"benpost" wrote in message
...
ive found a load of 2.5cm screws which i think are probably there for
the end panels... some have thread all the way to the screw head ,
others have a 5mm flat bit before the thread... anyone know which ones
i should use ? i dont know the difference.

In theory all screws should have a plain bit the thickness of what you are
screwing through to give maximum strength.

Having a thread in both pieces makes it harder to tighten the screws
correctly.
You avoid this problem by drilling a clearance hole in the part you are
screwing through.

You use a pilot hole to guide the actual thread into the other piece, if
needed.

There are various screws that are designed to avoid having to do some/all of
the above, their use may or may not be OK.
There is at least one that self drills, has a reduced dia. shank to avoid
having a clearance hole and countersinks itself.. OK for house building but
not furniture IMO. Don't use them on plugs either as they remove the plastic
needed to hold the screw in the hole.