Solid would have the advantage of being a bit heavier so increase tractive weight which depending on teh loco may be an advantage. Are ther any screwed fixings that go into one plate only? if so 3/16" would give good depth of engagement compared with 1/16"

Looks like the frames will be very much on show so may be better to stick with the two 1/16" ones and spacer

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Rod,

I thought I had made that reasonably clear in my first response to Eric:

"The stiffness [which is not quite the same as strength] should be very similar, and there may be manufacturing conveniences."

Modern manufacturing [Aircraft; Caravans; Lightweight Doors, etc. etc.] uses comparable techniques.

If the prototype used 1" thick plates instead of 3" thick plates, I would assume this provided a lot of the aforementioned manufacturing conveniences. [and should probably be carried-over to the model in honour of the designer's sound engineering principles]

MichaelG

If you have great confidence in your machining abilities you could use 3/16" and put a thick groove around the edges, even the cutouts with the right sort of cutter.

N..

But how many working model boilers are there that are NOT an "image" of the original?

Eric, do the cylinders pivot slightly as it looks like they would need to in order to keep the piston rod from binding up as the crosshead guides are not inline with the cylinder.

As Rod says it looks an interesting project, I found a couple more images on google that are a bit better than the sketch. Do you hope to have it pull you around the track or will it just get run on a test stand, if the latter then there should not be an issue with frame rigidity.

J

Looking again I see the cross head guides are inclined to match the cylinder

Why would you not make this from three layers of 1/16" MS?

Presumably one could invisibly rivet the three together to avoid any hassle, but the middle piece would have a different profile to the outer ones.