Distorted Vision coughed up some electrons that declared:

I'm in the process of replacing some of the switches and surface
moulded boxes in our house for cosmetic reasons. Some of the switches
are really dirty, scratched etc and some the moulded surface boxes are
cracked etc.

Anyway I have a question and I know its going to sound really stupid
to alot of you. But what is the best of breaking the knockouts on the
moulded boxes to ensure clean straight edges. The first one I tried I
used a pair of plier but it was a bit of a mess - good job they are so
cheap.
Am I missing something here. Is there a recommended way.

Many thanks!

Not stupid at all...

My amateur trick is to slice with sides with a junior hacksaw, snap out with
pliers, punch the inner skin with a screwdriver (if applicable) and finish
with a few strokes of a 1/4" full size coarse square file through the lot.
Dead neat and nice square smooth edges - not the fastest way though. If
doing a lot, I pre-prep them in one go on the bench with a big cup of
coffee.

Wonder what the pro's do?

Cheers

Tim