Originally Posted by
Cafe con Leche
That is an interesting point. Wonder if tapping the screw holes before actually putting in the screw would help with some materials. I know having a vertical drill press or mill worth it. You would want the the tapping to be as square as possible.
Waste of time again TRF topics-style. The hole being formed all the way it will guide the tapping screw along, but I wouldn't use any cutting tools on plastics, they remove too much material, they're for steel and metals in general. Plastic works by moving out of the way a bit and gripping to provide friction to hold screws in, not by being cut and tightening screws in.
Get some silicone oil in the hole before you use the screw to tap it all the way, back off the screw half a turn for each turn (or 1/2 in - 1/4 out).
Even better, use Xray diff screws - they're machine screws and you can pre-tap with a "normal" one (i.e. not countersunk which will take a larger standard hex which gives more purchase). Same procedure - oil, 1/2 in 1/4 out.