On Fri, 29 Oct 2004 11:25:07 +0000, usene wrote:

I'd like to have some 'ball park' figures for the torque which typical
wood screws can handle. Can anyone give me some typical figures or
point me at a web site that has them? I would emphasise that I'm
after the torque figure, i.e. the amount of twist needed to break
them. I realise this doesn't directly relate to the strength of the
screw holding things together which would simply be given by the
tensile stregth of the screw.

I'd prefer the figures for metric screws (i.e. diameters in mm) and in
Nm but I'm quite happy to convert if necessary. The actual screws I'm
using are ScrewFix TurboGold and the stainless steel versions of the
same. I would guess however that most good quality screws are going
to be similar, I'm not after accurate figures, just an idea of what
is likely to break them.

In my experience it is much more easy to over cook 4mm screws by
forgetting to reduce the torque setting then it is to break them.
In fact the only way in my experience is not drill a masonry hole
deep enough and then to get a really good screw/hole/plug combination.

I would reckon that you would never break a 4mm screw on the high speed
setting (you'd stall the motor first). A typical pro quality 12v cordless
is rated at about 20Nm. The high speed would typically be around 6Nm.

So I guess the ball park to break a 4mm gold screw is the better part of
20 Nm. I would reckon that it is nigh on impossible to get that tightness
into softwood only hardwood or a blind masonry hole.


--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html