Notes on Cutting Plexiglass

‘Needed to install a 4″ vent for a portable AC here the other day, and the only way to do it was by replacing a pane in my shop’s 80 year old recycled window. I’ve not had good experiences trying to get clean, straight cuts in Plexiglass in the past, but this worked well.

Turns out a sharp 40-tooth carbide blade in a table saw does a very nice job, and I’ll bet a finer plywood type blade would be even better if I had one on hand. Taping off both sides before cutting would’ve probably made it cleaner, too, but since I’ll be puttying over the edges anyway, a tiny amount of chipping didn’t matter this time. I was glad to be wearing a face shield, though, as the tiny chips coming off this stuff are sticky and not very tasty. 

The next issue was cutting a fairly clean 4-1/4″ diameter round hole for the hood. I have a 4-1/8″ hole saw for dryer vents, but it’s as aggressive as a ticked-off pit bull pup, so there’s no way that’d work (thought about running it backwards, but it’s pretty coarse toothed).

A circle was cut very nicely with the spiral saw and circle-cutting attachment (many saws come with one, as mine did), and the RotoZip(tm) made fast work of it. Just be sure and clamp the pane securely to your work surface first (I had visions of that 1/8″ thick piece of plastic flying off and slicing me cleanly in half at the waist. Ow.) Again, taping would’ve improved the quality of the cut, but this one doesn’t show, either.

The job turned out very nicely, and my fear of cutting Plexiglass has been replaced by a new respect for the material, and just how handy it is. 

PS – I was cutting a used piece of this plastic, and it was for my workshop so I didn’t care too much about scratching it during fabricating. Plexiglass ordinarily sells with a sheet of protective film on both sides, and you’ll want to do all the cutting with that left on, to reduce scratching. It peels right off when the piece is finished. 

Just a little something I was taught this week in the ‘school of hard knocks’, so I thought I’d share it.

God bless!

Dave
John 14:6

About Dave Harnish

I've been an appliance repair tech since 1972, with interests in most everything, including Bible study (I'm one of those KJV-only geezers), old Sunbeam Mixmasters, Maytag wringer washers, the outdoors, birds, hunting, metalworking, firewood cutting, and most anything going on outside on our mountain here in N. PA's 'Endless Mountains'.
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