Trevithick

[Brian Rupnow]

Today was a day for fettling and fitting. The new elbows on the 4 way valve gave me the clearance I needed, so I was able to bolt the end with cylinder attached to the boiler.  I routed the air supply hose from the 4 way valve to the hose barb in the back plate, and routed the exhaust thru the backplate and into the smoke stack. The only new part  machined today is the arm attached to the bronze gear which sets on the flywheel shaft. I'm hoping that my local nut and bolt store has 3/16" shoulder bolts, which will attach the "connecting rods" to the new arm and to the flywheel. I'm thinking that the boiler would look a lot better with a flange at each end. I may buy some material to add a flange to each end of the the boiler.

[Brian Rupnow]

Well Rats!!! Nobody in Barrie carries 3/16" shoulder bolts. I went a head and made my own, now I can connect my connecting rods to the flywheel and crank arm.

[Brian Rupnow]

If I had some 1/8" rod bent and threaded, I'd have connecting rods finished. The four brass ends are shown in place in this picture. I've got so much junk on top of my "assembly table" hat it's hard to see. Tomorrow I'll make and install connecting rods.

[Brian Rupnow]

It's time for a change in my game plan. I had originally planned on using 1/8" diameter cold rolled steel round-bar with soldered brass ends for connecting rods. Tried that yesterday, but found that 1/8" is far too skinny and bendable. not going to work. Went out today and spent some of the Rupnow fortune on spherical rod ends. The con-rod diameter will now match the o.d. of the female rod ends.

[Brian Rupnow]

Here we have the "heavy con-rod" on the non gear side, with a spherical rod end on each end. As things work out, the con rod on this side doesn't really need an offset, which is fine with me. Tomorrow I will work on the gear side con rod, which definitely will have an offset in it to clear the hub on the 108 tooth gear.

[crueby]

 

[Brian Rupnow]

Couple of things I should mention.-- That new con-rod is way too large in diameter, but it won't deflect under load, and once the engine is running it will be replaced with a smaller diameter piece.--And--I picked up a piece of material today large enough to create "flanges" for the ends of the boiler. I think that if these boiler "flanges" are added they will do much to make this model look more like the original Trevithick engine. It's a bit difficult to imagine with the 3D model being more colors than the rainbow, but I think it will look better.

[Brian Rupnow]

I couldn't stand how big and clunky a 1/2" diameter con rod looked. Today I made new con rods from  5/16" diameter cold rolled steel to replace the first one which was 1/2" diameter aluminum. Everything looks a lot more proportional now. Video to follow when my camera battery is charged.

[Brian Rupnow]

This is a video of the Trevithick engine being put through all of it's mechanical paces. It is an extremely interesting engine to see working.---Brian
<a href="https://www.youtube.com/watch?v=URKQz_K08UI" target="_blank">http://www.youtube.com/watch?v=URKQz_K08UI</a>

[Art K]

Brian,
Your Trevithick looks great a literal mechanical marvel. Unfortunate thing that the rails failed.
Art

[Craig DeShong]

Very interesting Brian, can’t wait to see it run.  It’s going to be a gangly looking thing with that cross head sliding in and out in front as it moves along!

[Brian Rupnow]

Sometimes the game plan changes in the middle of the game. I originally did not intend to have flanges at either end of the boiler. Last week I decided I actually did want them, as separate rings that I could slide over the ends of the boiler and attach with small bolts. The only fly in the ointment was that I had already dedicated the space at one end of the boiler to support a guide rod mechanism for the slider that moves the valve. Today, I turned up some plate on my faceplate to get a curvature identical to the o.d. of the rings (one of the rings is leaning against the headstock in the picture), and then welded the resulting pieces to the rings. My tig welding is improving, but it is not very artistic. So, at this point the pieces are welded to the rings, and the resulting welds are slathered with J.B. weld which won't be dry until tomorrow. When they have dried, I will work some artistic magic on them and then attach the rings to my boiler.

[Brian Rupnow]

No real machining work this morning, but a couple of hours spent updating the 3d model to reflect what was actually built. Here you can see the heavier connecting rods and the updated boiler rings which have the guide rod supports built into them.

[Brian Rupnow]

Spent a very large part of the day working out tight spots and freeing everything up. This is a finicky kind of job, and it can't be done until everything is almost finished and assembled. Also got a start on the valve valve actuator rod. The two rings which go on the ends of the boiler are leaning up against the engine.

[Brian Rupnow]

Elvis has not left the building. Elvis is up to his neck in adding the flanges to the boiler and adding the valve linkage. I really, really hate making changes part way thru a job. I can make it end up pretty, as if I'd planned it this way all along, but it adds a whole page to my frustrations list. Oh well, one end is finished. Tomorrow, who knows?--The canary may sing for me!!