Charlie wrote:
We have had a number of 4 tube florescent light fixtures
One of the "shades" recently decided to crack and break
The replacement shades that I can find are all about 1/4 inch too wide
I can't seem to trim it to fit.

I had to replace 130 or so of those in an office building a while back.
I used a straight edge and a router with a 1/2" carbide straight
cutting bit, no chips, no cracks, no problems. VERY FAST,, I HAD to
keep it moving, burned plastic smells terrible :-)

Tom in KY, wear a dust mask to keep those particles out of your lungs!