<object width="425" height="344"><param name="movie" value="http://www.youtube.com/v/ZpdCfigUKyQ&hl=en&fs=1"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/ZpdCfigUKyQ&hl=en&fs=1" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="425" height="344"></embed></object> Cooling seems to be the problem. Both test peices shattered as they cooled. This was standard auto saftey glass. I clamped to ground cable to the window frame to get the arch going. After that, no ground was needed.
That is on Tempered safety glass! I wonder if you would have better luck with laminated windshields? I think that cutting tempered glass leaves a release point for the temper causing the glass to shatter.
No photo's (have to wait for my wife, I'm a computer retard) but I went ahead and blasted a laminated windshield and it was a disaster. The glass was cracking as I cut. Long (2 to3 inch) cracks every half inch or so. Also the plastic melted all over the place making a real mess. I'm not even going to mention the smell. So yes, a plasma cutter will cut glass. However, a lot more work is going to have to be done to see if it can be a useful tool.
I tried it on laminated glass...sure you may get a little 1/4" cut but the cracks are still going to be there...you are trying to melt the glass in a localized area with the torch...that makes for high heat in one area and none everywhere else....= cracks. Maybe I'm missing something but cutting glass with a plasma cutter is possible....just not without breaking the glass and making it useless.
Running the plasma cutter without anything conductive to ground burns up the tip of the plasma cutter really fast. Instead of the plasma being between the gun and the metal you're cutting, the plasma is all inside the tip, and it just destroys the tip pretty quickly. The little pinhole in the tip flares out into a big ugly burned up hole. Plasma cutters are only meant to keep the plasma going only for a short time without a ground to help with cutting stuff like expanded metal or mesh. A few times when I tried to cut metal after forgetting to hook up the ground, it just destroyed the "consumables" of the cutter in about 10 seconds, and the quality of the cut was horrible. I've heard some people put sheet metal or foil over non-conductive stuff they're trying to cut. I don't think it's possible to plasma cut glass without cracking it or shattering it though. Try hitting glass with an oxy-acetylene torch and you'll have the same shattering problems due to thermal shock. Another thing you might want to worry about is breathing the silica dust from the vaporized glass, which is probably not too good for your lungs.
Yeah, all in all I'm going to say the whole thing is a bust. Hard on equiptment, and and glass simple can't handle the temp.