Making blowhole in Plexi window

[Dominat0r]

Hey guys...im tossed in the air as to how the best (safe) way to make a blowhole in my plexi glass.

Im worried about cracking, so i was thinking of masking of the area in tape maybe?

Would it be ok to use a Hole saw on a drill for this?

Any thoughts would be great.

 

[Top Nurse]

Masking tape and hole saw. Low rpms or you will melt the plastic. Water cooled hole saw cutting (with a garden hose) works great. Just don't step in H20 while holding onto the juice

 

[racercarl]

I use a hole saw and start on one side then finish on the other, backed by a SOLID piece of wood, the plexi is taped and marked and I go really slow, almost no preasure and don't let the drill bind at all. Haven't broken one in a long time (knocking on wood) hope I didn't just jinx myself

 

[Nivram]

The way I did it was to mask it in one direction on one side of the plastic, then mask it at a 90 degree angle on the other (not sure that it was necessary, but thought it might give a bit of extra strength in every direction......strange, the things ya think of sometimes, huh?? LOL ).
Like the others said, go slow, back it up with wood, and keep the rpm's down. A cordless drill/driver is what I used, and it worked just fine.

Word of warning, as well.......when you drill the holes for the fan screws, take just as much care to back up the material. I drilled a perfect blow hole one time, then got impatient, and didn't back up the material to drill the screw holes......which cost me a re-do, since I make a nice 2" long crack in the material!!

 

[lord_emperor]

I've always used a jigsaw and not with any particular amount of caution either.

 

[IcedFoxtrotter]

It would be best to sandwich it between two pieces of pressboard or plywood to cut it, to keep the edges smooth. I would use a jigsaw as well with an ultra fine blade - a finishing blade preferably or a thin rope saw. I would also use two people - one to cut and one to hold the garden hose on the cut to keep it cool. Clamp it realy hard, otherwise you will probably get hairline cracks like this:

 

[Ducay]

When I did the dual blowholes in my window heres what I did: (note, plexi wasnt attached yet)

-Masked off the entire area to be cut and then some (on both sides)
-Drew in my template including center point for bit
-Clamped plexi to work bench with two C-clamps and a couple folds of paper towl inbetween them.
-Drilled a pilot hole in the center
-Busted out the 3" hole and gave'r
-Drilled my screw holes
-Remove tape (duh)
-Clean up any bits hanging around

Heres how mine tured out (some camera glare)

 

[Dominat0r]

awesome work, thanks for the pictures.

About how much tape did you use to mask off?

 

[Randolf]

use a circle cutter and a drill press. you can get any size of hole that thr cutter will allow. I picked up a 1"-8" cutter at lowes for $6. basically a drill bit with a cutting ti that spins around it. nice and smooth cut