2.5" Scale 36 Ton Class B Shay

[littleevan99]

I'll start this off with a link to my other build that this project evolved from: http://www.chaski.org/homemachinist/vie ... 5&t=106921

I've made so many changes to the design that I think it deserves its own build log. This all started late last year when I got the bug to start working on my Shay again, and to build it the way I had wanted to for a few years. I did my research and started designing, and re designing parts for the Shay using Fusion 360. The goal was to keep it simple, and use as much of John's parts as designed or slightly modified. What I've ended up with is a fairly accurate representation of a 36 Ton Class B Shay. I've made some patterns, and had parts cast at a local foundry. So far that being the bottom bearing bracket for the engine, and I'm currently working on the pattern for the larger steam dome base. Future patterns being a new sand dome base for the extended wagontop boiler, and possibly a smokestack casting. At the moment the goal is to finish the engine first. So far I've machined the bottom bearing bracket, and it turned out quite nice for my first casting. This project will be a long drawn out one, but I'm happy with how it's looking so far.

The 3d model is a work in progress, but it is far enough along to give an overview of the Shay.

Originally though I was planning on a wagontop boiler for this Shay, but moved on to the other one shown above. I still may build it this way if I change my mind down the road, but I figure this shows the evolution of the design as I've made changes to it.

Below are some pictures of work on the engine thus far.

The wood pattern I made for the bottom bearing bracket. My first try at making one, and it turned out alright. Next time I need to locate the dowels to the back half of the pattern to get a better finish on the front. I'm also planning to modify it to have cores to eliminate most of the repetitive machine work to hollow out the casting.

As machined the casting was quite oversized on the height and some other dimensions. I went back and had to increase the length of the main bearings to get them all the same size, thus increasing the overall length from the original plan. The height is due to me adding too much material with the pattern height. I was expecting it to shrink quite a bit, and it didn't as it was actually bigger than the pattern! I'm guessing that they had to wrap the pattern quite a bit to get it to release from the mold and that's something else I should probably fix.

Lastly, the I've made the bearing caps for it out of 1018 CRS.

That's it, more to follow.

[Steamer Al]

Thanks for sharing your progress! Shay's will always have a special place in my heart. My grandfather used to fire a wood burning shay for a logging company just before the second world war. Look forward to seeing the progress!

Alex

[Soot n' Cinders]

I cant wait to see where this goes! Ive toyed with the idea of making a 3 truck version. From what I can tell, Johns castings would make a nice 50-60 ton class C shay. But from what I hear, John isnt making any more castings so they're off the market till the business sells.

[Pipescs]

Having reached the point in life I can start Johns Shay, I look forward to your post. Very interested in your Progress.

[littleevan99]

Haven't made any progress building the Shay in the last year. I got busy doing some other projects for other people with a boiler for my grandpa's Ken Schroeder Shay being one of them, and getting my 2-10-2T running. I had some downtime at the end of the year after a procedure that gave me the time to tinker with the design some more and allowed me to finalize it. The current running design is a ground up rebuild of the frame as I determined that the frame I had already built is too nice to cut up and attempt to splice back together with a spacer. That led into me drawing it up as a 42T Shay, and while I like it my crankcase is a little too short to make it look right. It's even too short for the 36T model, but I played around with some dimensions and got the proportions correct. It's very close to the Lima drawings minus the engine length being a little too short. Proportionally it looks correct when compared to the real thing.

Below are some photos that show the 36T and 42T model as well as the finished engine with all the reverse linkage included.

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36T Wagontop v35 Engine.png (715.71 KiB) Viewed 78281 times

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Screenshot 2023-04-20 100327.png (615.73 KiB) Viewed 78281 times

Lastly, I 3D printed some patterns for the steam and sand domes. I haven't gotten around to finishing them up yet, but they're on my to do list.

[littleevan99]

Started working on the Shay again, and to start I farmed out the reverse links and die blocks to a friend in the hobby who will wire EDM them and get them machined up nicely for me. On the home front I started on the crosshead guides, and below are some pictures of the facing operation to get them to the correct heights. These castings had some pretty hard spots on the bottoms near the edges where they get bolted down. I originally tried flycutting them but the flycutter kept deflecting when it got to the chilled spots, so the facemill came out and worked much better. Next up is to get a center drilled into them so I can indicate and drill the mounting holes. Then, I can make a jig to turn the tops and get them bored out. My goal for 2024 is to try and have the engine running on air at some point.

[littleevan99]

Got the crosshead guides all machined up a few days ago, and they turned out great! I'd say they're on par with the crankcase casting in time to setup and machine. At some point I need to cut the reliefs for the connecting rods, and the mounting spots for the mounting bracket to the frame. Some day, but up next is the main bearings then the crank.

[Dick_Morris]

I'd make a big boring bar out of some hardened drill rod to avoid the flex from the long stick out.

My understanding is that there isn't a big difference in rigidity for different types of steel. Solid carbide bars are more rigid, as are steel bars that are a larger diameter. Another option is to mount the workpiece on the cross slide and mount the boring bar between centers.

[littleevan99]

I'd make a big boring bar out of some hardened drill rod to avoid the flex from the long stick out.

My understanding is that there isn't a big difference in rigidity for different types of steel. Solid carbide bars are more rigid, as are steel bars that are a larger diameter. Another option is to mount the workpiece on the cross slide and mount the boring bar between centers.

I was leaning more towards a large diameter steel boring bar. I have one on hand, but it was about 3" too short.

[littleevan99]

Got a lot done in the past few months when I have time to work on things. The crank main bearings are done, and they took longer than I was hoping to complete. Mostly to ensure that everything was straight, and lined up correctly. Trying to keep it brief, they started out as cutoffs from a round bar of C932 bronze, faced to length, squared up, milled to fit the block, slitted in half, both halves faced to the right height, and here's where I had problems. I was originally going to use the crankcase as my boring fixture, but the block stands up too tall on the mill! So I had to go to plan b and make a fixture out of stuff I had laying around. Once it was all set up it was as simple as drill, bore, and ream .001" undersize to give me room to lap the bearings to the final size and to make sure they're parallel to each other. The pictures attached of it. It worked out well, and all the bearings came out lined up as close as they were gonna be. After that got taken care of I used a piece of the same material that the crank will be made from, and lapped the bearings to the final size. After all that I machined a slot into the top half of the bearings to hold oil or grease, and a small axial groove to channel whatever I decide to lube it with. Next up is the crank! Working on the throws at the moment, and I made a few of the eccentrics that go in between the #2 and #3 crank throws.

[littleevan99]

A addon post as well, here's how I made the eccentrics, and machined the blocks for the oil cups that I'm on the fence about using(more on that later).

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I only had enough cast iron for two eccentrics to start with. Mainly just needed these to get me started on the crank.

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Here's the fixture I made out of parts from the scrap bin to bore them.

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Reaming them to be a tight sliding fit to the crankshaft.

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I tilted the head 20 degrees or so to counterbore the block for the oil cups.

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Lastly cross drilling the block to meet up with the hole in the slot.

A question for the forum. I noticed that even steam oil tends to get sucked right out of the reservoir I machined into the bearings and block when running a shaft through the engine with a drill. Maybe the hole through the bearings is too big, but it's only a 1/16". Putting a felt wick in the hole might help, but I'm on the fence about making some more prototypical grease cups like this class of Shay had and running grease instead. Any ideas on here about that? I'm open to suggestion. This engine runs a little fast for grease according to the literature I've read.