Cutting fiberglass

Table saw, or skill saw both with a fine bladed saw blade.

Saber saw if it binds up you could rip the fiberglass. Boards and clamps would help a lot.

A circular saw

I would take Joe's advice and clamp a board for a straight cut and also use a tungsten carbide router bit and a router, of course, to cut the material. That's how circuit boards are cut so cleanly. I'll let you do the googling for the tool bit....good luck, Ross

I don't know if a saber saw would be my choice, especially since you want a straight cut, but clamp a board onto that fiberglass panel and go to it.

Fiberglass cuts just fine with almost any saw. The big problem is that it dulls the heck out of any blade almost immediately. Whether you use a tablesaw, circular saw, or a saber saw whatever, don't use your expensive blade...

Personally, I'd use the saber saw. The blades are cheap.

KB

And wear a dust mask. I didn't and coughed for hours.

Harry K

That's why you want to use tungsten carbide....fibergalss is very abrasive...Ross

What ever you do, use put masking tape on both side so that the cut is in the middle of the tape. I would use a board as a guide, don't use pressure to smash it down, and cut it with a Skil saw (use a fairly fine tooth blade). A sabre saw isn't a good idea.

I have cut the stuff you are likely speaking of. I used a utility knife and scored it from the back side and snapped it in two. Cuts really similarly to ABS sheet. YMMV

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MUADIB®

You'd have to better with a saber saw than moi to do a straight cut with a saber saw.

I usually cut FRP (which I assume is what you're talking about) using a table saw with a backwards plywood blade. The real key is *support* -- as you say, that stuff is floppy, and wants to go anywhere but straight. BTW -- be sure to cut outside -- you'll spew fine dust everywhere, and that crap can't be good for your lungs.