My PM Steam Engine #3 Build, so far- NOW COMPLETE

ErichKeane

Making scrap at ludicrous speed.
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I have been crapping up EricB's thread with a bit of updates on my #3 (https://www.hobby-machinist.com/threads/the-journey-begins-pm-research-5.83114/) so I figured I'd stop that and put a place for me to post mine! I have been pretty terrible about pictures/videos, but I have a couple that I've attached.

I started with the base. I have a photo of one of my setups, the one where I I milled the bottom. I was quite impressed with this part of the casting! IMG_20200322_155359.jpg

I ended up milling EVERYTHING on the base in 1 go. I DID make a few observations: I milled the cylinder mounting face with the casting 'right side up', but instead of 'spot facing' the driveshaft mounts milled them at the same time so that I would have additional square faces. Additionally, it saved me a setup (having to flip the casting solely to spot-face!).

Unfortunately, I had two problems: First, this was before I was photocopying the plans and was going off of a photo on my phone. I misread the dimension on the oil holes, and drilled them 1/8 instead of 1/16. This ends up being a touch fortuitous as my eagle 66 oiler fits right in the holes :)

My second problem came when I went to mill the crankshaft holes. They are indexed a distance off the cylinder mounting face, however when I measured that distance out, my hole would have been precariously near the edge of the casting! I ended up going back and re-facing the cylinder mounting face and taking off an additional 75 thou. I had initially milled JUST enough to clean up the casting, which was apparently way too little.

Next, I attacked the crankshaft. This ends up being just a facing operation on two sides of the rod. The dimensions specify this to 3.0" (which the tolerance callout doesn't have a spec for!). I was able to machine it to about 3 thou of that tolerance, just to later find out that it is way too long and I'll likely re-part it down another 3/4" or so.

After that, I started a couple of parts at the same time, since I found my drill chuck wouldn't hold the smaller drill bits and needed to wait for a new one. I had a handful of problems so far due to having tooling that is too 'large' for the project (including a 16" lathe and a nearly-full-size knee mill). I'll still explain my feelings on each part as I went through though:

First, the flywheel. I was able to trivially face each side and drill the center hole on the lathe. The grub-screw mounting was a touch challenging because I didn't have a center long enough, yet small enough to do so. Instead, I just went with a long end-mill and faced it flat, then prayed the drill bit would just find center, and it seemed to work out fine!

However, facing the outside dimension was a disappointing endeavor. I mounted it on the driveshaft with the grub screw and mounted that in my collet chuck. I was able to get it mostly faced (taking REALLY fine cuts, about 4 thou-diameter at a time). Unfortunately, even at 500+ rpm (my max speed), the HSS finishing bit I ground for this (with a slight radius) ended up catching and basically 'threading' the driveshaft with the grub screw as a cutter! It cleaned it up with files and Emory paper, but remaking it (or perhaps trying again after loctiting it to the driveshaft!) might be in order.

Next the eccentric hub: This actually was a pretty easy task. I used my 4 jaw to do the offset, and a custom ground 'parting' type tool to cut everything. I managed to get every dimension on the part sub-thou out of shear luck, save 1. The 'smaller' diameter is actually significantly smaller than the 1/2" dimension. I found that in order to get it to actually be 'round' (meaning 'cut' all the way around), I needed to go about 40 thou smaller in diameter. Since that dimension doesn't particularly matter, and a 0.100" wall on the inner face is sufficient, I decided to go on and live with the smaller size.

The eccentric 'ring' was easy, I popped it into my 6 jaw, then just did some small boring. The set screw on the mill was no issue either.

Next, I did the cross-head caps. These took about 5 minutes each in the mill. I was incredibly impressed with the consistency of the castings! I did a 'back' facing operation on each, then took a bit of meat off of each to hit the dimensioned 'height'. Measuring on the castings is difficult, and the size isn't particularly important, but I'm roughly within the 1/64" tolerance on the height. They are at least consistent with eachother, which I think is what counts. Drilliing was simple with the DRO, and I was impressed that the 1.500" dimension ended up hitting just about dead center of each boss! .750" actually hit dead center of the middle boss as well, these castings/dimensions were right on.

Next, I did the crank casting. I did a simple facing operation on the lathe, followed by drilling/reaming the crankshaft hole. Then I moved to the mill to drill the offset. I was holding it by the rear 'boss' and was afraid that the 4 jaws wouldn't be holding it right otherwise (plus, setting it up that way would cause me to drill into my jaw!). Another grub-screw, and we were done with that!

The connecting rod itself was pretty easy, though the casting had a bit of an 'offset' on it that took a while to file reasonably. I ended up having to go back later and file off even more to make it clear the cross-head cap. Additionally, facing the part that goes into the cross-head cap was a bit of an adventure, since I didn't have it well supported. If I were to go back in time, I would have done a better job at that. Drilling/reaming was easy though!

I did the cross-head-cap entirely in the mill. Annoyingly, it was almost exactly at dimension in width and height already (I'd been hoping to 'file fit' it a bit), but some time on some 1200 grit sandpaper cleaned up the faces and got it sliding perfectly in the base. I cut it within 2 thou on every dimension. However, I was a touch disappointed by the fit of the connecting rod, there is sufficient 'slide' side to side due to the room in the dimension. If I were to do it again, I would have not widened it nearly as much. It is a 1/8" connecting rod in a 5/32" width slot. I'm actually oversized on the connecting rod, and undersized on the cross-head-cap, and still have a decent amount of clearance on both sides.

Last, I did the 'crank bearing', which goes between the crank and the connecting rod. The 5/8" CRS that they gave to work with was too short after cutting the eccentric to hold in my collet chuck or chucks (I tried, it popped out a few times :/) so I used some mystery steel that I had around. I suspect it was 1040, but my dimensions went just right! I filed it almost flush to the connecting rod itself, just enough that the connecting rod can spin, but still making sure it spun freely.

Then, I assembled what I have! I still didn't do the standoffs for the cross-head caps, so those aren't in place and forgot the washer between the connecting rod and the bolt, but was able to 'hand run' what I have so far:

IMG_20200331_170002.jpgIMG_20200331_170006.jpg
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I'm using a pretty heavy oil (Vactra #2) since that is what I have. It moves smoothly, albeit stops quickly (I think because of the oil). I might try some mineral oil when I run it for real. Also, pardon the mess of 'blue' on the base :) I'll have to clean that before painting.

My next step is the standoffs so that I can have it assembled up to that point. After that, I believe I have to start the cylinder casting itself, which I've been putting off. It seems like the most intense and challenging part so I'm not particularly looking forward to it! However, everything else seems to be sized based on that. There's a couple of parts I could probably do (the eccentric rod), but I don't have my die-holders yet :)
 
Alright, a little more work today.

First, I did the slide-spacers (4x). I ended up NOT using the material from the kit and just used some 1/2" brass I had around, which was probably a good choice since I ended up messing up about a dozen of them before getting 4 that worked. My first attempt I tried to do the OD and ID for all of them, then part off, but my parting blade was big enough that it was just snapping the brass off. I then made a 2nd attempt but my parting blade (despite being cut with the leading edge on the right) was leaving a flange. I figured I'd be smart and use the mill to make them all the same height. This WORKED, but I took too much off! It locked up the whole engine when I put them on.

FINALLY, I tried again, left it a little over dimension (I think my spot facing is actually 2-3 thou deep instead of flush) and it works! The crosshead has no up/down movement, but slides perfectly:

IMG_20200401_170645.jpg

All in all, what I thought was going to be the easiest part was in fact the hardest!

Then, I decided to bite the bullet and just start on the part that really scares me, the cylinder. This is the casting that EVERYTHING else seems to depend on! First, I faced the 'outboard head' side, then flipped it in the mill and did the inboard head side. The material was oversized by 1/8", so taking a touch more than 60 thou per side worked about right. I used a square on the casting line to get the orientation right. After that, I used coax-indicator to find the center of the outer 'ring', the set up the boring head to bore the cylinder. I ended up being right at .500 on my calipers, and 4 tenths under on my micrometers, so I decided that was good enough. I can cut the piston a little small if necessary :)

I then used my DRO to cut the bolt-circle, then used it to offset the valve seat. That was drilled, counter-drilled, and reamed:

IMG_20200401_170641.jpg

A little time on some sandpaper/glass cleaned up the faces, and this fixturing seems complete!
IMG_20200401_171504.jpg

Next time in the shop I need to cut the intake, the valve passageways, and 1 more bolt circle. I'll be quite relieved when this part is complete, but I probably have another day or two of shop time before thats the case. Fortunately, this is the last 'non replaceable' casting (meaning I can't just turn a replacement out of raw stock), so getting through this puts me on the home stretch!
 

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Alright, quite a bit more work today! First, I finished the cylinder! Most of it was pretty easy (flipped over for the bolt circle, drilling the intake port and drilling the straight shots), but the 20 degree ports were tough! I didn't end up having a 5/32" end mill to counter-bore them, so I used 3/16", hopefully I don't regret that.

I did both of the heads in the lathe, which went pretty easily, then moved to the mill for the bolt circles. The DRO Bolt Circle tool is becoming my new favorite :) The fit on them was just right! I DID mess up the inboard one slightly, I didn't pay attention to the plans initially and ended up needing to do the face against the base as a second operation. The result was a VERY small hold with my 6 jaw! otherwise, they went easily!

IMG_20200402_172254.jpgIMG_20200402_172258.jpg

Then, one I'm particularly proud of, the piston! The piston has some .050" features, so I had to grind myself a HSS bit to do so! It took about 1/2" to do so! I just used my tool grinder and didn't think about the surface grinder for it, but getting a 3/8" bit (my smallest!) cut down to 50 thou was time consuming!

It also looks super silly in my CA tool holder on my huge lathe. However, it went really well! The piston was 6 thou oversized (length wise) when taking it out of the lathe, but after deburring and sanding on some 500 grit paper, I got it down to 3 thou too long. Hopefully thats OK, but if not, it is easy enough to take a few thou off with sandpaper. Diameter wise, I'm RIGHT on. I ended up using the dials and got it just right for the cylinder fit! It is loose enough it goes in dead-easy, but tight enough that it doesn't seem to move on its own (without a VERY light touch pushing it). There are rings still, so hopefully that makes it work alright:IMG_20200402_172732.jpgMVIMG_20200402_172733.jpg
 

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Looking good so far!

Silly question but rather than removing the extra material from the cylinder mounting face, couldn't you have just made a slightly longer piston rod? That's probably not a critical dimension. I realize that would that have required a longer eccentric rod too.

Eric
 
Looking good so far!

Silly question but rather than removing the extra material from the cylinder mounting face, couldn't you have just made a slightly longer piston rod? That's probably not a critical dimension. I realize that would that have required a longer eccentric rod too.

Eric
Thanks! Yes, I likely could have, though I haven't built an engine before so I was a little afraid of changing dimensions too much. One thing I've discovered in this kit as I go along is how wacky/unnecessarily tight the tolerances are in some cases, and how underspecified they are in other cases. I like the kit in general, but they specified the crank-shaft as 3.0" (which isn't mentioned in the tolerances list with a single decimal), instead of 3". Also, fractional inches are supposed to be +/- 1/64th of an inch, but in a number of cases they don't matter at all.

In this case, I probably could have just made longer rods, but at the time I just wasn't confident enough in how this all worked to just make that decision.
 
Alright, did quite a bit of work today! First, I did the eccentric rod, which is just threading both sides of the rod. A few seconds with scotchbrite and a file cleaned up the stock, then it threaded nicely!

Next, the piston rod. This one went... poorly. My first attempt I was attempting to face it off to clean up the end, and folded it to about a 30 degree angle. Woops! Second try produced a working part, but I left more thread on the piston end than I thought was a good idea. I didn't realize until after I made it that the shoulder is where the piston indexes, so I didn't want the rod to stick out too far. SO, I remade it. Fortunately I had a random 1/8" brass rod in my scrap pile.

Then... the valve. I took the 1/4" piece in the kit, put it into my collet chuck, then started turning it down. I did a cut that should have got it to right at the required dimension, then tried the cylinder on it, and it was loose as a goose! SO, I flipped the stock over and tried again. This time, I was ultra careful and measured, and took spring passes, and measured, and light cuts, and more spring passes. This time, the end I was measuring got down to .498 on the spot! I put it on, STILL LOOSE!

I am losing my mind I think! Turns out, I was turning about a 15 thou taper :/ I pulled off my tool, and realized it had a nick in the cutting edge, so I needed a regrind. I put the very last piece of my brass stock in the lathe, which I had about 1/2" to hold in the collet chuck. I turned it down slowly and carefully, and got it darn near perfect. .498 +/- 2 tenths along the entire size. I was thrilled! SO, it came to cut the low spots. I put my parting tool in and just about the moment I touched the part, it popped out of the collet chuck and the tool left a nice gouge all the way down the side. I had to order more brass, so until next week!

I then did all the hex parts. The nuts went easy enough, as did the packing nut. The valve linkage was a touch of a pain because I didn't have a bottoming tap... so I made one! I brought my normal tap to the grinder and turned that little guy into a bottom tap!

I assembled everything without gaskets, rings, packing, or the valve and played with it. It turns pretty easy, though the piston might be a touch tight. It might get a bit of scotchbrite before running for real.

SO, I now need to:
1- Finish the valve.
2- Paint!
3- Cut Gaskets
4- Assemble and test!
 
alright, I lucked out! The local Ace Hardware actually had some 3/8" brass in stock, so I got to work on the valve today! Short of it: It took 3 tries. The first one I did pretty well, I used an ultra sharp non-radiused tool, and did 3 spring passes. It was within a 1/10th on each end. I cut the airways in it, and just needed to part it off, drill the other side, and drill the cross holes! I did my normal trick of a piece of cardboard under it, and it bounced off and into the ether. It apparently missed the chip tray, the floor, and anything else I could think of.

I advanced my metal and tried again. This time, I missed the diameter by a touch (it actually would have been OK I think, I later tried it in the part and it fit fine). SO, 3rd time is the charm! Its right on in just about every dimension (the 1st one was about 4 thou over tolerance in the air passageway).

So after that took a few hours, I cleaned the parts with Acetone and painted it hunter green. I still haven't got the tap/die for the intake yet so I haven't tapped that or made a hose barb, but that might be the plan for tomorrow (USPS shows it out for delivery :) ).

I still have to do the intake, cut the gaskets, and then give it a shot, but I'm getting close! Looks like it'll be just about 2-3 weeks of after-work/weekends (when not with my baby) start to finish.

Any suggestions for another steam project? Most of the PM stuff seems really similar in design to this one, and I'm not sure I want to do pay the price of a Stuart model :) I might just have to go down my normal projects list otherwise :)
 
Well, my paint solidified pretty quickly (only a 1 hour 'handling' time). I spent quite a few hours in the house assembling. I got the 3/16-40 tap and die in, so I cut that, then put everything together. My eccentric rod was WAY too long, so I ended up taking about 3/16" off with the belt sander. It took me a while to conceptualize how the valve works, so I had a couple of false thoughts (including making the cut deeper, going into where the exhaust comes out, down to ~1/16" instead of the ~1/8" that end up when you cut it by plans), but I finally got it together!

Tomorrow I'll try to create a hose barb for the intake, and see if I can get this under power! I might also see if I can set the engine in the mill while I do so to do the hr of break in. I might just get this under air power this weekend!
 
Alright, made a crappy 'hose barb' today, which was basically just some 3/8 brass rod tapped 3/16-40 for 1/4" on one end, and drilled through (left the other ~1" 'raw' 3/8" brass stock). While I was making it, I also set it up on the mill to do a quick 'break in' period, running it about 30-40 RPM just to get things running.

I found some silicon hose that I have from some car projects and zip tied it on to the 3/8". I could then push the air compressor's blower nozzle into the other end and let her rip! She starts easy as pie other than in 1 or 2 orientations (as expected) and seems to run smoothly. The surface its on (just my wood bench) makes it sound like its knocking, but that is just it bouncing on the wood. I ran it on chainsaw bar oil as someone on youtube suggested.

I DID leave out the gaskets (since the one I made I made a mess of!) and get a slgiht leak from each, so perhaps I need to give those another shot. I still haven't mounted it to anything (or cut the mounting holes!), so thats probably a project for the future. I'm quite happy with the green/brass color combo, I wasn't sure when I picked up the paint, but I thought it turned out sharp! Anyway, here's a video! Starts out ~20 PSI, go down to 'basically off (below my gauge), and up to 60 PSI:

 
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