# Introducing ... the "Steel Webster"



## awake (Mar 8, 2020)

My very first IC engine (actually, first engine of any kind) - based on the Webster design, but modified to suit personal preferences and materials on hand. A major difference, as suggested by the title, is that it is made (almost) entirely of steel. The only exceptions are the piston (cast iron), the cylinder fins (aluminum), the small end bearings and rocker arm bearings (brass), and the valve guides (bronze). Except for the plain bearings just mentioned, all other bearings are metric sized, flanged ball bearings (metric because they are cheap on eBay).

A major goal was to use materials on hand rather than buying - thus the use of steel throughout, as I have plenty of that but not a lot of aluminum, particularly in the sizes that would be needed. As it turned out, the only items purchased for this engine - not counting tooling, which I assure my wife does _not_ count - were the ignition components (points, condenser, coil, spark plug), a package of needles to make the needle valve, and a couple of different sizes of flanged bearings (eBay specials, fortunately purchased before everything in China came to a stand-still). Everything else came out of my scrap bin. For the flywheel, I did have to weld up two smaller pieces of steel to get the blank.

I have put this in the Work In Progress thread ... but not sure this is the right place, because I am posting this mostly ex-post-facto. I began the build on November 16, 2019, and while there are still some things to be done (mounting the gas tank, for example), it did achieve its first run last night (or maybe it was early this morning!).

However, I have been taking detailed pictures along the way (with occasional lapses), and I would be interested in detailing the build a step at a time, explaining design choices (some of which do not match the good advice I read here!). Question is, would that be of interest to anyone? And if so, is this the right forum to put the build posts in? I await your feedback (please be gentle - remember that I am a newbie!), and even if the consensus is not to provide the detail, I will want to follow up (in whatever forum is appropriate) with some questions about how to fine-tune it - I don't really know what I'm listening for as I attempt to adjust the needle valve and throttle.

But for now, here is the YouTube video of its second run (I was so excited and surprised when it started up the first time, with almost no fiddling and adjusting, that I failed to get a video of it - and I promptly killed it when I tried adjusting the needle valve):



And a few graphics of the CAD design:


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## minh-thanh (Mar 8, 2020)

awake !
I don't think the time to build and complete a project affects the "In Progress" name.
I'm not new or old, in the time (not long) I joined this forum, I realized this was the real place for model engine builders.
Congratulations and look forward to In Progress of your engine !


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## Cogsy (Mar 9, 2020)

Congrats on a runner, it's always a great feeling the first time they fire up. This forum is the place for your build log, feel free to just continue this thread if you like.


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## awake (Mar 10, 2020)

Thanks Cogsy and Minh Thanh!

Cogsy, a follow-up question (directed to Cogsy, because I think I remember him giving guidance on copyright issues in previous threads, but of course happy to hear from anyone!): I have completely redrawn the plans as I have made my various modifications to the basic design. Is it okay for me to post them as I go through the build? While I will happily take credit (or blame) for the modifications I have made, I certainly would not want anyone to think that this is a completely original design; at the same time, I am vain enough to hope that my interpretation of the Webster might be of value to someone. 

I am not sure exactly what the copyright is on the Webster plans - public domain? Or ... ? Likewise, the Chuck Fellows carburetor, on which I based the design for the carburetor I used - public domain, or ... ??


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## Cogsy (Mar 10, 2020)

Truthfully, I have no definite answer on either question as I don't know the copyright on either of them for sure. I think they're both in the public domain so it should be OK (with attribution) as they are certainly available quite freely. I doubt it would cause any issues so my guess would be it'd be fine to do so.


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## awake (Mar 10, 2020)

Thanks, I will proceed accordingly.


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## Longboy (Mar 11, 2020)

awake said:


> .........I am not sure exactly what the copyright is on the Webster plans - public domain? Or ... ? Likewise, the Chuck Fellows carburetor, on which I based the design for the carburetor I used - public domain, or ... ??



Joe Webster offered up his plans for this engine free on the internet about 10 yrs ago. Probably one of the best things to happen for this hobby as The Webster has been recommended to
newbie's by machinists as their intro build. You see many on Youtube with mods or as per plan and you see modelers continue afterwards..........thanks to Joe.


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## aka9950202 (Mar 11, 2020)

Longboy, 

I agree with you. It would be nice to see other designers offer plans for free. A 4 in line that is basic and runs would be great.  It allows you to gain confidence before moving on to more complex engines.

Cheers, 

Andrew in Melbourne


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## awake (Mar 19, 2020)

Finally I'm getting a chance to start the build log - sorry it has taken so long. Work has been crazy busy as we have worked to adjust to the new paradigms enforced by the current pandemic!

The build log begins with the frame (the .pdf file is also included as a link):




Now, before we go any further, I plead for grace - I have not a single bit of training in drafting, so I am sure I have not laid this out or drawn it up in the best possible way. I would greatly appreciate [gentle and kind] pointers on how I could improve these drawings!

As I mentioned in the opening post, a significant part of what drove my interpretation of the Webster was use of materials on hand, which meant almost entirely steel. The frame is no exception; it began life as a couple of pieces of fairly heavy c-channel - which first had to be wire-brushed to remove the rust:





After chamfering the mating edges, these were clamped together ...







 ... tacked, and welded. Yes, it had been a while since I had done any TIG welding, and the results show the lack of practice:









To clean this up, I mostly used my restored Southbend 7" shaper - I really like using the shaper for squaring up parts, since I can let it run while I do something else:





I didnt get a picture of  what happened next - I milled off the closed "top" and cut / milled the sides to give me the overall shape that I wanted. You can see that shape in the next picture below:





The picture above shows that not everything happened in logical sequence - as you can see, before I trimmed this end to be flat and to length, I had already made and added the bearing flanges - which was premature, as later I had to remove one of them to complete other parts of the frame and the ultimate assembly.

Not shown are the various operations I did to give me a flat inside surface where needed (rather than the angled and rough surface of the c-channel) - again, the shaper did the bulk of this work, but some of the setups were a little on the "just barely" side.

I don't have pictures of drilling the various holes in either side of the frame (yes, I hear that sigh of relief!) - and indeed I didn't drill them all at the same time, because I kept figuring out new holes that were needed as the design went along! But here is a picture of what is arguably the most important hole, the main bore in which the bearing flanges mount, which in turn hold the crankshaft:





Finally, a shot of an operation that actually occured after the first run, when I further tweaked the design to create a mount for the gas tank - this notch will accommodate a bit of tubing with a set screw in it, allowing it to clamp the rod that holds the gas tank mount at the desired height:


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## Longboy (Mar 19, 2020)

Surely to be the most brawny indestructible Webster out there!  Will you have a flywheel in steel too?  Gonna weigh 8-9 lbs.


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## awake (Mar 19, 2020)

Yes, the flywheel is steel - that episode is coming soon! I'll give you a hint: just as the frame featured welding, so did the flywheel ...

I didn't think to weigh the flywheel by itself, and at this point the engine has been stripped, cleaned, finalized with the last few tweaks, and re-assembled, with Loctite added to strategic points. Some of it is the "blue" type that can be removed, in case I have to disassemble again ... but it turns out that, at least with the design as I worked it out, this has to go together in a very specific order, and it is a bit of a pain. Okay, more than a bit of a pain.

All that to say, you've got me curious now about the weight of the flywheel, but I am _not_ going to disassemble the engine to weigh it. What I will do, though, is weigh the whole engine - it is definitely chunky, but not all that heavy, I don't think.


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## Longboy (Mar 19, 2020)

https://www.industrialmetalsupply.com/Weight-Calculator


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## awake (Mar 19, 2020)

Part 2 of the build log is very brief, but it turned out to be one of the better design decisions I made:





The primary motivation for these bearing holders was to have enough "meat" to be able to mount two flange bearings on each side of the frame. The secondary motivation was that this approach would make it easy if I decided to change the diameter of the crankshaft - instead of reboring the frame, I could just make a couple of simple parts to hold a different set of bearings. As it turned out, I never did the latter; I used F6800 bearings, 10mm bore, with a 10mm (.394") crankshaft, and it worked out well.

Making these was quite simple - hardly worth taking pictures, so I only took a few:










I said this proved to be a valuable design decision - even though I never needed to change to a different size of bearings. Here's why: The relatively large bore in which these bearing flanges sit greatly eased the assembly of the crankshaft and the components that ride on it. I could partially assemble the crank shaft with the bearing flange, the crank gear, and the keys, and then slide the whole assembly in through the bore. Given the way I made the crank, with interrupted keyways, I don't know if I could have successfully assembled everything otherwise.


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## Picko (Mar 20, 2020)

Thanks Andrew, I'm enjoying this. I'm yet to build a combustion engine but when I do the Webster will be on my list.
Oh, by the way, I'm a draftsman and your drawings look fine to me - except for those funny dimensions """ .
 Cheers John


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## awake (Mar 20, 2020)

Hi Picko,

The irony is that a lot of my design is metric, particularly any of the bits that ride in bearings, since I can get metric bearings far cheaper than inch-based bearings. (Or at least, I could, through eBay - don't know if how that supply chain is going to look going forward!) I also have a metric tap for M3x.5, but the smallest I have in inch taps is 6-32 - so a couple of the smallest screws in this design are M3x.5. I wish I could say that this reflects my international outlook ... but as with everything else in this design, it just represents laziness and cheapness - using what I have on hand or can get cheap!


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## awake (Mar 20, 2020)

Part 3 of the build log is the crankshaft:





A few notes about the design - as you can see, I chose to go with a built-up crankshaft for my first time. I also chose to go with an interrupted keyway, but I'm not sure that was my most brilliant decision - as I alluded to in a previous post, this caused problems with assembly, since I couldn't slide the key along the keyway as I put the shaft through the bearings. One other note is the pin end, sized at a hair under 6mm so that the pin can ride in 6mm ID bearings used in the big end of the connecting rods. The length of the pin is a few thousands longer than the thickness of the big end with the bearings installed - this allows a small custom washer and a 3mm screw to fasten tightly to the end to hold the big end in place without binding up the bearings. (On final assembly, I added a dab of blue Loctite to this screw, but in the initial runs it did not seem inclined to loosen, somewhat to my surprise.)

I'm afraid I didn't take many pictures. Here is the main shaft underway:





And here is the pin in progress:





Cutting the keyway ...









A couple of things to note here. One is that I was, for the first time, using a 2mm endmill, smallest I've used to date. Why not use a 1/8" endmill? Part of the reason is that, originally, I was planning to make the keyway 3mm rather than 1/8", since the shaft itself is 10mm - keeping it in the metric family, so to speak. But I didn't have a ready source of 3mm keys, and I did have several 1/8" keys, so I switched to 1/8". Meanwhile, past experience suggests that endmills can cut just a bit larger than their diameter, so I prefer to use a smaller endmill and then shave the sides to size.

Something else that sharp-eyed readers might note in the picture above - you can see that the shaft is held in a 3/8" 5C collet. The use of the collet in the spin indexer was just a convenient way to grip this round part ... but wait; didn't I say the shaft was 10mm, .393" rather than .375"? No, 5C collets cannot expand that much! If you look back at the plans, you'll see that the end of the shaft, the part that goes into / connects with the web, is at 3/8" diameter, so the shaft is being held by that little stub in the 5C collet - but it is quite secure because I put a center in the other end, and as you can see, I am supporting that end.

Finally, a poor shot of the web end of the crankshaft after I assembled it - actually in place on the assembled engine, because for some reason* I neglected to take a picture of the finished crankshaft by itself:





*for some reason ... maybe embarrassment over the poor execution? In keeping with the spirit already established in the making of the frame, I decided to TIG weld the parts together. How did I do? Well ... the picture shows the results after cleaning it up as much as I could ... still not so great. But it works, so I'm calling that good for a first attempt!


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## awake (Mar 21, 2020)

Part 4 of the build log gets into something that I think might be more interesting than some of the other parts - the flywheel. To be sure, the plans are quite simple:





However, the execution was - perhaps - unconventional.

I was looking for a flywheel with diameter of 3.75", at least .75" thick at the rim. I had on hand some pieces of 1" thick steel, 4" wide, but not a piece that was 4" long. So, having already established the pattern of using welding as a primary tool in this build, I prepared two pieces, 4 x 2 x 1" in size. Part of the preparation was setting each piece at a 60° angle in the mill vise and cutting bevels to facilitate a full-penetration weld:









To weld these together into what I hoped would be a solid 4 x 4 x 1" blank, I began by spacing the two pieces with a 1/8" gap to help with penetration, then tacked and ran a root pass on each side using TIG welding:













Not the best-looking root pass, but good penetration. I probably should have finished welding it up with TIG, but I was a bit concerned about the rods and argon that would be consumed, so I switched to stick welding with 7018 to provide quicker and less expensive build up - at least, in theory:





As the picture above shows, the results were so-so -- the 7018 is old, and not nearly as dry as it should be, so I struggled with porosity and inclusions here. When that occurred, I tried to grind it out and build up again. Maybe it would have been less time and trouble to have stayed with TIG throughout!

To be continued ...


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## awake (Mar 21, 2020)

Continuing part 4 of the build log, the flywheel:

Once the blank was all welded up, I began preparing the blank, starting with a carbide-insert face mill in the Bridgeport:





In general, 7018 weld on mild steel machines reasonably nicely, but I had also filled in some gaps or defects with TIG. Normally, TIG welded mild steel machines beautifully, but if someone happens to dip the tungsten into the weld, it forms a small spot that is hard as a rock. I'm not saying that I did such a thing ... but I did feel the need to start out with carbide. 

Once the surface was brought down nearly to level, I further prepared the blank using the shaper, getting the two faces flat and parallel:





Then I cut the corners off on the bandsaw to get a rough octagon (no pictures of that), mounted the blank in the 4-jaw chuck on the lathe with roughly half of the blank above the jaws, and began the roughing passes to get an oversized round blank:





In the picture above, note the centering mark that I had put in the blank to help get it roughly centered in the 4-jaw chuck.

Once one side was roughed in, I turned the piece over, switched back to the three jaw chuck, and mounted it up to the octagonal rim that remained on the other half of the blank. Now I could rough this other side, again leaving it oversized at this point (and also leaving just a tiny "rim" of the former octagon that had to wait for a later step). At this point, I began to do the finish turning on the exposed face:





Once the face was finished, I bored it to a nice, tight, but sliding fit on the 10mm crankshaft. In the picture below, the rim area is still oversized in diameter, but the inner hub and web are to final size::





Just after this picture was taken, I finalized the face portion of the rim as well, facing the rim down to the proper height above the web.

I removed the flywheel, switched to the 3-jaw chuck, and mounted some 1.125" diameter mild steel stock (scavenged long ago from some now-forgotten source). I turned a .9" long stub mandrel down to a nice sliding fit in the bore of the flywheel, with a flat face behind it (neglected to take a picture of that). Leaving this mandrel mounted so that it stayed perfectly true, I used Loctite to attach the flywheel to the mandrel and let it set up overnight. The first go round, I tried using the "blue" version that would be easier to remove, and I got as far as roughing out the inner hub and web, but ultimately it just couldn't take the torque, so I had to clean it up and do it again, this time using the "red" version. I held it firmly in place using the drill chuck in the tailstock while it set up overnight:





With the flywheel Loctited (is that a word??) to the mandrel, I could turn the rim to final diameter, including cutting off the little bit of octagonal "flange" that was left in previous steps:





To be further continued ...


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## awake (Mar 21, 2020)

Further continuation of part 4 of the build log, the flywheel:

At this point, what is now the backside of the flywheel, up against the face of the mandrel, is fully finished, including the height of the both the inner hub and the rim relative to the web. Careful measurements were taken of the OD of the inner hub and the ID of the outer rim. Also, in the last bit of the previous post, we had finalized the overall OD of the flywheel.

Now to finish the exposed face to size. The rim area can be faced to achieve the desired .75" total thickness:





But the web is another matter - how to measure it? The movable anvil of the micrometer can go up into the inset area of the web, but not so for the fixed anvil.

The answer, of course, is to use a gauge block in the back side of the web, against which the fixed anvil can set; after measuring up into the inset area with the movable anvil, just subtract the size of the gauge block from the measurement, and hey presto! We get the current thickness of the web.

One small problem: I don't have any gauge blocks. (On my wish list, in case anyone was wondering what to get me for my next birthday ... ) But the problem is not insurmountable; I just need to turn a piece of scrap so that it has parallel faces, measure it carefully, and use it as my gauge block. But another problem, not so small: my whole procedure depended on leaving the mandrel mounted in the 3-jaw so that it would stay true, and thus also the flywheel would stay true as I cut it. If I removed the mandrel to turn a piece of scrap, I'd lose my carefully planned precision.

This is where having a second lathe is invaluable. (Note to spouse: See? This really was a good purchase!) I turned a bit of scrap in my rebuilt 7x14 lathe, measured it carefully , and then used it to take the measurements of the web of the flywheel:













This allowed me to cut the web to final size, and once that was done, to finalize the ID of the rim and the OD of the inner hub. Voila! The turning is complete on the flywheel:





Now it is just a matter of cutting the keyway. To be continued one more time ...


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## awake (Mar 21, 2020)

The final continuation of part 4 of the build log, the flywheel. If you have stayed with this all the way through, you deserve a special treat; please help yourself to your beverage of choice and settle in for the final installment!

I cut the key way in the flywheel (and later on, in the cam gear and the ignition cam/starter spud) using the shaper. First, of course, I had to make a cutter. I tried a couple of approaches, but settled on a cutter ground from the remains of a 1/2" end mill:









Never, ever, ever would I throw away an end mill just because it is no longer usable as an end mill - heaven forbid that I waste all that HSS that is just waiting to be ground into something useful! (This is also meant as a note to my spouse, who seems to think I am a pack rat!)

I also had to make something that would let me mount this cutter in the shaper. Here is what I came up with:




 As the picture shows, I cut a scrap piece of 1" thick mild steel to give me a "leg" that can go into the tool holder on the shaper, a body with a round hole to accept the cutter, and two cross holes that hold split-cotter clamps. (Only one of the latter is in use in, because I had to extend the cutter out further than I had first anticipated - but just the one held securely, with no fuss or muss.)

Here is the cutter in action, cutting the key way in the flywheel:





The cutter was ground to around .100" wide, rather than the full .125" needed for the key way. Part of that had to do with what was usable from the old endmill that formed the cutter blank, and part of it had to do with the thought that a narrower cutter would chatter less, and allow me to "sneak up" on the proper size, shaving down the flanks until the key just fit:





After cutting 4 key ways this way, though, I am wondering if I should have gone ahead and ground it to the desired final size - something different to try next time, I suppose. I have lots more broken 1/2" endmills. 

Finally, the flywheel is done:





Well, almost done - I still had to hold the flywheel at a bit of an angle to drill and tap the hub for the set screws that screw down onto the key - one set screw on each side, placed over the key way. Fortunately unfortunately, I neglected to take a picture of my rather sketchy set up, but I did accomplish the task in the end. After breaking a tap. Which fortunately I was able to persuade out. (I did NOT want to have to go through all of that again to make a new flywheel!)

The good news is that the finished flywheel runs absolutely true. The even better news for you, patient reader, is that this part of the build log is finally complete!


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## stragenmitsuko (Mar 21, 2020)

A wel documented build with a lot of pictures is always a pleasure to follow . 

pat


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## awake (Mar 21, 2020)

Thanks!


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## a41capt (Mar 22, 2020)

Awake,

I don’t see where you locked your clapper down for the internal keyway, or am I mistaken?  If you didn’t lock it down, we’re there any problems with the return stoke, or was there enough clearance for your tool in the early stages of the cut for clearance?

I need to do a similar operation, but a little deeper, and I’m wondering if my tool holder will be rigid enough to not chatter in the cut groove.

Also, I’m thinking as you did in that I could possibly get away with grinding the cutter to create a tight fit for my key rather than “sneaking up on” the width as you did. I too save ALL my broken HSS end mills just for moments like these, so sign me up as a pack rat too!

I’m using a tight and great running Atlas-Craftsman 7B.

Thanks in advance for any wisdom you can pass along!

John W


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## awake (Mar 22, 2020)

Hi John,

You are right - I did not lock the clapper down. I had read that that was the thing to do, and had contemplated how I would need to drill and tap for set screws on either side of the clapper. But something else I read or saw somewhere suggested that it might be possible to do the job without locking, so I tried it, and it worked just fine, with a couple of caveats below. Yes, there was enough clearance - part of why I had to grind the cutter I did, since some of the other options I considered would not have cleared!

A few small bits of experience - more working observations and caveats on my experience to date than any true wisdom, since I have only cut a grand total of 4 key ways on the shaper (no, as I was writing this I remembered that, in addition to having to remake a gear, I also wound up remaking the ignition cam to incorporate a starter spud, and then I remembered that I also cut a key way in a small pulley a while back, though using a different cutter, so actually it has been a grand total of 6 key ways!): 

I did cut one part (can't remember off hand if it was one of the gears or one of the ignition cams) with the tool turned the other way around, i.e., cutting at the top rather than the bottom. That may be where it would have really be helpful to lock the clapper - you can quickly visualize that in this configuration, if the clapper moves, it will bring the cutter up into the work, rather than away from it. I got away with it, but it was clear that this was not the best way to do it.

A second observation / caveat, which may be obvious, but just in case - each time that I increased the depth of cut, even though only 2-3 thou at a time, it helped to let the shaper take at least two or three strokes - this may again be where a locked clapper would have helped, because it clearly took 2-3 strokes before it was finished cutting. Of course, it may also be a matter of the shape of the cutter - I am still not sure what the optimal rake might be for this operation.

Third observation - clearance IS an issue, not only for the cutter (which wasn't actually a problem since I had sized that to leave clearance), but rather for all the other bits. The tool has to reach a good ways out to get into and through the bore - and it has to do so without running the screw for the tool holder into the part. One solution would be to extend the "leg" of the holder a lot farther down than I did on the holder I made / show above; another would be to make the body of the cutter holder (or the tool itself) extend further outward, so that less of it is "overshadowed" by the tool holder. Thus the use of only one split cotter clamp - I had to pull the tool further out to allow it to complete the cut without hitting the tool holder. I also had to find a shorter tool holder clamp screw, and in fact on the last key way I cut, just the other day, I substituted a set screw to reduce it even further.

There is a corollary to the last observation - with the tool having to stick a ways out, you may have to find a way to move the part back further in the vice or on the table. The very first key way that I cut, which I just now remembered, was a small pulley for a wood working tool; for that one, I mounted a right-angle fixture to the table and clamped the part to that. But you will see at least one picture above that I had a "duh!" moment when I realized I could move the part further back in the vice simply by putting a scrap piece in front of it.

Hope this helps - I look forward to hearing how you get on, and any improvements you come up with on the process - there is clearly room for improvement!


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## awake (Mar 23, 2020)

Part 5 of the build log is the rod:






Once again this will have to be a multi-part post, as I took quite a few pictures - despite being a relatively small part, the rod took quite a lot of setup and machining, including figuring out how to use my Christmas gift - a 6" rotary table.

The process began with machining a 5/16" thick blank from which the rod would be cut - once again using my trusty shaper to get it flat, parallel, and to size:





Next was boring the hole for the big end, sized to accept a pair of F686 flanged bearings with a light press fit. (I also drilled the hole to accept the plain bearings for the small end - nominally .250", but the exact size didn't matter, since I later made the bearings to fit):





The next operation may look rather strange in the picture, but hopefully will make sense when you look at the plans - I drilled 4 holes, carefully located using the DRO and started using a center drill, which will define the transitions between the rounded ends and the slightly tapered body of the rod:





The next step was to make a mounting plate with "buttons," each tapped and drilled at the top :





The buttons were sized and positioned precisely to accept the rod blank, and a screw and washer in each button held it securely in place. The plate is enough larger than the rod blank to allow clamping onto the rotary table, and it also acts as sacrificial material for the milling process:





Part 5 continues below ...


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## awake (Mar 23, 2020)

Continuation of part 5 of the build log, the rod:

The next bit took a while as I began trying to figure out the best way to center the new 6" rotary table under the spindle of the mill. I put an MT2 dead center in the center hole of the RT, and started out trying to use a DTI to center it:





I was not getting entirely consistent results this way, so I tried switching to an edge finder, and compared the results; they did not exactly agree, but I got it within .003" or so and got frustrated and quit decided it was good enough:





With the RT centered on the mill spindle as best I could, zeroed the DRO X & Y. Then I clamped the mounting block in place, centering the big end "button" under the spindle using the edge finder - thus it should also be centered to the RT. I also used the edge finder to line up the small end button so that it was exactly 0° along the X-axis, and I zeroed the dial on the RT:





Getting the RT centered AND the part centered on the RT was by far the hardest and most time consuming part of making the rod - is there an easier way to go about it? (I was badly lusting after a Volstro rotary attachment by the time I got done with this!)

Once centered and aligned, however, the actual machining proceeded pretty much according to plan. First I moved the X-axis to position the 0.250" diameter cutter on the OD radius of the big end. I raised the knee until I just grazed the blank, zeroed it, then raised it .031" and rotated the RT 360° to machine the boss around the big end:





I continued to rotate the RT until the cutter was aligned with one of the .250" holes previously drilled to define the transitions, raised the knee another 50 thou or so, and rotated the RT to cut around to the other transition hole on the other side; rinse and repeat until the OD of the boss was completely cut out.

Next I reset the RT to 0°, lowered the knee back to where I was taking a .031" deep cut, and machined away the inset section of the body of the rod:





Once again I reset the RT to 0°, moved the X- and Y- axes to position the cutter at the location of one of the transition holes, rotated the RT 2°,  lowered the knee 50 thou or so, and began cutting the tapered flank of the body section, stopping when I reached the transition hole at the small end. Rinse and repeat until the flank is completely cut away:





I lowered the knee again, rotated the RT to 2° on the other side of 0, positioned the X and Y axes to the other transition hole at the big end, and again raised the knee and began cutting the other flank of the rod by 50 thou or so at a time. Finally, the sides of the rod, along with the OD of the big end, were completely machined:





I removed the screws holding the blank in place, flipped the piece over, and took the .031" deep cut around the boss and down the length of the inset section of the body of the rod. Then I reset the X and Y axes back to 0,0 (centered over the RT), removed the blank from the mounting plate, unclamped the mounting plate, and reversed it to center the small end on the RT / under the spindle. This time I tried using the cone side of the edge finder, and I decided that was way better than trying to center the part using the edges:





I followed a similar process to the one described above to cut the boss section on each side of the small end, as well as the OD of the small end. At last, the rod is complete:





Well, almost - we still need bearings! Continued one more time ...


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## awake (Mar 23, 2020)

Final continuation of part 5 of the build log, the rod:

The next step was to make the plain bearings for the small end. Unfortunately I did not have any 660 bronze smaller than .75" in diameter, so I had to turn that down - but these plain bearings are very short, so not too much waste. I turned down a length to the diameter of the flange and drilled out a .125" hole through the middle. Using a dial indicator to get the exact length, I turned down the body of the bearing to .251" diameter and .150" long, then moved over to leave a .020" thick flange and parted it off:





I repeated the last few steps and then I had two plain bearings. Note that the length of these bearings will leave a .013" gap in the middle of the small end of the rod. I drilled through the top side of the small end using my smallest center drill, giving me a "dimple" in the top and a tiny hole through, so that oil can drip through from the cylinder to the piston, from the piston to the small end, and make its way around the .013" gap to lubricate the wrist pin. At least, that's my theory!

You may have noted that these plain bearings were sized at .251", to go into a hole in the small end that is a nominal .250" - in other words, a press (or rather, a shrink) fit. .001" is actually more interference than I thought I really needed, so I actually sized it for about .0005" of interference. I heated up the small end of the rod using my trusty heat gun (a bit of an impulse buy on an extra-cheap sale, but it has proved to be invaluable over the few years I've had it):





With big end heated up nicely, I only had to press very lightly, really just a slip fit, to seat the bearings on either side. Of course, once the rod cooled down, the bearings were going nowhere:










There is nothing much to the wrist pin (the plans for which are actually together with the piston, coming as part 6 of the build log); the main consideration is achieving a rather precise OD of .187":





 This precise sizing was intended to fit into an equally rather precise hole of .188" diameter through the small end bushing. Two problems: the first is, how to hold the rod at this point, with all of its rounded and angled surfaces? The answer was to use the mounting block again, this time in the vice. I mounted the big end on the mounting block and screwed it down with the small end hanging over the edge so that I could drill through; this worked way better than it seemed that it should - I was able to drill without movement or chatter:





The other problem was how to get the precise .188" diameter hole when I didn't have a reamer of that size. The answer was an old-timer's trick  - I "snuck up" on it by drilling it first with a 5/32" drill (through the undersized hole that I had predrilled in the bearings); then I drilled again with an 11/64" drill; then one last time with a 3/16" drill. The idea is that the 5/32" drill will drill a bit oversize, as is typical for the average twist drill; the 11/64" will mostly just clean that up; and the 3/16" drill will basically act like a reamer. It worked; the result was a very nice sliding fit on my wrist pin:





The final step was the addition of F686 bearings in the big end. These were a light press fit, and I used them that way throughout the first few runs of the engine, but once I took it apart, finalized everything, and reassembled, they were secured with "red" Loctite:





The rod is now complete; on to the piston!


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## kvom (Mar 25, 2020)

With regard to the frame drawing and dimensions, I'd make a few changes for ease of use.

There's no dimension for the height of the lower part of the rail, and the angle cut in the side could be indicated as many builders would probably mill these with the work set at an angle in the vise.

If you use the bottom of the frame as the reference and dimension from there up I think the vertical positioning will end up very consistent.


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## awake (Mar 26, 2020)

kvom, many thanks! I will add those in. Actually, the dimension of the lower part of the rail WAS in the plans - but I made a change in the model, and it confused the part of the software that turns the 3d model into plans, so I had to re-do several of the dimensions. Obviously I missed that one!

On the angle, I confess I left it out because the exact angle is completely non-critical - but it is a trivial matter to add it in for anyone who would like to have it.

Again, many thanks!


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## awake (Mar 28, 2020)

Whew! It has been an insanely busy week. Apparently "work at home" has been translated into, "it's really easy to schedule a virtual meeting, and I'm sure you have nothing else to do, so let's schedule 10 or 20 of them!" Sheesh - glad it's finally the weekend so I can focus on something _important_!

Here is part 6 of the Steel Webster build log, the piston:




As you will see, I did not take many pictures - this went more easily than I thought it might. The following picture shows the OD of the piston already completed, but not yet parted to size. Here's the most interesting bit of this part of the build log - if you look below the piston in the chuck, you will see a rusty chunk of cast iron, cut off of an old pump housing. This is the other side of the stock from which I made the piston that is mounted in the lathe! I cut a piece down on the bandsaw as best I could, then shaved down the lumpy outside to get something round enough to hold in the chuck. Then I turned it down ... and as you can see, it turned beautifully:





Since the stock that I reclaimed in this way was more than long enough, I decided to try making some cast-iron rings. First I reversed the piston in the chuck and protected it by my highly sophisticated aluminum shim (AKA cut-up Coke can); then I OD I wanted for the rings; then I bored it out to the ID:





I then parted out 5 rings using a narrow parting tool; not shown is the dial indicator clamped to the ways that lets me control the movement of the carriage, and thus the thickness of the rings, very precisely:





The round rod that you see is just a bit of cold-rolled steel that I put in a drill chuck in the tail stock; it is there only to catch the rings as they come off the blank:




Confession: I haven't actually done anything with these ring blanks. Since this was my first engine build, I decided to try going with a viton o-ring, and that seems to be working well - just a single o-ring, but you will note in the first picture above that I cut two grooves for rings - this in case I decide to experiment with the CI rings down the road.

I failed to take any pictures of the next couple of steps: After getting as many rings as I could from the blank, I made the final facing cuts to bring the piston to the desired length. I then mounted it in the mill vise "crosswise," i.e., with the axis of the piston set along the Y-axis, resting on parallels. After finding the center and the end of the pistion, I drilled the wrist-pin hole, using my "sneak-up-on-it" approach described in the build log for the rod.

I could then put the piston in the mill vise using the drill bit through the wrist pin hole to line up the wrist pin parallel to the vise; this let me then mill the oval slot where the small end of the rod will reside at a right angle to the wrist pin:









You may be wondering about the threaded hole that shows up in these pictures - that was part of my original reclaimed cast-iron blank. I had carefully planned how to cut the blank out of the chunk of CI so that I would be roughly centered on that hole - otherwise, I would not have been able to get a big enough blank to work with!

Not shown, but easy to do, was the final step, remounting the piston "crosswise" as described above, and once again using a drill bit through the wrist pin holes to align the wrist pin parallel to the table. Then I found the center and the end, and drilled out the 0.094" hole that allows oil to drip through to the matching hole in the small end of the rod. In Webster's original plans, this should have a brass tube pressed in to carry the oil right up to the small end ... I haven't done that, at least not yet - maybe a later improvement.

One bit about which I am quite uncertain - my decision on how to keep the wrist-pin from floating out and scoring the cylinder. As you can see in the plans, I chamfered the outside of the wrist-pin holes. For the final installation of the wrist pin, I cleaned it all well and used a bit of red Loctite as the first line of defense. Then after that was set, I came back and lightly staked the ends of the wrist pin so that they protrude a bit into the chamfer. Had I done a better job, that would have been the end of it ... but I didn't get the wrist pin positioned quite right when Loctiting in place, so I had to do some strategic filing to bring the end of the wrist pin back down to where it would not scrape the cylinder. The engine runs nicely, so it did work, but clearly I need to refine my technique ...


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## a41capt (Mar 28, 2020)

One bit about which I am quite uncertain - my decision on how to keep the wrist-pin from floating out and scoring the cylinder. As you can see in the plans, I chamfered the outside of the wrist-pin holes. For the final installation of the wrist pin, I cleaned it all well and used a bit of red Loctite as the first line of defense. Then after that was set, I came back and lightly staked the ends of the wrist pin so that they protrude a bit into the chamfer. Had I done a better job, that would have been the end of it ... but I didn't get the wrist pin positioned quite right when Loctiting in place, so I had to do some strategic filing to bring the end of the wrist pin back down to where it would not scrape the cylinder. The engine runs nicely, so it did work, but clearly I need to refine my technique ...
[/QUOTE]

On my Henry Ford Kitchen Sink Engine, I drilled and tapped two holes at #4-40 in the piston above the wrist pin, and then marked and lightly filed flats in the wrist pin corresponding to the tapped holes.  I hold the wrist pin in place with two #4-40 allen head set screws to keep it from walking.

John W


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## awake (Mar 28, 2020)

John, that's actually what the Webster plans call for. I don't have a 4-40 tap, and didn't think there was enough room to use 6-32, so I tried this. Dunno ... the engine is running fine thus far; I ran a tank of gas through it today, playing with various adjustments to see what ignition timing / mixture / throttle settings it liked best. So far so good ... but next time I'm either going with the set screws, or brass rivets on the ends of the wrist pin.


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## awake (Mar 28, 2020)

Part 7 of the Steel Webster build log - the cylinder:





I lucked out in having a scrap piece of DOM tubing with an .875" ID; the exterior was a little rusty, but the interior was pristine. Using this meant having to make the complete cylinder in two parts, with the fins cut from a separate piece of aluminum. That mostly went well ... mostly.

First step was to face it, cut it just over the desired length, and face the other side to the target length of 2.5":





At first I was thinking I would turn this short length "between centers," and I experimented a bit with using the live center in the tailstock as I began to rough it out:





But I just wasn't confident that I could guarantee that the tube would set on the centers perfectly concentrically, since I didn't have a way to cut a center seat that was perfectly concentric to the bore. Well ... I could have swapped in the 4-jaw chuck, centered on the bore, and cut a seat, but I decide to go a different route and made an arbor. I began by facing and center drilling each end of a 4.5" long piece of cold rolled steel. Then I put my "machine-in-place" dead center in the three-jaw, set the compound to cut the 60° included angle, and skimmed it so that I had a perfect dead center to work with:









I mounted the arbor blank between centers and machined it with .75" diameter ends, a little under 1" long, and the center section just over 2.5" long at just under .875" for a nice sliding fit in the nascent cylinder; here is the arbor in process:





I installed the arbor in the cylinder with Loctite; after it set up overnight, I could return to machining the OD of the cylinder. The arbor worked great, letting me flip end for end as needed to machine the details:






Continued below ...


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## awake (Mar 28, 2020)

Part 7 of the build log, the cylinder, continued:

Once the cylinder (or should that be, the cylinder liner??) was finished, I began work on the cylinder fins. I had a small bit of 1.75" diameter aluminum on hand, so I cut it just over length, faced it, flipped it, and faced it to final length. Then I drilled out the center - I don't recall for sure, but probably drilled it using a .75" drill:





Next were the boring operations, first boring to 1.073" diameter for a shrink fit on the 1.075" diameter cylinder:





Then I bored out the 1.25" diameter x .125" deep recess into which the "lip" of the cylinder liner sits:





I heated up the aluminum using my heat gun and dropped it over the cylinder, which was still mounted on the arbor. Once cooled, they were nicely locked together:





I re-mounted and re-skimmed my "machine-in-place" dead center so that it was perfectly true, then mounted the arbor with the cylinder liner and the aluminum part back between centers:





I turned the OD of the aluminum just enough to clean it up ... well, to clean most of it up; as I already knew, this chunk of aluminum had had a hard life, and there were several dings in it that I chose to leave, wanting to maximize the diameter of the fins:





Continued one more time below ...


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## awake (Mar 28, 2020)

Part 7 of the build log, the cylinder, continued:

Once the OD was (mostly) cleaned up, I set up my dial indicator and began to cut the space between the fins:





 If I do say so myself, the end result was perfect:





... or not. Take a closer look at the picture above, and see if you can spot my mistake. The end in the foreground is the part that goes into the head; the .25" thick part of the aluminum that is supposed to receive the screws is supposed to be down on this end, not the other end. Agh! I decided to see if it would work anyway, so I cut another slot to make two fins out of what was the .25" thick part - one of them thinner than all the others:





I heated up the cylinder+fins with my heat gun until the Loctite bond was loosened, pressed out the arbor, and cleaned up the bore. Then I set the cylinder assembly into the milling vise, found the center, and located for the 4 holes that hold the cylinder to the head. I drilled and tapped each through the first two fins; in the plans I show 8-32 screws, but in fact I wound up drilling and tapping for 6-32:









And voila! One not-so-perfect cylinder, complete with an extra fin. The fact that the 6-32 screws that hold the cylinder to the head are going through two thin fins means that I have to be very careful in tightening it up, but it has worked thus far!


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## David Willoughby (Mar 29, 2020)

An excellent job with precise specs. Thanks for the post


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## kvom (Mar 29, 2020)

"94.000 thou" isn't proper dimensioning.  .094 is.


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## awake (Mar 29, 2020)

kvom said:


> "94.000 thou" isn't proper dimensioning.  .094 is.



You are so right. This is a bug in the software I am using that drove me crazy. Later on I discovered how to over-ride it, and I tried to go back and do so on earlier sheets, but obviously missed some!


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## awake (Apr 2, 2020)

Part 8 of the build log, the head - only a few pictures of this one:





After cutting, squaring up, and bringing the blank to size (the latter two operations on my trusty shaper, though the mill would have worked fine as well), I used the DRO on the mill to locate the four cylinder mounting holes and the central hole for the spark plug, and drilled these with the appropriate bits - no pictures of any of that, I'm afraid.

Next I transferred the blank to the 4-jaw chuck on the lathe, using parallels to stand it off (I need to make one of those spider jigs ...), and using a DTI to center precisely on the center spark-plug hole:





I bored out the .502" deep recess for a nice firm slip-fit with the cylinder:






After flipping it over, re-centering on the spark plug hole, and boring out the shallow recess for the spark plug, I moved over to the mill to complete the drilling and tapping of the various .188", 6-32, 10-24, and 1/4-20 holes as shown on the plans. Of course, no home-machinist project would be complete without a broken tap, right?





I got lucky with this one and was able to wiggle it out. I then went on and milled the .2" deep inset in the side, where it mounts to the frame.

I don't have pictures of it, but there was one more important step with this head. After all the milling was complete, I took the side where the valve cage connects (the side showing in the picture above) and worked it smooth and flat against some wet/dry paper on a piece of glass. I did the same with the valve cage after screwing the three pieces together. This gave me a tight seal with good compression without having to use any gasket.

In case the question arises - why do the boring on the lathe, when it is already centered up on the mill? The reason is that I don't have a boring head with a facing function, so it was easier to get nice flat faces on each side using the lathe.


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## awake (Apr 2, 2020)

Part 9 of the build log, the valve block:





For the valve block, I tweaked the design to give me a bit more room to use slightly larger fasteners than called for in Joe's original plans; I also wanted to have each of the three parts of the valve block be the same thickness. The reason for that was so that I could machine all three parts from one blank, which I prepared on the mill:





If you have been following along this build log, I know you were expecting me to say that I prepared the blank on the shaper. Why the mill, this time? Because, while I love the satin finish that comes off the shaper, for this part I really needed the shiny-smooth finish that I get from the carbide face mill.

You'll notice that the blank is large enough to accommodate all three pieces, all of which are almost, but not quite, the same - one, the center piece, has a smaller central hole, and one, the bottom piece, is drilled and tapped for 6-32 threads while the others are drilled for 6-32 through holes:





What may not be obvious in the picture above is that, in the process of drilling and tapping the 6-32 holes in what will become the bottom piece, I managed to break, not one, but TWO 6-32 taps:





Along with the broken tap in the head, this now makes 3 broken 6-32 taps. Clearly I am doing something wrong ... or else, 6-32 is a size invented by the devil to make life miserable for home machinists. These two broken taps had to be milled out with a 2mm carbide end mill - no pictures of that, but it was successful, and was able to save the part.

Once all the holes were drilled, but before cutting the three pieces apart, I began working on the faces to get them smooth and flat. This began with a cheap diamond sharpening block:




Followed by increasingly fine grits of wet-dry paper on a smooth glass surface:






Frustratingly, the camera makes the final results look far less smooth than they actually were. Here are the three parts after cutting them apart; in the picture it looks like they are all scratched up, but in reality they are smooth enough that, when screwed together, they sealed to provide good compression with no gasket needed:




The next step was to fasten the blocks together and mill the edges to size:





Then I drilled the holes that go in the side of the middle block:





The remaining steps had to wait until the valve guides were made, which will be part 10 of the build log.


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## Longboy (Apr 3, 2020)

In aluminum, I have broken 3 flute 6-32 taps.  Ended my misery in a hurry using 2 flute since. Maybe do the same in steel!


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## a41capt (Apr 3, 2020)

Thanks for the detailed build Awake.  The Webster will probably be my next engine as soon as I finish my Kitchen Sink Engine.

I wish I’d have picked the Webster for my first IC engine instead of the Henry Ford replica. That leaky low compression S.O.B. Is causing me to pull out what remains of my hair at a frightening pace!

I read every one of your posts with great interest knowing that your work-arounds and improvements will make my project easier, and your pics are great!

John W


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## mnay (Apr 3, 2020)

Great job.  Excellent build log.  I have a couple of engines under my belt, but I still have the Webster on my bucket list!!!
Mike


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## awake (Apr 3, 2020)

Thank you all!

All of the broken taps have been 2-flute spiral-point taps, which is actually part of what got me into trouble. I am used to using this style of type in larger sizes, where one can power-tap quite easily and safely. Not so much in 6-32 size, as it turns out. 

The other tap I broke during this project was an 8-32, one of the two through the flywheel to secure it to the keyed shaft. The problem there was a matter of awkward setup - the configuration of the flywheel called for the set screws to be put in at an angle, matching the "draft" angle of the flywheel hub - and in fact, there would not have been any way to get into the spot without having that angle to help clear the rim. But I did not have a very secure setup for holding the flywheel at the proper angle, and the results were predictable. That one was a particular bear to remove, especially because of the limited clearance. At least one 2mm carbide endmill was sacrificed to the machining gods in the process ...


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## a41capt (Apr 10, 2020)

Awake, do you have a link to the video of your Steel Webster running?

John W


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## awake (Apr 10, 2020)

Sure! Here are the two that I've put up on YouTube - the first was the night that I first got it running, with a rats nest of wires and the gas tank just propped to the side:



The second was after I completed the "ignition box" that contains the 12v battery (of the type used in uninterruptible power supplies) and the coil, along with the plywood mount for the engine with the connectors to connect to the ignition box:


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## awake (Apr 10, 2020)

Part 10 of the build log includes the valves, valve guides, and springs:







I began by working on the guides. First I machined the inside of the guides, including the valve seat (though that doesn't show up well in this picture:





I thought I had a great idea for how I would machine the outside of the guides to be perfectly concentric with the insides - I machined a jig with a body over which the valve guide fit snugly, including a .094" stem that ended in a 2mm thread:





 This let me set the valve guide in place and secure it with a 2mm nut:






Well, it seemed like a good idea at the time ... but in order to hold the valve guide securely, I had to screw down the nut rather firmly ... and the tiny 2mm thread broke off.  So I machined the .094" stem away, leaving just the .219" section. Note that all this time I had not removed the jig from the lathe, so it was still perfectly true. I loctited one of the guides in place, let it set, and then machined the outside profile:





 Still without removing the jig, I used my heat gun to break the bond and remove the finished guide:





Then I loctited the other guide in place and repeated the procedure. I wound up with two guides with which I was pretty happy. Here is one of the two, along with the part of the valve block into which it was then loctited in place:





Part 10 continues below ...


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## awake (Apr 10, 2020)

Part 10 of the build log, the valves/guides/springs, continued:

Next I made the valves. I elected to do this with the stem secured by a live center in the tail stock, with the compound adjusted so that I could cut the 45° head of the valve in the same setup as turning the stem:





To let me cut right up to the live center but also be able to cut the head of the valve, I needed to be able to cut both LH and RH, so I used a round-nosed cutting tool:





 Of course, I left the stem extra-long and made use of emery paper to get the stems to exact size (well, within .0002" or so), testing using a valve guide. (I kept the valve guide and the valve as a matched set, to allow for any variations between the valve guides.)

I chose not to try to part the valves off, but rather cut them off using the bandsaw, then trimmed the bottoms of the valves in my 7x14 lathe:





 Finally I had two valves that fit smoothly in two valve guides ...





... or not. I did not have a very good .040" drill bit to drill the cross hole that I originally planned to hold the spring and its keeper in place, and I mucked up one of the valves. Sigh ... I remade the valves, this time according to the revised plans shown in the previous post.

The valve spring keeper was next, and it began by machining a bit of CRS to the outside diameter and drilling the .094" hole through the center:





I machined the shallow cavity that holds the c-clip:





Using a ground HSS parting tool, I machined the .188" diameter section over which the spring fits:





I used the same parting tool to part it off, and made the second keeper in the same way. Voila! Two valve spring keepers:





Of course, I should have made three ... because down the road, when I was getting ready for the final assembly, I lost one, and had to make another. 

Part 10 of the build log concludes in the next post ...


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## awake (Apr 10, 2020)

Part 10 of the build log, the valves/guides/springs, final continuation:

Since I redesigned the valves to use c-clips, I had to make the c-clips. The first bit was easy enough - machine the OD, drill a 2mm (0.079") hole, and part off to the desired thickness:





That, of course, gave me an "O" rather than a "C"; the hard part was how to cut out the opening. I set a piece of scrap in the vise on the mill and milled a slot just wide enough to hold the O's that I had parted off:





I used medium strength (blue) loctite to secure the blanks in the slot; in retrospect, I should have used superglue or red loctite. However, this time I had made an extra blank just in case:





I used a 2mm endmill, taking very light cuts, to cut out the openings:





Good thing I made the extra blank - as I noted above, the blue loctite was not quite adequate, and one of the 3 blanks shifted loose, preventing me from completing the machining on it. Fortunately, the others stayed in place, allowing me to complete the 2 c-clips I needed:





The last bit in this part of the build was to make the valve springs. This was the first time I have attempted to make springs, and I have to say that I was pleased by how it went.

Before making springs, I had to make two accessories. First I made a "gripper" - not a very elegant piece, and I don't have any pictures or design to show - just a couple of pieces of scrap steel with a small slot between, such that I could clamp down using the tool holder screws to get the desired grip on the wire. Second, I made an arbor of the appropriate size - or at least, what I hoped was the appropriate size; I had trouble finding a table in Machinery's Handbook that quite gave me what I needed, so I had to extrapolate. (It seemed to work.) I drilled a .040" cross hole though it as a way to hold  the start of the music wire.

Finally I could make the springs. I calculated and set the thread pitch that would give me the desired number of turns over the length called for in the plans, put the wire through the gripper and through the hole in the arbor, and adjusted the grip tension:





On the slowest speed of my lathe (30 rpm), I let it build a few starter turns, then engaged the half nuts to create the body of the spring, then disengaged and let it make a couple of finishing turns:





After snipping the wire, it sprang open a bit, just as the book said it would:





I trimmed down the start and finish turns, and tried it out - and it worked beautifully. My first spring (and the second that followed it) were a success!

This concludes part 10 of the build log. Next up will be a relatively simple part, the rocker arm.


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## L98fiero (Apr 11, 2020)

awake said:


> Thank you all!
> 
> All of the broken taps have been 2-flute spiral-point taps, which is actually part of what got me into trouble. I am used to using this style of type in larger sizes, where one can power-tap quite easily and safely. Not so much in 6-32 size, as it turns out.


One thing to remember as well, if you're breaking taps, is that if you are going 2 diameters deep in mild steel and about three in aluminum, you can use a 60% thread depth, going to 75 - 77% which is where most of the thread charts go, increases the torque on the tap exponentially.


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## awake (Apr 12, 2020)

Thanks L98 - I do know that ... but rarely remember to consider it when grabbing a drill bit.


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## awake (Apr 12, 2020)

Part 11 of the build log, the rocker arm:





Only took a few pictures of this part - it was relatively quick and simple. I cut a blank out, milled it to size, and started drilling the holes, first for the the M3 screw that holds the follower bearing in place and for the .219" hole  for the bronze bushings (shown as .250" on the plan - I changed it when I built it, but haven't yet updated the plans):





 I turned the piece 90° so that I could drill a hole to locate the end of the slot for the bearing, and then milled the slot until it fit the bearing:













Finally I milled to size the end where the tappet adjustment screw goes:





And that's all the pictures I have of this part. Not shown was tapping for the M3 screw, drilling and tapping for the 10-32 tappet adjustment screw, drilling the oiling hole, and filing to finish the slot so that the bearing could move freely. I also failed to take any pictures of making the bushings which get loctited into the rocker arm, or of making the pin which gets loctited into the frame and on which the rocker arm bushings ride. Those bits were probably more exciting than the part I've shown above ... oh, well.


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## awake (Apr 22, 2020)

Part 12 of the build log, the gears:





In my design, the exhaust cam is part of the larger gear, and the smaller gear has a hub section on each side, to allow for spacing of the flywheel and a place for the set screw. Both gears begin with slightly oversize blanks, with the critical dimensions being the 13mm (.512") ID of the larger gear (sized for a slight press fit of a pair of F686 bearings on which this gear will ride) and the 10mm (.394") ID of the smaller gear (for a close sliding fit on the crank shaft):











Along with the blanks, I made arbors to run between centers, one for each blank:










The blanks were loctited to the arbors, and once set, I machined the OD of each blank; shown here is the machining of the smaller gear:










Continued below ...


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## awake (Apr 22, 2020)

Continuation of part 12 of the build log, the gears:

Since the gear blanks are mounted on arbors, it is easy to transfer them over to the dividing head on the mill to cut the teeth. Initially I cut the gears using my module 1 "semi-hob":





This is a home-made cutter, but unlike a true hob, the teeth are just horizontal, rather than being a continuous helix. To get the best results with this sort of cutter requires making multiple passes per tooth, with each pass slightly rotated and offset. In other words, it can be tedious ... and even more tedious when someone (who will not be identified) messes up the math and winds up having to cut the smaller gear twice.

When I finished cutting the teeth on larger gear, I also switched over to an endmill and began cutting the cam in stages:





 After a bit of smoothing with a file and emery paper, I had a very nice cam gear with cam (attachment 3):





All that remained was to remove each of the blanks from the arbors using my trusty heat gun:





Naturally, I immediately mounted the gears on the crankshaft and on the pin in the frame on which the cam gear rides ... at which point I discovered that, when one _designs_ for a 24 and 48 tooth gear set, and then winds up _cutting_ a 20 and 40 tooth gear set, for some reason the gears do not mesh. (I failed to take a picture ... it was the most deflated feeling to see these beautiful gears sitting with a good quarter inch of air in between.)

So, I had to make new blanks, and cut both gears again ... and at that point I decided to break down and buy a couple of M1 gear cutters. They were inexpensive imports, but seemed to do an adequate job:





With the CORRECT gears cut, I still needed to put the key way in the smaller gear, which I did with my trusty 7" shaper:









I also needed to drill and tap for the set screw that bears on the key. To position it correctly, I used a long key in the keyway to "hang" it over the jaws of the vice, then tightened up the vice and removed the key. Then I drilled and and tapped the set screw:





This concludes the building of the gears; next up will be the ignition.


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## a41capt (Apr 22, 2020)

I like the idea of cutting the key way with the cutter inverted.  No need to tie the clapper down!

Did you do this one with a single width cut also?

John W


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## stragenmitsuko (Apr 23, 2020)

Can I sidetrack here for a moment ? 
I've always liked the idea of one cutter cuts all for a given module . 
Altough tempted , I never tried it myself .

If I understand correctly , the cutter is basicly a rack to wich each gear , regardless of the nr of teeth must mesh . 
The only parameter needed to make the cutter is the pressure angle . 
Sofar I perfectly understand .

But then ,  after the first pass wich cuts each tooth to its maximum depth , the Z axis must be lowered or raised a certain amount , and the gear neads to be indexed again with 1/2 or even 1/4 of a division added or substracted . 
That iteration produces a perfcect involute in theory .

Only I'v never been able to figure how to do it . 

How do you calculate the Z amount . 
Haven't got a clue really . 

For the indexing . 
I suppose a 20T gear could be set up as an 80T , where you would use 1 , 5 , 9 , 13  for the primary pass 
2 , 6 , 10 and 4,8,12,16 for the +/-1/4 and 3 ,7, 11 , 15 for the 0.5 pass and so on .  
Even with a computerized dividing head that would take considerable time and concentration . 

Does that make any sence


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## awake (Apr 23, 2020)

John, I thought it would be a good idea to cut inverted for just that reason ... but I felt like it was a better experience cutting the other way, with the clapper free to move. After cutting a few key ways on the shaper, I am wondering exactly what the logic is for immobilizing the clapper. Of course, this probably means I am doing it all wrong!

No, the cutter is only .085" wide, so once I got to depth I had to shave off the sides. This did help in terms of getting the key way lined up correctly, since despite my best measurements with the mark-one eyeball gauge, I was a bit off to one side at first.  But that just meant I mostly shaved the other side, and voila! I won't presume to say it is perfect, but definitely it is a nicely functional key way.


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## awake (Apr 23, 2020)

Stragen (or Mitsuko?), that makes perfect sense. I'm attaching a .pdf of an article that I have been (slowly) working on for submission to the HSM magazine that is mostly about how I designed and used the "straight rack" cutter shown above. It illustrates (or at least, attempts to illustrate) what is going on when using a cutter like this.

I'd love to get feedback on whether it makes sense - I had to do a lot of condensing to squeeze it into an appropriate length. See if it helps, and if not, that will help me to try to make the article more clear!


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## Cogsy (Apr 24, 2020)

For the 'straight rack', I imagine it could make quite a difference in precision for something like change gears for a lathe, but for non-critical applications like cam gears for a model, the same type of cutter but only doing 1 pass at full depth produces a decent facsimile of the involute shape. It is made up of facets of course, but a few minutes of running together with oil seems to knock off the high spots and they quieten down considerably. I've never had a set fail or wear out yet, although my engines don't see huge amounts of running. I will say the straight rack method is a lot easier when you only have to do 1 revolution + 3 teeth of the blank to get a decent gear.


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## awake (Apr 24, 2020)

Cogsy, it may have been a post of yours some time back that talked about using only one pass, and I mentally marked it at the time as something I needed to consider. As always, theory is an excellent guide to experience, but ultimately, experience trumps theory!


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## stragenmitsuko (Apr 24, 2020)

The article makes a lot of sense , especially if you already understand ( more or less ) what's goin on  . 
The trick for the calculations seems to be think in degrees instead of divisions like I did .  
Then it's just basic trigonometry  . 

Indeed there are not that much passes  needed as one would inituitively think . 
The gears will wear in quite nicely and remove the  high spots themselves . 
In fact , that is how the involute profile was "invented" . It comes naturally  .
I don't know , maybe some grinding paste could be used running them in ? 

One small remark re the article , the pages where you staircased the pictures are a bit difficult to read . 
Wich text goes with what ? Maybe some outlines could improve that . 


Patrick  
Stragenmitsuko btw is just a relic from a time where everyone used a nickname .


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## Cogsy (Apr 24, 2020)

awake said:


> Cogsy, it may have been a post of yours some time back that talked about using only one pass, and I mentally marked it at the time as something I needed to consider. As always, theory is an excellent guide to experience, but ultimately, experience trumps theory!



I can't take the credit for the idea - here's the link to the page which describes the tool with the following pages covering the math, etc. to construct one (if you're interested to see how it compares with yours) LINK.


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## awake (Apr 25, 2020)

stragenmitsuko said:


> The article makes a lot of sense , especially if you already understand ( more or less ) what's goin on  .
> The trick for the calculations seems to be think in degrees instead of divisions like I did .
> Then it's just basic trigonometry  .



Thanks!



stragenmitsuko said:


> One small remark re the article , the pages where you staircased the pictures are a bit difficult to read .
> Wich text goes with what ? Maybe some outlines could improve that .



Yep, I thought the same thing when I was re-reading this. Ultimately I plan to send it in to a magazine, with text and pictures separate, and they will do the layout. (It's a three-part series, and I need to finish part 3, so it hasn't been submitted yet.) I had done this version with pictures just so that I could get a sense of the overall length.


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## awake (Apr 25, 2020)

Cogsy said:


> I can't take the credit for the idea - here's the link to the page which describes the tool with the following pages covering the math, etc. to construct one (if you're interested to see how it compares with yours) LINK.



Interesting. I actually wrote the article some years ago (haven't sent it in yet because I still need to finish the 3rd article in the 3-part series, and I just haven't had a chance to do it). I wonder if this site was already up before I wrote the article, or vice versa. In any case, there was no interaction between the site and the article, so it must be a case of great minds thinking alike ... I should say, great _and modest_ minds.


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## Cogsy (Apr 25, 2020)

I first used the helicron site around 2013 from memory, 2014 at the very latest, so it's been around for a while.


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## awake (Apr 26, 2020)

Oi. I went back and looked at the dates on the files - apparently I finished writing this article in early April, 2014 ... but the actual making of the cutter and gears went back to February 2009. I guess I need to get on the stick and finish this set of articles!!


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## awake (May 3, 2020)

Part 13 of the build log, the ignition components:






The only hard part of the ignition components is the points mount. The first step was to prepared a slightly oversized blank, including not only milling to thickness but also drilling the two .159" diameters holes that will later be tapped 10-32, along with a counter-sunk hole in the middle of the axis of rotation just large enough to take a drywall screw. I also drilled the .219" hole that accepts a protrusion from the points, and a start and stop hole for the curved slot. 

With the blank prepared, it is time to cut all the curves in this piece. The curved top and the curved slot allow the mount to be adjusted easily while still staying securely attached to the frame. The key to making these curves in a non-CNC shop is, of course, a rotary table. After centering the rotary table under the spindle and setting the DRO accordingly, I fastened a piece of scrap plywood to the table with four bolt. Then I used the DRO to determine the placement for drilling screw holes to match the center hole and the .159" holes that I had prepared in the blank: 





I then fastened the blank to the plywood with a drywall screw in the center and two pan-head screws that just fit in the .159" holes, thus both securing the blank for cutting and locating it correctly on the RT:






Now it was simply a matter of setting the proper radius and rotating the RT to the proper angles to cut the curved slot, the curved bottom, the straight part of the right side, and the angled part of the right side:

















Continued below ...


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## awake (May 3, 2020)

Continuing part 13 of the build log, the ignition components:

I continued cutting around the periphery of the points mount, cutting the rounded top and down the left side:





Then I positioned the cutter and began to cut out the middle hole:





 When that was finished, the part was complete:





It fit perfectly on the bearing boss around which it rotates to set the timing:









The only other pictures I took as I made the rest of the components were a couple as I made the combination ignition cam / starter hub:









Not shown are the making of the small retainer (which helps to hold the points mount against the frame while allowing it to rotate to adjust the timing), nor the drilling & tapping of the hole to mount the retainer and the hole to mount the screw that clamps the points in the selected timing position - nothing complicated about any of these.

Next up is the carburetor!


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## awake (May 3, 2020)

Part 14 of the build log, the carburetor:





As shown on the plans, this is a slightly modified version of Chuck Fellows' carburetor. When I went looking for his carb on the internet, I found that he had put out several variations, some using a .125" throat and some a .156" throat. Not knowing which to choose, I decided to hit a joyous fortuneteller (aka, strike a happy medium) and designed this with a .140" throat.

The hardest part of the build, by far, was making the needle assembly. It would have made it a bit easier to use a length of 8-32 screw, and probably a lot easier if I had used brass ... but this is the Steel Webster, so I made it out of a piece of steel hex stock. Three times. Or was it four? Let's just say it took more than one try! Particularly difficult was drilling those itty-bitty holes, but I got it done in the end:





Unfortunately, after I finally succeeded in successfully drilling it, I then discovered that one _must_ support a long thin stem when trying to single-point the 8-32 threads. Failing to do that meant scrapping yet another part and having to do the drilling again:





Fortunately, the rest of the carb was pretty easy and straightforward. I prepared a rectangular blank for the body and center drilled each end to locate the throat; then I mounted it between centers:





Then I turned the round sections on each side:









Making the needle control screw was easier than I had thought it might be, except that I had my welder settings wrong when I welded the needle in place. (Yes, even there I went with welding. Someday I will attempt silver brazing!) Here it is in the turning phase:






Voila! A completed carburetor. The plans showed a 10-24 SHCS for the throttle, but I wound up threading 10-32 instead, and I'm glad I did - no, I can't "blip" the engine with this throttle, but I can control its speed very easily and smoothly. I also went ahead and turned a thumbscrew with 10-32 threads, and added a spring to both the throttle and the needle adjustment to hold them where they are set.





Next up is the gas tank ...


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## awake (May 26, 2020)

Part 15 of the build log is the gas tank:










Let me say from the beginning: don't do it this way. I thought it was a simple and elegant design, but in fact, it was a royal pain. Perhaps a clue should have been that it took 2 sheets just to draw it up. It didn't turn out very well ... but it does work, so I suppose it was not all bad.

The tank began with a scrap piece of steel pipe; I turned the outside to 1" OD and bored the inside to .875":










There was also a bit of additional boring, called out in the first drawing (sheet 15) - a section bored to .886" to create a lip to hold a flange, a threading relief, and the outermost .157" length bored to .897". This last part is then threaded to .926" x 32 tpi:





I mentioned the lip that would support a flange - this flange is depicted on the second drawing (sheet 16). It was intended to be a press fit into the .886 section that was bored in the pipe, with a face groove that would hold a viton o-ring - the same size o-ring that I used for the cylinder "ring," since I got a pack of 10:










I also machined the threads for the screw-in end cap:





Not shown - I then machined the bore and chamfers in this end cap, parted it off, and machine in the two holes in the outer face used to screw the end cap into place.

Part 15 continues below ...


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## awake (May 26, 2020)

Part 15 of the build log, the gas tank, continued:

Next I machined the inlet and outlet pieces, including machining a curve in the face so that it would fit snugly against the OD of the pipe:









Not shown was machining of the fixed end cap - just a simple piece to fit into the non-threaded end of the pipe. But you can see the cap, along with all of the other pieces machined to this point, in the picture below:





The next step was TIG-welding the fixed end cap in place. With a little clean up, that came out pretty well:





By contrast, TIG-welding the outlet pipe in place was ... well, it was successful. It doesn't leak. I was able to thread it for the outlet pipe. It also looks like crap:





I was hoping I would do better with the inlet pipe. I used my "third hand" to hold it in place on the pipe:





I fired up the TIG welder again, and ... once again, it doesn't leak. Need I say more?? Clearly I need more practice on TIG welding small parts:





I failed to take pictures of machining the outlet pipe, or of the thin circle of acrylic that serves as the window - no particular problems with either of those. I did get a picture of part of the machining of the inlet cap - again, no problems there:





So, how did it all work out in the end? Well, first off, the press fit of the flange didn't achieve a seal, so I had to back-fill it with some sealant. Then I had to do it over when I realized that the first sealant I used was not rated for exposure to gas (and proved it by swelling up and detaching).

But, in the end, despite the sloppy welding and other challenges, it came out half-way decent, and achieved my goal of allowing me to see the level of fuel in the tank:









This build log is just about done - just the gas tank mount and a few odds and ends left!


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## Cogsy (May 26, 2020)

Interesting - I wasn't aware acrylic could stand up to gasoline. I machined a fairly complex part out of extruded acrylic rod a few months ago and polished it up so it was nice and optically clear, then hit it with a spray of isopropyl alcohol to remove any oil residue before I used it. Within the space of a few seconds it had turned into what looked like a piece of shattered safety glass in the shape of my part. As soon as I picked it up it fell into pieces. So now I'm very careful with what solvents I get near my acrylic!


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## awake (May 27, 2020)

According to this link, Cast vs Extruded Acrylic Tubing and Rod (which despite the title that shows up, should take you to a chart on chemical resistance), acrylic has good resistance at 68°F/20°C, but only fair at 122°F/50°C - so not the best ever, but good enough. With isopropyl alchohol, it drops to fair and not recommended, respectively.


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## Rugbyears (Jul 7, 2020)

@awake - what a wonderful thread.


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## awake (Jul 8, 2020)

Thanks!


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