Christian McArdle wrote:
Even one of those monitor shelves on a flexible arm is only fixed with
red plugs and 5mm screws and seems perfectly sound even with a
heavyish monitor on it.

I use 5mm or 6mm screws into brown plugs myself, drilled with a 6.5mm SDS
bit. The yellow plugs scare me for anothing bigger than holding up a paper
calendar. If I'm doing anything heavy, like kitchen cupboards, then I go for
the full rawlbolt.

Why do you go for the smaller rawlplugs? It's not like screws or plugs are
expensive.

Because almost everything I fix uses 3.5 or 4mm screws and these hold
best in 4mm plugs in my experience. You can hang a heck of a lot of
weight on just a single 4mm screw. A quick calculation suggests
that a 4mm screw's tensile breaking strain will be almost a ton
(probably more than a ton if it's stronger than mild steel), so the
screw isn't going to break with any remotely normal load on it. I
find that yellow plugs with 4mm screws are just about immovable.

--
Chris Green