Trevithick

[Brian Rupnow]

Yesterday I made a new rod end for the cylinder, and machined a new separate flange, which weirdly enough doesn't get bolted to anything on the cylinder. It does bolt to the outside of the boiler endplate and is there for show, but nothing functional. Today I cut the boiler tube to the correct length on my lathe. That steel tube had some kind of nasty varnish on the outside diameter, so I used my angle grinder and then my jitterbug sander to clean up the outside diameter while the tube was turning in the lathe. Tomorrow I will pick up some new material to make the boiler end-plates from, and Tuesday I pick up my water-jet cut flywheel. Most of this engine will get painted, so I'm not too concerned about using a combination of steel and aluminum parts.

[Brian Rupnow]

Now that, boys and girls, is a beautiful thing!! Water jet cutting leaves great edges that need very little clean-up. If it wasn't so expensive, I would have more of it done. The flywheel is laying on top of a bunch of plates which will be finished before the end of the day using conventional machining techniques.

[crueby]

That wheel came out great. How parallel are the inner/outer edges to each other? Close enough not to need any more milling?

[Brian Rupnow]

As far as I can tell, it only needs a slight kiss on the o.d. and to have a hub bolted on.

[propforward]

Now that, boys and girls, is a beautiful thing!! Water jet cutting leaves great edges that need very little clean-up. If it wasn't so expensive, I would have more of it done. The flywheel is laying on top of a bunch of plates which will be finished before the end of the day using conventional machining techniques.

Very nice work.

It might be that the post processing of your CAD files is where some of the expense is.

If you're not already doing it, you might ask them what file type they are using to program their waterjet, and see if you can supply what they need. We use dxf files up to a very specific year version on ours - and convert to that from solidworks in the flat pattern.

Also, if your edges are coming out so niceley, maybe see about upping the cut speed, and living with a slightly rougher edge with some stock on it for clean up later on. Might save a bit of time, and therefore money. But - may increase their programming time. Might be a wash.

Don't know, just some thoughts for you to run by your waterjet people if you like.

[Brian Rupnow]

I supplied the water-jet cutter with the file he asked for. I have no control over what cut speed the guy uses. interesting thought though--I sent the drawing out to four places for quotes and received quotes of $125, $80, $50 and $47. It pays to shop around.

[Art K]

Brian,
That is a mighty fine looking flywheel. This project is coming along good.
Art

[Brian Rupnow]

I haven't ran off. There is a lot of time spent on fitting and creating new platework, and I didn't want to post every single part that I made. The cylinder is fitted into the boiler, with a little bit of design change to allow for clearances. The plate stands that support the boiler and provide bearing surfaces for the axles are almost finished, but as you can see, they haven't been drilled for axles yet. Tomorrow I will finish those plates and machine two more that run parallel to the boiler, and drill and tap the boiler shell for the bolts which holds the end stands in place. The wheels are going to be the last parts made for this engine. I can actually go ahead and make all the parts required to make the engine run without finishing the wheels and the gears.

[Brian Rupnow]

Todays job was to finish all of the axle brackets and assemble them to the boiler shell. This gets a bit tricky, because with no real suspension, if things are a bit off you end up with one wheel out of the four "up in the air".--It won't matter so much on this model, because it's not going to be a high miler, but I do like to get it right.

[Charles Lamont]

Two rigid axles was not an option on the replica Catch Me Who Can.  With only one driving axle it is easier to arrange. The carrying axle has axleboxes sliding in horns in the usual way, and a transverse leaf spring hidden under the boiler. This should also make the footplate ride a bit less rough. ISTR one of the Coalbrookdale Engine replicas broke an axle quite early in its career. 

[Brian Rupnow]

And behold, the great horned beast!! Is it not a beautiful thing? I think it's a Rupnowsaurus!!!

[crueby]

Looks like a torture device for shop gnomes.

[Brian Rupnow]

You know that saying about "Old dogs can't learn new tricks".--Not really true---I'm an old dog and I'm still learning new tricks. The cross-head on this engine (purple colored) has a long protrusion welded on top of it that operates the rotary valve. The fact that it is quite long will make the cross-head want to bind as it moves under pressure from the cylinder. This is technically called an "overturning moment". The way to overcome that binding is to make the area on the cross-head which slides along the cross-head guides as long as possible. Since that is probably the next thing I'm going to build, an update to the 3D model was called for.

[Brian Rupnow]

Today I finished the cross-head, and I'm quite pleased with the results.  In the 3D model I posted yesterday, I thought that the extended bearing surfaces added to the cross-head looked kind of "clunky", so I changed the design after I  had posted the model, and made the two extension pieces from round brass, which extend completely thru the rectangular body. They are loctited in place. The vertical part of the cross-head which operates the valve control rod is silver soldered to the cross-head main body.

[crueby]

Watching along here, great stuff.