Cutting 1/2in Glass?

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Forum topic by Mark828 posted 03-18-2013 03:36 AM 1006 views 0 times favorited 7 replies Add to Favorites Watch
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95 posts in 2106 days

03-18-2013 03:36 AM

Topic tags/keywords: question sharpening

Ive been looking into sharpening my chisels and plane blades lately and I see either granite or glass will do the trick for a good reference surface. So I got a hold of what used to be an outdoor table top ( about 3 1/2’ by 2’) and its either 3/8 or half an inch thick. It’s real heavy so I would like to cut it down to more workable pieces for sharpening. I can’t imagine trying to score it and tap it would work but I could be wrong?

If anyone has any suggestions or experience with something similar, guidance would be much appreciated.

As always, Thanks a Ton!


7 replies so far

View tomd's profile


2171 posts in 3948 days

#1 posted 03-18-2013 03:41 AM

If it is from an outdoor table it maybe tempered glass, you can’t cut that.

-- Tom D

View Mark828's profile


95 posts in 2106 days

#2 posted 03-18-2013 04:16 AM

Hmmm interesting. Is there anyway to distinguish whether or not its tempered. Cause if its not I’m just gonna wing it… and go all out on safety gear haha.

View paratrooper34's profile


915 posts in 3130 days

#3 posted 03-18-2013 10:47 AM

A quick check with google shows there are other ways to check for tempered glass other than smashing it. While the sites I looked at all said you can examine the shattered remains, it was always last on the list. Seems a little odd to recommend smashing it when there are a couple of other ways to figure it out. So here you go:

1. Check the corners of the piece of glass. If the glass is tempered, it is required for the manufacturer to etch the four corners, identifying it as tempered or safety glass.

2. Look for dimpling and imperfections, which were caused during the heating process. Tongs used to remove tempered glass from heat often leave small impressions in the glass that can identified if you look closely.

3. View glass at an angle through polarized sunglasses. Polarized sunglasses expose black lines in the glass that occurred during the heating process. These lines become more prominent at sharper angles.

4. Hold the glass out straight and look for signs of warping or bending. Sometimes the heating process causes mild warping that is easy to identify.

5. Analyze the shattered remains. Safety glass is designed to shatter completely, leaving behind no large shards on which a person might harm themselves.

Good Luck

-- Mike

View Cosmicsniper's profile


2202 posts in 3336 days

#4 posted 03-18-2013 01:29 PM

I’ve tried to cut a 1/4” mirror before. I got scared. No way I’d try to cut 1/2” myself.

Alternatively, why not just get a small plate of granite…it’s cheap (and sometimes free). Granite tiles works well for this.

-- jay,

View Mark828's profile


95 posts in 2106 days

#5 posted 03-18-2013 01:43 PM

Ive heard of people going to a granite shop and asking for scraps for either free or for a few bills. Is this true?

View paratrooper34's profile


915 posts in 3130 days

#6 posted 03-18-2013 01:54 PM

Mark, although I haven’t done that, I heard of some other people who had success with picking up scraps at those places. I’ve also seen off cuts at the big box stores that sell for pennies on the dollar as well.

-- Mike

View JayT's profile


5935 posts in 2389 days

#7 posted 03-18-2013 02:39 PM

Mark, that’s exactly what I did. I walked into a countertop fabrication shop and asked what they would charge me for a cut-off piece. The guy just laughed, pointed at a stack of scrap on a pallet and said to take as much as I wanted, ‘cuz they were just going to dump in a pit as fill. I found a decent piece a couple layers down, took it out and re-stacked the rest very nicely. I think the key was going in offering to pay for it instead of asking for something for free.

A tip I picked up at the Woodworking Show was to try and get the granite after it has been cut and machined flat, but before polishing. Since polishing is done by hand, it actually induces small imperfections and waves that were not there when the machines finished. Probably not enough to really make a difference, but if it is avoidable, why take the chance.

Another option is finding an installer and seeing if you can get a cut-out from a kitchen sink.

-- In matters of style, swim with the current; in matters of principle, stand like a rock. Thomas Jefferson

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