Cutting window glass

So, I've got a busted window, and I've got a lot of window glass salvaged from another project, and I've got a glass cutter I inherited from my father, and I think, "How hard can it be to cut a piece of glass to fit this window?"
Answer: pretty hard.
Here's what I've learned so far:
1) get an new glass cutter, the old one is dull 2) clean the glass first 3) lubricate the cutter with kerosene 4) cut in *one* smooth stroke 5) bear down hard, should hear a crackling sound 6) tap along the cut 7) snap the glass while the cut is fresh
I can do short cuts, up to about 2 feet. But I need to do a 45" long straight cut, and the glass just won't snap!
Any advice?
Is there any way to make a series of short cuts instead of one long one?
Thanks,
--- Chip
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the table covering up to near the cut and press down firmly.

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Cutting glass with a good cutter isn't that difficult..
However, old glass is hardly worth working with if it isn't the correct size to begin with.. Glass gets harder and more difficult with age (years).
Also, the glass cutters with the little metal wheel are not the best. A diamond tipped cutter is best.
When you score you glass, make sure it is laying on a 'dead flat' surface. Avoid putting weight onto it other than to score the surface.
Use a good straight edge. Start your score at one end of your straight edge and follow through continiously to the other end. Don't go over your score a second time, Big mistake if you do!
No need to score the opposite side unless it is laminated safety glass.
Once scored, you should be able to snap it off over the edge of your work table.
If you scored it correctly with a good quality cutter, you should have a clean cut and now need for trimming.
Steve
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On Wed, 12 Nov 2003 00:51:57 +0000 (UTC), snipped-for-privacy@blue.seas.upenn.edu (Charles H. Buchholtz) wrote:

Get a straight and sharp length of material (wood works fine) and position the glass score over the edge. The glass should snap easily. If you are trying to cut a long narrow piece, sandwich the glass between two pieces of material. It is more difficult to cut several short pieces than a long one, you'll end up with a serrated edge. Sandpaper the freshly cut edge.
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Charles H. Buchholtz ( snipped-for-privacy@blue.seas.upenn.edu) wrote:
: Here's what I've learned so far:
: 1) get an new glass cutter, the old one is dull : 2) clean the glass first : 3) lubricate the cutter with kerosene : 4) cut in *one* smooth stroke : 5) bear down hard, should hear a crackling sound : 6) tap along the cut : 7) snap the glass while the cut is fresh
: I can do short cuts, up to about 2 feet. But I need to do a 45" long : straight cut, and the glass just won't snap!
Well, I've learned something else: "Make sure the glass is not tempered glass". The short practive cuts were in smaller sheets of regular glass, but it turns out that the large sheet I had (which I didn't want to practice on because it was the only one big enough for the window) was tempered glass. I could score it perfectly, clamp it to a table along the score line, and sit on it and bounce up and down and it wouldn't break.
But I've got no problem cutting the regular glass I was practicing on.
Thank you all for your help,
--- Chip
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wrote:

if it was tempered glass, it would have shattered into a bazillion pieces when you first cut at the edge.
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Charles Spitzer ( snipped-for-privacy@nospam.stratus.com) wrote:
: if it was tempered glass, it would have shattered into a bazillion pieces : when you first cut at the edge.
Well, I cut with a wheeled cutter and got a good crackling sound and left a groove I could feel with my fingernail. But I could sit on it and bounce up and down and it wouldn't break. The piece of glass was criss-crossed with grooves, because I kept trying slightly different techniques to try to get it to break.
Finally, I gave up and asked my local hardware store to come over and replace my window pane. I described what happened, and they said that if it didn't break when I jumped up and down on it, it must be tempered glass.
So, I figured I'd throw out the sheet I had been working on, since it was criss-crossed with scratches and I couldn't cut it anyhow. Since it wouldn't fit in the trash, and it was already clamped to my work table with a section overhanging, I figured I'd just hit it with hammer to break it into pieces. I took an eight pound hammer, put on my goggles, and whacked it. The hammer bounced off. I whacked it harder - same thing. So I raised up that hammer and really put some back into it. That's when the glass shattered into a zillion tiny pieces. The entire pane shattered - even the part that was clamped flat to the table.
So I don't know if it was safety glass or tempered glass or something else, but I don't feel so bad about not being able to cut it.
--- Chip
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wrote:

Huh? I don't think tempered glass would shatter like you mention. Safety glass would, but not tempered glass. It's my understanding that tempered glass is designed NOT to shatter and is used in larger window and door glass, or for glass shelves where higher strength is necessary
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http://computer.howstuffworks.com/question508.htm
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wrote:

then you thunk wrong. you're thinking of safety or laminated glass, which is in car windshields. the rest of the car windows are tempered, and can be shattered by taking a nail and ramming it hard into the glass, preferably in an edge. a blunt object (like a wide faced hammer, like the OP used) won't shatter tempered glass without a good deal of effort. i've seen people drive golf balls into tempered glass from short range without any breaks.
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wrote:

Guess I did thunk wrong :)
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