[modeleng] Swaging stainless steel tube

Firstly, thanks for the replies on the automatic drain cocks, especially to 
Baggo - I'd seen those drain cocks on Helen Longish but had forgotten about 
them. At the moment, the information is filed away for later use.

This week's problem involves some stainless superheater tubes. I know you 
are supposed to TIG weld them, but I don't have the equipment (or the 
ability for that matter ;-). I'm thinking of screwing the firebox ends into 
the return bend and using a high temp silver solder to caulk the joint, so I 
won't be relying on the strength of the silver solder. The return bends 
probably won't see the fire directly anyway - This is on a Sweet Pea and the 
received wisdom is to make a thick stainless "brick arch" at the front of 
the grate/ashpan assembly. The Sweet Pea has a marine firebox, by the way.

Anyway, back to the point. I'm very short of space in the superheater flues 
and it would help if I could reduce the outside diameter of the tube from 
8mm (a tad over 5/16") to 9/32", but not lose any wall thickness at that 
point.

What I've got in mind is 3 small ball races set into something that I can 
squeeze them together as the tube rotates in the lathe. This will make the 
swaged length equal to the width of the ball race, which will be plenty for 
what I want.

The tube is 316 stainless.

Before I go and do it (and I'm going to anyway!) - What is the considered 
opinion of the group? Will it work?

Thanks,

JohnP 


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