# Ductile or malleable clamps?



## Bristol_Rob (22 Nov 2020)

Guys

I see Rutlands selling ductile and malleable F clamps. 
Whilst I can Google the descriptions I can't seem to understand which is right for general woodworking?

Thoughts?


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## Trevanion (22 Nov 2020)

Both work practically the same, although ductile iron is probably the better choice of the two.

Malleable iron goes through an annealing process of sorts to make it more flexible similar to tempering a hardened piece of steel, ductile iron has added elements in the casting such as magnesium and also a differing grain structure with softer carbons than conventional cast iron which makes it much more durable and flexible.


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## Bristol_Rob (22 Nov 2020)

So would one be able to be clamped at higher lbs/sq inch? Is that the practical benefit?

Is using a clamp that has a little flex better than a stronger clamp that ultimately fails?


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## Lons (22 Nov 2020)

I can't imagine in a woodworking situation, needing to tighten a clamp so hard that the metal itself fails due to the pressure. It's never happened to me so genuine observation and I'd be interested in other's experiences, I had G clamp twist slightly once but it was a cheapo and entirely my fault and even that is still in use.


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## Trevanion (22 Nov 2020)

Bristol_Rob said:


> Is using a clamp that has a little flex better than a stronger clamp that ultimately fails?



Both are just more flexible variations of regular cast iron that have gone through two different processes, a clamp made from regular cast iron would have to be made pretty hefty to take very heavy clamping forces without snapping but the ductile and malleble iron can be made lighter-weight without breaking the same as regular cast iron would.

A forged steel clamp however is even better again but it really is all a bit semantical.



Lons said:


> I can't imagine in a woodworking situation, needing to tighten a clamp so hard that the metal itself fails due to the pressure. It's never happened to me so genuine observation and I'd be interested in other's experiences, I had G clamp twist slightly once but it was a cheapo and entirely my fault and even that is still in use.



I've also never had it happen but I've always had decent clamps, although I did break a cast brass one once trying to bend it back after it got mis-shapen.


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## Tris (22 Nov 2020)

Daft question perhaps but does it make a difference to the chances of damaging them if dropped?
Just wondering as I've snapped a cheapo F clamp that way before.


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## Jelly (22 Nov 2020)

Tris said:


> Daft question perhaps but does it make a difference to the chances of damaging them if dropped?
> Just wondering as I've snapped a cheapo F clamp that way before.



Both will perform rather better compared to standard white C.I. with regards to toughness (as in resistance to brittle failure due to shock loading)...

Ductile should be a little better, but not so much as to make a difference, and neither will be nearly as good as a medium/low carbon steel.


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