DIYbanter - View Single Post - Kitchen unit fitting sequence

Chris Green

wrote:
On Friday, 23 August 2019 20:33:05 UTC+1, Chris Green wrote:
A well fixed steel screw will hold an incredible weight in shear. My
rule of thumb for steel's strength is 40 tons/sq in which gives a
shear strength of somewhere around a ton for a 5mm screw. The screw
will probably fall out first of course but I do always wonder why
people use great fat fixings for holding a few tens of kilograms.
Nearly all my fixings are 3.5mm or 4mm screws in yellow plugs and I
can assure you they *don't* fall out or break.

Many do. Some suffer from masonry crumbling, or the masonry simply snaps.
Most people fail to clear the dust out, resulting in a weak bond. And the
ida that you can reliably safely support a ton on a bit of 5mm wire sideways
strikes me as decidedly optimistic.

I wasn't suggesting supporting a ton on one screw, I was just pointing
out that big screws are unnecessary. It is of course necessary to
ensure that the screw is soundly fixed in the wall which, I find,
doesn't depend much on the size of the screw. *Longer* screws often
help but *fatter* screws are not a lot of help.

--
Chris Green
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