23, 2021)

I wanted to wind down for the Thanksgiving holiday by machining some standalone parts that I could fully complete. The first of these was the alternator. My camera's SD card failed and took the alternator's construction photos along with it, and so I staged a photo showing its disassembled parts. The aluminum housing was bead blasted to simulate the surface finish on the full-size casting. The armature spins in a set of inner/outer ball bearings. Its cooling fins were Alodine'd to simulate a period cad-plated finish. The steel mounting brackets turned out to be the trickiest pieces to machine. I thought I had finished the head long ago, but one last drilled/tapped hole was needed for the upper bracket. Unfortunately, the alternator's output voltage and current turned out much too low to charge the battery, and so the alternator's only real function will be to tension the fan belt.

Another of these parts was the mechanical fuel pump that I also 'cad plated'. Since I normally run electric fuel pumps on my model engines, its sole function will be a block-off plate.

The last pieces machined before Thanksgiving were a spin-on oil filter and the dip stick and dip stick tube. The filter was Gun Kote'd white to match the Motorcraft filter that was stock on the engine. - Terry


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## cwelkie (Nov 24, 2021)

Simply beautiful ...


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## propclock (Nov 24, 2021)

Outstanding details , what no printed logo on the oil filter? 
Always inspirational, thanks for posting.


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## Sparkplug (Nov 25, 2021)

Hi.  I've come late to this particular feast, I'm only a few weeks into my build, I have a basic question regarding the two helical gears for the distributor drive, is there a particular reason why they have to be a14 tooth gear?  Surely if the gears are 1:1 ratio they could be larger, say 10 teeth as these are readily available. 
Regards.


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## gbritnell (Nov 25, 2021)

Hi Sparkplug,
The gears have to be that size so they will pass through the cam bores.


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## Sparkplug (Nov 25, 2021)

Hi. George. 
         That wasn't what I was asking, it was the number of teeth, the o/d of the 10 tooth gear is 8mm. So making the bore 8mm rather than 5/16th should be fine and as the ratio is 1:1they should work okay, I was only making sure there wasn't some reason for 14 teeth that I was unaware of. 
Regards.


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## Charles Lamont (Nov 25, 2021)

The involute tooth profile for gears with few teeth (less than 12, say) gets nasty, with a lot of undercut that weakens the teeth, and, I should think, would make the skew gears tricky to cut. This can sometimes be mitigated by measures such as addendum modification but I don't think that would be applicable in this case.  A few more teeth, 14 for example, makes the tooth profile more sensible and makes for a smoother drive. On the other hand, bigger teeth (larger module or smaller DP) are stronger. In a fixed, limited space, the design choices will be a compromise. Do you hold something against 14-toothed gears?


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## gbritnell (Nov 25, 2021)

The outside diameter of the gear is based on the diametral pitch of the gear. The D.P. is 72 so the calculated O.D. is .303. Are you asking if a 10 tooth MOD. gear would work? A 10 tooth, 72 D.P. gear won't work. The cam bore could be changed to M8 (.315) but I don't see how that relates to your gear question.


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## Sparkplug (Nov 25, 2021)

Charles Lamont said:


> The involute tooth profile for gears with few teeth (less than 12, say) gets nasty, with a lot of undercut that weakens the teeth, and, I should think, would make the skew gears tricky to cut. This can sometimes be mitigated by measures such as addendum modification but I don't think that would be applicable in this case.  A few more teeth, 14 for example, makes the tooth profile more sensible and makes for a smoother drive. On the other hand, bigger teeth (larger module of smaller DP) are stronger. In a fixed, limited space, the design choices will be a compromise. Do you hold something against 14-toothed gears?


I've nothing at all against 14 tooth gears, I'm sure the vast majority lead blameless lives, but as I've only got a very modestly equipped workshop producing them would be nigh on impossible.   But I can source two 8mm diameter x 10 tooth 45 degree helical gears from Germany for 16 euros, so all I wanted to find out was the reason that 14 tooth gears were specified


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## mayhugh1 (Nov 25, 2021)

The stock bore for the cam bearings is .312" which was probably selected so a standard reamer could be used. There's enough excess block material around it so you could increase that to .320" or so (and the cam bearings accordingly) so you could use the commercial gear set you found. So long as the tooth ratio is 1:1 I would think a 10 tooth gear set would work. - Terry


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## Sparkplug (Nov 25, 2021)

mayhugh1 said:


> The stock bore for the cam bearings is .312" which was probably selected so a standard reamer could be used. There's enough excess block material around it so you could increase that to .320" or so (and the cam bearings accordingly) so you could use the commercial gear set you found. So long as the tooth ratio is 1:1 any number of terth will work. - Terry


Thanks for the vote of confidence Terry, I can't see any reason why it won't work. I suspect few engineers don't have a cnc with a forth axis as I don't know of any other way, except for a dividing head driven by a gear train from the table feed to produce these gears, so have no other choice than to use commercially available gears.


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## mayhugh1 (Nov 25, 2021)

Sparkplug said:


> Thanks for the vote of confidence Terry, I can't see any reason why it won't work. I suspect few engineers don't have a cnc with a forth axis as I don't know of any other way, except for a dividing head driven by a gear train from the table feed to produce these gears, so have no other choice than to use commercially available gears.


CNC isn't actually required. Here's how George did it using a Chuck Fellows fixture:



You can search this forum for Chuck's work. - Terry


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## Sparkplug (Nov 26, 2021)

mayhugh1 said:


> CNC isn't actually required. Here's how George did it using a Chuck Fellows fixture:
> 
> 
> 
> You can search this forum for Chuck's work. - Terry



Ingenious, I take my hat off to people who think out of the box.  But, on balance the choice between the time and effort in making the fixture and with no real guarantee that my efforts would be successful versus a set of precision gears for 18 euros, although a tough one, I think I'll go with German gears.  But thanks for posting the video, you truly do learn something new every day with this game!


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## Alec Ryals (Nov 26, 2021)

mayhugh1 said:


> CNC isn't actually required. Here's how George did it using a Chuck Fellows fixture:
> 
> 
> 
> You can search this forum for Chuck's work. - Terry




Hello,
Were can i find info on this gear cutting fixture


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## gbritnell (Nov 26, 2021)

Do a search for helical gear cutting lathe attachment.  It will come up under Chuck Fellows posting


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## Basil (Nov 26, 2021)

Very impressive! Nice to know I can make a helical gear when the need arises.


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## Alec Ryals (Nov 27, 2021)

Thank You
Unfortunately the pictures are gone ?


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## mayhugh1 (Nov 27, 2021)

Alec,
Chuck created a PDF with everything you need to know to build and use it:



			https://www.homemodelenginemachinist.com/attachments/helicalattachment-pdf.97853/
		


Terry


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## mayhugh1 (Dec 3, 2021)

Although the crankshaft and block were machined long ago, the main bearings were not. A portion of the block's machining included recesses for seven 7/8" diameter bearings. These were machined using a single g-code routine in hopes of getting them all identical and in a straight line through the center of the crankcase. Ballbearings were installed in the two outside recesses, but the five inner ones have been awaiting two-piece bronze bearings.

Their machining began by turning work-holding spigots on the ends of a pair of SAE660 rounds. Each was sized for five bearing halves plus a spare, and their o.d.'s were turned to what will be the finished diameter of the bearings. One of these blanks, used for the halves that will be mounted inside the recesses, was marked for later return to the lathe in its same orientation.

After careful setup on the mill, half the diameter of each blank was machined away. The two workpieces were then clamped together with hose clamps while the hole pairs for the bearings' mounting bolts were drilled, counterbored, and temporarily tapped. With the workpiece halves joined together with temporary screws, the assembly was returned to the lathe where the through-hole for the bearings' i.d.'s was drilled and reamed.

When the crankshaft was machined, its two outer journals were turned just under .375" for their fits inside the ball bearings. The inner journals, although identical, wound up slightly elliptical with cross-measured diameters of .366"/.367" resulting from unavoidable flex during machining. To compensate for these errors and to provide adequate clearance in the engine's pump-less splash oil system, a .370" reamer was run through the assembly before the bearings were parted from it.

After parting, but before separation, each bearing half was engraved with locator numbers to avoid mix-ups during assembly. In addition, an oil collection slot was machined into each bearing's top half to aid lubrication. After reaming out the threaded holes for mounting bolt clearances, the bearings were installed and test fitted one-by-one.

I'm not a fan of brute-force spinning a tight crankshaft with an external power source until it 'loosens up". Instead, the fitting was done by bluing and scraping each bearing and/or machined recess as needed. This was a tedious process that required some dozen hours and something I'd put off as long as possible.
Rather than begin fitting using the actual crankshaft, I started with a .375" diameter test bar whose diameter between ends had been carefully turned down to .368". This diameter was chosen to arrive at a fit that would hopefully allow the crankshaft to be dropped in with minimal cleanup.

My initial plan was to fit the bronze bearings one-by-one to the test bar with it installed in the ballbearings. However, I discovered four of the five mounted bearings had actually come out as hoped and would require minimal work if the front ballbearing was instead lowered .0015" by scraping its recess. So, I ended up first fitting the five bronze bearings to the bar without the ball bearings and then fitting the front ballbearing to the bar.

With all the scraping/polishing completed, the crankshaft actually did drop in as hoped. When turned by hand without the ballbearings, the .001" errors in all five of the crankshaft's dry egg-shaped journals could be felt as tiny 'bumps' telling me the fits were as good as I could expect. Squirting a drop of oil into the oil collection slots made the bumps all but disappear. Installing the ballbearings totally eliminated them.

I've never found the fitting of a multi-cylinder crankshaft to be satisfying. Regardless of the steps taken to stiffen a long skinny crankshaft during its machining, there's always a bit of flex that leaves circularity errors in its lathe-turned journals. And these errors invariably limit the quality of the bearing fits. It could be argued that unless the journals are ground, some variation of the brute force fitting technique is good enough. I've spent a small fortune on tool post grinders though and still don't have a usable solution for crankshafts running on my lathe. - Terry


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## gbritnell (Dec 4, 2021)

Very nice Terry! I like what you did with the bearings. I agree with you on the task of machining and fitting crank to bearings. Not my most enviable process!


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## CFLBob (Dec 4, 2021)

One question, Terry:  is that brass or bronze bar in the top picture ("Sanity checking...") the 0.875' diameter you mentioned and the same as the one in the lathe?  

Just to confirm I understand.


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## mayhugh1 (Dec 4, 2021)

CFLBob said:


> One question, Terry:  is that brass or bronze bar in the top picture ("Sanity checking...") the 0.875' diameter you mentioned and the same as the one in the lathe?
> 
> Just to confirm I understand.


Yes, they're one and the same. - Terry


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## mayhugh1 (Dec 13, 2021)

The connecting rods were machined from 7075 aluminum. Since there aren't any sleeve bearings, the rod journals and wrist pins turn directly in the aluminum. The rods were machined integral with their caps in two-piece workpieces temporarily held together with the rod bolts. A few extra bolts were added to ensure the workpiece halves remained safely together after the rods were cut completely free of it.

The only 7075 material I had on hand required laying the rods out perpendicular to the material's rolled direction. I wondered if this orientation might compromise the rods' tensile strength, but I found an online white paper with experimental results showing less than a 5% loss in strength. 

The rod machining was done in cookie sheet fashion with two batches of four rod/caps per batch. Workpiece preparation included care to minimize registration errors when they were flipped over for their second face machining. Each rod/cap pair was engraved with matching numbers to avoid mixing parts during assembly.

The rod bolts were protected during machining by temporarily modifying the cap design with extra added material. This additional material hid the bolts from the CAM software which would otherwise have cut them into chips. It was removed later in a separate setup.

After machining the top faces of the rod/cap pairs in each batch, the troughs left around them were filled with Devcon 5 minute epoxy and allowed to cure for several hours. This epoxy kept the rod/cap pairs safely attached to their workpieces during their bottom face machining. While still hot, the finished parts released cleanly from the Devcon after a half-hour oven bake at 225F.

A drip oil passage drilled through the top end of each rod should help with wrist pin lubrication. The assembled rods and caps were bead blasted before finally finishing the caps. A simple fixture helped with the consistency of these operations.
































The rods were fitted to the rod journals with the same bluing and scraping technique used on the main journals. Unfortunately, the crank's four inside rod journals had nearly the same .001" circularity errors found on the main journals. Since the rod journals don't turn a full 360 degrees inside the rods, their final fits were a bit closer. - Terry


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## djswain1 (Dec 15, 2021)

CFLBob said:


> One question, Terry:  is that brass or bronze bar in the top picture ("Sanity checking...")


Hi Bob  Terry mentioned he used SAE660 which I googled:
SAE660 or C93200 is a Leaded (Tin) continuously cast bronze and is a standard in the industry for light/medium bearing applications. Leaded (Tin) Bronze SAE660 or C93200 is suitable for various applications under medium loads.
Cheers, Dave.


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## djswain1 (Dec 15, 2021)

Those conrods are tiny.. excellent work I like the epoxy technique as well


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## mayhugh1 (Dec 21, 2021)

Piston machining began with four workpieces turned from scrap-box drops of 6061. Each workpiece was a pair of piston blanks with a work-holding spigot between them, and both ends were faced and turned to the pistons' final diameter. In hindsight, the workpieces would have been more useful had the piston bottoms rather than the tops been at the ends of the blanks.

Several changes were made to the original piston design. They were lengthened to increase by a couple points the 5+ compression ratio estimated by my modeling. A third groove was also added to the two ring design to help with oil control.

During a downstroke, the piston's bottom ring is expected to scrape oil from the cylinder wall. Oil accumulated in the clearance space between the piston and cylinder wall tends to resist this scraping, and some of it will get by the bottom ring especially if the top ring is doing its job and completely sealing the combustion chamber. Some of the oil trapped between the two rings can find its way into the combustion chamber. Although a little oil is desirable for lubrication, too much will cause a smoky exhaust and plug fouling.

If a groove is cut around the piston just below the bottom ring, the scraped oil will be provided another evacuation path, and the bottom ring won't have to work as hard. Since a single downstroke will most likely fill this groove, holes drilled through it can direct the oil into the interior of the piston where it may even help with wrist pin lubrication. Oil control grooves aren't new, and I've used them on a few other engines. After a few calculations, though, I've realized the typically used eight drain holes may be woefully inadequate. For these pistons I used eighteen .050" holes.

A collet block and vise stop were set up on the mill to drill and ream the wrist pin holes through the eight candidate pistons. It was important that these holes be precisely perpendicular to the pistons' axes to prevent binding inside the cylinder and accompanying rod bearing wear. The blank was then moved back to the lathe where the three grooves were cut. An extra thousandth was also taken off the piston's diameter above the top ring. From the ring calculations, the widths and depths of the grooves were selected to provide .001" ring clearance and .006" behind each ring. The oil groove was .050" wide. After machining the pistons' interiors a rotary was set up, and eighteen equally spaced drain holes were drilled through the oil groove using a carbide circuit board drill.































The wrist pins were machined from drill rod but not hardened. Their ends were drilled and aluminum rivets pressed in to protect the cylinder walls from scouring. The piston ring dimensions have been calculated, but they will be machined later. - Terry


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## propclock (Dec 21, 2021)

Again Thanks for posting. I truly appreciate the time you take to show your expertise.


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## e.picler (Dec 22, 2021)

Terry,
This is really a state of the art work. One more extraordinary engine building from you. Congratulation!!!!
Edi


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## mayhugh1 (Dec 31, 2021)

Piston Rings Part 1.

I follow George Trimble's method when making my piston rings. The only change I've made to the process published in his original S.I.C. articles is to use a three hour 975F normalization rather than the 1475F he recommended. In addition, I light test each ring before it's installed.

My yields have typically been limited by circularity errors that show up in the finished blanks just before slicing rings from them. I use class 40 gray cast iron drops from a variety of sources accumulated over the years. I've measured circularity errors as high as eight tenths over portions of some of my blanks, and these errors have sometimes shown up days after being finished. Sometimes less than half of a blank passes my acceptance criteria of two tenths, and occasionally an entire blank was discarded. Once a ring has been sliced from a blank, it's nearly impossible to evaluate without being fully finished and light-tested. After harvesting rings from well-behaved portions of the blanks, my light-tested yields have typically been 80%-90%.

When starting a large batch of rings, I often prepare more than one blank. Even though only a dozen rings plus spares were needed for this engine, I prepared two blanks with enough total candidate material for some 60 rings. Starting with one inch raw material, the finished diameter of the blanks (and therefore the ring diameter) was .748". At a ring thickness of only .032" and .019" width, I was initially concerned with their strength and their tendency to break during installation. After a few tests though I found them to be quite flexible and very easily to install. George was also concerned about their fragility and increased the thickness of his rings to .044" and their widths to .031".

The candidate areas of the blanks were drilled/bored to their finished i.d.'s after being roughed down to .780" diameter. In order to help relieve any remaining casting stresses and minimize circularity errors, the semi-finished blanks received an eight hour 700F heat soak. This step isn't part of Trimble's process but seemed to improve the yields in my last two builds.

A day later, the blanks' o.d.'s were turned and polished with 400g paper to their final diameter plus/minus a tenth. After being allowed to 'settle out' over the holidays, their final circularities were checked using three quadrature measurements along their lengths. One blank showed no errors and had enough material for 30 candidate rings. About a third of the second blank showed errors approaching four tenths but had enough 'good' material for some 25 rings.

I began by slicing rings from the second blank. Flashing was removed and the inside corners of the parted rings broken using a 1/4" diameter hard ceramic file. The flat sides were then lapped for a .001" piston groove clearance using a simple shop-made fixture and 600g grinding grease on a glass plate. Fine finishes on these surfaces are important because their seal with the lower walls of the pistons' grooves is an important component of the combustion chamber's total seal.
The Trimble article recommends a straight radial break in each ring for proper contact with the spreader dowel in the heat treating fixture. Although 'good enough' results might be achieved by simply snapping the rings, I constructed a single purpose cleaver several years ago. Just before heat treating, each ring was cleaved and the running gap set to .004" with a diamond file. The gaps were verified inside a (spare) honed liner machined along with the original six block liners.

Since I (hopefully) had more than enough candidate rings from the first blank, I didn't slice any from the second finished blank.






























blank. - Terry


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## minh-thanh (Dec 31, 2021)

Hi  Terry  !


mayhugh1 said:


> . In order to help relieve any remaining casting stresses and minimize circularity errors, the semi-finished blanks received an eight hour 700F heat soak. This step isn't part of Trimble's process but seemed to improve the yields in my last two builds.



Can you explain more ?
Thanks !


----------



## mayhugh1 (Dec 31, 2021)

Minh Thanh,
Well, I'm not sure what else I can add. Some cast iron is left with residual internal stresses after being cast and cooled, and these stresses can cause a part to distort as it's being machined and these stresses relieved. I don't know if it's true, but I've read that some machine manufacturers allow their castings to 'age' as much as a year before they're finally machined. I started heat soaking my ring blanks before finally finishing them in hopes of speeding up the aging process. My temperature and time probably aren't sufficient, but I figure the heat soak can't hurt. Although I have no firm evidence that it makes a difference, it did seem to help reduce the circularity errors in the rings in my last two builds. In addition to the heat soak, I also took advantage of the holidays and allowed the blanks to 'age' for nearly a week after the heat soak before slicing off the rings. After all that, a portion of one of the blanks wound up changing what I would call 'too much' after all. - Terry


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## minh-thanh (Dec 31, 2021)

Terry !
Thanks for sharing your experience !
I will try
Thanks !


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## xpylonracer (Jan 1, 2022)

Thanks for the description Terry but could you please provide some detail of the construction and operation of the Cleaving Device ?

xpylonracer


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## Peter Twissell (Jan 1, 2022)

Thanks for a comprehensive description and photos, very useful.
I wonder whether the blanks would remain more stable if they were of more consistent section, i.e. without the significantly larger diameter and wall thickness at the chucking end.


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## gld (Jan 1, 2022)

_"I light test each ring before it's installed."_

Hi Terry,

How do you perform this light test, and what are you looking for?

Thank you for taking the time to post the progress of your builds. 

Gary


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## mayhugh1 (Jan 1, 2022)

xpylonracer said:


> Thanks for the description Terry but could you please provide some detail of the construction and operation of the Cleaving Device ?
> 
> xpylonracer


Xpylonracer,

As you can see from this view looking down on the cleaver, it is made up of two HSS cutting tools that slide in a slot. The ends of the cutting tools have been ground to 60 degree angles, and they have been shimmed to precisely align. The ring is placed in the cross slot and the top screw is adjusted so the top cutting tool is in contact with the ring's back face which is also in contact with the wall of the cross slot. This one time adjustment prevents the ring from twisting during the cleaving process. The ring is cleaved by turning the bottom screw which drives the bottom cutting tool into the ring.  - Terry


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## mayhugh1 (Jan 1, 2022)

gld said:


> _"I light test each ring before it's installed."_
> 
> Hi Terry,
> 
> ...


Gary,
I'm working on that right now and will post a Part 2 soon. - Terry


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## mayhugh1 (Jan 1, 2022)

Peter Twissell said:


> Thanks for a comprehensive description and photos, very useful.
> I wonder whether the blanks would remain more stable if they were of more consistent section, i.e. without the significantly larger diameter and wall thickness at the chucking end.


Peter,
One thing I've learned along the way is that the workholding spigot needs to be solid and some distance away from the candidate ring material. If not, the lathe chuck, even a collet chuck, can distort the adjacent candidate material. Even though the machined blank might indicate perfect while chucked, circularity errors can show up after it's taken out of the chuck. - Terry


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## Peter Twissell (Jan 1, 2022)

Thanks Terry.
I have machined thin walled tubular parts which had to be chucked for subsequent operations.
For those parts, I made a light push fit plug which would support the tube to prevent distortion when gripped in the chuck.
The plug was pushed out of the part after machining and could be re-used for the next part.
The parts were stainless steel. I'm not sure the process would work with cast iron and perhaps it's just not worth the fiddle!
Pete.


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## kuhncw (Jan 1, 2022)

Terry, what are the holes or divots in the ends of the HSS cutting tools in your ring cleaver. 

Thanks.

Chuck


----------



## mayhugh1 (Jan 1, 2022)

kuhncw said:


> Terry, what are the holes or divots in the ends of the HSS cutting tools in your ring cleaver.
> 
> Thanks.
> 
> Chuck


Chuck,
They are divots. The adjusting screws move the cutters forward, but since they're not spring loaded some method is needed to pull them back. The divots provide a place to grab them. The one in the top cutter really isn't needed, but the bottom one is used after cleaving (if that's even a word). - Terry


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## xpylonracer (Jan 2, 2022)

Terry
Thanks for the details of the Cleaving device.

xpylonracer


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## Charles Lamont (Jan 2, 2022)

Terry, have you tried the Chaddock method, in which the last operation on the rings is a shave off the OD to final size?

IMHO that would eliminate the preliminary heat treatment, blank roundness, light testing, and much of the high scrap rate.


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## mayhugh1 (Jan 2, 2022)

Charles Lamont said:


> Terry, have you tried the Chaddock method, in which the last operation on the rings is a shave off the OD to final size?
> 
> IMHO that would eliminate the preliminary heat treatment, blank roundness, light testing, and much of the high scrap rate.


Charles,
I tried that technique more than a dozen years ago on my very first engine - the Howell V-twin. I was just learning to machine at the time and don't recall the details right now, but I do remember struggling with its fixturing requirements. I shifted over to Trimble's method on my next engine. I probably need to take another look at it. Plenty has changed since those days. - Terry


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## dnalot (Jan 2, 2022)

mayhugh1 said:


> cleaving (if that's even a word)



I think cleaving is the act of creating cleavage but I'm not certain of that. I mean I don't know that as a fact I just know its true.

Mark T


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## Ghosty (Jan 2, 2022)

Here you are, straight out of the dictionary.
Cheers
Andrew


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## mayhugh1 (Jan 2, 2022)

Piston Rings Part 2.

The Trimble articles describe the construction of a special purpose fixture required to support the rings during their heat treatment. Equations were provided for the dimensions of a mandrel and spreader dowel which are its key components. This fixture isn't difficult to make, but its dimensions are specific to a particular ring diameter, and this one was my fourth.

In the past, I've enclosed the fixture'd assembly in an argon-filled stainless steel foil bag order to protect the rings from scale deposits during heat treatment. After a number of builds I realized that scale build-up really wasn't a problem in the controlled temperature environment of an oven, but mysterious deposits continued to show up on the rings even when they were bagged. Typically, minor burnishing with a white Scotch Brite pad was enough to remove them while still supported on the mandrel.

Initially I suspected the deposits were lead coming out of the 12L14 that I typically used to machine the mandrel, but switching to 1020 didn't eliminate them. I didn't bag the Ford rings, but I machined the fixture from 303 stainless and thoroughly cleaned it and the rings with acetone before heating.

The fixture'd rings were heat soaked at 975F for three hours and allowed to cool overnight. Those pesky black deposits showed up again but only on the rings themselves and the spreader dowel which was a length of drill rod. The stainless steel mandrel, bolt, and nuts remained clean and shiny. This makes me wonder if those deposits are actually carbon coming out of solution from the cast iron and, this time, also out of the high carbon alloy of the drill rod.

Although they were easily burnished from the ring surfaces while still on the mandrel, this time the rings were stuck fast together. This wasn't at all unusual, but in the past the rings were easily separated with a sharp Xacto knife (starting from the ring gap). I didn't account for the rings' smaller areas when I tightened the mandrel bolt to clamp everything together, and this time probably got it too tight. Eventually, I got them apart, but I had to reheat the stack (sans mandrel) to 400F to do it.

After separation, their faces were lapped one last time on a glass plate using 1000 grit grease. After a thorough cleaning in solvent, their outside surfaces were individually burnished with a Q-tip in a lame attempt to polish them free of any remaining deposits.

The final step was to sort the rings by light testing them. A simple fixture was turned from black Delrin to adapt a 200 lumen flashlight to the bottom end of the spare liner inside which each ring was checked. Admittedly, my grading/acceptance criteria is pretty subjective, but it's kept particularly poor rings out of my engines.

The tests were done in a totally dark room where, ideally, light should only be seen escaping through the ring gap. Such rings received an "A" grade and will become the top compression ring in each cylinder. With all the machining and measuring uncertainties that can creep into the numerous process steps while trying to work within tenths, A's can be tough to get. Out of 23 rings, I wound up with only 6.

Rings that showed faint wisps of light leakage between the ring and cylinder wall were graded "B". My guesstimate is that the imperfections in these rings were due to circularity errors on the order of a few tenths and might even be a result of remnant deposits. These rings will likely bed into their cylinders during the first few several seconds of running (or maybe even during starting). I wound up with 8 of these, and they're destined for the pistons' second groove.

The "C" rings were saved as spares. Relative to the B rings, their leakages were noticeably brighter and were perhaps due to circularity errors that slipped through my process. More likely, however, they're a result of mishandling after being sliced from the blank. I wound up with 9 of these.

I should add that none of these C rings showed enough leakage through the ring'd test cylinder to be seen in daylight only. Whether or not they would have been 'good enough" for use is anyone's guess, but their grade will keep them out of the engine unless there's an installation catastrophe with the A's and B's.

Since I had more than enough A and B rings to cover my needs (and since I really don't enjoy making rings), the number one blank wasn't processed any further. The finished rings will be installed when the head is finally assembled to the block.

I have to say that even though the quality of the starting blanks was on par with what I've come to expect during my other builds, the quality of the finished rings was disappointing. Out of 23 completed rings, I expected to have some 15 A's and maybe 1 or 2 C's. My relatively poor yield may have been related to the tiny dimensions of these rather fragile rings. Compared with the hundreds of 1"+ rings I've made, these smaller more flexible rings were difficult to work with and seemingly more susceptible to handling damage especially while removing those #@% deposits. - Terry


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## minh-thanh (Jan 3, 2022)

Hi Mayhugh1  !
I think...maybe this affects your ring





When I fix the rings on the fixture, I usually press lightly - Bolts just keep the rings in place. then, the surface of the rings is usually flat before and after firing - or at least nearly flat . And it seems to make the rings better


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## awake (Jan 3, 2022)

Excellent as always - the pictures of your ring testing fixture was particularly helpful!


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## dnalot (Jan 3, 2022)

When I built my Holt I made my rings as you did and I made an interesting observation. Before heat treating I wrapped the rings with thick paper and secured it with scotch tape. I then covered the fixture with the rings with very fine "olivine" sand to help reduce the oxygen around the rings. I figured the paper would use up whatever oxygen was near the rings. The area that was covered with paper and scotch tape had very little carbon build up and it was these rings that turned out best. 

Mark T


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## Rustkolector (Jan 3, 2022)

Brownells sells a water based anti scaling coating that I have used with success. Its hot working range is 1000 -2300 F which is probably close enough to your heat soak range. When used the rings come out a uniform gray color after washing in hot water.  
Jeff


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## L98fiero (Jan 4, 2022)

Rustkolector said:


> Brownells sells a water based anti scaling coating that I have used with success. Its hot working range is 1000 -2300 F which is probably close enough to your heat soak range. When used the rings come out a uniform gray color after washing in hot water.
> Jeff


Here is a formula I got off a blade forum, can't remember which or I'd give the poster credit.

5oz boric acid (roach powder)
3oz borax ( 20 mule team is fine)
8oz denatured alcohol ( the cheap paint store variety, not the drug store stuff)
2oz satanite ( our old refractory friend)
3-4oz ocher (any color ocher - finely sifted dried red clay would probably work)
3-4oz gum tragacanth ( bottle of leather edge dressing)
water

Mix,adding additional alcohol until it becomes a well mixed thick paste.Add water until it becomes a slurry ( I think it needs some water to allow proper hydration and solution of some ingredients). Try it on a piece of steel to check results, and adjust the ingredients as needed. Keep in a tightly capped container,away from heat. Shake well each use, and paint it on with a small brush, or dip the blade and let the excess run back into the container. A batch should last for a long time.

Do not use above 1600F as the borates will become corrosive.


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## mayhugh1 (Jan 17, 2022)

The bell housing should be a fun part to machine and, never having done one before, I've been looking forward to it. My hope since the beginning of this build has been to replace the faux starter in the original design with an electric motor.

My quarter scale Knucklehead's cranking requirement of 320 oz-in (23 kg-cm) was handled by a geared motor running through a one-way clutch. That motor was large for the scale of the engine, but a significant portion of it and its running gear were hidden inside the crankcase. Assuming a similar requirement for the fifth scale Ford and a 4:1 gear reduction from its ring gear, the motor would need to supply some 80 oz-in or 6 kg-cm.

A standard 22 mm (dia.) dc motor would be a perfect fit on the Ford, and George's bell housing could be easily adapted to it. However, published data on these motors show their torque to be hopelessly low even at stall.

A 390 size motor which is a little large for the engine's scale is the biggest I'd want to mount on its bell housing. Unfortunately, data on these motors show their torque is too low as well. However, there are some intriguing Youtube videos showing the (now defunct) Conley quarter scale V-8's being started with what might be a 390 brushed motor. I haven't been able to get an accurate enough estimate of its diameter to be really sure though.

A 550 or 750 size motor could be made to work, but their huge diameters would look out of place on the engine. A motor this size would be best hidden under the engine's display stand while driving it through a chain and sprocket. I spent nearly two weeks trying to come up with a configuration I'd be willing to live with, but in the end decided I'd rather drill-start the engine than mount it on top of a box.

Robotic parts suppliers (as well as Jameco), provide speed-torque data for their motors to help customers make informed selections. There's also an industry that supplies motors to RC enthusiasts that have been performance tuned using the armature wire gage. These suppliers use the actual number of wire turns on the armature segments of their brushed motors in order to compare them. I haven't a clue as to how to convert Turns to oz-in.

I ordered a couple of these 'performance' 390 motors to just try them. I chose 24 and 32 Turn motors for a relative comparison. I figured the best motors would be those marked with warnings about not being toys and cautions about dangerous hot surfaces.

Orders for 'in stock' motors were placed a few months ago from two different domestic suppliers. These motors are all manufactured in China, and so the first thing I received was schooling about a new definition of what 'in stock' can mean nowadays. After a few weeks I inquired as to why the motors hadn't shown up and was told their 'in stock' motors were in stock 'in the supply chain.'

Eventually they arrived, but before starting on the bell housing I wanted to do some testing. I did machine the engine's flywheel, however, and to be safe included both a ring gear and a socket for a drill starter. For my ballpark testing, each motor under test was fitted with a pinion gear, and both it and the flywheel were mounted to a heavy plate.

in the first test, the 83 tooth flywheel was driven by the 32 turn motor fitted with a 20 tooth pinion gear. I powered the 7.5 volt motor with a 12 volt sealed lead acid battery, and the test was performed by using the motor to lift a dead weight attached to the flywheel. The measured stall torque referred to the motor's shaft turned out to be 96 oz-in. This was a healthy although unsustainable improvement over the 20 oz-in typically advertised for 390 motors but was an indication that a 390 motor was not going to work.






















Another seat-of-pants test was to slow down the free spinning flywheel with my hand and compare the load on my hand with the felt torque needed to spin the flywheels on both my Knucklehead and Howell V-8. The results were clearly definitive and very disappointing. And so before finally getting the bell housing, I have some thinking to do. - Terry


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## dsage (Jan 17, 2022)

Terry:
Have you researched Brushless DC motors (called BLDC) and their torque?


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## mayhugh1 (Jan 17, 2022)

dsage said:


> Terry:
> Have you researched Brushless DC motors (called BLDC) and their torque?


Dave,
No, I didn't look at them for this build, but I did for the Merlin. I still have the motors and controllers I bought when I looked at them for that project. If I remember correctly, there wasn't much advantage over brushed motors for a starter application and the peripheral electronics added more stuff to hide. - Terry


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## dsage (Jan 17, 2022)

Ok. I figured you would have checked them out. I assumed they had a lot more torque for a comparable size.
Good to know.
Thanks


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## petertha (Jan 17, 2022)

I wonder if a planetary gear drive might help. It adds more length but diameter stays within the motor can OD. Another site I was on had the rpm/torque curves, this one just has the nominal specs. Yes an RC (brushless) setup is more peripheral stuff; ESC, throttle control... & likely more expensive for what you require.





						Planetary Gear Motors - RobotShop
					

Planetary Gear Motors and other robot products. At RobotShop, you will find everything about robotics.




					www.robotshop.com


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## mayhugh1 (Jan 17, 2022)

petertha said:


> I wonder if a planetary gear drive might help. It adds more length but diameter stays within the motor can OD. Another site I was on had the rpm/torque curves, this one just has the nominal specs. Yes an RC (brushless) setup is more peripheral stuff; ESC, throttle control... & likely more expensive for what you require.
> 
> 
> 
> ...


Peter,
It was one of those very geared motors I used on the Knucklehead. I thought long and hard about using one of the ones I still have on hand. But, they're not only 550 size motors but with the planetary drive they would stick out past the front of the Ford engine. - Terry


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## Charles Lamont (Jan 18, 2022)

I did some experiments with a small motor and several different ratios of Meccano gears to crank the Westbury Seagull. I found that for that engine and the chosen motor, the best ratio was 50:1. Partly written up at Seagull Engine Construction Diary - Starter but although the gearbox is almost complete and has been tested, I am afraid the 'diary' write-up has mostly caught up to 2017. The gearbox model I recently posted under another thread, but here it is again: https://www.homemodelenginemachinist.com/attachments/starter-gearbox-pdf.132891/


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## Arild (Jan 18, 2022)

mayhugh1 said:


> The bell housing should be a fun part to machine and, never having done one before, I've been looking forward to it. My hope since the beginning of this build has been to replace the faux starter in the original design with an electric motor.
> 
> My quarter scale Knucklehead's cranking requirement of 320 oz-in (23 kg-cm) was handled by a geared motor running through a one-way clutch. That motor was large for the scale of the engine, but a significant portion of it and its running gear were hidden inside the crankcase. Assuming a similar requirement for the fifth scale Ford and a 4:1 gear reduction from its ring gear, the motor would need to supply some 80 oz-in or 6 kg-cm.
> 
> ...


Hi, what you also can do is to open up the brush-motor and re-wind with a much thicker copper wire. This will dramatically increase the torque! They can not run long time, because the motor brush will melt (normally held in place with plastic). But for a start motor it's ok.


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## mayhugh1 (Jan 18, 2022)

Arild said:


> Hi, what you also can do is to open up the brush-motor and re-wind with a much thicker copper wire. This will dramatically increase the torque! They can not run long time, because the motor brush will melt (normally held in place with plastic). But for a start motor it's ok.


I think that is what's done to create what's called a lower Turn motor. I believe the armature space is always filled with wire. - Terry


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## mayhugh1 (Jan 18, 2022)

Charles Lamont said:


> I did some experiments with a small motor and several different ratios of Meccano gears to crank the Westbury Seagull. I found that for that engine and the chosen motor, the best ratio was 50:1. Partly written up at Seagull Engine Construction Diary - Starter but although the gearbox is almost complete and has been tested, I am afraid the 'diary' write-up has mostly caught up to 2017. The gearbox model I recently posted under another thread, but here it is again: https://www.homemodelenginemachinist.com/attachments/starter-gearbox-pdf.132891/


Yeah, I agree my paltry 4:1 rear ratio is a big part of my problem. I can't get the motor close enough to the ring gear for a smaller pinion and higher ratio. An additional gearbox is really needed but I'll want it inside the bell housing which makes the design difficult. Also, by the time I add a couple more gear meshes, a one-way driving clutch becomes a necessity, and then I have something else to stuff into the bell housing. - Terry


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## srobovak (Jan 18, 2022)

Hi Terry,
What's the black box mounted on the very right of the holding plate close to the switch?
Thanks


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## propclock (Jan 18, 2022)

How about putting the starter in the transmission through a 1 way bearing, as in ,shrink your drill starter
inside the soon to be cnc'd transmission?


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## awake (Jan 18, 2022)

Hmm ... I wonder if the motor and planetary out of a cheap cordless drill (e.g., Harbor Freight or equivalent) would be small enough but powerful enough for the purpose?


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## mayhugh1 (Jan 18, 2022)

srobovak said:


> Hi Terry,
> What's the black box mounted on the very right of the holding plate close to the switch?
> Thanks


It's a relay to handle the motor current.


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## Arild (Jan 19, 2022)

mayhugh1 said:


> I think that is what's done to create what's called a lower Turn motor. I believe the armature space is always filled with wire. - Terry


Yes, correct, thicker wire result in less turn tu fill up the space. I've done this on R/C car-motor, and it make a huge change in torque!


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## Bentwings (Jan 19, 2022)

Arild said:


> Hi, what you also can do is to open up the brush-motor and re-wind with a much thicker copper wire. This will dramatically increase the torque! They can not run long time, because the motor brush will melt (normally held in place with plastic). But for a start motor it's ok.


 also race cars use a drawn or spun round bell housing to protect against clutch explosions so possibly you could simulate this out of bar stock aluminum technically those aren’t race legal but would look great on your motor. If you are creative you could make a starter pocket just like the full size cnc would be crazy cool otherwise I’d probably weld or bolt the thing in . We used to rewind slot car motors like noted there were a few real scale smoky melt downs. Otherwise read up on stepper motor conversions. I have at least half a dozen I’ll drive with generated power from my new steamer when it’s operational stepper can have a lot of torque for their size you may need a driver to use an un modified one . I’m really new to them so I have to side step here as I’m on unstable ground LOL. Motor is great


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## mayhugh1 (Jan 27, 2022)

My final candidate for a 390 ring gear starter was a Nichibo MD5-2445. This 12 volt motor was selected from Jameco's published inventory of 66 motors with comprehensive specs. Although its speed/torque data wasn't encouraging, I was curious to see how it performance would stack up against the 7.5 volt RC aftermarket motors recently tested. It was worth trying since the smaller Ford might be happy with a lower cranking rpm and not require the entire 50 watts in my original starter requirements. Unfortunately, testing showed it was considerably less powerful.

Although they fell short of my requirements, the RC aftermarket motors did appear to deliver more power than specified for same size generic motors. I'd hoped to get additional short term performance from them using 12 volts but ended up damaging their commutators after only a few minutes at moderate loads.

With only a 4:1 ring gear reducer, cranking loads will drag the operating point of a 390 motor into territory where internal dissipation literally kills it. Additional gear reduction is needed so the required torque is available with the motor running at a more efficient operating point. This doesn't mean though that it won't have to deliver the required 50 watts of mechanical power, and this doesn't seem feasible for a 390 brushed motor. If the RC motors had been able to handle 12 volts, additional off-board gear reduction might have gotten them near the ballpark.

I considered hiding a 550 gear motor inside a faux transmission housing as suggested by Propclock, but it also wound up well outside the scaled envelope of the engine. (A quarter scale engine would be much easier to work with.) I finally gave up and decided to drill-start the engine after all.

So, a bell housing for a faux starter was machined. I started with George's design but modified it to enclose the entire flywheel. Construction began with squaring up a 6061 workpiece. The bell housing's interior was machined first and included drilling and temporary tapping the housing's mounting bolt holes. The interior was temporarily packed with clay for vibration control and then mounted to a fixture plate. With full access to the workpiece's outside surface, the bell housing's exterior could be machined. A final operation machined the clutch fork opening in the side of the housing. Total machining time was about 6 hours. Finally, the entire bell housing was bead blasted to simulate the surface of an aluminum casting. A machined cover plate and faux starter motor will wrap up this portion of the build. - Terry


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## propclock (Jan 27, 2022)

Beautiful ! I need a bead blaster. How do you mask the flat machined parts as in the webs?
Always inspiring.


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## mayhugh1 (Jan 27, 2022)

propclock said:


> Beautiful ! I need a bead blaster. How do you mask the flat machined parts as in the webs?
> Always inspiring.


Thanks. They weren't masked - just sanded after bead blasting. - Terry


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## propclock (Jan 27, 2022)

Thanks that makes sense.


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## Eccentric (Jan 27, 2022)

Beautiful as always Terry.  How did you index the part when you flipped it over from the inside machining to the outside machining? Did you simply touch off the the edges of the squared off workpiece?

Greg


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## mayhugh1 (Jan 27, 2022)

Eccentric said:


> Beautiful as always Terry.  How did you index the part when you flipped it over from the inside machining to the outside machining? Did you simply touch off the the edges of the squared off workpiece


Thanks. The holes in the fixture plate were drilled using the same code that drilled the mounting holes in the bell housing during its internal machining. The center hole through the housing was done at the same time. Once the part was flipped and mounted to the plate, the center through hole was used to reference the part for the outside machining. - Terry


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## kvom (Jan 28, 2022)

I saw George's engine again at CF;  it's a lot smaller than I had thought when following this build.


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## Ram50V8 (Jan 28, 2022)

I have been following this build from the beginning since I do love the old 300 Fords. As it happens I have a complete 300 EFI motor and drive train sitting next to me. The typical ring gear count would be 164 tooth with a 9 tooth starter pinion giving a ratio of 18.2 to 1.


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## mayhugh1 (Jan 28, 2022)

Ram50V8 said:


> I have been following this build from the beginning since I do love the old 300 Fords. As it happens I have a complete 300 EFI motor and drive train sitting next to me. The typical ring gear count would be 164 tooth with a 9 tooth starter pinion giving a ratio of 18.2 to 1.



When I first started this project and before doing any math, I was assuming I'd have a 20:1 ring gear reduction available to me. It wasn't until I started designing actual parts that I realized that with a 2" diameter flywheel, the pinion would have to be some .1" in diameter to get that much reduction. By the time all the other real world issues were accounted for I was left with a paltry 4:1, and I knew I was in trouble. - Terry


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## Peter Twissell (Jan 28, 2022)

I don't suppose your flywheel is thick enough to fit a planetary gear inside it, arranged to drive the ring gear at 4 or 5 times the flywheel speed, with a roller clutch in the sun wheel, so that the whole lot runs at crank speed when not driven by the starter?


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## Eccentric (Jan 28, 2022)

Peter,

It is hard to realize how small this engine really is.  Look back at the last batch of pictures Terry put up. In one he has a one/two/three block clamped to the work piece for vibration dampening.  The one/two/three block looks huge next to the bell housing.   I can't imagine getting anything inside of it but a flywheel.


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## mayhugh1 (Jan 28, 2022)

Peter Twissell said:


> I don't suppose your flywheel is thick enough to fit a planetary gear inside it, arranged to drive the ring gear at 4 or 5 times the flywheel speed, with a roller clutch in the sun wheel, so that the whole lot runs at crank speed when not driven by the starter?


That's pretty clever. I need to think about it. The current flywheel isn't thick enough, but a new one could be made thick enough. - Terry


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## mayhugh1 (Feb 1, 2022)

A bell housing cover plate was designed and machined to fully enclose the flywheel. After broaching the flywheel for the crankshaft key, the 83 tooth ring gear that I'd hoped to become part of a functional starter was covered up. I staged a photo of one of my 390 test motors sitting in the bell housing as a memento of the weeks spent trying to bend reality. Work then began on it cosmetic replacement that turned out to be rather tricky to machine.

The motor's 3/4" diameter main body was turned on the lathe, and the details on its end were machined on the mill. Its distinctive bendix cover contained a lot of filleting and was machined as a separate part of the starter. Its complex shape left little usable area for work-holding while its bottom concave surface was machined. It was then permanently joined to the body with a single Loctite'd screw.

As shown in the photos, the motor received three different surface finishes: bead blasting, bare polished metal, and black Gun Kote. Remarkably, and quite by accident, the exhaust pipe assembly made earlier fit nicely around the starter. - Terry


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## ddmckee54 (Feb 1, 2022)

When you said "it's held on with a single loctited screw", I assume you were talking about the Bendixx cover.  How is the faux starter motor held in place, since it has no visible means of support?


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## mayhugh1 (Feb 1, 2022)

ddmckee54 said:


> When you said "it's held on with a single loctited screw", I assume you were talking about the Bendixx cover.  How is the faux starter motor held in place, since it has no visible means of support?


There's a hidden 8-32 flat head screw through the cover plate and into the rear of the motor's  main body. - Terry


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## ddmckee54 (Feb 2, 2022)

I thought it was probably something like that.  Scale studs and nuts, with a scale flange on the starter would have been slightly over the top.


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## mayhugh1 (Feb 2, 2022)

ddmckee54 said:


> I thought it was probably something like that.  Scale studs and nuts, with a scale flange on the starter would have been slightly over the top.


Actually, I would have added the mounting flange, but I'd designed the cover plate to handle both the 390 and faux motors. The brush motors all attach with a pair of screws in the end of their front face and didn't require a flange. I guess I thought I might come back with a 390 solution someday. - Terry


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## ddmckee54 (Feb 3, 2022)

You've probably already covered this, but did you look into using a motor with a planetary gearbox attached for the starter?

Other than the fact that it would be about twice a long, look REALLY out of place, require an actual Bendix or some type of over-running clutch....  Yeah, nevermind.


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## petertha (Feb 3, 2022)

Not even sure it would work, but I had a look around some RC gear drive motors I'm familiar with. This one is one of the smaller ones, 320 watts on 6.7:1 reduction, The motor can is 22mm (0.87") but the gear drive about doubles the overall length. They are spendy. Also brushless, so you are into a specific (RC) speed control unit although the voltage might be a good match (3S lipo = nominal 12V).








						Powerline Micro 1010/19 68g - Powertrains - Geared
					

The new Powerline Micro 1010 Turbo is optimised for 3S LiPo power of F5J models weighing up to 1400 g. Max current 34A on a 3S LiPo with a max capacity 600 mAh....




					www.hyperflight.co.uk
				




I've seen some gear reductions on the brushed motors similar to what Terry has, but the power was significantly less. For reference I think cordless drills might be in the 500W range? depending on cell count etc. Hard to miniaturize that by a large factor.


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## Peter Twissell (Feb 3, 2022)

Brushless motors are not well suited as starters.
The controller will try to ramp up the motor speed and if the motor doesn't keep up, it gets out of synchronisation with the electronic 'commutation' and produces no torque.
This can be overcome if the motor is fitted with an angle encoder, so the controller can match the wave form and frequency, but everything then gets more expensive again.


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## petertha (Feb 3, 2022)

That's interesting Peter, never considered that. Not to detract from the build thread but how is that different to the motor throttling the propeller load up & down & holding anywhere in between like it normally does? Do you mean once the engine has started it will have potential to over-drive the brushless commutation timing, or just these kinds of motors in general?


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## Peter Twissell (Feb 4, 2022)

Brushless controllers which run "open loop", without motor position sensors, are programmed to limit the rate at which motor rpm changes.
Ann inertial load, such as a propeller, will allow the motor to pick up speed in direct proportion to the torque.
A starter is loaded in a less predictable way and may well be effectively stalled when power is first applied.
If a sensorless  brushless starter were used, when the engine starts and tries to overdrive the motor, the motor will act as a brake until the Bendix disengages.


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## mayhugh1 (Feb 10, 2022)

Before starting on the bottom end assembly, the motor mounts were machined to support and help steady the block. A baseplate will come later after I've finally decided between a fuel pump and a conventional gravity fed tank. The mounts could have quickly been made from angle stock, but with none on hand they were wastefully machined from thick bar stock. After bead-blasting they were gold anodized using the home anodizing setup described in my Offy build. While the chemicals were still laid out, the bell housing was clear anodized to darken its color and to reduce the chances of oil and grease stains later on.

But, the anodizing didn't go smoothly this time. The two front mounts turned out great on my first try, but my beginners luck ran out on the rear mount. Initially its color was off just a bit, and not knowing any better I decided to re-do it. After again bead blasting and etching it in lye, I wasn't able to get an anodizing current to flow through it. I expected the problem was likely a poor electrical connection to the part which in my experience in an ongoing problem with this process. However, nothing I did including replacing the electrolyte and wire brushing the lead electrodes would reestablish current. The unregulated power supply I'd been using had a maximum output voltage of some 24 volts, and my typical 1-2 amp anodizing current was well within its capability.

The part's surface was redone a third time and with multiple electrical connections but still no joy. Finally, switching to a constant current supply with 2X more output voltage solved the problem, but strangely it had to be cranked up to nearly 50 volts to get 800 ma. of anodizing current. After 20 minutes in the tank I noticed the part had taken on a slight golden tinge similar to its original color. After the color dip and sealing steps, ohmmeter measurements showed the part was finally anodized, and its color was as nice and uniform as I could ask for.

I couldn't find any online discussion about what I'd run into, but I had a suspicion the subsequent bead blasting's hadn't removed the entire initial anodized layer after all. Although my ohmmeter measurements had indicated zero surface resistance, my probes were making contact to only a relatively few microscopically high points that had actually been cleaned off by bead blasting. This tiny effective area wasn't indicative of the entire part's surface, and the very thin insulating islands remaining between them required a high punch-through voltage in order to get significant current flowing. After thinking about it, I was amazed that the part turned out as well as it did.

During assembly, the ring'd pistons were attached to the crankshaft through the top of the block. The shop-made installation tool shown in one of the photos was used to eliminate potential damage to the rings. The dimensions of its two-piece design aren't critical, but the i.d. should closely match the piston's diameter. An o-ring held the halves in place around the piston and the rings squeezed down inside their grooves so the piston could be safely slid into its cylinder. The only tricky part was lining up the rods with their journals inside the narrow spaces between the crankshaft webs.

With the crank fully assembled, the block was sealed to the pan with a two-piece .015" thick Teflon gasket set. Adhesive backed vinyl was used to seal the pan to the front and rear main (ball) bearings. The shape of the flywheel along with the rings' friction will make it awkward to precisely position the crankshaft during timing adjustments. So, the adapter that will eventually be used to drill start the engine was machined next since it can also be used to manually rotate the crank.

The drill starter consists of a machined body into which a one-way clutch was pressed. The inner bearing for the clutch was machined from drill rod and then hardened. Its hex shaped end matches the socketed rear of the flywheel. The inner bearing is loosely retained to the body with a 6-32 SHCS. - Terry


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## a41capt (Feb 10, 2022)

Amazing work Terry!  I’ve given home anodizing a try in the past and I’m setting up to anodize the parts on my Webster.  First time I’ve tried to pretty up an engine!

John W


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## ddmckee54 (Feb 11, 2022)

I liked your ring compressor.  The bell housing and engine mounts look good too.


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## a41capt (Feb 11, 2022)

Terry, what are you using as a sealant for the dye on anodized parts?  Do you just use the boiling water method, or are you using a commercial sealant?

Thanks in advance,
John W


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## mayhugh1 (Feb 11, 2022)

a41capt said:


> Terry, what are you using as a sealant for the dye on anodized parts?  Do you just use the boiling water method, or are you using a commercial sealant?
> 
> Thanks in advance,
> John W


Just 20 minutes in boiling water...


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## a41capt (Feb 11, 2022)

mayhugh1 said:


> Just 20 minutes in boiling water...


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## Bentwings (Feb 13, 2022)

Nice work . I’ve wanted to try this for a long time  I’m making an aluminum electric boiler for my steam engine  I’d like to use som an fittings they are blue red or black so I could make the boils som cool color too . I have not done much anodizingbin industry . The boiler is kinda high tech  being aluminum I’m under fire for deviating from traditional copper in modeling but copper has structural limits that need to evconsidered . Aluminum can handl pretty high temps as long as you stay in limits my unit is more direct fired so I don’t have that issue copper works ok too but cxcess heat and raw fire ca be dangerous so they have closer guide lines I’m more or less on my own as few build electric in the first place so strict rule I have to us material properties anodizing defects don’t seem to be well published . I’ve not had any issues with anodized parts in race cars boats still get coorosion but with proper anodes it goes away I’ve had a lot of  hard anodizing done in industry snd racing  and it worked well for where it was used 
Byron


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## Peter Twissell (Feb 13, 2022)

Byron, I'd be very cautious with an aluminium boiler.
Aluminium loses a lot of its tensile strength as temperature rises and is prone to fatigue.
Anodising makes things worse, as it introduces a brittle surface which in turn generates crack initiation points.
Copper is relatively ductile, so in the case of a boiler failure, is more likely to open a leak than split apart catastrophically.
Aluminium has about half the stiffness of copper, so it will move more under pressure, putting additional stress on joints.
I have used aluminium bodied hydraulic accumulators, but they are wrapped in carbon fibre to overcome the stiffness issue and are rated to 120C maximum temperature.


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## mayhugh1 (Feb 13, 2022)

Before installing the head, the crankshaft was rotated to TDC of cylinder number one and its position memorialized with a mark scribed on the crankshaft pulley next to the timing indicator. This mark will be used later to adjust the distributor timing just as it's done on the full-size engine.

The head, along with the Teflon head gasket made earlier, was then installed using fourteen 5-40 steel SHCS's. Standard length screws were shortened to obtain maximum possible purchase (6 threads) inside the block.

At this point it was possible to leak check the entire coolant system using a vacuum test. Unfortunately, it failed miserably. An easily fixed leak was discovered at the water pump where an interference with the timing gear housing prevented it from fully seating on its gasket. However, a more serious problem remained. Eventually, a leaky liner was discovered after removing the pan and flooding the bottom of the block with oil. With the coolant system now pressurized, bubbles could be seen escaping from the bottom of the liner in cylinder number two.

Although some builders use press-fit liners that are honed after installation, I prefer to completely finish mine outside the block. Since they're machined with close sliding fits inside the cylinders, they must be sealed with Loctite. With the 3/16" glue surface left around the bottom of each liner, I was surprised to discover a leak.

Resealing the liner began with a solvent flush of the coolant system to remove any traces of oil that might have been drawn into the leak during the vacuum test. After removing the head, the block was set on a pair of wood blocks with the bottom facing down. Any remaining solvent was allowed to drain through the leak for the next few hours. Using a needle syringe and working through the two transfer passages on either side of number 2 cylinder, Loctite 290 (a wicking grade) was squirted into the space surrounding the liner. The Loctite began leaking through the liner half an hour or so later. Clean paper towels under the block helped keep track of the sealing progress.

Several hours later, Loctite 609 (slightly more viscous press fit) was added. The draining slowed greatly after a few more hours, and then the block was set inside my home-made welding rod oven for an accelerated cure. With an inside temperature of 140F, the block was allowed to cure overnight.
A couple pressurized solvent flushes were used the next day to remove any uncured Loctite remaining inside the block. After reinstalling the head, the vacuum test was repeated showing the coolant system was finally leak free.

The next step is to machine and install the lifters and pushrods, but I only just discovered I'll have to order the material for them. - Terry


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## ddmckee54 (Feb 14, 2022)

30cc's coolant capacity, wonder what that is in 1/5 scale gallons?


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## Arild (Feb 15, 2022)

ddmckee54 said:


> 30cc's coolant capacity, wonder what that is in 1/5 scale gallons?


Volume capacity should be 125 times more (5x5x5). So, 0.030 liter (30cc) equal to 3.75liter!


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## ddmckee54 (Feb 15, 2022)

Hmmmm...  The Ford Maverick with the 250CID engine had a 9.2L coolant capacity.  Terry, you're gonna have to put some BIG tanks on the radiator for this thing to get close to factory specs for coolant capacity.


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## mayhugh1 (Feb 15, 2022)

And that's the reason why you never see IC engines continuously idling during shows like the compressed air powered steam engines. - Terry


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## propclock (Feb 15, 2022)

Hit and miss run all day long.


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## stevehuckss396 (Feb 15, 2022)

propclock said:


> Hit and miss run all day long.


 
Make it hit every time and run 1000 rpm and see if it will run all day.


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## Bentwings (Feb 17, 2022)

mayhugh1 said:


> Before installing the head, the crankshaft was rotated to TDC of cylinder number one and its position memorialized with a mark scribed on the crankshaft pulley next to the timing indicator. This mark will be used later to adjust the distributor timing just as it's done on the full-size engine.
> 
> The head, along with the Teflon head gasket made earlier, was then installed using fourteen 5-40 steel SHCS's. Standard length screws were shortened to obtain maximum possible purchase (6 threads) inside the block.
> 
> ...


Very nice I’m envious. 
the race car uses light press in or pound in cast iron sleeves they use a special slide hammer to remove them when warm they pop right out but if left in and the aluminum block cools they can be a real bear to remove. Water cooled blocks ar now antiques. They are solid aluminum now we’re i to build a model engine I’d do as you have and use coolant . Most model plane engines are air cooled. There is very little issue with cylinders unless run excessively lean or with too little oil in gas 4 strokes are pretty much like lawn mower engines scaled down. Most Rc flyers use two stroke twins for big power 4 strokes twins are just too heavy for power output. Turbo and supercharging just does not work well on model motors the electric stuff is prett big too batteries are big lithium things subject to fires especially in crashes Very expensive too. . There are at least half a dozen model engines I’d like to build were my eyesight better. I’m just happy that I can work with my steamer and maybe a couple turbines . I just got one of my computers back so I’m going to see if I can revive some cad skills maybe get some 3 d printed stuff. That’s come a long ways . 
byron


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## Figor (Feb 17, 2022)

Very nice work. I still have my 1979 F150 with the 300 six in it. Pretty amazing engine.


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## mayhugh1 (Feb 19, 2022)

The tappets and pushrods were both made from drill rod, but only the tappets were hardened. The pushrods were finished with ball ends on my little CNC lathe, and the tappets were plunge cut with a matching socket using a spherical end mill in the lathe's tailstock.

As shown in the rendering of the rod/socket model, the socket depth was made equal to the diameter of the rod. Since the rod and tappet don't remain concentric during operation, some clearance is required between the two just above the ball. This clearance is provided by a slight bevel on the top inside edge of the tappet and by an undercut on the rod just behind its ball. The resulting geometry provides space that can accumulate and retain oil. Valve lash was set using a piece of .003" shim stock as a feeler gage.

The calibrated crankshaft pulley and timing indicator were used to time the camshaft to the crankshaft. With the crankshaft positioned 15 degrees BTDC and the camshaft rotated to the start of cylinder number one's intake opening event, the driven cam gear was locked to the flange on the end of the camshaft with four SHCS's. Sanity checks made by manually turning the crankshaft with a spark plug temporarily inserted into each cylinder one at a time showed plenty of compression.

With 45 cc's of oil in the crankcase, the crankshaft webs are barely wetted. Unfortunately, dip sticks seem to be yet another thing that's difficult to scale down. I've yet to come up with one that can be reliably read. The Ford's dipstick was fashioned from a piece of 1/16" steel rod with a filed flat bottom end on which a clean oil meniscus is essentially invisible. Stippling the flat portion of the stick helped a little as did blackening with a torch to reduce reflections. Even still, oil readings are barely visible. If I were doing things over, I'd position the faux oil filter at an appropriate position on the side of the block so its threaded hole could serve as an overflow indicator.

The final photo shows the prototype spark plug I've been secretly working on. It has a 3/32 zirconium electrode that should handle a full two joule ignition. The plug's body was designed to withstand the six figure voltages that the plug's .093" gap is likely to generate during compression. The extremely long plug wires that will be required to reach the plugs will contain RFI suppression to meet CE requirements. - Terry.


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## Peter Twissell (Feb 19, 2022)

The prototype spark plug has a very long insulator.
Is this only for prototype, or did you calculate that this length is necessary to prevent arcing?


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## mayhugh1 (Feb 19, 2022)

Peter Twissell said:


> The prototype spark plug has a very long insulator.
> Is this only for prototype, or did you calculate that this length is necessary to prevent arcing?


Testing has shown final design will have to be another inch longer. I'm calling it the 'Terry Plug' or TP for short.


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## Eccentric (Feb 19, 2022)

Your engine is Beautiful Terry.  Without  anything in the picture to lend scale, I would swear that it is the real thing.  I have a Ford 300 powering the tug in my hangar, couldn't tell you the color of it for all the grime-its a work horse.  You make me want to steam clean it.


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## propclock (Feb 20, 2022)

Ab Fab. Your work is always inspiring. 

 Just a small note for what it is worth to others.  For somewhat larger engines  the stainless steel
stiffener from old  wind shield wiper  blades makes great dip stick stock. And Free!
Appropriate for ~ 1/4 scale engines .  Way too big for this beauty. 
 Learned from my friend Dwight Giles.


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## mayhugh1 (Mar 9, 2022)

What started out as work on the ignition system got away from me and turned into a huge machining project. My previous assembly stopped short of installing the distributor which required the ignition system to time it. At its heart will be one of Roy Sholl's Magnum CDI's that's capable of 5 krpm on a six cylinder engine. The prank TP project is out of my system, and model engine spark plugs (Viper ZR1's, 10-40 thread, 6mm hex) will be used.

The CDI is an already potted module that I've used before, but I like to add my own front-end electronics that won't require a live ignition for timing adjustments. These additional parts along with the CDI add a lot of bulk around a small model engine. Since I want its display to be more about the engine than its running gear, I decided to hide the ignition and hopefully the fuel tank as well.

A 12" x 8" x 1/4" base plate cut from hot rolled steel will eventually be bolted to the engine through an intermediate riser block. The running gear will be hidden inside machined recesses in the bottom of the aluminum riser. The block is big enough to possibly include the fuel tank and pump, and so their machining was done as well.

For fuel delivery I prefer a recirculating fuel loop over a gravity-fed tank because of the consistent fuel level it can present to the carburetor and the flexibility it provides in placing (or hiding) the tank. There are some downsides though: 1) the fuel pump requires its own space, and 2) my pump of choice which is intended to fuel RC planes is a constant volume gear pump. Speed control of this pump typically isn't enough on its own to control turbulences inside a tiny carburetor fuel bowl. The fixes I've come up with require bowl volume, and so the Ford carburetor that doesn't even have a bowl is going to be a problem.

The riser required some ten hours of machining time, but its modeling required much more. The fuel and ignition systems were safely separated and the small signal electronics were separated from the (electrically) noisy CDI and its high voltage output. Unlike some of the other model engine control modules I've designed, I was also determined to make this one easy to assemble and maintain. The fuel tank was hogged out of the riser's left-over volume and will be later sealed with a JB-Welded cover.

The baseplate was painted with Rustoleum Multicolor Textured paint which is gas and oil resistant and





























 nicely covers unprepped hot rolled surfaces. The riser was bead blasted and will be painted with a similar shade Gun Kote. - Terry


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## stewart drummond (Mar 9, 2022)

first inline six cylinder with a firing order that isnt 1-5-3-6-2-4 ? , even a 'real' 300 cube ford is 1-5-3-6-2-4 , i think youll find every in- line- six ever made will run in that order , not that it 'wont ' run but vibration wise you'll find out 
pretty quick , why its never done


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## mayhugh1 (Mar 10, 2022)

stewart drummond said:


> first inline six cylinder with a firing order that isnt 1-5-3-6-2-4 ? , even a 'real' 300 cube ford is 1-5-3-6-2-4 , i think youll find every in- line- six ever made will run in that order , not that it 'wont ' run but vibration wise you'll find out
> pretty quick , why its never done


Not sure what you're trying to say. The firing order is 1-5-3-6-2-4.


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## ddmckee54 (Mar 14, 2022)

For shame Terry, a 6 volt electrical system?  I know that volts don't scale, but every Ford 300 would have started its' life as a 12 volt system.  It looks like you've got plenty of extra room in the base to fit in a DC-DC converter, and feed it with a proper 12 volts.  That way when the battery dies at a show, you can just pull the battery out of somebody's car and hook it up to your engine with a set of jumper cables. 

Did I say that everything looks outstanding?

Don


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## Steamchick (Mar 14, 2022)

But a 6V system will probably fire-up using your phone battery?
K2


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## mayhugh1 (Mar 17, 2022)

The fuel tank cover was sealed with JB-Weld. A machined 'o-ring' groove around the face of the tank was filled with the epoxy to ensure a continuous leak free seal. A filler neck with an o-ring'd gas cap completed the tank assembly. After installing the pump and motor, the tank was filled with gas and the entire fuel system exercised for several minutes using a dummy loop to check for leaks.

A threaded Delrin feed-thru was created to route the CDI's high voltage output through the top surface of the riser and into the center tower of the distributor cap. Just for fun, the feed-thru was machined to resemble an automotive ignition coil.

After installing and testing the support electronics around the CDI, the distributor timing was initially set to 10 degrees BTDC using the already calibrated notch on the crankshaft pulley. Eighth inch high voltage silicone plug wire was used, and the boots were fashioned from repurposed automotive vacuum fittings.




























The remainder of the engine's front end was assembled. The photos show the completed engine to date. Only the carburetor and radiator remain to finish up the 'build' portion of this project. Since the bowl design is probably going to be troublesome, the carburetor will be left until the end. The radiator will be tackled next. - Terry


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## ozzie46 (Mar 17, 2022)

Amazing!!
Ron


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## CFLBob (Mar 17, 2022)

Gorgeous.  Even the soldering is pretty.  

Is that 1.8oz fuel tank all that's in the base?  How long does it run on that?


Bob


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## Vietti (Mar 17, 2022)

Its all overwhelming amazing!!  Look forward to see it run.  Is the fuel gauge operational and if so how in the world??


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## mayhugh1 (Mar 17, 2022)

CFLBob said:


> Gorgeous.  Even the soldering is pretty.
> 
> Is that 1.8oz fuel tank all that's in the base?  How long does it run on that?
> 
> ...


Don't know yet for sure but probably 2-3 average runs. - Terry


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## mayhugh1 (Mar 17, 2022)

Vietti said:


> Its all overwhelming amazing!!  Look forward to see it run.  Is the fuel gauge operational and if so how in the world??


That's actually not a fuel gauge, but a screwdriver adjustable potentiometer that controls the speed of the fuel pump and therefore flow in the recirculating fuel loop. It's there to tame the flow rate of the pump which will help control the turbulence in the fuel bowl. - Terry


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## mayhugh1 (Mar 27, 2022)

For a radiator, I decided to reuse the strategy I came up with for the Offy's coolant system. My argument was that I felt the volume taken up by the fins in the core of a scaled radiator might be put to better use holding additional coolant. These fins can take up as much as two thirds of the core volume of a model engine radiator.

The real effectiveness of the fins in a full-size automotive radiator core relies upon a layer of turbulent air around them created by a healthy flow through them. Although an electric fan can force the needed air through a model radiator, the typical crank driven fan is pretty much ineffective. What's more, the thermal conductivity of the brass typically used in model radiator construction for its solder-ability is surprisingly poor compared with aluminum.

An all aluminum finless radiator seemed to work well with the Offy, and so I decided to build something similar for the Ford. I also wanted to keep its size in line with the engine's scale.

The first step was to decide upon a set of dimensions. I started with a total radiator volume of ten times the engine's coolant capacity which was measured earlier to be 30 cc. After playing with the dimensions, I settled upon a 4" x 4.5" x 1" core plus upper and lower tanks. These dimensions actually weren't too far away from those of a scaled heavy duty truck radiator.

Upper and lower tanks were machined from 6061, and the inlet and outlet locations were selected for convenient hookups to the engine. The core was also machined from aluminum. Its interior was hogged out by chain drilling through both ends of the workpiece before being finished with an end mill. The front and back surfaces were grooved for a core 'look'. The three components were bead blasted and thoroughly cleaned for painting after assembly.

JB Weld was used to bond the tanks to the core. After mixing, it was thinned with 20% acetone to improve its flowability. It was injected into a trough surrounding the core inside each tank using a syringe. The final gravity-flowed adhesive resembled the solder fillets in a full size radiator. After a 24 hour cure, the radiator was baked for a few hours at 250F to finish outgassing the epoxy. I've learned from experience that this pre bake-out step helps prevents bubbling under the Gun Kote during its oven cure. The radiator was finished in satin black. An o-ring'd cap, inlet/outlet ports and clamps, and mounting brackets should wrap up the coolant system. - Terry


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## Charles Lamont (Mar 28, 2022)

mayhugh1 said:


> For a radiator, I decided to reuse the strategy I came up with for the Offy's coolant system. My argument was that I felt the volume taken up by the fins in the core of a scaled radiator might be put to better use holding additional coolant. These fins can take up as much as two thirds of the core volume of a model engine radiator.
> 
> The real effectiveness of the fins in a full-size automotive radiator core relies upon a layer of turbulent air around them created by a healthy flow through them. Although an electric fan can force the needed air through a model radiator, the typical crank driven fan is pretty much ineffective. What's more, the thermal conductivity of the brass typically used in model radiator construction for its solder-ability is surprisingly poor compared with aluminum.



Naturally, I had to have a think about this.

In any heat exchanger, the material used for the wall makes very little difference to the overal thermal resistance. With any reasonably conductive metal the temperature drop across the wall pales into insignificance when compared with the fluid boundary layers. This will be especially true when relying on natural convection over the outer surface. 

While it looks radiatorish, I think you are saying that this thing is more of a heat sink? The volumetric specfic heats of aluminium alloy and brass are about 2400 and 3200  kJ/K.m^3 repectively, so if you made to the same design out of brass, the case would have a 1/3 greater heat capacity. However, as there is less volume of metal than water, and the water has a volumetric specific heat around 4000 kJ/K.m^3, the overal difference would probably be less than 10%.


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## ddmckee54 (Mar 28, 2022)

Terry:

I was only joking about the "BIG TANKS" back in post #342.  Your 300cc radiator capacity, if we "scaled" it up to full size, would come in at 37+ liters.  Whether it'll keep your 300 cool or not, you've definitely exceeded the 9.2L factory cooling system capacity.  If you call it a radiator or a heat-sink is just semantics, but it LOOKS very radiator-ish.

Don


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## Steamchick (Mar 29, 2022)

It looks excellent! I think you are probably right with your calcs/estimates of model radiators and fans... A friend made his own design of 3 cylinder petrol engine (maybe 5cc total?) and it idles nicely around 1200rpm. at shows.... But then overheats after 10 mins or so of running. His "radiator/heat sink" is 4 x 3/8" square aluminium blocks with big holes through, top and bottom brass tanks (glued on I think?) with fins machined into the square blocks. All put together make a nice radiator, with coolant driven by a water pump of the engine. Sorry I don't have a picture. The maker reckoned he needed to make it 3 times bigger.... => 4in long x 2 in high!
K2


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## mayhugh1 (Apr 7, 2022)

The hardware needed to mount and connect the radiator to the engine was completed next. Threaded inlet and outlet hose barbs were turned from 303 stainless and Loctite'd into the tanks. Aluminum-to-stainless bonds are challenging for Locite, and so the parts were pre-coated with the manufacturer's recommended primer to help kick off the bonding process.

A threaded radiator cap was also machined from 303 and then polished. An o-ring inside a machined groove in the filler neck seals the cap to the radiator.

The mounting bracket made to secure the radiator to the display stand may be a little over the top, but I wanted something other than a pair of boring L-brackets. It was machined from aluminum and Gun Kote'd gray to match the riser block under the engine.

For hose clamps, I had three shop-made clamps left over from my Offy build:

270 Offy (post 447).

I really needed four, but there wasn't enough space around the engine's water pump inlet for one anyway. The tiny spring clamps you can find in huge assortments on Amazon are designed for silicone tubing and won't seal the stiffer Tygon tubing that I'm using.

One of the photos shows a tool I made to twist a loop of copper wire around the water pump's inlet. My shade tree clamp isn't pretty but it's functional and well hidden under the alternator. The right angle bends in the both upper and lower hoses are tight, and metal springs were used inside them to prevent collapse.

I dread the first-time filling of a new engine's coolant system. Potential leak sources inside these little engines can be many, and internal leaks can be difficult to locate and a real pain to fix. Hopefully, my earlier liner-to-block leak repair is permanent, but I decided to add an additional preventative step.

Several years ago, I ran into porosity problems with the thin-wall head castings on my Merlin, and I investigated a number of coolant sealers to avoid an engine teardown. Regardless of a dozen manufacturers' guarantees, I found only one that I trusted for use inside a model engine. This was an OEM product developed decades ago by General Motors to solve porosity leaks in their early production aluminum heads. A couple of these tablets were dropped into the radiators of every new aluminum-headed GM production engine for many years. It's an organic material made up of ground walnut shells and ginger root whose fibers tend to migrate into and seal pinhole leaks. The same product was recommended for use at every coolant change for these cars.

My testing involved experimenting with various size holes in paper cups, and after gaining confidence with the GM product I added a bit to the Merlin's coolant system. Both pinholes were plugged within minutes during the next run with no apparent side effects and no further issues since. My small engine dose was a piece about the size of a small pea broken off a tablet and crushed into dust with my fingers. The material imparts a slight brownish tinge to glycol coolant, and under a magnifying glass its tiny fibers can be seen in suspension throughout the coolant. There's no 'goop' to clog the cooling passages in a model engine nor its water pump. It's intended for tiny pinholes and is not a radiator repair product.

I used this sealer as a preventative measure in my Offy because I was concerned about the lack of head gasket 'meat' around the coolant transfer passages. After filling the Ford with coolant and monitoring its level in the transparent upper hose for a few days to ensure no leaks, I added the sealer for peace of mind.

I was pleasantly surprised to see coolant moving through the upper hose into the radiator when the crankshaft was spun with an electric drill. It's been my experience that cranking speeds aren't high enough to move coolant through a model engine with a centrifugal. - Terry


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## Eccentric (Apr 7, 2022)

Looking Fabulous, really coming along Terry.  The "Ford" radiator mount is a nice touch.  Interesting story about GM's use of the Cooling System Seal Tabs in early aluminum headed engines.  I just went and boungt a life time supply (one package) on Amazon for $4.02.


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## petertha (Apr 8, 2022)

Very nice work Terry.

Re the wire clamp, where I thought you were going was a miniature wire hose clamp gizmo (below infomercial is typical). I found an Ebay source of small diameter flexible SS wire that comes in 0.2, 0.4, 0.6, 0.8m dia. The 0.8mm I tested have is a bit too fat & stiff to mimic the loops & tie backs but hoping one of the thinner flavors will work when it arrives. 

My other option is to cut the extended ears off automotive style wire clamps so they don't look so ungainly. A bit more fiddly to install that way but the wire has the right sealing tension on my silicone tubing.


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## mayhugh1 (Apr 8, 2022)

petertha said:


> Very nice work Terry.
> 
> Re the wire clamp, where I thought you were going was a miniature wire hose clamp gizmo (below infomercial is typical). I found an Ebay source of small diameter flexible SS wire that comes in 0.2, 0.4, 0.6, 0.8m dia. The 0.8mm I tested have is a bit too fat & stiff to mimic the loops & tie backs but hoping one of the thinner flavors will work when it arrives.
> 
> My other option is to cut the extended ears off automotive style wire clamps so they don't look so ungainly. A bit more fiddly to install that way but the wire has the right sealing tension on my silicone tubing.



Peter,
Thanks for the info. I was familiar with the clamp 'gizmo' but even a miniaturized shop-made version of it wouldn't have fit in the space I had to work with around my water pump inlet. It does make a professional looking clamp though. The spring clamps in the photo you provided are the ones I mentioned that I've had trouble sealing my clear Tygon tubing. They do work great on soft silicone, though. -Terry


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## Steamchick (Apr 8, 2022)

Well done Terry! - It looks so good, I bet Henry F. would be proud to display it!
I am sure you'll be running soon and we can see the video.
K2


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## minh-thanh (Apr 8, 2022)

*Another mechanical masterpiece is coming !!!*


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## a41capt (Apr 10, 2022)

Mighty pretty Terry!

John W


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## perko7 (Apr 11, 2022)

mayhugh1 said:


> The hardware needed to mount and connect the radiator to the engine was completed next. Threaded inlet and outlet hose barbs were turned from 303 stainless and Loctite'd into the tanks. Aluminum-to-stainless bonds are challenging for Locite, and so the parts were pre-coated with the manufacturer's recommended primer to help kick off the bonding process.
> 
> A threaded radiator cap was also machined from 303 and then polished. An o-ring inside a machined groove in the filler neck seals the cap to the radiator.
> 
> ...


My dad used to always say to add some ground pepper to the water if there were any small leaks as the pepper would get trapped in the hole and swell up thereby sealing it. Never tried it myself but he seemed to think it worked.


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## Steamchick (Apr 12, 2022)

Hi Perko: Hot Stuff! But I dislike "sludge inducers", that usually produce unwanted sludge in places that cause other problems. So I rather prefer "proper" sealing techniques, like vacuum impregnation of porous castings with resin, etc. Professionally done, the chemistry of the resins is selected for lifetime durability at the service temperatures involved. Better still, is "no leaks".
Seriously, a dab of vaseline will stop a bleeding boxer or rugby player from dripping blood - all be it temporarily! But there is no way you would want anything less than a "proper" medical elastoplast and healing after the match. Likewise, "bodge!" sealants on engines, etc... I have used rad-seal on leaking radiators, sometimes for a couple of years, but have had it "wash away" from the flush when changing the coolant at 3-year service intervals (_necessary _to refresh the anti-corrosive properties of the solution). A replacement radiator was the proper solution to the leak. I have even done a "zinc alloy" solder repair to an aircon radiator, that lasted 4 or 5 years before corrosion caused it to leak again. So I consider this a temporary fix. On castings, I have seen fatigue cracks (in my job) and they were often "dirty" from some leak preventative gunge... which had no mechanical properties to prevent the casting form cracking further and failing at an embarrassing moment.
Take care with pepper. It is an acid, so may react badly with some metals and liquids, or encourage electrolytic corrosion somewhere you don't want.
K2


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## perko7 (Apr 12, 2022)

Thanks for that. As I said, pepper was not something I was inclined to try, I prefer the 'fix it properly' method too.


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## mayhugh1 (Apr 24, 2022)

The carburetor and its 'fixins' should be the final parts for this build. George designed a carburetor specifically for this engine, and I wanted to stick to its internals as closely as possible. The recirculating fuel loop I want to use though will require the addition of a fuel bowl.

My fuel loops are complicated by their constant displacement gear pumps which were originally intended to fuel up RC planes. Adding a simple speed control to their drive motor doesn't reduce the flow enough to reliably work in my application. Keeping the bowl filled without overrunning its drain requires the motor to run at a speed too close to zero. In the past I've used a .020" restriction in the pump's output line in order to raise the head pressure and force an internal leak through the pump's gears. This restriction which had to be placed well away from the carb in order to avoid a jet spray inside the bowl, raised the operating point of the motor for a more consistent rpm.

For the Inline 6, I experimented with a more elegant solution - a 'splitter' that returned a portion of the pump's output to the tank before it reached the bowl. The splitter required its own return-to-tank line which I was willing to add if the splitter could have be hidden in the floor of the bowl. It turned out that its performance while so close to the bowl was limited. Building the splitter into its own enclosure well outside the bowl improved things, but I didn't like the extra chunk of hardware. The splitter really belongs inside the fuel tank, but I was long past redesigning the tank. In the end, I went back to using a restrictor.

Some experimenting was also needed to optimize the shape and size of the fuel bowl. A tiny bowl with a pressurized inlet, negative pressure outlet, and gravity fed drain provides some challenges. The drain tube height inside the bowl establishes its steady-state fuel level which I want to be 1/8" below the spray bar. But, unless an accounting is made for surface tension across the drain's input, the actual level can be very different and inconsistently high. Another issue is that a maelstrom can be generated between a tiny bowl's inlet and drain, and this can affect fuel flow to the needle valve.

After a week or so, I had a tested bowl design that I was happy with, and I began the design of the carb body. The bowl was integrated into a body that used George's internals as well as the existing mounting pad on the intake manifold. The mount proved particularly troublesome, and the carb's installation will require some heroic effort with a tiny crowfoot fashioned from a 5/32" open end wrench.

Machining of the carb body began with a block of aluminum squared up to body's outside finished dimensions. Its six faces were carefully machined in as many setups. Despite two power brown-outs during machining and a couple operator errors that forced some design changes along the way, I was able to continually rescue the original workpiece and finally hold the finished carb body in my hands. The body was bead blasted, dipped in NaOH, and then alodine'd for a poor man's gold iridite like appearance.

The carb body was a fun side project that included a few 'firsts' for me. I don't think I've before put so much machining into such a small chunk of metal. I only recently discovered SolidWork's Text functionality, and I used it instead of my CAM software to add the engraving to the front of the carb. Another 'first' was the waterline machining operation using a 1/32" end mill that it required. Now, it's on to the 'fixins'. - Terry


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## Eccentric (Apr 24, 2022)

Terry,

Your parts look amazing, like they were die cast.  How much hand finishing do you do before bead blasting?


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## mayhugh1 (Apr 24, 2022)

Eccentric said:


> Terry,
> 
> Your parts look amazing, like they were die cast.  How much hand finishing do you do before bead blasting?


Actually, none. I'm willing to spend the time to let the machine do it. I've learned it's best to keep my hands away from the parts if I can. - Terry


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## CFLBob (Apr 24, 2022)

Terry,  

What CAM program are you using?  Part of Solidworks or does it read their files? 


Bob


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## mayhugh1 (Apr 24, 2022)

CFLBob said:


> Terry,
> 
> What CAM program are you using?  Part of Solidworks or does it read their files?
> 
> ...


I'm using Sprutcam which imports native SolidWorks files directly. The version I'm using (SC-7) is some 22 years old now. At the time it was only few hundred dollars and was the most affordable continuous 4 axis CAM programs available. I've used it for all my camshafts. Many have likely never heard of the software. It was a Russian program marketed by Tormach and now by Sprutcam USA. I wrote and put into the public domain the Mach3 lathe post (originally named MyMachTurn) and assisted with the PCNC mill post. I'm told Sprutcam was (is?) widely used in Europe, but it never seemed to catch on in the states. Their badly translated user manual probably had something to do with that. It's the CAM program I learned on, and the only one I've ever used. - Terry


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## CFLBob (Apr 24, 2022)

mayhugh1 said:


> I'm using Sprutcam which imports native SolidWorks files directly. The version I'm using (SC-7) is some 22 years old now. At the time it was only few hundred dollars and was the most affordable continuous 4 axis CAM programs available. I've used it for all my camshafts. Many have likely never heard of the software. It was a Russian program marketed by Tormach and now by Sprutcam USA. I wrote and put into the public domain the Mach3 lathe post (originally named MyMachTurn) and assisted with the PCNC mill post. I'm told Sprutcam was (is?) widely used in Europe, but it never seemed to catch on in the states. Their badly translated user manual probably had something to do with that. It's the CAM program I learned on, and the only one I've ever used. - Terry



Interesting.  I've been having issues with my CAM program, DeskProto, not doing things I'd like it to do.  I'm adapting, but there are still some things I don't think it can be convinced to do.


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## mayhugh1 (Apr 24, 2022)

mayhugh1 said:


> Actually, none. I spend the time to get the machine do it as  much as possible. I find it best to keep my hands off the parts as much as possible. - Terry


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## a41capt (Apr 24, 2022)

mayhugh1 said:


> The carburetor and its 'fixins' should be the final parts for this build. George designed a carburetor specifically for this engine, and I wanted to stick to its internals as closely as possible. The recirculating fuel loop I want to use though will require the addition of a fuel bowl.
> 
> My fuel loops are complicated by their constant displacement gear pumps which were originally intended to fuel up RC planes. Adding a simple speed control to their drive motor doesn't reduce the flow enough to reliably work in my application. Keeping the bowl filled without overrunning its drain requires the motor to run at a speed too close to zero. In the past I've used a .020" restriction in the pump's output line in order to raise the head pressure and force an internal leak through the pump's gears. This restriction which had to be placed well away from the carb in order to avoid a jet spray inside the bowl, raised the operating point of the motor for a more consistent rpm.
> 
> ...


That’s beautiful Terry! I love the Holley logo as well.  Damn Brother, truly amazing work!!!

John W


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## burkLane (Apr 25, 2022)

mayhugh1 said:


> I'm using Sprutcam which imports native SolidWorks files directly. The version I'm using (SC-7) is some 22 years old now. At the time it was only few hundred dollars and was the most affordable continuous 4 axis CAM programs available. I've used it for all my camshafts. Many have likely never heard of the software. It was a Russian program marketed by Tormach and now by Sprutcam USA. I wrote and put into the public domain the Mach3 lathe post (originally named MyMachTurn) and assisted with the PCNC mill post. I'm told Sprutcam was (is?) widely used in Europe, but it never seemed to catch on in the states. Their badly translated user manual probably had something to do with that. It's the CAM program I learned on, and the only one I've ever used. - Terry



Your name is still listed and shown when compiling g-code as one of the authors on the pcnc mill Sprutcam post to this day.


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## mikehinz (Apr 25, 2022)

mayhugh1 said:


> The carburetor and its 'fixins' should be the final parts for this build. George designed a carburetor specifically for this engine, and I wanted to stick to its internals as closely as possible. The recirculating fuel loop I want to use though will require the addition of a fuel bowl.
> 
> My fuel loops are complicated by their constant displacement gear pumps which were originally intended to fuel up RC planes. Adding a simple speed control to their drive motor doesn't reduce the flow enough to reliably work in my application. Keeping the bowl filled without overrunning its drain requires the motor to run at a speed too close to zero. In the past I've used a .020" restriction in the pump's output line in order to raise the head pressure and force an internal leak through the pump's gears. This restriction which had to be placed well away from the carb in order to avoid a jet spray inside the bowl, raised the operating point of the motor for a more consistent rpm.
> 
> ...


Hi, may I ask exactly what material you're bead or sand blasting with?  Also what sort of blasting gun are you using?  Your results are outstanding!

Mike


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## mayhugh1 (Apr 25, 2022)

mikehinz said:


> Hi, may I ask exactly what material you're bead or sand blasting with?  Also what sort of blasting gun are you using?  Your results are outstanding!
> 
> Mike


I bought the cabinet back in the mid-90's from, I think, Eastwood. I remember purchasing a spare nozzle at the same time, as I thought they might wear out quickly,  but I'm still running with the original one. The glass bead media I use was purchased from the local Harbor Freight at the same time. I know you can buy different grades of glass media, but I'm not sure what this one is. It's whatever Harbor Freight was importing at the time, and I can tell you it's seen a lot of use since then. - Terry


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## mayhugh1 (May 6, 2022)

A bowl gasket and heat insulator mounting block were machined while waiting for the delivery of an 8-80 tap and die set. Model engine carb adjustments are traditionally sensitive especially when using gasoline. Every cold start seems to require some re-tweaking regardless of how well the engine was running when last shut down. I've often wondered is this might be caused by a bit of corrosion between the dissimilar metals in the needle and spray bar. In any event, adjusting the Ford's needle valve with an air cleaner assembly in place will be awkward, and so I thought (without thinking) an ultra fine pitch thread might make things a little easier. I nearly always cut external threads on my lathe, but the 8-80 was too intimidating and I went with the 'simpler' die.

An 8-80 thread is rare, and I wasn't able to find an on-line chart with dimensional data nor any help in the gun/knife forums. Using the tap was pretty straightforward, but I had a lot of difficulty with the die. Coming up with a close-fitting thread half inch thread pair was unexpectedly difficult and very sensitive to the die's spreader screw. The initial quarter inch of the male threads was the problem. Even with the die supported in the lathe's tailstock die holder, useable results required a very light touch while getting the threads started and a minimal grip on the die holder during the rest of the threading process. I practiced on a half dozen test parts after ruining half as many spray bar bodies before I had a workable technique.

The final spray bar body with its .040" diameter spray bar and .020" orifice was machined from 12L14 using very sharp tools, lots of patience, and some re-tweaking of my lathe's tailstock. Aluminum proved to be too soft and gummy, but I was able to make a part in bearing bronze. Another unexpected difficulty involved center drilling the .020" orifice with a sensitive drill holder. Imperfections in every center-drill I owned left a microscopic center nub that prevented the tiny drill from starting on the part's exact center. I was eventually able to get a clean start using a 1/8" 60 degree carbide v-cutter.

A sewing needle was epoxied in the bronze needle holder that was tapped with the less troublesome 8-80 female threads. A Delrin bushing inserted inside the spray bar holder keeps the needle centered at the entrance to the spray bar orifice. A Delrin collar located between the the spray bar holder and the needle assembly prevents damage when the needle is fully closed.

Two throttle assemblies with integrally machined Venturi's were made - one from bearing bronze and one from Delrin. Delrin's natural lubricity allowed a snug fit without a lot of cantilevered weight hanging from the carb body. Both the throttle and needle assemblies were made long enough to allow access from beneath a three inch air cleaner assembly.

The bowl was filled with fuel, and a low pressure air stream directed through the Venturi over a paper towel. Under wide open throttle, the resulting spray pattern showed at least three full turns between full OFF and full ON.

Mounting the carb on the engine proved every bit as difficult as I expected. It eventually required the temporary removal of both the throttle assembly and the needle valve in order to set the nuts on the manifold mounting studs. After tightening down the carb and before coming up with an air cleaner assembly, I decided to test start the engine. The tank was filled with gasoline and the engine spun up using my clutched drill starter made earlier.

The engine startled me when it immediately took off and ran, but it died before I got my fingers on the needle valve. Something didn't feel right when I tried to restart it, and I soon realized the flywheel was slipping on the crankshaft. After removing the bell housing I could see that the key that was supposed to secure the flywheel to the crankshaft had either sheared or worked its way up into the companion slot in the flywheel. I hadn't noticed before, but the broached slot in the flywheel seems much too deep in comparison with the depth of the machined slot in the crankshaft. I used standard hardened/ground 1/16" key stock, and so I won't know what really happened until I get the flywheel off. The two are now stuck fast together and will require machining a custom puller to separate them. Craaaaap! - Terry


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## propclock (May 7, 2022)

Wow That is a bummer.  Hope it works out well in the future. 
8-80 , I thought 1/4 80 was tough enough  All my hope for a happy ending.


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## gbritnell (May 7, 2022)

Hi Terry
It's hard to believe the key moved out of place but it's certainly missing from the picture.  I can't wait to hear your engine run!


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## mayhugh1 (May 13, 2022)

With a stack of wood shims under the oil pan, the bell housing was removed so I could work on the rear of the engine. The flywheel was stuck fast on the crankshaft and without provisions made for jackscrews to remove it, a shop-made puller was needed to separate them. The reason for its enormous arms was to simplify the machining needed to get a strong enough pair of fingers through the .040" gap between the flywheel's o.d. and the bell housing mount. The size of that gap was arbitrarily chosen, and I'm glad it wasn't even smaller.

The damage, although significant, was confined to the last quarter inch of the rear of the crankshaft. A short and embarrassing explanation of what happened is that the slot in the flywheel was much too deep for the key.

The broach used on the flywheel was from an ancient Enco boxed assortment that included pieces of square key stock. With the end of the crankshaft previously milled with a .035" deep slot to accept half of a 1/16" square key, I assumed the broach would cut a similar slot in the flywheel. In reality, it was designed to cut a full 1/16" deep slot.

The slot actually wound up a bit shallow at the rear end of the flywheel thanks to its sloppy bushing, and this was enough to lock the flywheel to the crankshaft until it was put under load. With the end of the key deep inside the flywheel's long rear snout, the error wasn't obvious during assembly.

Even worse however, I wondered where else I might have made the same mistake. The next day was spent going over the notes and photographs of all my other builds. It was mostly serendipity, but the only other place where I seem to have pulled the same trick was in the timing pulley on the other end of the Ford's crankshaft. Since it's negligibly loaded, I can wait until there's a reason to pull the radiator before addressing it.

The damage to the crankshaft increased its clearance inside the rear third of the flywheel by a couple thousandths which would have added unacceptable wobble. The problem was almost totally eliminated with a centering bushing that replaced the existing flywheel retainer and effectively extended the length of the crankshaft.

I also deepened the crank's .035" slot using the maligned broach which I modified for use as a scraper. I planned to deepen the existing slot to .070", but after a couple hours I stopped at .045" since the slot had veered off course from the crank's centerline and could introduce a new problem. A one-off key was ground from tool steel with the final result being a snug-fitting wobble-free flywheel that was safely secured to the crankshaft.

I'd been looking forward to starting on the air cleaner assembly to top off the engine and hide the unsightly throttle and needle valve. But with the engine running, it was difficult to not at least address its extremely smokey exhaust. This is the first engine I've built that doesn't use an oil pump and instead relies upon 'splash' lubrication which in is affected by the level of oil in the sump.

I don't believe it's necessary for the rods or crank webs in a closed crankcase multi-cylinder engine to dip into the crankcase oil. The back-and-forth air pumping between cylinders will create an oil storm inside the crankcase that will keep all its internals wet. In a full-size engine this windage is a power-robbing nuisance. In an essentially unloaded model engine it can be used to advantage to supply enough lubrication to control wear without overcoming the typical oil controls machined into model pistons.

I found the best way to add oil to this engine is through the dipstick port using a hypodermic needle. I began with 45cc of 10W-30 which was enough to wet the ends of the connecting rods when at their lowest positions. A rendered cross-section of the crankcase shows the three levels I tried. The 45cc's smoked like crazy and spit lots of oil out the exhaust. The highly aerated oil was drained and replaced with 35cc. With this amount the connecting rods were just barely above the oil, and the results were nearly acceptable but not yet suitable for indoor running. Reducing the oil level to 20cc cleaned up the exhaust entirely with only light smoke puffs during acceleration. I'll likely try 25cc at the next oil change.

Currently, the engine starts easily and idles at what seems to be a very low rpm. It's been rev'd up a few times, but after the flywheel incident we still have trust issues between us to overcome. The needle and air bleed haven't yet been optimized, and I'm still running with my initial 5 degrees BTDC timing. The engine's shakedown and fine tuning will continue, and I'll post a video when the air cleaner is finished. - Terry


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## gbritnell (May 13, 2022)

Hi Terry,
I'm glad to hear that the flywheel key fiasco didn't result in major damage. I run my engine at about 15 degrees of advance. This is the old hot rudders seat of the pants timing method. Advance until it runs the best then back off a touch. 
gbritnell


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## Basil (May 13, 2022)

Another awesome build Terry. I would have been sweating with how much pressure would have been required to pull the flywheel off and wondering how badly the assembly might have galled. Top job!


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## ShopShoe (May 13, 2022)

When you first posted about this setback I was really sorry to hear it.

However, I am amazed at your analysis of the cause of the problem and the ingenious solutions you came up with.

As always, your builds are awesome and I learn so much from them, even if my humble projects don't even approach what you can do.

Thank You for posting "Warts and All,"

--ShopShoe


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## a41capt (May 13, 2022)

Nice recovery Terry.  Glad it worked out so well, I worried that your crankshaft received irreparable damage, but knowing your ingenuity, I figured you’d already have a plan!

John W


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## mayhugh1 (May 23, 2022)

Fine tuning was simpler than expected. With the engine rev'd up as high as I was comfortable with, the needle valve was adjusted for a peak. Although the tuning was a bit broader than I'm accustomed to, I'm not sure it was worth the hassle I ran into with the needle's 8-80 threads. The engine idles nicely at the same needle setting which was surprising since I expected to have to fiddle with the air bleed screw. The position of the screw in the air bleed hole doesn't seem to have much effect, but leakage around it through the air bleed hole might be. The constant fuel level presented to the carburetor's spray bar by the recirculating loop tends to add consistency to the tuning.

The radiator warms up after a two minute run which means coolant does circulate - probably with a lot of help from thermal siphoning. I haven't yet run into any hot start problems, but that may change when the air cleaner assembly is added. Hot exhaust manifold air trapped below the air cleaner could help or hurt performance. I may take some IR photos later.

Since the flywheel is enclosed by the bell housing, and the front of the engine is blocked by the radiator, there isn't a convenient was to measure rpm with either an optical or mechanical tach. In hindsight, a tach output integrated into the CDI's front-end board would have been nice to have. Later, I'll likely couple a scope to the distributor's tower wire in order to get a measurement of the engine's rpm range.

So far, the engine is free of oil and coolant leaks. The well-sealed crankcase was a bonus and allows control of the crankcase gasses which will be vented through the rocker cover as they were in the full-size engine. A piece of tissue held over the filler cap hole is visibly affected by the crankcase pressure pulses. The oil mist that's dragged along with those gasses will tend to fill the volume under the rocker cover and provide lubrication for the roller rocker top-end. Since the primary path into the rocker cover is through the oil drain holes located behind the side-mounted tappet cover, the lifters will be wetted as well. The filler cap I machined is very similar to the one that was on my '72 truck engine.

I'd been looking forward to the air cleaner assembly because it would be an interesting machining challenge and something I'd not done before. Along with the bell housing, it turned out to be one of my favorite parts of this build. I don't plan to run an air filter, but the housing will add realism and reinforce the stock appearance of the engine. A major goal for the housing's design was to lower the apparent height of the carburetor whose bowl turned out be larger than I wanted. Its weirdly long throttle and needle valve were in anticipation of a 3" diameter air cleaner assembly that will set down over them.

The three piece air cleaner assembly includes a baseplate, cover, and an air intake snout. Since the assembly will end up virtually sealed to the top of the carburetor, the snout was made functional. It's through-hole was plunge cut with a 3/8" end mill and the end openings worked with needle files. Minimum weight was a key consideration for the whole assembly since the carburetor it mounts to is held onto the intake manifold with only a pair of 2-56 studs. All the material that was removed from the baseplate gives it's interior something of an unexpected appearance.































The cover was machined on the mill although it could have more easily done on the lathe. My final post will include photos of the completed engine and a video of it running. - Terry


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## a41capt (May 23, 2022)

Love it!  Looks like it just came out of my old Ford F100!!!

John W


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## propclock (May 24, 2022)

AbFab as always you are an inspiration. Super happy  the  crank keyway
issue was resolved. Again thanks for all your efforts posting and lessons learned.


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## ddmckee54 (May 24, 2022)

You're going to make a filter element for it aren't you?

I mean you went to all the trouble of making that FINE looking air cleaner, you're going to make it functional - right?  Maybe a cut-up foam lawn-mower filter element?  You want to get 100,000 miles out of that engine it's got to breathe clean air.

The return to tank line looks awfully close to the exhaust down-pipe, any concerns about the heat affecting the fuel lines?  (Maybe there's more clearance than the picture makes it appear to have?)

Don


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## mayhugh1 (May 24, 2022)

ddmckee54 said:


> You're going to make a filter element for it aren't you?
> 
> I mean you went to all the trouble of making that FINE looking air cleaner, you're going to make it functional - right?  Maybe a cut-up foam lawn-mower filter element?  You want to get 100,000 miles out of that engine it's got to breathe clean air.
> 
> ...


It's the camera angle making the fuel lines look so close to the exhaust. The natural curve in the return line along with the tubing loom keeps them both safely away from the heat. - Terry


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## Eccentric (May 24, 2022)

Terry,

This might be a simple, inexpense, non-invasive way to measure RPM.  The long black wire picks up the ignition signal inductively through the spark plug lead.  The tach is programmable for many different engine cylinder configurations.  Even if it is just used as a diagnostic tool, it is nice to have around.


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## mayhugh1 (May 24, 2022)

Eccentric said:


> Terry,
> 
> This might be a simple, inexpense, non-invasive way to measure RPM.  The long black wire picks up the ignition signal inductively through the spark plug lead.  The tach is programmable for many different engine cylinder configurations.  Even if it is just used as a diagnostic tool, it is nice to have around.
> 
> ...


Thanks! I just ordered one...


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## minh-thanh (May 25, 2022)

Hi Mayhugh1  !

I have a question ,
  Does your engine have an oil pump ?
If not, is 20 cc of oil enough to lubricate the engine ?
 Thanks !


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## mayhugh1 (May 25, 2022)

minh-thanh said:


> Hi Mayhugh1  !
> 
> I have a question ,
> Does your engine have an oil pump ?
> ...


There's no oil pump. The way I determined the amount of oil to run in the sump was to run with the highest level of sump oil that would not smoke badly and spit oil out the exhaust. I don't think it's necessary to have a high oil level for the connecting rods to dip into. There will be plenty of windage in the crankcase to lube the moving parts in an engine that's not being asked to do real work. The pistons of a multi-cylinder engine moving up and down in their cylinders create alternating pressure and vacuum pulses inside the crankcase that create an oil storm that should lubricate everything well enough without overcoming the pistons' oil control scheme. One indication that this seems to be working is that the top-end is also wet with oil which must be getting dragged along with the vented gasses through the filler cap. ymmv - Terry


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## ddmckee54 (May 25, 2022)

mayhugh1 said:


> One indication that this seems to be working is that the top-end is also wet with oil which must be getting dragged along with the vented gasses through the filler cap.


Well there's your next project isn't it?  You've obviously got to build a working PCV valve to vent that airborne oil back into the intake, can't let it be slobbering all over that frabjus valve cover.

Don


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## KennyMcCormick315 (May 25, 2022)

ddmckee54 said:


> Well there's your next project isn't it?  You've obviously got to build a working PCV valve to vent that airborne oil back into the intake, can't let it be slobbering all over that frabjus valve cover.
> 
> Don


Eh, as the owner of two 300's in full scale....they really just don't look right unless they're soaked stem to stern in oil. They're notorious for valve cover and sideplate leaks in particular. One of mine leaks so much oil it doesn't even get oil changes anymore because the oil doesn't stay in the bloody thing long enough to need changed in the first place!

PCV would be a nice scale detail, but I fear it might end up like my _other_ 300, in that it would be pushing so much oil down the carb that air filters turn jet black within a month. That one doesn't really leak very much anymore as I've replaced the valve cover and sideplate gaskets within the last ten years, but it also has 350k miles on it and the top end is worn plumb out so it has a metric -beep-load of blowby pushing oil mist out the PCV hose and down the carb. Given this model is known to lubricate the valve train by pushing oil mist quite heavily into the valve cover it'd probably be no different.

Damn good engines though. I love them to death, no matter the scale! I would love to hear mayhugh's example running under heavy load; it makes them sing such a beautiful song!


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## Peter Twissell (May 27, 2022)

"One of mine leaks so much oil it doesn't even get oil changes anymore because the oil doesn't stay in the bloody thing long enough to need changed in the first place! "

This is a common misconception. The leaks in the engine are all acting like filters, so while oil is leaking out, the sludge and particles which accumulate in the oil are staying in the e


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## mayhugh1 (May 29, 2022)

The inductive tach recommended by Eccentric arrived. Mine's a slightly different model but still very easy to set up for a 6 cylinder engine (or any other number of cylinders). From its lope I was sure I had the engine idling at 800-900 rpm, but the tach kept telling me the real number was nearly twice that. I thought a setup issue or electrical noise was causing too-high readings, but after a lot of troubleshooting I was finally convinced the tach was working as it should.

With my confidence in the engine growing, the carburetor was retuned for a top end of 5k rpm even though full throttle was 7k. These higher speeds required the fuel pump to be bumped up in order to maintain a constant level of fuel in the bowl. Still, the air bleed adjustment didn't seem to have much effect.

Carburetor tuning doesn't seem to be affected by the air cleaner. Suction through the intake snout is noticeable though, and the engine will immediately stall when it's covered. It'll be used as a choke during cool weather starting.

With the rocker cover and air cleaner removed, I took a number of IR photos over various surfaces of the engine during and after a two minute run. The first two photos are overviews of both sides of the engine as viewed from its rear taken at the end of the run. The siamese'd intake manifold eventually rises to the same temperature as the exhaust manifold which is some 250F.

The third photo is a closeup of the intake and exhaust manifold surfaces taken well into the run. The intake runners which are cooled by fuel while the engine is running are some 20F cooler than the exhaust runners. All three photos show the carburetor as the coolest part of the engine - most likely a result of the cooling provided by the recirculating fuel. The fourth photo shows the effect of manifold heat on the carburetor about midway through the run. Although the temperature of the carburetor's base has risen, the important area around the Venturi remains cool to help keep tuning consistent.

The fifth photo is a closeup view of the top surfaces of the head taken near the end of the run. It's 177F temperature is representative of the hotspots between the rocker assemblies and above the combustion chambers along the entire length of the head. These hotspots are uniform across the width of the head despite the fact that one of the head's longitudinal coolant passages was blocked during construction and is non-functional.

The sixth photo shows the temperature gradient across the front face of the radiator at some 1-1/2 minutes into the run. There's a 10F gradient from top to bottom with the hottest area at the top of the radiator being some 140F. This temperature is 30F-40F cooler than the hotspots in the head. This gradient all but disappears during a longer run when the face of the radiator settles out to 135F.

The last photo is a view of the port side of the engine midway into the run. With the side of the head at 155F, the crankcase is a fairly uniform 143F with the oil pan some 20F cooler. All in all, the photos show a pretty effective cooling system that I wasn't expecting and head temperatures considerably lower than I expected.

This build has been so much fun that I'm having trouble ending it. I never considered designing a pcv valve, but I did press out a brass 2-56 wing nut for the air cleaner cover which I then nickel plated. That nut is similar to the ones used on some Ford engines from the same period. - Terry


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## gbritnell (May 29, 2022)

Ah come on Terry you're killing us here!  When are we going to see the video?


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## propclock (May 29, 2022)

Sorry If I missed it in previous posts, but how are you taking the IR photo's ?
That is exceptional in all respects. Thank as always for your excellent work and meaningful
and educational posts. Thank you.


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## mayhugh1 (May 29, 2022)

propclock said:


> Sorry If I missed it in previous posts, but how are you taking the IR photo's ?
> That is exceptional in all respects. Thank as always for your excellent work and meaningful
> and educational posts. Thank you.


I used an IR camera that my oldest son gave me  for Christmas several years ago. It's very similar to this one:



			https://www.amazon.com/Resolution-Pocket-Sized-Temperature-Measurement-Hti-Xintai/dp/B07M5CQ44L/ref=sr_1_16?crid=1FM85HJPR1VYC&keywords=ir+camera&qid=1653851827&sprefix=ir+camera%2Caps%2C163&sr=8-16
		


I used it to measure the effectiveness of the finless radiator that I designed for my Offy, but I got so wrapped up with its tuning and oiling system that I forgot to post any picture results. Since I used a similar radiator on the Ford, I thought the photos might be of interest. - Terry


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## mayhugh1 (May 29, 2022)

And finally here's the video:


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## pileskis (May 29, 2022)

Simply outstanding!
Beautiful craftsmanship all around.

What’s next?
I enjoy following along everyone of your builds.

Sid


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## kuhncw (May 29, 2022)

Very nicely done, Terry.  Thanks for the detailed posts.

Chuck


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## minh-thanh (May 29, 2022)

Like I said : Any engine you do is really great !
I love how you do everything perfectly , that's something I haven't done yet - hopefully one day..
Thanks for share .


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## gbritnell (May 29, 2022)

FANTASTIC,  What a wonderful rendition.  It runs great.  Thanks for the great documentation.


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## ozzie46 (May 30, 2022)

Absolutely fantastic!!!!

Ron


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## ShopShoe (May 30, 2022)

Fantastic. Wonderful, Super.

I've been waiting to see it running and I am glad to see it in such glory.

Whatever you do next, I'll be watching.

--ShopShoe


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## srobovak (May 30, 2022)

great job! 
i enjoyed this thread very much - 6 cylinder in-line is my favourite type of engine. 
thanks a lot for your time and for educating all of us following your thread.
all the best in your next project!
branislav


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## ajoeiam (May 31, 2022)

Hmmmmmmmm - - -  what's next?

(LOL)


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## dsage (May 31, 2022)

Fantastic job Terry. (as usual). Another piece for your wonderful collection. I really appreciate your detailed build logs and learn a lot from them.
Thanks


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## a41capt (Jun 1, 2022)

Terry, this is exactly as I expected it!  Truly fantastic work, an exquisite running representation of a fine engine.  I only hope that some day I can come close to your level of craftsmanship.

Thank you for sharing!
John W


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## CFLBob (Jun 1, 2022)

In addition to congratulating you for presenting a work of art, I want to thank you for the journey.  I don't remember exactly when I first came across this build but have been following it for most of the time and have learned lots.  To me, that's what it's all about.  


Bob


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## kvom (Jun 1, 2022)

Can't imagine what the next project will be.  Terry has really hit all the main themes for IC engines.


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## ddmckee54 (Jun 1, 2022)

OOOHHH, OOOHH, I know...  The Chrysler turbine?  Or doesn't that count as IC?  

Or maybe German aircraft engine, he built a Merlin.  Gotta keep the Yin and Yang balanced dontchaknow.

Or what about that 30 cylinder monster Chrysler built for the Sherman?


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## Steamchick (Jun 2, 2022)

Superb!
K2


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## KennyMcCormick315 (Jun 2, 2022)

That thing sounds pretty damn good! Though the idle is definitely up; real thing ticks over at just 500rpm or so. Makes me wonder if it's just scaling of physics laws that makes it so excruciatingly hard to get these small engines to idle as slow as their namesakes in full scale. Thermal camera shows nice and even heating which says all six pots are hitting; the MkI earball confirms that much.

Maybe CR is up? Cam grind? That thing does seem to have the kinda growl I hear from actual 300s with comp 264s in them. Not a bad thing by any stretch!


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## Steamchick (Jun 3, 2022)

Kenny, you are right about the laws of physics, scale and speed.  Designing a model engine, you can work to the SAME piston max speed (to do with rings rubbing bores) as a full sized engines, but at 1/10th scale the engine is running 10 x faster. See what I mean?
Also, to get the SAME pressures and combustion flame speed in the combustion chamber...  which affects idle running. Cam timing, ignition timing, flywheel mass, etc. all have an influence, and some modellers tweak the "tune" of the engine to slow them down. But that moves away from "exact" scaling...
But there are dozens of factors, some linear, some square and some cube - that screw-up scale engines working exactly like full sized ones. e.g. the 100th of the power, but 1/10th of the friction for a 1/10th scale engine: Yes, the laws of physics apply, but also the laws of mathematics (squares, cubes, etc.).
But I agree it is a fantastic model!
K2


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## KennyMcCormick315 (Jun 3, 2022)

Steamchick said:


> Kenny, you are right about the laws of physics, scale and speed.  Designing a model engine, you can work to the SAME piston max speed (to do with rings rubbing bores) as a full sized engines, but at 1/10th scale the engine is running 10 x faster. See what I mean?
> Also, to get the SAME pressures and combustion flame speed in the combustion chamber...  which affects idle running. Cam timing, ignition timing, flywheel mass, etc. all have an influence, and some modellers tweak the "tune" of the engine to slow them down. But that moves away from "exact" scaling...
> But there are dozens of factors, some linear, some square and some cube - that screw-up scale engines working exactly like full sized ones. e.g. the 100th of the power, but 1/10th of the friction for a 1/10th scale engine: Yes, the laws of physics apply, but also the laws of mathematics (squares, cubes, etc.).
> But I agree it is a fantastic model!
> K2


yeah I imagine getting it to idle at 500-600RPM would require an insanely oversized and out-of-scale flywheel that would never fit inside that bellhousing. Either that or it would have to be made out of something like tungsten or depleted uranium.

I can also see that in my commercially made RC engines. My Fox 049 FAI has had an airbleed carb fitted to it and I can get that tiny little bugger to idle at about 4500-5500. My Super Tiger G3250 will tick over at 1800RPM all day long. My Saito 125GK is more content to lope over at ~2200RPM than my FS26 Surpass is. Physics just does not like small engines running slowly. Can also see timing playing its role; my OS 25AX will idle along happily at 2750RPM while my Kyosho KE-25 won't even think about anything lower than 5 grand or so despite both engines being single cylinder 2-stroke glow mills of the same displacement; the Kyosho unit is much MUCH more aggressively timed.


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## stevehuckss396 (Jun 4, 2022)

Another trick to get a lower idle is to cut your cam with good amount of duration and overlap. Most of the model engine plans I look at (except mine) have 220 to 240 degrees duration I made my v8 280 duration resulting in  60 degrees overlap. 

What many people forget is the valves don't start to lift until all the valve lash is out of the valve train. Long story short, not enough duration and excessive valve lash can choke off an engine. Too much and it will start to lope like a hotrod. 

That sweet spot is probably different for every engine. In a multi-cylinder engine imo there can be more almost every time. In the event that you "over cammed" and don't like the sound just add lash and you can reduce duration and overlap. 

Worked for me. I get alot of positive comments on how low my engine idles. Didn't want it to sound like a 2 stroke. Mission accomplished.


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## Steamchick (Jun 4, 2022)

I worked with a guy who did a Doctorate and PhD on mass-elastic systems. He improved the tuning of the valve train on some Cummins engines (his sponsor for his thesis) before the job he had alongside me. He explained to me that most "time delay" between cams and valves is not clearances, but elasticity in the valve train (mostly push-rod systems). That is why so many engines now have "direct" action of "cams on valves". Much better for valve timing control, especially with variable valve timing. And on models with push-rods, as the stiffness of systems relies on a cube of dimensions, like volume, and mass of parts, there is a curious symmetry of how the mass -elastic characteristics of valve trains actually scale effectively. Otherwise they would not work.
Interesting how you have tuned the overlap to tune the idle performance. (If I understand correctly?).
Well done on a superb model.
K2


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## stevehuckss396 (Jun 4, 2022)

I'm not going to get into why so I don't muddy up this awesome thread but those effects are probably not applicable to our models.


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## Charles Lamont (Jun 4, 2022)

stevehuckss396 said:


> What many people forget is the valves don't start to lift until all the valve lash is out of the valve train.


At the risk af adding mud:

That's why you have relief round the heel of the cam, and ramps to take up the valve clearance by the time you get to the start of the flank.

If you rely on increased clearance to reduce the duration, somewere in the valve train there will be an impact when the cam takes up the slack, instead of smoothly acceleratng it from rest. So you will definitely get (a minute amount of) elastic deflection as the train tries to come up to the speed of the cam.

Low idle speed sure, but I want minimum mechanical noise too.


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## stevehuckss396 (Jun 4, 2022)

I'm not sure a hit from 5 extra thousands of lash and 6 lbs springs would count as an impact. Can't compare real life engines with models. Apples to oranges.


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## Steamchick (Jun 5, 2022)

Hi Charles, to try and clarify the "mud" of mass-elastic systems: I was referring to the natural elasticity within the components _after _the slack has been eliminated. Tension members stretch a tiny amount, Rockers & pins bend (Loaded like a beam),  push-rods in compression compress (all-be-it another tiny amount) - All of which is significant in push-rod engines (and my 6m long push-rods in HV circuit breakers). - And possibly in model engines with fine piano wire push-rods? Unless you have had to study this and re-design systems according to the effects of the system elasticity, you are probably not aware that this is something high speed engines have "suffered" from, for generations. (Race car enthusiasts cope with it usually without appreciating what they are doing).
An Horologist friend used his smallest gauge piano wire on his push-rods on a model, and they buckled at high engine speed - when the acceleration force applied by the cam to operate the valve increased. (The forces go up as the inverse of the t-squared bit of acceleration! - so as event time comes down, forces rise dramatically!). So he used the next size of wire: Mass increased as the square of the wire diameter (F = Ma stuff), but the stiffness of the "rod" increased as the cube of the diameter = so "simply Much better" - and demonstrated mathematically.
My point (Badly made?) was that the total real "lash" in a pushrod valve train comprises 2 elements: Clearance AND elasticity of the valve train. AT high revs, the elasticity (Or stiffness if you prefer) becomes more significant, usually appreciated just as valve bounce occurs. But that is another dynamic issue we don't need to discuss here.
Ultimately, we are all discussing the "ether" when we should simply appreciate a beautifully made model.
(Controller: please delete this post if inappropriate to the subject).
K2


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## mu38&Bg# (Jun 5, 2022)

Everything is a spring.


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## Steamchick (Jun 6, 2022)

Yes. And springs "delay" outputs relative to input motion. They also store energy that is released later as kinetic energy. Hence the study university study of mass-elastic systems for Cummins diesels that my Doctor colleague modelled on the computer.
Enough Mud.
K2


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## stevehuckss396 (Jun 6, 2022)

If this discussion is interesting and everyone still would like to continue with it I suggest a new thread be created on the topic. We have already infringed upon this build thread enough and gone way off topic. Please reserve all further discussion in this thread to the 300 build Edit

Thank you.


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## minh-thanh (Jun 6, 2022)

stevehuckss396 said:


> a new thread be created on the topic.
> respect for Mr mayhugh1.
> Thank you.


 
It's really simple, but I don't understand ....why...
The forum has a place called " *General Engine Discussion* ", Please !!!


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## minh-thanh (Jun 8, 2022)

mayhugh1 said:


> More Photos ...View attachment 126150
> View attachment 126151
> View attachment 126152
> View attachment 126153


 Hi mayhugh1  !
I have a question :
When sandblasting, what method do you use to protect  holes  bolts  and other surfaces that do not require sandblasting ?
  Thank you !


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## mayhugh1 (Jun 8, 2022)

minh-thanh said:


> Hi mayhugh1  !
> I have a question :
> When sandblasting, what method do you use to protect  holes  bolts  and other surfaces that do not require sandblasting ?
> Thank you !


Hi,
I put screws into all threaded holes, and I cover (rarely) flat surfaces that I want protected with yellow vinyl tape purchased from Harbor Freight a number of years ago. - Terry


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## SmithDoor (Jun 9, 2022)

minh-thanh said:


> Hi mayhugh1  !
> I have a question :
> When sandblasting, what method do you use to protect  holes  bolts  and other surfaces that do not require sandblasting ?
> Thank you !


Remember if you sand blast a block or was flood you have to remove the sand from all oil port. It is big pain. 
I like high pressure washer or steam then you only dealing with water in ports. I use airgun and hot summer day. 

Dave


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