# Homebrew boxer twin prototype



## Lakc (Oct 28, 2010)

*Boxxer twin prototype*​
 Having finally worked up the courage to start a build thread, and finding the spare time, I offer this up to our community. I cant promise any great contributions to the art, only the hope that some might find some things here useful. We learn from our mistakes, and I have made many so far, with no reason to believe that will change, as I hopefully complete this project. If your capable of learning from the mistakes of others, I should be able to teach you a whole lot! Some folks have spoke of having a preference for showing a build warts and all. I can say this build has been mostly warts. My hope for this first prototype is simply to make noise, not necessarily look pretty. It should be a rather simple build, we can work the warts out on the next one with experiance.




 This engine design started approx 14 months ago, mostly as an exercise in CAD drawing. Unfortunate circumstances forced me to put it away, and almost a full year later I was able to work on it again. It is almost entirely of my own design. Some of you may recognise the cylinder head resembles the Edwards radial engine. The reason behind that is in my research to eventually build the Edwards, I was not entirely satisfied with the cylinder head drawings. This engine is partially the result of my desire to test my design on a simpler engine. Of course, one opportunity seems to breed another. In that respect, I utilized this opportunity to add a few "firsts" to my list, gearcutting, alloy steel crankshaft, pressurized oiling system, oil pump, and bronze bearings. The drawings are still slightly unfinished, mostly just I's to be dotted and such, but I am confident enough in its viability to forge ahead.

 Bogs recently commented in another thread about patience. I fully admit that is a quality I lack, and hope to improve upon in this hobby. Many things conspire against me in this respect, leaving me precious little time to devote to my projects. The addiction to the good feelings that come from making progress, keep pushing me to do more in less time. Often this leads to disaster, and the proverbial scrap bin, or going back to "change the prints to match". Occasionally, it leads to efficiency. For the benefit of our impressionable readers, do not emulate my faults, just try to learn from them. I am guilty of starting a way more complicated project then this, and not finishing it. As such, with a few types of parts, this is not my first rodeo as they say, but the spectre of an unfinished project in my past has become a haunting one. I am hoping that this forum could provide a service to me by kicking me in the rear if I begin to slack off. I have a full time job, house, and a family, so my goal would be to get some kind of updates done each week.

Prequal

There is somewhat of a prequal, and you can read the thread in the casting forum here http://www.homemodelenginemachinist.com/index.php?topic=10845.0
The actual sequence of events does not start with the castings, but it fits along as a seperate side project if you will. For those of you who are turned off at the prospect of doing your own casting work, you do not need to worry. This engine can easily be built from barstock, and the maximum thickness of the case is only 1". I am sure some people would even consider barstock easier then the casting route. There have been times I would be inclined to agree with that sentiment, but I would like to make several of these, so the form work should pay off. 

Gearcutting

The first order of the feasibility study would be cutting the gears. Revisiting the drawings a year after I first drew the engine basics, I had to reverse engineer the dimensions to determine what the gears specifications were. There is good news and bad news here. The good news is I picked simple tooth counts to index, 18 and 36 tooth. This ensured even my lowly enco cheapie 5c spindex would work. The bad news, aside from my mislaying the pictures, is to obtain the required .94 inch spacing it required 29dp gears. Good luck finding them commercially. That may have been a subtle nudge to myself to force my hand at the hob method of gear generation. Whatever the forgotten reasoning, the hob and gears were quite simple to make. Once I had the gears, I knew I had to build the engine. 
I will include a write-up on the gears and hob once the pictures have been found. _Edit Pics found, a few of them at least, down a few posts._

Crankshaft

Our story now picks up in early September. The most trying part of any engine build to me is the crankshaft, so I start with that first. We begin by chopping off a length of 1" 4140 steel from McMaster-Carr.







Chucked into the 3 jaw, I used a dial indicator and plastic hammer to center it as best as possible before attacking it with the center drill. The part was flipped over and centering was repeated on the other side. I always seem to have great patience at the beginning of the project. I suppose it helps when you havent made your first mistake yet. 






Once the centers are picked up we move over to layout and scribe lines parallel on each end of the bar.





Over to the mill, the line was picked up with the wiggler and adjusted parallel to the vise jaws. Center was found, two more centers added for the crankpins. At this point I had a change of plans. I milled a 5/16x5/16 slot parallel to the centers to assist in keeping the alignment when I flipped the bar over for the other side centers. A 5/16 square toolbit worked admirably in this function.





Second verse was pretty much same as the first, flipped over, we had centers in each end of the bar in the appropriate places.

 Time to move back to the lathe, centers in place, we began making mistakes I mean learning right away. Mistake one was thinking regular steel tooling would cut this alloy crank. Look at this horrible finish.




Once I switched to carbide tooling things got noticibly better, when I started using coolant/lube I was achieving good finishes again. I got lazy with cutting brass and aluminum, this was some tough stuff. 4140 comes in a leaded version, 4140L, which may make this part easier. With carbide and coolant/lube (astrocut2000) it was a good exercise. 
The journals were .25 wide. I found the best way to attack this was with a .25 square soldered bit head on. There was some wandering of the bit at first, but as I progressively tightened and retightened every part of the holder, tailstock, and crossslide this eventually went away. If you have ever done this, you know the tedium involved in hearing the thunk of the bit taking its offset cut, and gently moving the bit forward in time to the revolution. I spun it up rather fast and took approx .003 cuts with each thunk, developing a rythum with the machine. This shot is the first journal finished, you can see the layout lines for the remainder of the cuts. All measuring was done with a dial indicator, the layout was for a visual doublecheck. 





Second journal went much smoother and quicker. Plunge straight in, no real stopping. Lathe speed was kept higher as the diameter decreased. Look at all the .003x.250 shavings in the first pic.









Now is the point where 4140 really started to pay off. Under tight load between centers, I only measured about .oo4 spring in the journal gaps, and that was reefed down much tighter then it needed to be. This stuff is strong! Here is a left hand positive rake soldered carbide bit taking out the center marks. 





Starting to look like a crankshaft, the nose gets a taper down to a 1/4-28 thread. 










Thats about a good place to stop for now, more coming soon, lotta pics to rearrange and find. In a few more days, given the time, we will be caught up in real time.


----------



## nfk (Oct 29, 2010)

Looking good!
I`ve found 4140 a pain to machine, my lathe lacks rigidity for that stuff.
Lots of cutting fluid helps a lot.
For the next engine i`m thinking of give silver solder a try.

Norberto


----------



## bearcar1 (Oct 29, 2010)

Hi Jeff, that looks good. I had to go back and scan through your series of pics in the photobucket and realized that you had what I assume to be a spacer taped into the gap of that first journal to keep the part from flexing too much, however I did not see any such steps being taken in the later shots while you were cutting the end shafts. I'd be scared to not have some such support in there for fear of having the thingie flex just once and ruin the piece, knowing my luck it would surely, as I'm sitting here, happen. I'm looking forward to see your prototype progress into a workable model. 

BC1
Jim


----------



## Lakc (Oct 31, 2010)

nfk  said:
			
		

> Looking good!
> I`ve found 4140 a pain to machine, my lathe lacks rigidity for that stuff.
> Lots of cutting fluid helps a lot.
> For the next engine i`m thinking of give silver solder a try.
> ...



Thanks Norberto. I stuck with it and kept retightening everything to help the rigidity, but the cutting fluid did wonders as well. 



			
				bearcar1  said:
			
		

> Hi Jeff, that looks good. I had to go back and scan through your series of pics in the photobucket and realized that you had what I assume to be a spacer taped into the gap of that first journal to keep the part from flexing too much, however I did not see any such steps being taken in the later shots while you were cutting the end shafts. I'd be scared to not have some such support in there for fear of having the thingie flex just once and ruin the piece, knowing my luck it would surely, as I'm sitting here, happen. I'm looking forward to see your prototype progress into a workable model.
> 
> BC1
> Jim



Thanks Jim. The spacer didnt seem necessary once I measured the deflection, and I had forgotten about it quickly after. The crank pins are .312, and there was only a few thou deflection when overtightening the tailstock, well under its elastic limit. 4140 is some pretty stiff stuff, and in that respect, did make the job easier.


----------



## Lakc (Oct 31, 2010)

*Gearcutting via the Hob method*​
I am really glad I deceided to give this a try. Taken in small steps, it is really straightforward. I reviewed a few threads from this board and some nice webpages, utilized a few of Marv Klotz's gearcutting utilities to doublecheck the math (thanks Marv!) and in the end I came out with this; 20 degree pressure angle, 29 diametrical pitch, rack form.





5 rack teeth cut into a 3/4 bar of A1 tool steel serves as the hob. This proved sufficient for the 36 tooth gear but more teeth on the hob may be necessary for higher tooth counts. I hardened the hob by heating it with a propane torch and dropping it into a bucket of used motor oil. I made a mandrel for the hob from the same tool steel so future hobs would have a place to live. 

The crank gear blank was cut from 7075 aluminum, and mounted on a cobbled up split expanding mandrel. A small piece of brass tubing was slipped over the mandrel first to keep the cutting forces from pushing the gear off the split part. The center gap on the hob was adjusted equal to the centerline of the index and locked in place. I kissed the gear blank to zero the handwheel and dialed in the full tooth depth. Cutting the aluminum was slightly gummy so we resorted to flooding the cutter with astrocut and that helped immensely. 





The coolant made a mess but the gear came out beautifully! 18 and 36 tooth were really easy to index on this cheap indexer.


----------



## Lakc (Nov 3, 2010)

*Machining the case castings*​
The thread in the casting section shows much of the trials and tribulations of casting the actual case halves, you can review it here: http://www.homemodelenginemachinist.com/index.php?topic=10845.0

The main benefits of casting are mostly cosmetic and repeatability. This engine can be made out of barstock easily. When working on castings, the trickiest thing to do is find a good datum point to measure from. The forms were second generation castings, which tended to loose some squareness. With the associated draft angles on the 4 sides, the best point was considered the deck just below the cylinder attachment boss. Special tool #1 was made to hold the face of casting the parallel to the table.










Here is one half done, showing a minor shrinkage cavity which will be machined out later. One casting is significantly higher then the other. That one was tackled first with a standard endmill before switching back to the flycutter.













Once I had a flat surface I went back and measured the height variation, on average it was acceptable +- .007". This left the cylinder mounting boss just about .065" proud of the face, taking about .030" cut of the cast surface. It may have been more luck then skill, but those measurements were approx the design ideas. This was also the easiest cut, as the face is 1 inch, I simply lowered the cutter to a 1-2-3 block to set the depth and milled it away. 











Now that I had 4 surfaces all parallel to each other I finally got to see how well each half fit together at the proper parting line. Disappointment began to sink in as the variation was worse then hoped. I actually aligned the halves by eye with a best fit mentality. What I should have done was realized the imprtance of the offcenter oil pump boss in the rear, and made everything else fit that. Hindsight, of course, is 20/20 and I went with the best fit of the 3 easy edges instead. I clamped them down and drilled the flange #20 followed by a 3/16 reamer in two places. Two spring pins installed in these holes would facilitate alignment of the halves for here on out.











Back in the vise, the front timing gear boss is trued up with a dial indicator clamped to the ram, gently persuaded into place with a few taps of a plastic mallett, then machined true. Now I had my third surface at exactly 90 degrees to the first ones, this was used to rough trim the crankshaft and oil pump bosses.














Now I scribe a few lines inboard of the edge and drill #6 holes and clearance drill down to the other half. I flipped the case over and repeated on the same hand side, leaving a pair of screws straddling the crankshaft centerline threading into the other engine half. I wanted these bolts holding the halves tight for the upcoming boring operation. 





Another day or so went by as I thought about the upcoming operation. I had actually never tried boring along the parting lines of a case like this, but there did not seem to be another good way to accomplish this. I had roughed the centerline out earlier based on the bosses for the purposes of the cross bolts. I now pulled out a pointed center and wondered aloud how the hades are you supposed to use this tool? Anyway, I had my ideas how it would help me here. Adjusting the center against the side of the vise for minimum point wiggle I eyeballed the parting line and the cross lines. Then I used a center drill followed by progressively larger drill bits and finished the bore off with a 1/2" reamer. Wound the table down .940" and did the same thing to the .250 camshaft bore. The smaller bore did falter a bit in the center, probably too much pecking without clearing all the chips, but it exited and began clean. I was pleasantly suprised to find everything worked as hoped.














Uploaded with ImageShack.us
At this point I will end todays installment, and bid you to join me next time for the "how things go wrong and how to adjust for them" follys. 

Feel free to chime in if you can tell me exactly how you use those pointed centers.


----------



## Lakc (Nov 4, 2010)

*Case machining continued*​
Right about now is when things fall apart.  The cylinder is measured off the side of the casting along the centerline and bored through 1" diameter. Then I flip the casting over and with a roughing mill a full depth (.850") rough cut is done by eye. I switch to a long endmill and begin to check measurements against the print. I zig along the side and much to my suprise I break into the bolt threads.





I am still approximately .050" shy of desired width of the inside of the case. The attaching bolts wont allow any further width expansion, although they are still useful, owing to the 3/4" thread engagement. I am discouraged and figgure I will probably need to start over. :'(

Looking back over the various parts and drawings I find at least part of the reason for the problems. I had recreated the cad drawings to make the masters with additional draft angles, but somehow I missed a dimension somewhere and left both masters .040" too short. Adding a double shrinkage allowance might account for the remaining discrepancy, I am not sure. I will have to double check before I order the version 2 masters. Lesson learned, the hard way. I took the rest of the day off and considered how to start another set of castings. After some reflection, that path did not seem too desirable. There could be further issues and lessons to learn that may catch me in the future with this design, so I wanted to go as far as possible. The crankshaft had plenty of extra meat on the counterweights, and could be shortened easily, as well as less work to redo if I started another engine. So I ended up shortening the crankshaft, shaving a little from the crank/thrust bearings. The game was back on! We will just have to keep our eyes open for any other adjustments this will force me to make. Once I sit down to do the version 2 blueprints, I will be a whole lot wiser.






*Back to the mill!*​
For some reason, I always considered this the fun part of the build, hogging out the crankcase. This time, its becoming a bit of a chore with some tight cuts into the threads. I am not happy about it but lets just see how it will break.  Side A was cleaned up as best as possible. The curved section is only cut approx .430 deep to provide a bore for the cam followers to ride in. Side B was blued and the halves joined together, a bent tip scriber transferring the rough outline through the cylinder opening. The cylinder mounting flange was bored through 1" again and the roughing mill does the lions share of the stock removal.




The halves were fitted together with the newly shaved crankshaft and only required minimal fitting. Endplay was good and the case screws held ample torque. Now to make a few more things fit. With a 1/2 collet both my boring head and drill chuck interchange quickly. The block is screwed together and clamped with the forward side up for the next boring operation. I chucked up a piece of .25 round stock and used that to find center for the cam bore. Using the boring head we make clearance for the cam gear, move the table back .940 and make the smaller bore for the crank gear.




Time for a little fun, we get to test fit everything together and begin to see what it looks like. 





And now, were almost caught up to real-time.


----------



## Lakc (Nov 4, 2010)

I would like to offer my apologies to everyone. Someone very kindly dropped a clue rake on my head about the image sizes and load times. I have reloaded most of the images to correct this. This will still be a very image intensive thread, but I will attempt to keep the pictures both relevent and reasonable in size for now on. Apologies again, for being so inconsiderate.


----------



## GailInNM (Nov 5, 2010)

Looks good, Jeff.
I like boxers so this thread is high on my watch list. I also like the "warts and all" approach as it helps save me from making the same mistakes my self. Then I can make my own mistakes.
Gail in NM


----------



## Lakc (Nov 5, 2010)

Thanks Gail! More warts coming but I am trying.... 

*Oil pump *​
One of the many "firsts" I scheduled into this project would be a pressure oiling system. If this engine would be done for production for a large company, oiling would be from a gerrotor style pump driven directly off the crankshaft. 

http://en.wikipedia.org/wiki/Gerotor

While that is undoubtably the best way to do things, it is probably difficult to reproduce in a home shop. I only say probably because I dont have the first clue on how I would produce one. It might be easy, but it is definately beyond my skills at this point. Model size gerotor's are available rather commonly, as scrap automotive electic fuel pumps here in the states, but they are still too big for my intended purposes.

 There is a way to use two spur gears to pump fluids, and that is the way I settled on doing it. Two gears meshing will carry fluid around the outside of the teeth, producing pressure just before the gears mesh again. While I dont expect to hold tolerances close enough to obtain maximum output, I hope to obtain a useable flow of oil. For gear material, I bought 12" of 20PA 32DP 12 tooth spur gear stock from Mcmaster for approx $23. These have a .375 pitch diameter, and need to be bored and cut to length. 

 Center was found with another probable misuse of the pointy centering tool. We bore using the existing hole .428 down to approx .1 from the inside, setting and checking the repeatability of the power downfeed stop. Boring with a power downfeed is a bit of a luxury, but avoids a lot of possible mistakes when hand feeding. 





 The two case halves are assymetric in the rear to allow for the oil pump idler gear offset from the centerline. This is where I should have paid more attention to the alignment of the case halves, as the offset portion is not at a right angle 

to the case halves and the camshaft centerline. This was compensated for by scribing the layout dye with a 3/4 endmill, so I have the proper radius to offset the second gear in the center of the casting. 















Center was picked up off the scribe mark, followed by a center drill and #20 then a 3/16 reamer. An endmill begins the hole and boring head takes over from there. 









A gear cut for an earlier test pump used as a gauge.




The remaining 10" or so of pinion stock I had was then chucked up nearly flush with a homemade pot chuck, center drilled, #20 and 3/16 reamer followed in a series of short pecks with the drill to keep it as straight as possible. Plenty of coolant/lube us used.









The pot chuck is held tightly to the face of the barely loosened jaws of the 3 jaw with a wrench and the pinion is advanced by gently tapping it up with a brass drift. In theory, this should minimize the error in retightening the pot chuck. It is then skimmed to .435 od and parted off .320 deep











And sitting on the tail of the camshaft it is starting to look like an oil pump. 







Next installment will likely bring me up to date. Its more necessary then fun but we will do keyways.


----------



## metalmad (Nov 5, 2010)

hi jeff
dont know if its my fault, but i have only been able to see parts of meny of your pics,
which is a shame, cos i recon a picture is worth a thousand words.
anyway. 
looking forward to your next posting, in what is starting to look like a very nice little motor
pete in australia.


----------



## ozzie46 (Nov 6, 2010)

metalmad  said:
			
		

> hi jeff
> dont know if its my fault, but i have only been able to see parts of meny of your pics,
> which is a shame, cos i recon a picture is worth a thousand words.



 I'm having the same problem. Wonder if using a site like photobucket would help wiyh this?

 Excellent work. Following along with envy.

 Ron


----------



## Lakc (Nov 6, 2010)

Thanks for the comments guys. I am not sure what the problem is with imageshack. I have flushed my cache by several different methods and still dont see the problem, but imageshack has been kinda slow lately. I will keep hammering away at it.


----------



## Lakc (Nov 7, 2010)

Thanks for all the positive comments! Hopefully, imageshack has sorted out its problems, but I am investigating another source for images soon. 

*Keyways*​
 Not the most sexy part of any build but definately important. In the continuing tradition of using some areas to make up for deficiencies in others, we will make a cut length to fit key for the cam gear. 

 First, we catch up on crankshaft work. A variety of holding methods are used to whittle away the outside counterweights. The part of the crankshaft between the two connecting rod pins will be left as is in case any other changes are called for. I also ended up redrilling the oil hole from the front bearing as I flipped my angles backwards drilling down from the rod pin. 









Cutting the keyway was straightforward. 1/16 carbide endmill taking .003 deep cuts for .063. Slot was started in the missed oiling hole to cover it up. A 1/8 square piece of steel was milled down to make a 1/16x1/8 key. Once back on the block the gear depth was set and I removed the excess key with a file. 





















Now we put two keys in the camshaft, on for the timing gear and one for the oil pump drive. The cam was made out of 3/8 4140L, and thus I did not have extra material to leave a face for the timing gear to but up against. Here we cut the keyway almost completely through and use a variable depth key to center the gear. The timing gear is also cut to less then full depth.













The tiny keyway is adjusted for length to keep the cam gear at the correct depth.

The oil pump gear fits at the back of the camshaft, it is slotted 1/16 the full depth. More tiny mill work, done mostly under magnification. 










 Now all the turney bits turn the other bits. This is really fun! We are almost caught up, although I do have a few more pictures in the can. Next up is finishing the oil pump, and then likely we will be putting the bumps on the bumpstick.


----------



## Artie (Nov 8, 2010)

Jeff, this is fantastic and Im thoroughly enjoying your write up! :bow:

Looking forward to the next instalment...

Rob T ;D


----------



## Lakc (Nov 13, 2010)

Thanks Artie!

 We have made a bit more progress, and have some neet new toys for the next part. Been real busy but I will have some picture updates coming soon. Perhaps sometime this afternoon or tomorrow. I have already finished off the oil pump (for now) and added some lobes to the test camshaft, currently working on the first cylinder.

 I am hoping this thread makes it to the second page before I post any more pictures, just to keep the loading time down. If not, I will just use thumbnails for the rest of this page.


----------



## Lakc (Nov 14, 2010)

*Oil pump*​Lots of work here, mostly under magnification. These are the tightest tolerances I have ever tried to work to. As most of them are outside of my measuring capability, I make it tight and had fit a lot of it. Once the keyways were installed there was, as expected, significant binding in spots. Tooth by tooth, each oil pump gear was deburred under a magnifying lens and that got rid of most of it. I blued the cavities and hand scraped some areas, and rebored the one cavity another .001 larger to make up for a slight offset in the gear center bore. An 8260? rod I had purchased for the wrist pins was used for an idler shaft for the offset gear. Then we measure and cut the oil pump cavity to give approx .002 clearance, which will later be reduced to .0003 by hand filing. 














 Then I take a chunk of 3/8 aluminum and ream two 3/16 holes .375 apart to a depth of .312. It is dyed up and placed over the protruding camshaft end with the idler shaft holding the idler gear in position. Held tight, it is scribed with the outline of the casting. With my template visiable in the vise I drill the inlet and outlet holes. Back at the computer, I finally draw the cover and figure out the proper angle for the outlet port, which is a drilling that intersects the camshaft bore and pump outlet, as well as allowing a flat area to tap 10-32 for a pressure relief valve. Looking at the remaining area scribed, I can get 1 4-40 screw in a fatter section of the casting, and 3 2-56 screws to hold the remainder of the cover on. They are drilled in the cover first and transferred to the block. Later, I can shape this ugly but functional cover back to the scribe marks. For now, the flat surfaces allow easy vise chucking.


----------



## Lakc (Nov 14, 2010)

*Camshaft*​
 This started as a rough part, and has only gotten rougher. I dont know if it will survive as a working part but it has been an experiance. Early on, right after the crankshaft, I took a piece of 3/8 4140L and turned the journals, lobes, and thrust surfaces, as well as double ended drilling through to act as the oil feed from the pump to the front main bearing. This was only mockup quality as I made the lobes slightly offset from the drawing, but we have pressed on regardless. 

The part was chucked up in a Sherline 4 jaw attached to a rotary table. I dont have the proper tailstock for this so I supported it with a shimmed V block. The cam is flat sided, so the first flat was indicated and slowly nibbled down to the baseline depth. Once at depth the rotary table allowed nearly effortless cutting by rotating the cam to the next flat angle.


















 You can see where the lobes were offset from the drawing. In practice, it likely wont matter much because of the .375 mushroom tappets. The slight nose radius is put in with a few easy passes of a file. I went with 3 lobe design to make the pushrod angles a little bit flatter, opposed motors often use only two lobes. I may eventually scrap this part as the timing is suspect, done long ago and I had lost my notes. But for now its definately serving a useful purpose.

This essentially brings us up to date. ;D I have one cylinder complete and one block half cylinder bolt pattern drilled and tapped. Maybe another update tonight if I have them all completed


----------



## Lakc (Nov 14, 2010)

*Cylinders*​How to turn 420grams of steel into a 48 gram part​
 This is one of those parts that looked great on the cad program, but making it to print would be nearly impossible. I changed the block flange width from .035 to .050, just because I wanted it a bit stronger, but 10 .020 cooling fins were a pipe dream. 

To begin, we tap the part with a plastic hammer to center it for the accuracy of the center drill.







 Once faced off and centerdrilled, we go to the layout table. One of my new toys arrived Friday from Enco. I could have borrowed one from a friend but the height layout scriber is just too important not to have. First, we dye up the lump of 1 3/8 12l40 and scribe the important lines. Sorry about the blurry pic but this operation would have not come off as well without this accessory. 





The cylinder wall OD is 1", the bore will be .950. This is my first attempt at such a thinwall design. We turn the .350 deep protrusion to 1" and dive into the middle of the fins and flange, squaring it off with a square bit.


 

Then begins the nightmare of finning. I think I will stick to watercooled engines for now on. The .020 finning tool lasted about .035 before it broke. I went to .040 cuts and doubled the spacing. I eventually got through it, but the second shot is a rouge's gallery of failed cutters.









 Boring was pretty straightforward. My largest 1/2 shank drill is 17/32, so a lot of boring had to be done. If I do any more of these, Ill spring for a big drill and a .950 reamer and save an hour for each part. Why do you only think of the easy solutions on a Sunday.... Both cylinders came out within .001 of each other, just running a ball hone in them is all the bore needs now. Again, on a Sunday, my 1" ball hone has disappeared. Time to get a new one. Once bored, it is parted off and reversed in the chuck, and _lightly_ we take material off back to the overall height scribe line. There is not much material there and I could easily crush it with the 3 jaw. 








Two days worth of work, most of the time spent boring when I should have been drilling, and grinding toolbits for finning. With the right tools, everything but the finning could be done in an hour. I am not sure how to fin any better without a whole lot more rigidity in my cheap toolpost. Now it is beginning to look like an engine. 





Once we hone the cylinders and determine the final bore I can finalize the piston prints and we can make those. The con rod drawings are done, the cylinder head drawings are 90% finished, and we have some little things to do, like the bolt holes for the cylinders. It feels good to make some progress.


----------



## Lakc (Nov 20, 2010)

Thanks for the suggestion Phil. Once I get one running IC under my belt I probably wont be so anxious when I build the next one. There wasnt the normal level of forethought put into manufacturing those pieces, it was more like "it's only 3 inches of a 12 inch bar, not much lost if I screw it up". 

*Cylinder honing *​
 Not too much to see here. My 1" ball hone has disappeared but I did have some new stones for my two stone flex hone. Not even 200 revolutions on either cylinder, and I am quite proud to claim both came out .9507 bores. I used an old quart oil container cut down to contain the mess of grinding grit and kerosene I squirted on for lube. I also used the parted off stub as a guide for the hone to keep from bellmouthing the bore. 






*The felines derriere*​
 My new tool gloat now, from Enco. I did put some forethought into how I would find center for the block to cylinder mounting screws. At only ~3x the price Guy Lautard's bedside reader, which I believe has a method using regular wigglers, this tool does work, and does it with a bit of style.  Here we drill and tap the block and drill the cylinder mounting flange. One side is 6-32, when I realized I had to cut the screws down quite a bit to clear the cylinder barrel, I did the other side in 4-40.












*Rings*​ I spent a good part of this morning tweaking the piston drawings with the intention of making them today. This is my first dual ring design with one oil control ring and one compression. As I reread all my references I deceided that I should make the rings first. A few hours of reading, and thanks to Phil Burman's spreadsheet from Min_Int_Comb_Eng circa 2004, along with the collective works of Trimble and Walshaw, I settled on a set of .035x.035 thin rings, with the oil control ring a simple bevel top version. The piston will have many radial holes centered on the bottom land of the oil ring to flush the oil away. A bar of cast iron was turned down to .954 with .8807ID and the rings were parted off. The sharpie mark on the oil rings denotes the bevel edge. 








 I am pretty excited, as I have made pistons before but never rings, so there is another first I can check off my list. Once I get the pistons done, I will make the ring heat treating holder to specs, skim them down to .9507, and check the closing force to see how the wall pressure works out. If I need to adjust the holder from there we can accomodate that. 

Next up? Probably the pistons. Thanksgiving is next week, and I am looking forward to getting a lot more done with two extra days in the shop while the ladies do their shopping.


----------



## stevehuckss396 (Nov 21, 2010)

Hello Lakc!

How do you plan to temper your rings? If you want you could use my oven. Bring them over in the fixture and we can cook them at 950 for an hour or so. Sure beats the old torch and brick trick.


----------



## Lakc (Nov 21, 2010)

Thanks for the offer Steve, I will very likely take you up on it. 
I probably have enough materials to make a furnace, but thats a project for another day, unless a PLC suddenly drops in my lap.


----------



## NickG (Nov 22, 2010)

Jeff, this looks an intersting build - nice work so far. Will definitely be watching.

Nick


----------



## Lakc (Nov 22, 2010)

Thanks Nick, glad to have you along.

I have a piston, and it is reasonably close to print, but it needs a design change. I am not happy with bisecting #60 drill holes with the oil ring groove, there is just not enough hole there. It doesnt look right in the engineering sense, like those subconscious "back of the envelope" calculations are saying noo way. I learned a long time ago to trust that instinct, so its back to the drawing board for now. Hopefully, we will get something together over the upcoming holiday.


----------



## Lakc (Nov 22, 2010)

I suppose a picture of a 'failed' design might be helpful. :-\


----------



## Lakc (Dec 5, 2010)

*Pistons*​
 I am back at it, finally. The Thanksgiving holiday was filled with wallpaper removal and ressurecting a boarded up and plastered over laundry chute. The wife is happy, and I did the near impossible, loosing weight over the holiday, despite eating everything in sight. 

 I tweaked the drawing a little, adding .1" to the piston in various places above the wrist pin, and shrunk the connecting rod by .1". I also ordered a piece of A2 to make a ring groove cutter, and picked up a reduced shank 9/16 drill bit. Minor tooling additions, but they made a big difference. 

 I start with two pieces of 2024 about 1-3/4". It is a bit of a waste for a part just under 3/4" but there is no substitute for having a decent piece of stock to grip on, and a little clearance from the chuck jaws helps a lot too. The stock is squared up in the 3jaw with a dial indicator and gentle taps of a plastic hammer, then faced off to make a measuring datum and drilled .662 deep with a 9/16 drill. 









 Now the fun really begins. I move the drilled and faced blanks over to the 5C spindex, which has had a little attention paid to its lateral play since the last attempt. It was rather ,so it was greased up, and tightened up, best as I could. The wrist pin hole is drilled and reamed under power, .351" from the face. Then we move up to .478 and drill the 16 .0625" oil drain holes in 140 degree arcs between the wrist pins. I used a parabolic flute drill, and after bringing the drill bit to just spot itself, it was drilled under power from the quill. These holes just broke into the shoulder of the earlier 9/16 drill hole. This worked wonderfully, and the power downfeed probably saved me a drill bit or two because I couldnt get impatient. 









 Back at the lathe we do the same centering trick with the plastic mallet and dial indicator, helped a bit by keeping the written bar identification under the same #1 chuck jaw each time, we sucessfully recentered the part in the 3 jaw with under .001 runout. Then we turned a minimal amount of skin of the 1" bar to the .948 diameter.





The piece of A2 tool steel was earlier machined down to .037" width and hardened. I carefully aligned it to center and optically zero'ed it to the earlier faced off bottom of the piston. The carriage was moved so that the bottom side of the tool was bisecting the oil holes and the oil ring groove was cut .045 deep. It cut like butter and I couldnt have been happier.  No further drama ensued as I stepped up another .070 to cut the compression ring groove .039 deep. This was a great relief as my earlier hand ground form tools did not leave the ring groove square and wandered around a bit. These grooves came out quite clean and square. Cleaning up the work from this side of the piston, we bored the bottom interior .23" to .886" id.















 This piston has a 15 degree crown, and previously I attempted to part it off only to shatter a toolbit and give up, hacking it off semi flat. This time I centered the work with the 4 jaw and using the crosslide set to 15 degrees, I ran the lathe in reverse and trimmed the part from the backside. This left me with only one problem, that I could not measure the overall length of the part with the other side firmly in the chuck. I scribed a line .611" from the face where the crown starts, then I used a small measuring pocket microscope to determine how much to move the carriage. I can happily say that one part was only .002 too short, and the other .006. Close enough for that measurement in my book. 













 Now I have two happy pistons.  Identical enough in every respect, I am pleased and quite relieved it is all over. I will likely take a ball mill to the inside later, when I set the rotary table up, but that falls under the "pretty" heading more so then a functional one.

 As always, feel free to chime in if I am doing something the wrong or hard way, or especially if I am ignoring the obvious. I am self taught from a lot of reading, but not a lot of doing. I have learned a lot on this forum and others, so if you see a teaching moment, dive right in. 

 Next up? These pistons look a little naked, so I will probably make the jigs to heat treat and skim the rings. I likely wont do a write up on the wrist pins themselves, but its getting time to finalize the connecting rod drawings and they will likely be the next major pieces.


----------



## Lakc (Dec 7, 2010)

*Ring treating fixture*​
 Well, I am pleased as can be to still make progress, so here is a little update on where I am today. 

 First step was to split the rings. Start with a carbide scriber from McMaster Carr for <10$ to give a nice initial groove for the file to bite into. Then using the corner of the square file we make a couple passes and lay the groove made opposite an Enco scraper. Thumb pressure from the same hand holding the scraper easily parted the rings with no casualties.




 This picture I couldnt resist titling _*Pile of Perfectly Parted Piston rings*_, try and say that 3 times fast. 





 A chunk of 1 3/8 cast iron was spotted on center in the lathe. Moving to the mill a 3/16 hole was reamed .477 inches from center. A piece of 3/16 cold rolled steel rod had its shoulder turned down to .164 inches to provide the proper gap for the rings during stress relieving.




 Back in the lathe the center of the holder is drilled to tap 1/4-20 and turned down .905 diameter for a length .005 less then the entire stack of rings. 





 A cover is turned basically freehand with the only dimension critical being the depth, same .005 less then the stack of rings, and an F drill center hole for bolt clearance. The cover will hold the rings compressed flat for heat treating.









 Things are looking up, the list of remaining items is getting smaller, and while free time is never much in excess, the holidays should provide enough to make some serious headway.  It would be nice to get the connecting rods done next to complete the reciprocating assembly.


----------



## NickG (Dec 8, 2010)

Nice work on the pistons and rings Jeff. Must have a fairly high compression this engine does it?

Your work on the rings will make a nice tutorial for anybody else wanting to make cast iron piston rings.

 :bow:

Nick


----------



## Lakc (Dec 8, 2010)

NickG  said:
			
		

> Nice work on the pistons and rings Jeff. Must have a fairly high compression this engine does it?



I have not actually settled on a compression ratio yet, but 8:1 may be a stretch for a model and that was kind of a stretch goal.


> Your work on the rings will make a nice tutorial for anybody else wanting to make cast iron piston rings.
> Nick



Thanks Nick! I do not remember ever seeing it done in tutorial form before. I am sure its probably not the first, but rare enough I wanted to include it.


----------



## NickG (Dec 10, 2010)

Jeff,

I only guessed it may be because of the domed piston crowns but I don't know what the combustion chamer is like!

I'll certainly be looking this back up when I do them.

Cheers

Nick


----------



## Lakc (Dec 12, 2010)

I am glad you brought that up Nick, I ran the compression ratio calculations, and it was a measly 4.9:1! So I spent some time and wrote up a spreadsheet, added back the .1 inch I took off the connecting rod when I stretched the piston, and got 8.3:1 compression. With a .950 bore and .694 stroke making a bit of an oversquare engine, it was really sensitive to the tdc position.


----------



## Lakc (Dec 12, 2010)

*Connecting rods n stuff*​
Well, today we finish off the recriprocating parts of the engine. evil :big:

First we grab a bar of .250x.750 2024 aluminum and skinny it up to .690. We part off the two rods 1.58" length and two caps of only .220 length. I dont have a stop for my vise, so I used a 1-2-3 block across the end and drill 4-40 clearance holes in the caps and tap threads in the rods. Bolt the pieces together and it comes out reasonably square. There is going to be a bit of filing going on regardless so I am not too worried about a perfect fit at this time. These are simple rods, compact, and probably a bit on the bleeding edge thin towards the caps. They barely miss the opposite cylinder liner at bdc, so I cant make them any larger without adding some relief. They should be strong enough, if not, its only a couple inches of bar stock. 

For contouring the rods I broke out an old friend. I made this jig for another motor that had slightly larger rods and hoped to adapt it. Being slightly offsize it proved just slightly a pain in the @$$ to work with, and I deceided against using it. The other motor needed 6 rods, but I can get by without the jig for only two. I find the center of the rod and lock down that axis, using my edge finder to locate off the cap end to bore the big end of the rod and finish ream .344" Then I run a 1/8 ball end mill .100 deep towards the small end and bore and ream the little end .1875. Next I hang it off the side to come in with a 1/2 cutter and put the shoulder radius in, then flip it on its side and mill up the the radius leaving ~ .290" wide beam.















 Nothing too complicated there, pretty straightforward stuff. We took a variety of files to the rods to clean them up and skinny them up a little, as they invariably have clearance issues because I never seem to make the journals wide enough on the crankshaft. Next we break out another hotrod alloy steel for the wrist pins, 8620. Not much to show there I just drilled them hollow, polished it up with emory cloth and parted it off .850 long.









 With a couple simple jobs under my belt I started to get the itch to try something fancy. Ill just let the pics do the talking for a change.














 These .015 hard brass bearings were hammerformed with a plastic mallet and the actual rod. Will brass work? I have an idea it wont, even with pressurized oiling. I plan on electroplating babbit on the surface to get the proper clearances. Now you see the reason for the custom .344 chucking reamer. Even if it doesnt work, I have seen silver used for bearings in this same manner, and what fun is building an engine if you dont have to take care of it every now and then. 

I have reached a moment of truth, as they say, one of many such moments coming up. With suitable bearings to fit the rods to crank we spent a good hour filing spots here and there to make everything fit nicely. Then I spent a good half hour cleaning the engine for assembly. Lubed up and this is what we got!


----------



## stevehuckss396 (Dec 12, 2010)

Everything seems to be looking/working good!


----------



## mu38&Bg# (Dec 12, 2010)

I would probably forgo the rod bearings altogether. There are many model airplane engines using rod without bronze bushings in the big end. With pressure feed oil I think it would be OK without bearing inserts. I've been following from the beginning. It's an awesome build. Will you be flying it?

Greg


----------



## Artie (Dec 12, 2010)

loving this mate.... something about conrods and pistons... looks fantastic..... :bow:

Im with dieselpilot.... dont fix it if it isnt broken....

Awaiting the next instalment...


----------



## gbritnell (Dec 12, 2010)

For thin bearing shells such as you are trying to make the only thing I have ever heard of being used successfully is silver. You can purchase it in strip form from jewelery suppliers.
gbritnell


----------



## NickG (Dec 13, 2010)

Thanks for the explanation Jeff, 8.3 sounds good, same as my old mini! Will it be hard to turn over? Should be ok I would guess.

More great looking work there. That jig looks handy.

Nick


----------



## IronHorse (Dec 13, 2010)

I like your method of cutting the brass strips with the wood and slitting saw. I will have to try that one day.


IronHorse


----------



## Lakc (Dec 13, 2010)

Thanks for all the great comments guys!

Steve: Thanks, I still owe you a visit to bake some rings. I can only assume that your holiday schedule is as hectic as mine, and the fact they gave up salting our roads wont make it easier either.  Ill ship you off an e-mail when I begin to see the light at the end of the tunnel.

Greg/Artie: If I keep the clearances tight enough so they dont hammer it may work, but straight AL on steel would have worked as well. I am overcomplicating things a bit here. None of these parts are so big/complicated/expensive that it would hurt to remake them.

George: I dont remember the issue, but at my first NAMES show, I bought my first issues of SIC from George himself. I think there was a boxxer engine in those books that used silver for bearing material, and I have been scouting out jeweler supplier's ever since.

Nick: If I do everything right I am counting on healthy thump. 

IH: Thats something I did because I didnt want to stress/bend the metal via my usual method, the paper cutter. It left some nasty sharp rolled edges of kerf and I resorted to deburring it by holding it between two flat files, which worked rather well.

I am going to continue playing a bit with the recriprocating assembly, finalizing the oil flow, etc. Then its on to the cylinder heads!


----------



## Lakc (Dec 16, 2010)

*Meanwhile, back at the ranch..*​Subtitled, dotting the i's and crossing the t's​
The #2 rod is a little tighter then I would like to see, I suspect I didnt give the cutter enough "wiggle" at the final rod journal diameter and its a bit tight near the crankpin. All the fighting the #1 crankpin gave me its got plenty of clearance. It took a whole lot of file work to get it to fit in the first place, just some more of the fitting in of the reciprocating parts.

 I deceided it was time to see if the oil pump works. This required grooving and drilling the main bearings and two cross drilled passages narrowly avoiding one case attaching screw just behind the timing gears. I fumpled around and found my 3/8 expanding arbor and turned the main bearings to final size. The marked up photo's show the front oil drilling. I got a bit smarter and just used a slitting saw to groove the case for the rear bearing oil flow. You can also see the rear oil seal, a 3/8x1/2 "X" ring that I will try out. 

















 I roughed out a pressure relief valve and a pair of nipples for the oil feed and return lines. Dug around and found some old fuel tubing and cut the top off of a McMaster pipette to use as an impromptu oil tank. Low and behold the darn thing worked!








 Along the way I also managed to make some nylon bushings to keep the wrist pins off the cylinder walls, and few other little jobs that were necessary but didnt deserve mention. 

 I have also begun revisiting the cylinder head design. Using solid modelling, I am redrawing it as it would be machined to help visualize the steps to making it. I have a decision to make regarding how to proceed with the valve seats. I origionally thought of trying the cage method, and followed the recent discussions with Brian's hit and miss and George's cutting tool with much interest. 

 My only problem with the cage method is my lack of experiance with it. Since I am drawing this from scratch, that leaves me in somewhat shaky territory. I am very familiar with full size, shrunken fit, valve seats, and I wonder if that technology could be duplicated in model size? I had already begun exploring ways to grind valve seats ala full scale motors. 

 Because the holiday season and resulting committments have so far prevented me from taking Steve up on his gracious offer of a ring bake, I did put a ridiculously low bid and won this:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=200552413213
I already had most of the remaining components to make an oven on hand, so next I will try to cobble up a functional heat treat furnace, not just for a ring bake, but to more properly process all this tool steel I have acquired. A seat cutter like George's design comes to mind immiediately, but a seat cutter without teeth would be a valve seat installing arbor.......


----------



## gmac (Dec 18, 2010)

Jeff
Ron Colonna uses 0.010" pure silver sheet (not sterling silver) for his Offy engine which is a pressurized oiling system with dry sump. He also superglues the ears of the shells to the cap/rod halves.
Cheers
Garry


----------



## Lakc (Dec 23, 2010)

gmac  said:
			
		

> Ron Colonna uses 0.010" pure silver sheet (not sterling silver) for his Offy engine which is a pressurized oiling system with dry sump. He also superglues the ears of the shells to the cap/rod halves.
> Cheers
> Garry


Thanks Gary, I didnt know Ron used that too. I included allowances for the single tang overlap when I spec'd out the reamer, we will see how long it lasts.

*Sidetrip to Hades!*​When we last left off I was anticipating the arrival of an ebay purchase to throw together a cheap (and quick) heat treat oven. The results were a FAIL, but somewhat encouraging. 





What you see here is the ebay $12 special surplus temp controller, an old toaster oven (~$15 at wallmart 8 years ago), a brand new 120v relay and socket ($13 mcmaster), hi temp fiberglass rope seal ($6 mcmaster) a K type thermocouple (gift), and a few scraps of wood and wire. The controller was an "H" variant, which means it simply turns off at the desired temp. Not what I had in mind, but it would work if babysat and continually reset. Despite the approximately 1300 degree heating elements, the max temp achieved was 755 F. So, for the price of a day and a half work, I failed. I now have some high temp insulation to help with the heat loss, and a single 750 watt cartrige heater, so the second iteration of this is coming shortly.

*Of valves and cages*​
Earlier I mentioned I had never tried to make a caged valve system, and that hasnt changed. The forums have been pretty active with valve discussions lately, and I have weighed all the advice I have seen. I still dont have anything against the cage system, except my own inexperiance. While I have a lot of experiance with full size practice, I went that route for a test head. Cocentricity and accuracy in the setup will be challenging, so here is my take on it.

Start with a head! I always feel like a sculptor at this point, chop off a block of 1.5" square 6061 1.1" and true it up to 1" height. Then, get so darn excited you forget to take pictures of the 1 3/8 counterbore and 15 degree cut for the combustion chamber  Once off the lathe its back to the mill where I "lop the ears off" for another 15 degree cut. 








Now life gets interesting. Back to the lathe with a 3/8 stick of W1. Drill a bore with a 19/32 drill. In my case I ruined the part with a dull cobalt 19/32 drill :'( Out to production tool and 8 dollars later we have a replacement cobalt drill that actually cuts. Follow up with a delicate touch of a 90 degree countersink. Then we turn a whole length down to .350. Carbide inserts and plenty of lube keeps the surface finish up to snuff. Trying to part a .200 length off for a valve seat just dulled my A1 fin tool.  Switching to my commercial (hard) parting tool I find the piece wont part off, the tube just deflects away from the cutter. Trying to make lemonade out of lemons, this appearant work hardening is not a bad quality to have for a valve seat, but required an old nearly abandoned practice of a dremel mounted with an abrasive cutoff wheel to part off. This was the _very_ first tool I made when I bought that lathe 13 years ago, and I havent used it since, but it sure saved my bacon this time. 










Sorry, so excited I forget the pics of the seats by themselves.
Now that leaves me with all this stock sticking out, already turned to the same size as the seats. I turned a .1870 pilot on the end and proceeded to make a counterbore/reamer tool to ream the seat cavity in the head. Press fits are new to me as well, and a lot of creeping up on dimensions with abrasive cloth was indispensible. I also made an installer tool (also not pictured), similar except for a looser tolerance pilot, no cutting teeth, sized 19/32 for the inside dia of the seat, and made from cheap 10something cold rolled steel. I spent a hour reading machinery's handbook on making cutters, and found it (26th ed.) pretty lacking in the counterbore section. I did pick up a few interesting bits such as cutting the flutes .010 below center to give the sides some rake angle, (and a smidgeon smaller for the press fit), and to offset the teeth +- 1-2 degrees. Eventually I came up with this.




*
On to the drilling*​Keeping everything concentric is the major challenge here, and I took it to heart. I realized early on my drill chuck seems ever so slightly eccentric, mounted only with a 33 jacobs taper to a 1/2' straight shank for holding in a collet. To avoid using the chuck I ran out at the last minute back to production tool and bought a quality 3/16 R8 collet for the guide hole reamer, then I could use the 3/8 collet for the seat hole reamer. This worked marvelous, with the exception of forgetting to relieve the cutting teeth on the seat reamer I made, hence the first guide is slightly higher then the flush surface I was shooting for. A bit of quick work with the dremel fixxed the tool and the second seat came out exactly as planned. The press fit for the seats came out perfect as well, just a few stiff taps with a hammer drove them all the way home, with some red loctite for good measure. 














Now were all up to date again. You might be able to see in these pictures what I considered a problem with the origional Edwards radial plans, that when you bisect a cone off-center with a cylinder, the resultant surface is shaped just like a wave washer. Making the valves seal against that is one thing I saw omitted from the plans, which led me to cad model it, which in turn led me to this point. 

Coming up next, we have plenty of chips still to make. Bronze (yep, I splurged and bought the good stuff) will be turned into valve guides, and you will experiance the absolute horror as I mix in a metric dimension into an otherwise all english unit design. We have counterboring, and drilling through aluminum to bisect the tool steel valve seats for the ports. It may be coming up on Christmas, but the next installment looks like a better fit for halloween. :-\


----------



## Royal Viking (Dec 24, 2010)

I was wondering about your oven. At 755 deg F that thing must be pretty hot. Can you throw some additional insulation over the glass and sides to reduce heat loss ? I am wondering if the glass is only working as a barrier to preventing a draft.


----------



## Lakc (Dec 24, 2010)

Its entirely possible your correct about the glass RV. The most economical solution I could find was some 3"x1/2" rolls of foil backed hi temp insulation. I have 10' of the stuff to try out when I next get a chance.


----------



## stevehuckss396 (Dec 24, 2010)

Head looks cool.

Sorry the oven didn't work out.


----------



## Lakc (Dec 24, 2010)

Thanks Steve.
All is not lost. I have enough firebrick laying around to do it correctly I assume. Even still, the small time and monetary investment to get this far has purchased an invaluable education in what doesnt work. 
Whether it works or not, I still owe you and/or your club a visit. I think you guys meet where I used to go to the Mopar swap meets years ago.


----------



## Lakc (Dec 24, 2010)

*Success*​
With a little high temp insulation help from Mcmaster, it works fine. 




Ran right up to 950 without a problem. ;D


----------



## Royal Viking (Dec 31, 2010)

Nice, glad to see the insulation worked.  

That may work as a floor tile remover too...


----------



## Lakc (Jan 5, 2011)

Royal Viking  said:
			
		

> Nice, glad to see the insulation worked.
> 
> That may work as a floor tile remover too...



Well, the floor tile is perhaps the least flammable item in the room..... 8)
As its mounted on wood which has yet to show any heat distress, it appears there is little heat radiating downward. Still, I have a long cord attached to make it easy to yank out of the wall and a bucket of water off camera. 

*Warts is Warts*​
I had this wonderful stretch of time off over the holidays, and big dreams of staying warm indoors finishing this project. I hope everyone had a merry Christmas and a happy new year. Alas, fate has conspired against me, with every vehicle in my family requiring my utmost attention. I spent almost my entire vacation working 14 hour days out in the cold Michigan winter doing collision repair, chasing parts, welding exhaust back together, etc. I am still not done, with one vehicle down with a blown coolant bypass hose and a charging system problem, but I could not arrange picking it up tonight, so that left me with some now quite rare lathe time.

Now that I had an opportunity to work for fun, I tried to tackle a valve. I had a new secret weapon, a McMaster 3244A546 insert, price almost $6. I had wanted to try a "high performance bit" and this one is a grade 3503. Generously rounded for a fine finish, it is shaped similar to a banna boat with sides that gently slope away from the cutting point, turning its negative rake characteristics into somewhat of a positive rake cutter with 6 usuable sides. The valve material is just a 3' stick of O1 tool steel, and with plenty of lubrication the cutter did a fine job leaving a pretty good finish. The length was turned down between centers to .350 diameter and the 1" of stem to .1360 +- .0002 with very little final finish work needed with my standard 180-320-400 grit emory cloth stock.








Now is where the trouble begins. I quickly learn my thin parting tool is too short to groove and then part to length with a live or dead center in position. so I part the valve off at the face and mark it up with my height guage. 





Now the next big problem, the valve is too short to flip around in the lathe chuck and finish to length much less cut the e-clip groove. I thought of making a custom collet to hold in the three jaw, but I would first have to remove the bulge at the tip left by my cutting around the center. I am sure I will figgure something out but any suggestions in the meantime will be most welcome. I still have cars to fix, so it will be a few days before I can get back on this job. If I only had that 5C chuck and a 3.5mm collet I would be back in business. No, sorry, spending my way out of this corner I have machined myself into is not an option this soon after Christmas.


----------



## NickG (Jan 6, 2011)

Nice work. As soon as I saw that i thought just make a split collet. If it's an issue removing the bulge, you could make the collet split completely maybe with dowel pins to pin the 2 halves back together in the correct place? Otherwise just cut the bulge off and don't completely split the collet - I would have thought that would work as well as anything.

I know how you feel with cars to repair, both of our cars packed in in a big way recently, luckily I've managed to spend my way out of it and pay other people to do the work this time, although I haven't got the cars back yet!

Nick


----------



## Lakc (Jan 6, 2011)

NickG  said:
			
		

> Nice work. As soon as I saw that i thought just make a split collet. If it's an issue removing the bulge, you could make the collet split completely maybe with dowel pins to pin the 2 halves back together in the correct place? Otherwise just cut the bulge off and don't completely split the collet - I would have thought that would work as well as anything.


For lack of a surface grinder or commercial collet system, its looking like a home made split collet and hand grind the bulge.


> I know how you feel with cars to repair, both of our cars packed in in a big way recently, luckily I've managed to spend my way out of it and pay other people to do the work this time, although I haven't got the cars back yet!
> 
> Nick



Sorry to hear about that. My problem is more professional then monetary here. I spent the first decade of my working life in a car dealership, mostly repairing other technicians screw ups. For more then the last decade I have been phone support for those same technicians. With my luck, I just dont trust anyone else to work on my vehicles. :-[


----------



## NickG (Jan 7, 2011)

You're spot on there, that's why I started to live by the motto, 'if you want something doing properly, do it yourself' but these days I just can't find the time / motivation sometimes to do it myself!

Nick


----------



## Lakc (Jan 14, 2011)

Well, hopefully those things that should not be mentioned will stop breaking and allow me some time in the shop. 

Just a quickie update, tried the next valve backwards as compared to the first attempt. Both methods have drawbacks but this one provided a serviceable valve. Center drill 3/8 rod of tool steel and leave the tulip part towards the tailstock center with the stem pointing back at the chuck. This allows the chuck to support the grooving and final parting operation with the tailstock cleared out of the way of the toolpost. I will have to invest in one of those half centers one of these days. The .020" Grooving/parting tool is made from A2 tool steel, torch heated for the hardening and annealed in the homemade heat treat oven, which is coming in quite handy. The pictures tell the story pretty well so here they are.


















Hopefully, this weekend, we can put the valves behind us, and maybe even the first cylinder head itself. 
Sunday is a swap meet, (ham radio) but I will be picking up my loaned out oscilloscope because once we get the cylinder heads done we can change tack a little bit and begin work on an ignition system.


----------



## Lakc (Jan 23, 2011)

The cars have not stopped breaking but most of the failures have been non-critical so we have a litte bit of work done.

Valves themselves were too simple to get very hung up on. A few jigs and more careful machining could reduce the waste material a bit but for the sake of progress I moved along leaving the head oversizedx enough to allow my crossslide and toolholder to clear the tailstock and center. 

In this image you can see the "banna boat" sides of the cutting bit which sorta allow the negative rake bit to act like a positive rake one.





Here are the valves with grooves and e-clips as keepers, awaiting final head machining.





This was a bit of a pain as light cuts were necessary and I could not tighten the chuck as much as I wanted, but all the valves survived the experiance. 


Next up, maybe tonight, Ill post the pics from the valve guides (done), rockers and rocker stands (under construction).


----------



## Lakc (Jan 24, 2011)

_queue Ethel Merman_
*There's no progress like slow progress......*​
Well, its certainly better then no progress at all. :'( When last we left our intrepid hero, he was singing to a pile of metal the words to Pink Floyd's "one of these days", and thus was the result, soon to become rocker arms and rocker stands.





For this epsiode, the point of interest will be the four 1.5" long x.25" square pieces of W1 tool steel, chosen especially for the properties of being on hand and the correct size. 
The pieces were chucked up in the vise and 1/8" hole was drilled 1/4" in from one side and .64" from the first hole. My favorite 1/8" spade drill was held in an R8 collet in an attempt to drill and ream in one operation. It met its unfortunate demise on the third rocker due to my failure to clear the parallel completely from the hole before it broke through. Then the rockers were held lengthwise while a cut was taken out of the middle. Two right and two left handed rockers were designated.









Then it comes down to the business of making a jig. A piece of 3/8x1 scrap aluminum of gummy hardware store variety was placed in the vise and milled to approx 3/16 thick, leaving a small square island at one end. The center of "eyeball island" was found and the table locked down, where it was center drilled, drilled, and tapped 4-40. Another 4-40 hole was tapped .640 away in the milled off section. My personal favorite method of tapping is chucking up an archery target point in the chuck and using the point and ogive to center the tap handle with a little light pressure on the ram to maintain contact. 









Next my boring head is used to round off the island to exactly 7/16" to match the center reamed hole on my Sherline rotary table. 





Now comes the fun part. I was being tricky and actually doing all the machining on the backside of the jig. Now I flip it over and bolt the rockers on one at a time. The nose is given a 1/8" radius for approx 270 degrees, and the pivot point approximately 90 degrees. 










Now we create another jig. It doesnt come through well in the picture but this is the leaning tower of rocker arms. There is an 8 degree bevel on the bottom side. Here we take the square left opposite of the pivot and turn it into a trapezoid, and drill and tap a 6-32 hole near the end for an adjustable pushrod cup. Along the way, we re-learn the lesson that really tight is not always tight enough as the jig moves in the vise and my favorite cobalt roughing mill explodes throwing a large chunk against the wall with considerable force. :'(














They are still a little rough looking, but will do the job. Along the way I thought of several improvements to the design, but pretty much forged ahead anyway. Besides patience, I am trying to teach myself that Version 2.0 parts will never get built until you learn 1.0's lessons. That is why I called this a prototype, and I still have a lot to learn. 

Its slow progress, but still moving along. I am beginning to get confidence that this one will be finished soon.


----------



## Lakc (Jan 27, 2011)

Rocker arms and stands are done. Few misc pics to put up later. I am waffling on what to do about a spark plug still, but pretty much finished the drawing of the head, so here is a teaser until next update. ;D


----------



## krv3000 (Jan 27, 2011)

HI that will be a brill engine when finished


----------



## stevehuckss396 (Jan 27, 2011)

Lakc  said:
			
		

> Rocker arms and stands are done. Few misc pics to put up later. I am waffling on what to do about a spark plug still, but pretty much finished the drawing of the head, so here is a teaser until next update. ;D



What size plugs would you be needing? Dale Detrich has 1/4-32's for 12 bucks


----------



## Lakc (Jan 27, 2011)

krv3000  said:
			
		

> HI that will be a brill engine when finished



Thanks KRV, I am hoping its finished sooner then later. 



			
				stevehuckss396  said:
			
		

> What size plugs would you be needing? Dale Detrich has 1/4-32's for 12 bucks



Thats a possibility, if Dale is the man I will have to look him up. I have 1/4-32 thread drawn there now, but could go a little bigger if I had to. I currently have a full half inch of thread engagement, and thats longer then any 1/4-32 plug I have seen drawings for, but easily adjusted.

I have large quantities of Hydrostone, which would be interesting to try an mould an insulator out of. I also have had ideas of making moulds and using slip to make my own ceramic insulators. Machinable ceramics look like just the ticket but are way too expensive. Corian pen blanks are a possibility as well. Still, thats a whole nother discipline I probably shouldnt sidetrack myself with now.


----------



## stevehuckss396 (Jan 27, 2011)

http://www.daledetrich.com/

Give him a shout!

He is also a very good engine builder.


----------



## Lakc (Jan 28, 2011)

I fired him off an e-mail looking for some dimensions, so I can finalize the drawings and get back to cutting while waiting for them to arrive. Thanks again Steve! :bow:


----------



## Lakc (Feb 3, 2011)

*Head work continued*​
Been busy with the proverbial "other things" that keep coming up. The recent snow shut down most of Detroit, I got to work from home, with high hopes of playing hookey a little to get something done. Of course it was one the busiest days I have ever had. Have been fighting off a bit of a cold as well, not suprising since we have barely had 5 days with the temperature above freezing since well before Christmas. Getting frustrated by the lack of progress, I forced myself to complete one series of operations tonight. 

 I have a half completed head I want to fin, but a few operations are standing in its way. One, I wasnt looking forward too, but finished tonight, was drilling and counterboring the head bolt holes. The holes are on a 1 3/8 bolt circle, one on the vertical CL, two on either side at 45 degrees, and two below at 60 degrees. I started from the blind side of the cylinder counterbore, the top of the head, and did all operations measuring from the handwheels. Maybe next Christmas I will get that DRO. :'( I first counterbored with a .25" center cutting endmill, followed by a center drill, and then some monotonous pecking away with a #27 drill. I didnt want the bit to wander and force the hole off center. 






While the drilling came out good, it left some nasty breakthrough flashing peeled right up against the cylinder counterbore. Knowing I had a little surface chatter on the cylinder counterbore, I chucked up one of the stubs left over from the cylinder operation and spread a little 320 grit clover lapping compound, and lapped the head for a few seconds. I didnt get a full contact but the flashing is gone at least. I will check it against the actual cylinder later. Thats why we use head gaskets. 










We are still stuck on the spark plugs, will have to call on them tomorrow if I get the chance, but it is taking shape, albeit slower then I had planned.


----------



## Lakc (Feb 19, 2011)

*Heads taking shape*​
Well, its been a busy time here, unfortunatly not all time spent on the engine. As you may have guessed from the lack of updates disaster struck. Zigging when I should have zagged, and not paying attention to how deep to drill the intake and exhaust ports, I sent a 1/4" carbide endmill right through the valve seat. 
So I went back at it in production mode this time. Making two at the same time, I was caught back up by last weekend. A few tweaks to the drawing allowed for an easier 30 degree port angle.





Then we drilled for 1/4-32 plugs, backdrilled from the other side 1/2".




Manifold attaching holes and rocker holes were next. Plenty of 4-40 tapping. One casualty, knew it was gonna happen right before I did it. Must make a mental note to switch to decaf coffee before tapping numerous small holes.  Everything was done with the X-Y manual handwheels, but I laid the parts out conventionally for a double check.





Then came the fun part, finning the cylinders. I tried it dry, but was getting some AL buildup on the teeth, so I resorted to Astrocut 2000 from my oil can. This was undoubtedly the messiest operation I have ever done on the mill. Coolant spraying everywhere off the 2 1/2" x 1/16" side cutting slitting saw. It worked, beautifully in fact, with reasonable cutting speed despite the thinness of the cutter. 









The point where I have to make a mop bucket and mop the shop floor seemed like a good stopping point. In fact thats next on the list of things to do, as there is coolant everywhere. Then I will need to give some thought as to how to remove the one broken tap, although its not entirely necessary. What I am left with, however, looks suprisingly a lot like the assembly drawing.




I have some plans for later today, but I think I will attempt to drill the barrels for the head bolts. Not too much left to do here, its really taking shape.


----------



## stevehuckss396 (Feb 19, 2011)

Sorry to here about the problems. Unfortunitly boo boos are all part of the deal. Heads look great.


----------



## Lakc (Feb 19, 2011)

Thanks Steve. I did learn a lot on the first attempt, and it was real easy to retrace the steps to get caught back up.
The floor is now mopped up. The corner fins on the heads will take some sort of jig to machine, I will probably forgo them for now. The barrels are next up to drill and tap the head bolt holes, then we need cam followers, pushrods, rocker pivot pins, front cover and a prop drive. Lot of little stuff but were getting pretty close.


----------



## stevehuckss396 (Feb 20, 2011)

Most people dont realize it but 1/2 the work of building an engine is in the heads. Lots of little parts.


----------



## metalmad (Feb 20, 2011)

Mate 
Those heads look great!!
ohhhhhh I want a slitter toooooooooo 
Pete


----------



## Lakc (Feb 20, 2011)

Thanks for the comments guys, glad to see others enjoying the thread. I am having a ball watching this take shape. 

*Cylinder drilling and SECRET WEAPON*​
 I tend to think things through too much sometimes. Its nice when things go as planned, but having multiple contingency plans can drive you crazy :-[ But occasionally, those backup plans come in real handy. 

 First things first. We need a place for the head bolts to go on the cylinders. We pull out the old secret weapon and center inside the bore. I left the cylinders bolted to the case halves which simplified workholding and put the main offset direction along the good leadscrew. I have a new Rohm chuck with R8-6JT adaptor and its a pleasure to work with. My old Jacobs was a good chuck, but its runout was getting pretty bad, and it was only a 33JT-1/2" which isnt as sturdy, and has a nasty habit of falling out of the collet when loosened. New Jacobs chucks proudly proclaimed they were .004 runout, which seemed like a whole lot to me, and they wanted $91 for the R8-6JT adaptor. This Rohm seems better then the Jacobs was when it was new. 




 Once centered, we simply wound the one axis over to drill the one headbolt at the top of the cylinder. The centering tool is pretty tall so I used an extra long center drill to start the hole. 




 With the first headbolt drilled, I attached the head and used a transfer punch down the remaining 4 head bolt holes. These punch marks served as sanity checks in case I lost track of a dial turn somewhere. I still laid out the holes with the manual handwheels, and was happy the center punch marks and the handwheels agreed. The heads now had a place to go and it felt good!





*The next secret weapon*​I wanted to follow modern full size practice with press in valve seats. One disappointing part is the chatter I had when cutting the seat area with a 90 degree countersink.




 And here is where I had already overthought this one to death. If you have ever ground a full size valve seat, you know the seat grinder tool is quite a nice piece of kit. Hex ball driven full bearinged carrier for screw on grinding stones with a diamond dresser, and a selection of tapered pilots to drive into the valve guide. Obviously, a well thought out tool and perfect for the job, but not really scalable. With the guides ready to install and the seats all pressed in, it was time to try a mini version with as few compromises as possible. First stop, Home Depot, for a fresh fine Dremel grindstone, shank dia .1240.




 Setting the cross slide over 45 degrees, I clamped a small dressing stone (Dremel circa 1981) in the toolholder and turned (ground, dressed, broke?) a rough edge on the backside of the grinding stone. 

 I have had this idea for a while, so over a year ago I was looking through my favorite toy catalog (Mcmaster) and found the cheapest diamond dressing bit they had, $7 today, used to dress a convex radius on stones. A quickie adaptor for my toolholder and a last second tightening of the cross slide gibs, I dressed a perfectly flat 45 degree angle on the bottom of the stone.








 Now I am at the point where I goofed up when I went metric on the valve stems. I couldnt use the stone on the finish 3.5mm guides so I made one special guide with a .125 hole for the grinding stone stem. Using some Vactra for lube there was no discernable play between the guide and stone stem. The stone was inserted in the head and a dremel used to drive the stone at a relatively low speed (~2krpm). 




 You definately dont need to lay into it, you hold the stone off the seat, turn on the dremel and let it get up to speed, and just peck backwards 4-5 times letting the stone do the work. It was a lot of work to create a tool that did the job very quickly. If I wanted to dress some more stones at 30 and 60 degree angles, I could do a "3 angle valve job". All valve jobs have 3 angles, thats one of my pet peeves. 
Did it work? Let me know what you think.


----------



## stevehuckss396 (Feb 21, 2011)

I use the boring bar for my seats. Micro100 has tiny bars that are razor sharp. You get an almost mirror finish in brass. Then I make a special tool to press them in so there will be no damage.


It's starting to look like something now. You must be getting a bit stoked.


----------



## Lakc (Feb 21, 2011)

stevehuckss396  said:
			
		

> It's starting to look like something now. You must be getting a bit stoked.


Yes I am, but trying to keep my eye on the prize here, it has to make noise.


----------



## Lakc (Feb 23, 2011)

*Ring finishing*​The final sizing of the piston rings required a mandrel to hold the rings collapsed and shave the last .002 to make a perfect circle in the proper bore size. I turned a quick cast iron mandrel by cutting a stub on one side, reversing it and turning an outside diameter equal to the bore, and an inside diameter .005 in length shorter then the ring and a diameter equal to the rings inside diameter. A quick lid was constructed and turned down to just under bore size. The rings were clamped up one at a time, using a Sherline 4 jaw to hold tension, and slowly brought to a diameter that kept the ring gap closed when inserted into the bore. I reused the jig to make the rocker arm stands to file the gap, and checked it with a measuring microscope.


















With no headgasket and unlapped valves it still had great compression, and rather low drag. 


*Progress is progress*​
Well, in the effort to get something done we have been jumping all around doing a lot of little bits. Tonight I worked on bearing clearances a bit and made some quick and dirty cam followers. I had planned on using titanium actually, to save on the moving mass and suprisingly affordable in smaller sizes. However it was simpler to make some out of brass I had in stock, the trick parts can wait until I know it wont blow itself to bits when it starts up.  The goal here is to make noise, so even if it does self destruct I will consider it a success. 

Simplified design, I used a radius cutter to narrow the contact patch, which effectively lowers the duration and overlap of the cam. Both can be increased later with a flat or mushroom style tappet. Then a 1/8 ball mill makes a cup in the other end









Lots more little stuff to do, but it feels good the list is getting smaller.


----------



## Lakc (Mar 3, 2011)

*Odds and ends*​Always busy here, but not often on fun things. I am getting excited to be nearing the end here. 




For starters we needed a gear cover. I made a drawing but really only for cutting the stock to length. Its a simple 1/4" plate of anodized 6061 with a 3/8 hole for the crankshaft, a counterbore for the front crank X-ring, and a counterbore inside for the cam gear attching hardware. Two holes for screws were put in the cover, drilled and tapped the block, and the block casting outline was scribed on the backside once the cover was secure. This was then taken over to the bandsaw and roughed out, finished with the small disc sander and buffing wheel. The painters tape was there to protect the anodized surface. 




Next, we changed tack slightly by making some shims for the cylinder heads, using a transfer punch, and a hand punch. These were used to take the space of head gaskets while I worked up the proper dimensions for valve clearance. No spark plugs yet so I used some 4 cycle glow plugs, were close enough to running that the first pops will hopefully be on them. I am running out of the patience I mentioned when I started this thread. 




Back to the basic block, it was stripped bare and a third cross bolt was added to each side below the cam centerline. They are not symmetric due to one crank oiling hole but were placed on center of the meat of the block halves for some good clamping pressure. Two 4-40 screws were added to the top lip of the block for additional holding pressure. A hole was drilled and tapped into the bottom of the block for an oil return outlet. 




Rounding out the block updates, I drilled and tapped 4 #8 screw holes into the back for mounting purposes. 




Next everything was cleaned and put back together like it was going to run. This pic shows the extremely complicated way I manufactured the pads for the wrist pins.  A fair amount of drag with piston rings installed but felt good enough to motor on the lathe for some break in, and break in it did, quite a bit of very fine metal particles came out of the oil return port, mostly ferrous in nature. Even without head gaskets, the intake ports sucked and the exhaust ports blew, leading to a very happy home model engine machinist, if I can call myself that yet. ;D

Now I was at the point where I could generate some ideas for intake manifolds. A prop was procured and a prop drive washer was made, but isnt present in these pictures. Here is how she sits now.


----------



## metalmad (Mar 3, 2011)

Its a Beast !!
looking fantastic 
Pete


----------



## Artie (Mar 3, 2011)

Lakc  said:
			
		

> leading to a very happy home model engine machinist, if I can call myself that yet. ;D



You most certainly CAN! As Pete says, its a Beast mate! Been closely scrutinising your progress and enjoying every step of the way.... :bow:


----------



## nfk (Mar 4, 2011)

WOW!
It looks amazing!
I cant wait to hear it!


----------



## Lakc (Mar 5, 2011)

Thanks for the comments guys. If I fired it up right now it would probably have a bad rod knock, at it looks like I tweaked one connecting rod big end slightly in the vise. There are still a bunch of odd and ends to handle, and I had plans of doing much of it this morning, but I wake up and the power is out. My next project should be some type of steam generator, or at least a stem powered coffee grinder so I can have a cup of coffee. No idea on how long its going to take to restore power.

I did get the prop drive done, as well as the intake tube adaptors. Big thanks to Marv Klotz for his ogive program to make the prop nut. I leave you with a tiny teaser, hopefully before this laptop battery dies on me.


----------



## RManley (Mar 5, 2011)

I have been following this build from the start and have to say its looking really, really good. I have a soft spot for boxer twins as that is what my motorcycle has, in fact its what the Douglas motorcycle firm specialised in. Their engines got used for all sorts and your last photograph remineded me of some photos that I saw on the Douglas MCC forum.









(taken from http://www.douglasmotorcycles.net/index.php?topic=1849.0)

Keep up the good work - I can't wait to hear it start. 

Rob  :bow:


----------



## Lakc (Mar 5, 2011)

Thanks Rob. Those pics are one of my great fears, starting on mid size projects and combining with the sport pilot rules. ;D It would be great fun, right up until the divorce, or life insurance payment for enough coverage to allow me to stay married.


----------



## stevehuckss396 (Mar 5, 2011)

Lakc  said:
			
		

> I did get the prop drive done, as well as the intake tube adaptors.



I had no idea that it was going to be an aero engine!! Very nice job on the prop drive. Love the long nosed prop nut!


----------



## Lakc (Mar 5, 2011)

stevehuckss396  said:
			
		

> I had no idea that it was going to be an aero engine!!


 Not necessarily, but its the easiest way to start out imho. No need for a complicated starter system, and the formulas for determining horsepower via rpm and propeller combinations have already been worked out. Keeping a weight budget in the back of your mind sorta forces you think things through a bit more as well. I have been doing R/C stuff for many years, the usages for any small powerplant are only limited by your imagination. 


> Very nice job on the prop drive. Love the long nosed prop nut!



Thanks, but the credit goes to Marv Klotz, it would have took me a month of Sundays to figgure out how to step cut it like that.


----------



## Lakc (Mar 7, 2011)

Well, power was out on Saturday for half the day. Found myself in the workshop with a camping lantern cutting out head gaskets with an exacto knife. When I was done, they looked like they were made in the dark, but still somewhat functional. Then I botched the first attempt at making an intake manifold, broke a critical tap inside the block on the second attempt, recovered somewhat, but I am swearing off three flute taps for 4-40 sizes. A poor workman blames his tools, but its my poor choice of tools at fault here. I just dont believe there is sufficient room for chips and a third flute in a tap that small. One of those nice helical taps is on order. The hardest part has been machining the tube flanges. I plan on using them to crush an o-ring to seal the tubes and keep them in place. They are 1/8 2024 and they get HOT really quickly when finishing on the sander.

 The prop is too big to swing on my lathe (13x10 prop) so I removed it and replaced with spacer from scrap laying around. Ran it up on the lathe and found the cam timing seemed retarded a bit, so the minimum duration cam follower design is a little too minimum.  Next up is a degree wheel and some mushroom style followers. Here are a couple of pics of her all dressed up before I took her apart again.


----------



## Lakc (Mar 27, 2011)

Boy its been a tough month folks, apologies for the lack of updates. Havent had a whole lot of time to work in the shop. 





First thing was sit down and see how the cam timing actually came out. Cam timing isnt always as simple as the degrees of lobe you put on the camshaft. First set of cam followers I made were round ended where they rode on the camshaft. This has the effect of giving the minimum duration available, almost a knife edge riding on the camshaft on one tiny spot. The duration was too short, with wide gaps instead of overlap, I then made a set of "mushroom" style tappets, which significantly increased duration towards the design goal. This is one of those times whern I wish I had the mathematical wherewithall to do things on paper first. 

Next I had to make a better prop drive washer. I couldnt figgure out how to bore the internal taper, and when I tried it was waay to far off. So I tried my hand at a reamer, which seems satisfactory for now. The proper way, I believe, would be to make a conical insert, slit it, and use a straight bore on the prop drive. 





Which leads me to where we are today. After much fiddling with the valvetrain, shimmed some rocker stands, ball ending the pushrods multiple times, I have what seems to be decent compression. I fixxed the intake leaks with some plates squeezing o-rings to the tubes. I have pretty good draw out of the carb. What I cant seem to do is light off these 4 cycle glow plugs for more then a minute at a time. I usually use a AA style battery plug adaptor but these glow plugs stop glowing as soon as I run the tops off the batteries charge. I have a plan for that, Plan D to be exact, as plans A-C all involved too much time or money.  But here she sits for now.


----------



## nfk (Mar 28, 2011)

It`s coming along nicely!
I`m eager to hear it!

Norberto


----------



## stevehuckss396 (Mar 28, 2011)

Lakc  said:
			
		

> What I cant seem to do is light off these 4 cycle glow plugs for more then a minute at a time. I usually use a AA style battery plug adaptor but these glow plugs stop glowing as soon as I run the tops off the batteries charge. I have a plan for that, Plan D to be exact, as plans A-C all involved too much time or money.  But here she sits for now.




A while back I made some 4 channel glow drivers that you power from an automotive battery (12V). PM your address and i'll send one over.


----------



## Lakc (Mar 29, 2011)

Well, I managed to cobble up a commercial glow driver I had running the two plugs in series, fixxed a problem with the fuel tank pickup, and gave it another go this evening. We blew fuel out the exhaust ports and heard the happy sizzle of frying glow plugs, but no fire just yet. My current theory is not enough cylinder filling due to cam timing, effectively cutting the compression ratio down. I had to double head gasket the #1 cylinder to help a valve clearance problem and that didnt help compression much in itself. I made an 1.5" diameter degree wheel but cannot find it at the moment, I will recheck the cam timing, make a good pointer for that, and possibly thread a 1/4-40 thread adaptor for my airbrush compressor to act as a leakdown checker. I will have to sleep on it, and give it another go soon. The old saying about being too close to the problem to see the fix is a very real one.  

Thanks for the interest guys, will keep you all updated.


----------



## Lakc (Apr 16, 2011)

Sorry for the lack of updates. Somewhat discouraged by failure to start and recent real life events have conspired to put this project on the back burner for the past two weeks. 

When we last left this adventure, we had discovered some leaky valves, as they were never formerly lapped, this was not unexpected. What was unexpected, was how this tiny motor sprawled across the whole of every flat surface available.  Actually quite common, it always seems to take me by suprise. 





Also unexpected, was the rough surface of the valve face under magnification. A dedicated valve grinder project has to go on my list sooner or later.





Once we have the valves lapped and ready to reinstall, we added some heavier springs. These are quite stiff, and hope the additional seat pressure will help in the valve sealing.





Reassembled and without the rockers we tested again. Now the weak point is the head gaskets, simple fiber ones, which I had not held out much hope of working for any length of time. Next up is some fine copper wire o-rings which I hope will help enough to get it started. If not, there will be a series on making dies to fold an multi layer thin copper gasket sooner rather then later.


----------



## stevehuckss396 (Apr 16, 2011)

Order some teflon sheet from mcmaster carr and be done with it. Works great, wears great, any thickness you can imagine, and easy to work with.


----------



## Lakc (Apr 16, 2011)

Ok, so I go over to Mcmaster and look up teflon sheet. I pick a piece of .032 and finalize my order. Now, they have an instant delivery option, and I call them up to check on it. I am in luck, as they just repaired the Heisenberg compensator on their new transporter system. I add my coordinates, subtracting 6' on the Z axis for basement delivery, and click the button. Instantly, $392 charge appears on the visa, and a few moments later my shop is bathed in an eerie blue light as my order is beamed right to my bridgeport. ;D




Just kidding  Steve, thanks for the idea! I had a piece of teflon laying around for 3 years for another project and didnt even think about using it as a head gasket.

The round piece in the picture is the stub of material left in the chuck from when I made the cylinders. Gouging out the center and leaving a knife edge along the inner and outer surfaces, makes a handy rule die for cutting out head gaskets.

With a scrap wooden board for a backer, the die is pressed into the sheet in the vise.






Next, we put the punch out in the scrap cylinder head. Clamped in place the head bolt pattern was transferred onto the gasket as tiny dimples with a standard transfer punch.






These tiny little dimples are used to center the hand punch, and clearance holes are punched precisely in place. 







The result is now oodles of compression. Thanks Steve!


----------



## stevehuckss396 (Apr 16, 2011)

You are welcome. Grab a piece of sand paper and get rid of the brown coating stuff. Make sure both sides are white as snow. Stuff works great!!


----------



## LongRat (Apr 17, 2011)

Guys, I would be interested to hear how well the Teflon gasket method holds up to high temps. I have never seen this method used on small commercial engines, but it certainly looks like an easy method for making the gaskets.


----------



## stevehuckss396 (Apr 17, 2011)

LongRat  said:
			
		

> Guys, I would be interested to hear how well the Teflon gasket method holds up to high temps. I have never seen this method used on small commercial engines, but it certainly looks like an easy method for making the gaskets.




I wouldn't use it on 40,000RPM nitro engine but for a gas powered display engine they will last for many years.


----------



## Lakc (Apr 17, 2011)

Since this motor is definately in between the two extremes we will see how well it works. For now, it only needs to seal at room temps until I get it running. ;D If it eventually melts, it will already have exceeded the design goals for a prototype.


----------



## Lakc (Jun 2, 2011)

When we last left this project, we were dotting some I's and crossing T's. Only two pics for this update, they are the counterbored flanges for the intake tubes, and worked well keeping the o-ring in place enough to seal properly.








The head gaskets worked great, perhaps too good, as the compression ratio is too high for the rotating mass. We got a few pops out of it but no running. We did break the temporary motor mounts as the oversquare pistons fought back hard at tdc. I went out and borrowed a piece of steel from a friend, but nearly two months later I have not gotten back to it. That should change soon though, as I am almost caught up wearing the various hats of husband, father, homeowner, and master, which have dominated my time in this very wet springtime. We should have some more updates soon, because I am itching to make this thing fly.


----------



## stevehuckss396 (Jun 2, 2011)

Lakc  said:
			
		

> I am itching to make this thing fly.




so are we


----------



## Lakc (Jun 5, 2011)

*Dancing in place*​Got some devoted shop time in this week, got a few things done but in the end, it feel a bit like I got nowhere. 

We had to stop trying to start the motor when one of the mounts broke. Here is a pic of where we left off, you can see the fatigue crack across the mount at the bottom two mount bolts.




So, mounts are rather boring.  I also wanted to install a crankcase vent. This should have been obvious, but when both pistons move towards TDC or BDC in unison there is a tremendous pumping action generated. In boxxer motors you cant forget the vents. This necessitated a total teardown to drill and tap a 1/16npt hole.




This hole looks like it was firing. ;D

One of the things I thought would help overcome the compression would be a little more flywheel effect. I found an old kent moore transmission tool which was 1 3/4" diameter, not ideal, but it was the biggest thing I had that didnt already have the wrong size hole in it. I bored the hole tight for the crankshaft, but had no luck whatsoever trying to use the lathe shaping trick to put a keyway in this particular piece of mystery metal. I eventually milled the keyway with a 1/8 carbide endmill in a plunge cut. A quick moment with the belt sander made a brass half round half square key. I just hope it clears the oil pump cover or it may need a little extra work. 









Realizing there was no good place for this large vent, which was the smallest available and under 2 bucks, I settled on a spot that hopefully will miss the intake manifolds.





Then came the big decision. I wasnt totally happy with the first camshaft I made. It was functional, and should start and run the motor, but I wanted to make a cam that actually hit the numbers. The bearing surfaces hit the numbers, but the block turned out a little oversied, so I also wanted to add a couple of thou back on the journals. Aside from that, the base circle was a little wavy and that made lash adjustment nearly impossible. Finally, not the least of the reasons, was that I wanted to use my new dividing head I picked up at NAMES.  I didnt have a good height guage either back when I made the first cam, so layout was a breeze this time around. 









This cam was made with a slight radius to the lobes, instead of the flat ramp design like the first one. It was made by the milling method, using the calculator right off Ron Chernich's website. I had already made a proof test of a lobe this way several years ago. It works well if you can maintain your concentration and enter all the right data into his online calculator. 
This is what happens when you enter the wrong data. 




It seems if you have a .25 base circle on a piece of .375 your lift is only .062 not .125 
All was not lost however, only a 2.25 inch piece of 41L40. I corrected the calculations, transferred it to a spreadsheet, added a bunch of nmenonic notations to put the bumps in the right places and practiced on the wasted cam. That lobe came out perfect, taught me the virtues of developing a routine, and I quickly went to work on another cam blank.




Armed with this newfound knowledge from the school of hard knocks, the remaining 210 step cuts and 24 turns +16 holes for each base circle went rather uneventfully. At the very end I had something that looked like this. 




So I accomplished quite a bit, but never got around to the mount problem I set off to tackle in the first place. I have some nice shiny new pieces, but the engine is in different Mcmaster bags awaiting reassembly. Maybe sometime this week we will get around to that mount work.


----------



## Lakc (Jun 6, 2011)

Quick update, we stole a few moments away to work today. The oil drain return problem was slightly improved by drilling the drain nipple out to a 34 size. I needed to make a small spacer for the flywheel to clear the oil pump cover bolts but otherwise it fit fine. 





Then I dusted off a nearly 8 year old scratchbuilt plane to determine how to mount the engine. 





Thats a 6 point rubber mount system, from Mcmaster parts, where else, and if you look really closely you will see parts of that are riveted like a real airplane. Next we figgure out just what and how to incorporate this engine into the airframe best.


----------



## nfk (Jun 7, 2011)

Looking nice!
I would love to see it flying! :bow:

Norberto


----------



## picclock (Jun 7, 2011)

Just read the thread and it looks like a really nice engine. 

Cautionary note about the teflon gasket. The reason they are not used is that when it burns it gives off a highly toxic gases :- 

http://www.greenhealthwatch.com/newsstories/newslatest/latest0701/frying-pan-teflon.html 

it's interesting to note paragraph 3 and the dead birds.

I remember when using teflon in a high voltage test oven (only to 80C) there was a lot of extra paperwork for Health and Safety. 

Look forward to seeing it running - hope you will post a video.

Best Regards

picclock


----------



## Lakc (Jun 8, 2011)

Thanks for the comments guys. Indeed, one has to be careful not to burn teflon. This is rated to 500 degrees only, but for now running on alcohol I suspect there wont be any problems. Later on, with spark ignition and a different fuel, we may have to rethink the head gasket composition. Teflon coated multi layered steel is a common head gasket material for full size applications these days.


----------



## Lakc (Jun 17, 2011)

I have some really nice pictures of the engine mount work I did last weekend, but I will just leave this here instead for now. 
<object width="425" height="344"><param name="movie" value="http://www.youtube.com/v/gmaqTipno6Q?hl=en&fs=1"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/gmaqTipno6Q?hl=en&fs=1" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="425" height="344"></embed></object>


----------



## ronkh (Jun 17, 2011)

Lakc,

I have just spent at least the last two hours watching your build and all I can say is-

"Fantastic". Thank you for sharing, you must be extremely proud.
Brilliant video.

Regards,

Ron.


----------



## Lakc (Jun 17, 2011)

Thanks a lot Ron, glad you enjoyed the journey. I am far from through yet, but hearing it run was definately a major milestone.


----------



## Lakc (Jun 27, 2011)

Time for an update:
Spent a good deal of time this past weekend working on a carburetor. No new pics because my daughter had borrowed my camera for some silly reason involving the birth of another grandson, which took another chunk of my weekend. ;D 
For now, I will upload the pics of of the mount work and hopefully get caught up sometime this week.


A little cardboard for doodling, then once design is mostly set, layout onto a piece of steel.







Punch the holes first, before bending. I love my little hand punch.






A scale pressbrake would make an excellent project someday. Until then, its hammers and vice's.






One leg is slightly longer then the other, allowing this strange lashup.






Top mount installed with optional rubber motor mounts.






Bottom mount is more of the same, but less. Leaving my options open for now, this may end up as mounting point for several different accessories.





So now were almost caught up. Work is almost complete on the first carburetor. It may take several of them to come up with the performance I want.


----------



## Lakc (Jul 4, 2011)

Beautiful four day weekend, but I only managed to steal a little time away with the engine. 

This photo is the metering circuit of the carburetor. The brass piece was version 1 and the assembly is version 2. Both are 8-32 thread, with the brass piece drilled 3/4 way through in a clearance diameter for the needle and drilled the remainder of the way a smaller diameter to provide a jet/seat. The newer version was grooved with the corner of a 1/16 end mill and the smaller diameter was not drilled all the way through, the fuel exits the middle, where on version 1 the fuel dumped out the end. 





Along the way, we have been having problems with head gaskets still. Both head gaskets were replaced in seperate incidents. I changed the way to make them slightly, drilling the hole smaller then my punch and letting the head bolts self tap their way through the gasket. Not a whole lot of room there, but that seems to have helped.






As far as progress, here is a minute long video of the longest run so far. I promise to take some more pictures soon, as we are mobilizing this out to the garage. This thing can smoke out my shop vary quickly. 
[ame=http://www.youtube.com/watch?v=NW8GxeQBnZw]http://www.youtube.com/watch?v=NW8GxeQBnZw[/ame]
[youtube=425,350]<iframe width="425" height="349" src="http://www.youtube.com/embed/NW8GxeQBnZw?hl=en&fs=1" frameborder="0" allowfullscreen></iframe>[/youtube]


----------



## stevehuckss396 (Jul 4, 2011)

After all the work it took to get this far, are you still planning to fly it? I'm not sure I could do it. Be too afraid of smashing it.


----------



## Lakc (Jul 4, 2011)

That thing is pretty much a tank, my biggest fear has always been the radio loosing control and watching it fly away. :-[

Since the work involved in forms, tooling, setups, and drawing corrections has already been done, I could reproduce it with a hell of a lot less effort, and fully intend too, once the bugs have been wrung out.


----------



## metalmad (Jul 5, 2011)

Nice Run Jeff :bow: :bow:
Pete


----------



## cfellows (Jul 5, 2011)

That's one serious sounding engine! Very nice!

Chuck


----------



## kustomkb (Jul 5, 2011)

Awesome job Jeff! Sounds great!


----------



## Lakc (Jul 5, 2011)

Thanks for all the nice comments guys!
I am working on moving my base of testing operations outdoors to the garage. I have a test stand out there and that prop is putting out some serious wind, not to mention after that run I had to evacuate the shop for 2 hours to be able to breathe in there again. 
Several years ago I built a test stand with a few flowmeters for tuning engines, its time to put some work back into that stand and turn it into a mini dyno.


----------



## Lakc (Sep 19, 2011)

_*Back from the depths as it were. *_

Its been a while since updating last. The reasons are basically simple. Moving my base of operations as it were, out into the garage, and going from glow ignition to spark ignition. 

If your familiar with some of the discussions surrounding electronic ignition modules on the board, there are a lot of choices out there, none of which I am very happy with. There are several DIY projects out there that give programmable advance curves and capacitive discharge ignition capabilities. After seriously considering a couple of them, I deceided against them too.

That kinda left me to put up or shut up, put my money where my mouth is, so to speak. So welcome to a new chapter, and a brand new ignition system, and a heck of a lot of work, much still to be done. I started in early July with a blank slate, and in approximately a month, I had a version that passed testing in software only. Hardware testing on a bread board took another couple of weeks, and finally manufacturing a beta version on a circuit board for testing took until a week or so ago. Here is a pic of the hardware board about half finished. Its rough, not ready for production, but suitable for testing. 





Here is a pic of the 10 degree slot used for a hall effect crank trigger. 





Now that I had come that far, I spent a few days getting the test stand in working order again. 
We have an earlier microcontroller project that runs the throttle. There is an electronic karmann voltex airflow sensor that needs work still, and I dont have any of the flowmeters hooked up yet. I did stop by a friends and got a ring rolled for the prop, safety first folks.  Although I should have included a fire supression system. ;D





















With everything hooked up, we did a lot of cranking to preoil everything, then had a failure.

Classic fatigue crack, looks like I have to pay more attention to the radius on the corners. 











So more testing gets delayed yet again while I whip out another crankshaft. :'(


----------



## stevehuckss396 (Sep 19, 2011)

Well that stinks!

Better it broke while cranking than at 8000 RPM.


----------



## Lakc (Sep 19, 2011)

Yes, thats for sure. I had to have goofed something up somewhere with the crankshaft, thats way too early for a crack like that in 4140, but the results dont lie.


----------



## kcmillin (Sep 24, 2011)

Jeff, Sorry I am a bit late to the party.

 This is one awesome project you have going here.

It is pretty darn cool you want to put this in an R/C plane, I have been dreaming about doing that for some time now.

I really like your bench setup. There is a lot going on, plenty of data points to gather. Sounds like a lot of fun.

To bad about the crankshaft, like Steve said, lucky it happened when it did and not flying in the air.

Kel


----------



## steamer (Sep 24, 2011)

Jeff,

1144SP might be something to look at instead of 4140.  Great properties and far easier to machine.

Dave


----------



## Lakc (Sep 25, 2011)

Thanks for the comments guys, its really been a fun ride. 

Kel, I built that stand years ago to tune airplane motors, and keep changing the configurations. The three flowmeters on the bottom are low rate airflow that I use for fuel flow. The large manifold and clear plastic flowmeter at the top is a high rate airflow meter, but its not operational. Our small engines cant take the pumping losses associated with lifting the steel balls. To make it work, I would have to pressureize the inlet and balance it so the output pressure doesnt go over baro pressure. It would be easier to move to my electronic counter when I get the time. The U-tube and yardstick configuration on the right is the manometer. 

Dave, I have a couple of sticks of 1144, and planned to use that for future projects, neither is exactly the right size for this crank however. Not wanting to waste the 4140, and since it was the only 1.125 diameter piece I had, I wanted to turn it into 4140SP. 

 The 8 inch stick I had remaining was loaded into my budget heat treat oven, placed outside for safety, and I set the temp for 1200 degrees. It was a long slow climb from about 800 onward. The oven is really not insulated properly, and the elements get plenty hot, but its constanly fighting the heat loss. After about 3 hours of cooking, the temp had topped off at 1044 degrees. I held it there for an additional hour and thats as good as its gonna get for this weekend. That temp might have been enough, we shall see. There are a lot of different temps listed for stress relieving. 5 hours after I turned the oven off the bar was still quite warm. 

A little structural work, insulation work, and volume reduction, should make it a much better heat treat oven. However it did a pretty fine job for a $20 wallmart throwaway toaster oven.


----------



## steamer (Sep 25, 2011)

Cool furnace Lakc

Looking at the photo, looks like the crack started at the corner between the throw diameter and the web.... A classic stress concentration point.  I guess a bigger radius there on the next one?  Can you radius your conrod bearings to clear it?

Dave


----------



## Lakc (Sep 25, 2011)

Plenty of room for a bigger radius. Thats one of the changes I need to make. 

As fast as it failed, I am not so sure I didnt put the crack in there during the turning process. This time, I bought an endmill with a radius tip to hog it out first.


----------



## Niels Abildgaard (Sep 25, 2011)

If the breakage happened with the extra flywheel put on the rear end explanation can be another.
Imagine a torsional weak (two throw crankshaft?) with a flywheel at each end and a source of very varied frequencies and You will sooner or later have disaster from so called torsional vibrations.It is a specialist job to calculate and in Your case a heavier propeller is a much sounder scheme.

Kind regards and symphaty

Niels


----------



## Lakc (Sep 25, 2011)

Niels, thats a definate possibility, and something I havent even considered. Thanks for that bit of advice. 

Now, the extra flywheel is gone, replaced by a much thinner crank trigger window. Hopefully, I wont have this issue with the next crank.


----------



## rklopp (Sep 25, 2011)

The fracture surface appearance indicates the crack grew primarily due to bending stresses, not torsion. Perhaps the crank was not straight?


----------



## steamer (Sep 25, 2011)

Yes!
It does appear to be all in one plane doesn't it?

Dave


----------



## Lakc (Sep 25, 2011)

The crank was off .001 right after it was made. It was 1.125" 4140 stock turned down to 1.047 then cut using offset centers. I wouldnt rule out the possibility of any residual stresses bending it further over time that I wouldnt have remeasured. Hence I did take the time to attempt a stress relieve before making its replacement. 

Its replacement is giving me no end of bother in the planning stages. I have the case and bearings installed, and taking measurements (no easy task on the inside) has told me the crank pins were off centered of the bore by ~.080. The results have thinned the center web between the pins down to .090. That, in my opinion, is not enough meat to turn between centers. This is going to require some offset jig almost 2" long, which is a heck of a lot of overhang. I am going to have to think on this one a little bit.


----------



## steamer (Sep 25, 2011)

Hi Lakc, rklopp,

Actually I've been thinking about this. It's late but I think I've hit upon something, but feel free to tell me I'm wrong.

If the bearings were co-axial and the crank was "bent" then the crank would be aligned to the bearings during assembly,  As it rotated, nothing would bend any further. There wouldn't be any reverse cycling.  Fatique should not be an issue.

However, if the bearings were NOT colinear, then the shaft would have reverse cycling during rotation

Check the alignment of the bearings!....

Dave


----------



## Lakc (Sep 26, 2011)

Nice theory Dave, and worth noting. I did check the bearing alignment with a 3/8 round HSS tool blank and it slides through like butter. 
Using my big drill on the cone starter probably was the big contributor to any (axial?) loading, so in effect, it became a victim of my earlier starting problems. The friction rubber on cone allows a significant inbalance to exist at times.


----------



## mu38&Bg# (Sep 26, 2011)

Jeff, you might be right there. Without a bearing on the output end to take up thrust and side loads, the starter could have put a hurt on it.


----------



## Lakc (Sep 27, 2011)

Greg, the latest drawing took .1 off the total overhang length of the crank, so a little less leverage might help too.


----------

