Board logo

Cutting holes in toughened glass
Mr Whippy - 19/1/09 at 08:15 AM

Is this possible? Or will they just explode?! I had thought perhaps the hole could be ground through using a grinding bit like this –
turning slowly and heaps of water. But not sure tbh, I was under the impression just a scratch would cause it to break. I’m wanting to fit brackets for pop out windows that the fittings bolt through the glass, I'm also wanting to do this for the back window which is not available with such holes.

Any ideas?

Cheers




[Edited on 19/1/09 by Mr Whippy]


blakep82 - 19/1/09 at 08:18 AM

well, they need to cut out windscreens for cars somehow...
don't know how you'd do it, but it must be possible


dinosaurjuice - 19/1/09 at 08:19 AM

cant be done according to wikipedia, it would have to be annealed, reworked and then toughened again.


wiki link

will


Mr Whippy - 19/1/09 at 08:32 AM

Mind though that windscreens are ordinary glass glued to plastic, but side and back windows are heat treated or toughened. I have some spare glass lying around which I won't mind breaking but was wondering if there was a way to do it then round the holes edges to relieve the stresses afterwards.

Probably a lost cause but thought it worth asking…


MikeRJ - 19/1/09 at 08:36 AM

quote:
Originally posted by blakep82
well, they need to cut out windscreens for cars somehow...
don't know how you'd do it, but it must be possible


Modern windscreens are laminated, not toughened. You can't even cut toughened glass in a straight line, firstly the cutter won't score it as the outside is so tough, and even if you managed that it has so much internal stress that it would just shatter into thousands of pieces if you tried to break it.


BillHoll - 19/1/09 at 08:41 AM

I work for Pilkington Glass and the answer is No unless you want to be covered in glass. All glass is cut, drilled, printed and ground before toughning or lamminating.
Our research place could do it but you would need to get a second morgage to pay for it.


Mr Whippy - 19/1/09 at 08:57 AM

quote:
Originally posted by BillHoll
I work for Pilkington Glass and the answer is No unless you want to be covered in glass. All glass is cut, drilled, printed and ground before toughning or lamminating.
Our research place could do it but you would need to get a second morgage to pay for it.


cheers

do you think the glass could be annealed back to normal, drilled and then toughened again? The side windows are flat but the rear is very curved.

ta


BillHoll - 19/1/09 at 09:24 AM

This could be done, but you would need a glass company to do it on a roller furnace. Basically the glass would have to be heated to 750 deg C and then allowed to cool slowly. To toughen glass you heat it to 750 degC and then cool in about 25 seconds back to normal temperature as that is what toughens the glass.


nick205 - 19/1/09 at 09:42 AM

...only thinking aloud here Whip, but could you use perspex/lexan for the side and rear windows?

Alternatively, could you bond suitable metal brackets onto the surface of the glass?

There are some pretty serious adhesives available these days from the likes of 3M etc.

We use 3M tape to bond stainless steel fascia plates to the mild steel cases on some of our products at work. To date, we have not been able to seperate the parts once bonded.


Mr Whippy - 19/1/09 at 09:54 AM

quote:
Originally posted by nick205
...only thinking aloud here Whip, but could you use perspex/lexan for the side and rear windows?

Alternatively, could you bond suitable metal brackets onto the surface of the glass?

There are some pretty serious adhesives available these days from the likes of 3M etc.

We use 3M tape to bond stainless steel fascia plates to the mild steel cases on some of our products at work. To date, we have not been able to seperate the parts once bonded.


Cheers guys, very good info

The windows are for the beetle and hence the rear is extremely curved (double) and needs to be glass and all the windows will be hinged pop out ones. The adhesive idea sounds like it might work if I could make some brackets to glue on. Think I'll buy some and give it a go, see what gives first - the glass or the glue

Cheers

[Edited on 19/1/09 by Mr Whippy]


BillHoll - 19/1/09 at 11:11 AM

We use 3m tape to bond window fastenings and mirrors to automotive glass The mirror patches for bonding on the rear view mirror should be ok, all you need to do is ensure both surfaces are clean, heat them with a hairdrier and then hold them together for about 1 min. The patch reaches full cure after about 72 hours but is strong enough not to fall off once cooled.


maartenromijn - 19/1/09 at 11:55 AM

I have tried cutting a piece out of my hardened shower door. My advise is before you do anything put some kind of blanket underneith to collect the broken glass pieces.

I have used an angle grinder with diamond cutter disc. When I was almost finished, the glass broke. Next time (if any) I will do it more slowly, and use water to cool the glass.


Mr Whippy - 19/1/09 at 12:15 PM

I mind trying to remove a rear view mirror from a scrap car and it was so well glued on, the windscreen cracked in half so I suppose the glue would be more than up to the task. Cutting 14 holes, in glass will probably just end in lots of cleaning up...


Delinquent - 19/1/09 at 03:07 PM

For the rear glass yes glue would be your only option - but for the side glasses, it's surprisingly cheap to get shapes cut, drilled and then toughened - look for the nearest commercial glazier to you and give them a shout. I'm having 6 panes made up with 8 holes in each for a few bob.

Oh - and I also had pop out windows made for my Carson Top Beetle, so definitely doable in this instance

[Edited on 19/1/09 by Delinquent]