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I was wondering If anybody knows what type of steel the torsion bars are made from? I'm assuming they are all the same, but specifically the 2 used for the Sdkfz 7 kit.

Probably what's commonly sold as "Piano Wire".

Adrian.

Adrian Harris wrote: ↑

Fri Mar 21, 2025 11:19 pm

Probably what's commonly sold as "Piano Wire".

Adrian.

That would be my guess. That's what I've used in the past for scratch builds. Can't say I knew the hardness of the material I used, no longer have access to a hardness tester. But I did test a length of whatever I wanted to use, the exact length I wanted to use as a torsion bar. I'd test the deflection
using a spring balance, similarly to the way armorers tested the fusee spring in a Vickers MG; I would attach the spring balance to a proper swing arm and with a protractor see how much deflection I got at various weights of 'pull'. I knew that the weight of the model was more or less divided by the number of axles so when I found a rod or bar of steel that gave me the per axle deflection in degrees I wanted for a particular weight value I wanted, Bob's your uncle. The torsion bars I've made were generally thinner than those in the 1/6 scale as I was making them for 1/10 scale but the process should scale.

Easy Peasy....

Jerry

Adrian Harris wrote: ↑

Fri Mar 21, 2025 11:19 pm

Probably what's commonly sold as "Piano Wire".

Adrian.

Thanks Adrian. I did wonder if Piano wire could be used. I've found various companies selling 'spring steel', but it appears to be that it has to be heat treated before use. 'Piano Wire' doesn't....its ready to use.

A little late to the party but having the same issue with my KT I used Oil Tempered Spring Steel in metric ground sizes and it worked perfectly well.
it is already Heat Treated and tempered.
Martin.

Even later to the party - we don't use piano wire for torsion bars.
Torsion bars, leaf springs, volute springs etc are all heat treated sprung steel.
Kian