Trimming a "shade" for a 4 tube florescent(sp?) fixture

We have had a number of 4 tube florescent light fixtures installed in the basement since sometime in the late 1960's.
One of the "shades" recently decided to crack and break for whatever reason. The replacement shades that I can find are all about 1/4 inch to wide to allow it to sit flat within the frame for the light fixture.
Given the thickness, or lack thereof, I can't seem to trim it to fit. Everything I've tried results in a shattered shade.
Help.
Charlie. snipped-for-privacy@shaw.ca
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Very sharp knife. Score and snap or score and keep scoring until it falls off..
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we have run into this problem ourselves. you're looking in the wrong shelf. you want to find the replacement panel for the fixture already your size. not a drop in panel for the ceiling grid with a light above it, it won't fit and won't cut to size.
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It's called a diffuser, and spelling is fluorescent. The plastic is too brittle to cut with a saw. Try as another said - score it repeatedly with a utility knife, making sure to 'back-up' the cut with something solid to avoid flexing it too much. HTH
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PanHandler wrote:

Cuts fine, just flip the blade so the teeth point away from the cutting direction. Or if you live dangerously feed the panel through the saw from the outfeed side.
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home depot buffalo ny. look for the fixture itself and part for it.
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Charlie wrote:

By shade do you mean one of those flimsy translucent plastic panels? If so, you can cut the oversized piece on a table saw (or a circular saw). The trick is to use a saw blade with a lot of teeth (a plywood blade is fine) and put it on the arbor backwards. The saw will cut some but it mostly just melts through so the finished cut may have a rough curled piece of melted plastic, but you can take if off easy with a swipe or two of 150 grit sand paper.
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Charlie wrote:

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!
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