Forming tumblehome, (AKA turn in)

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Any tips on forming tumblehome, the slight curve in at the bottom of etched coach sides; so far I'm having limited success with a groove filed in a piece of wood then clip side to wood and squeeze a piece of brass rod to push the side into the groove. It works after a fashion but it's a bit fiddly to get and keep it lined up.
I initially tried rolling the brass rod over the lower part of the side placed on some sponge foam.

Cheers MIKE
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Hi Mike, 

Solid brass rods on 2 layers of 1/8" thick high density craft foam on plywood works for me. (N to O scale). You could get a metal roller. Are the etches brass or N/S? 

What you can also do is to clamp the side under a rod and gently use a wide blade chisel underneath to bend it up. Needs a larger diameter than the rolling rod, Copper plumbing size. You could also clamp the side to the tube in a vice and gently bend over to shape.

Nigel



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Thanks Nigel, they are brass etches (see my SR coaches topic), UK N gauge 1:148. I'll have another go!

Cheers MIKE
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Whilst I've never done anything in brass Mike, try continually rolling something over the sides, exerting medium pressure,  where you want the tumblehome to be. By "something", I'm thinking a round ruler or similar.  A rolling pin is too big and brass rod too small ………….

 If you do it on something like a cutting mat with just a slight "give", the brass should gradually take on the curve.  I don't think you can do it in a sinlge pass without special rolling gear ……………


My feeling is that sponge is too soft and it's likely to kink the brass.  As Nigel said, foam board might work but I'd think that too might be a tad soft.

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Rolling rods vary in diameter. In general a small diameter gives tight curves but a large roller needs more pressure. With a judicious use of pressure smaller diameters do a better job when curving tumblehomes as it is only the lower third to a half that needs curving.  This is N scale, you need to see what you are doing. Large diameter rollers are best used in a machine. 

I keep a range of diameters for generating curves. They are all small.On


Nigel

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