cutting laminated glass?

[NH-Rob]

I picked up some windshield glass out of a couple school busses and I am trying to cut them to make windows for my cab build. I watched a good video on youtube showing how it is done and it looks real easy YouTube - How to cut laminated glass. I am not having much luck with it. So far I am able to make it work 1 time out of 10. I scripe the glass and go to crack it and the darn stuff will not crack. I even tried scriping both sides of the glass first and still have no luck. By the time I get it to crack I end up breaking it in other spots too. I am having decent luck on small sections but anything with a big cut just does not work. Can some one give me some pointers?
Thanks,
Rob

 

[racerboy832]

When i saw them do it for my dad, they marked it, Put alcohol on it and lit it on fire. This made the laminate bend. They made it look real easy.

 

[/pine]

are you using a lubricant ?

 

[crazyal]

Lay the glass on a flat table. If possible buy a Fletcher glass cutter, even the cheap ones work the best. If there's any rust on the cutting wheel it's not going to work well. Use kerosene to lubricate the cutter, just paint it on the glass with a brush before you scribe it.

Slide the cut to the edge of the table and let the weight of the glass break along the score. Don't put too much force trying to break the glass or you'll break the other side and ruin the piece (this only works for straight cuts).

Another option would be if you have some old carpet you can put that down on the table first. The after scoring the glass you flip it and then you can push on the score and break the glass. Just start at one edge and work your way across the glass.

Either way you'll need to flip the glass. The best way is to flip it perpendicular to the score. Slide it half way off the table and pivot it on the corner of the table. Once flipped you'll need to cut the other layer of glass.

Also pick up some denatured alcohol and after making both cuts put a little on the cut. It will soften the plastic enough so you can use a razor blade to cut the plastic. The pros will set the alcohol of fire to heat up the glass a little to help soften the plastic and speed things up. What you'll want to do it slide the glass so the cut in the glass is near the edge of the table, say 1/8' to 1/4" still on the table and slowly let the cut open enough to get the razor into it to cut the plastic.

 

[MtnViewRanch]

Lay the glass on a flat table. If possible buy a Fletcher glass cutter, even the cheap ones work the best. If there's any rust on the cutting wheel it's not going to work well. Use kerosene to lubricate the cutter, just paint it on the glass with a brush before you scribe it.

Slide the cut to the edge of the table and let the weight of the glass break along the score. Don't put too much force trying to break the glass or you'll break the other side and ruin the piece (this only works for straight cuts).

Another option would be if you have some old carpet you can put that down on the table first. The after scoring the glass you flip it and then you can push on the score and break the glass. Just start at one edge and work your way across the glass.

Either way you'll need to flip the glass. The best way is to flip it perpendicular to the score. Slide it half way off the table and pivot it on the corner of the table. Once flipped you'll need to cut the other layer of glass.

Also pick up some denatured alcohol and after making both cuts put a little on the cut. It will soften the plastic enough so you can use a razor blade to cut the plastic. The pros will set the alcohol of fire to heat up the glass a little to help soften the plastic and speed things up. What you'll want to do it slide the glass so the cut in the glass is near the edge of the table, say 1/8' to 1/4" still on the table and slowly let the cut open enough to get the razor into it to cut the plastic.

Can't add much on how to do it better than this other than the oil lubed cutters are quite a bit better than the dry cutters, but either will work fine. We use the edge of an old tape measure tape to cut the laminate after heating with denatured alcohol. The tape is much thinner than a razor blade and is quite a bit easier to use than a razor blade in my opinion.

Good luck, it's not all that easy if you aren't use to cutting glass.

 

[toy]

You might be able to get a better score line with a hand held tile cutter.

 

[Nuno]

Hey Rob,

i have see how the Guys from the Glass Shop who mave made my Cab Glass do it.

They cut the Glass from both sides and then they heat the cut up with an Torch and push the cutted piece of Glass away.
The Heat will make the plastic lamination between glass plates soft like chewing gum.

i have not try it by my self but it looks very easy, maybe i will try it if sometime one of the glass will broke and must be replaced

 

[NH-Rob]

are you using a lubricant ?

I dip the cutter in keroseen first. I am using a new cutter that I got from ace hardware I think its a red devil or something. I have no problem cutting the laminated plastic the problem is just that the glass will not break. Does the preasure I put on the cutter make a difference? I have been using more preasure thinking the score line needs to be deeper but maybe thats wrong. Do you think the glass would snap easier if I heated the score line first?
Thanks for the help,
Rob

 

[mrmikey]

I was watching the glass guys at work awhile back and that's exactly how they did it, they make it look easy.
I think what happens if you don't use heat to allow the plastic to bend and stretch is that when you try to bend it it won't because of the tension of the plastic. You end up cracking it from the other side where it's trying to compress. Dunno for sure it's just my guess....Mike

 

[Gary Fowler]

My wife did stained glass for a while and I found that the glass breaks better with a light score than a heavy one. When I first tried to score it, I thought that if one swipe with the cutter was good, two would be better. The glass wouldnt break at the score when I ran the cutter twice and made a deep gouge line. Our instructor then told me that you just need light pressure on the glass cutter so that it leaves a V in the glass, too much pressure and the V gets a rounded bottom on it and takes the stress riser out. All you need is light pressure on the cutter so it makes a fine clean line. Use a good quality cutter and lub it with kero and light pressure and do both sides. The glass is only going to break from the side that it is scored, so you need to lightly bend the one side till it breaks then flip it and break the other side. Hope this helps. It works with sheet glass, but I have not tried to cut laminate glass.