Screw question - most flexible ?

Jul 19, 2006 8 Replies

What's the most flexible type of screw, ie one that won't break when bent? Steel and brass doesn't seem that flexible.



I have an application that needs a screw that won't sheer if bent more than 20 degrees (the application is a bit complex to go into here!).



A thought - are there screws made from thick wire (5mm or so), as is the case with wire nails? That would be ideal as wire nails are nice and flexible.



Thanks



I would try nylon machine screws, with inserts for them to screw into, but I wouldn't guarantee they would work.

If you want to high-tech, get some precipitation hardening stainless steel and make your own screws. That is the stuff that Army tank aerials are made from and it has to be able to flex a lot without breaking.

Colin Bignell

Take a normal screw and anneal it. Modern screws are hardened and so rather brittle. Heat to a dull red and let it cool slowly, and you will find you can bend it as you wish.

AWEM

Do you mean screw as in wood screw?

If you've got that much flexing, whatever the screw is fixed into won't last long. I'd use high tensile nuts and bolts.

I think that would cause problems in manufacture. So perhaps the easy way would be to anneal a standard one. But then it might be difficult to screw in without damage to it.

The message from "Andrew Mawson" contains these words:

But use a hardened one in the hole first, then take it out and run the floppy one in.

You are on a hiding to nothing. All screws will eventually fatigue if subjected to that sort of strain.

Does that apply to all types of screws, ie steel, brass, etc?

Thanks to everyone for the replies, most helpful. :-)

I think youre getting optimsitic here. Best bet is to go for as thin a screw as possible then soften it. The thinner the screw, the more it can bend before snap. But a thin softened screw is going to be one crappy screw.

Maybe tell us more about the app. Confess.

NT

Nope, brass, copper and aluminium are the opposite to steel, heat [1] and quench in cold water to anneal, heat and allow to cool as slow as poss' to harden.

Hope that helps, Dave H. (The engineer formerly known as Homeless)

[1] - Brass and copper until dull red, aluminium and its alloys until soap rubbed on the workpiece blackens. If you want to anneal just a part of the workpiece (eg rifle/pistol/howitzer cartridge case mouths which need to be soft while the rim of the case needs to be hard), stand the bit you want to remain hardened in water, heat and tip it over into the water.

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