Cutting hole in glass?

Question

im trying to get a cat flap fitted in a single pane of glass. Ive bought the flap, but no-one wants to do it, ive tried glaziers in the area, everyone sez they cant do it. Why is this? I even approached a double glazing firm, to get a price for a double glazed unit 4ft by 3ft, but they wont cut the hole. grrrrrrrrrrr

Answer 1

Woodtick is right on here. You might try to have a piece of plexiglas cut for the door but once again it is a stress point at the corners. Sorry. Edit... I know it may look funny but if you have to have glass try having the glass cut into 4 pieces and then assembling them with the door acting as the edge of the puzzle pieces. You could use clear silicone to glue them together for a weathertight seal. You could even have the glass made out of safety glass this way. Might even look kind of nice in a way.

Answer 2

Replace the glass with 4mm thick polycarbonate and drill/cut a hole in it using small drills (to start) and a jigsaw.

Polycarbonate is 200 x as strong as glass and won't smash if the cat misses the flap at speed!

Alternatively get a glazier/maker to divide up the window so the cat flap is in separate 'mini window' with plastic or wood surround to mount the flap in.

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NEW if you want try cutting glass yourself:

  Accept that there's a >90% chance of failure - this is the one of the hardest of the glaziers arts & wear protective gloves & googles!

Google shopping for circular glass cutter

Assuming the glass is not toughened or laminated (don't bother) toughened shows patterns with polaroid glasses, laminate has a thin line visible in the edge



To cut glass it must be absolutely squeaky clean, no dirt no grease wash with solvent.

If no better instructions are supplied with the cutter,

Mark the circle with the cutter in one deep cut

mark internal grid of diagonals and chords ensuring they don't extend over the circle

gently hit to break (hopefully, only) the centre out over support sand or entirely submerged in a tank of water

gently extend the hole to the limits of the circle by nibbling with glass / tile nipper cutter or pliers

Good luck!

Perspex is acrylic plastic

Polycarbonate is lexan

Answer 3

Cutting a square cornered hole in glass is very dangerous.  The sharp angles will stress the glass, and it will fail.  Trying to secure the frame to it will add more stress.  My advice would be to construct a panel out of plywood (you can get plywood with hardwood veneers, such as birch, oak, or maple for appearance purposes) and install the cat door in there.  Hope this helps.

Answer 4

Because there is no guarantee the glass won't crack or break.

Does it have to be glass?

Could you replace the pane of glass with a sheet of plywood and cut the hole in that?

.

Answer 5

What you are wanting to do will really push what can/can't be done with glass. Double glazing will be less able to cope with the hole, it will self destruct as the glass is put under stress as part of the manufacturing process.

Old fashioned methods would involve scoring the glass again and again to cut through the glass, normally on a bed of sand to reduce the risk of the glass splitting.

Best of luck

Answer 6

Since this is obviously either a sliding glass door or an exterior window, I would suggest installing the cat flap in a wall adjacent to the glass. If you use screws that are long enough, you can attach each piece of the flap to either side of the exterior wall. You can also frame in the sides to seal the wall and paint it white, so it looks less noticeable.

I've done that many times in houses where I wanted a doggie door to the outside, but not through French doors with full glass panes. I got the idea when looking at rentals once and saw that the owner had installed a cat door in the wall leading out to a small shed a couple feet high and about 2 feet square. The lid of the shed was a hinged piece of solid wood and the sides were screen mesh. They kept the cat box out there, so they didn't have to smell it. But, the cat couldn't get out and run away.