Sand blasting holes in glass?

[Corley]

To anyone with experience here...

I've tried drilling holes in glass in the past, with bad results. That is, the glass cracked out from the hole just as the drill bit went through. (special V shaped diamond coated drill bit for glass.) I gave up on that process.

The other day my wife wanted me to experiment with etching some patterns on glass, since I was doing some sand blasting anyway on the Model A parts. So she taped off an image of a humming bird, and I hit it with the sand. Turned out my nozzle and sand were a bit too much for the glass, and really cut into it almost immediately, making a depression of about .020" or so. Also tore the tape up pretty bad... I guess that the amount of blasting that it takes for rusty metal is way to severe for etching a pattern on glass.

It got me to thinking that it would be pretty easy to drill a hole in glass using sand blasting, if it didn't cause it to crack and break.

So, the question is: has anyone tried sand blasting holes in glass, and what would the correct proccess be for that, or is it a no-go. Something like a small windshield wiper hole would be nice if one could accomplish it easily with sand blasting. Curious minds want to know!

CB (AKA Corley)

PS I sand blasted some brass windshield slinder pieces that came out a beautiful brass patina. Do you suppose if I coat that with a paint clear coat it will stay looking nice?

 

[putz]

I have seen holes drilled in regular glass but tempered glass is hardened to break in unusual patterns.

This was taken from www.cruisersforum.com

Tempered glass is regular glass that has been heat treated to increase strength and thermal shock resistance to prevent injury by changing the break pattern.

All fabrication (cutting, drilling, edging) is done prior to tempering.

The manufacturing process of making tempered glass results in the glass having a large amount of stress between various portions of the glass. Highly tempered glass will often crack at the stress points near the hole. Since the amount of hidden stress increases with the degree of temper, the success rate of drilling tempered glass reduces with the increase in glass temper.

There is no way to know the amount of temper in a piece of tempered glass, so there is no way to evaluate the amount of risk involved in trying to drill it.

Therefore, experts DO NOT RECOMMEND attempting to drill tempered glass

 

[fordsbyjay]

What you need to do is drill the hole before they temper it. At least that is how it is normally done. The sandblasting thing sounds interesting though. I look forward to some more input.

 

[Corley]

BTW, the window that I experimented on was a door window from a Suzuki XL7, so I assume it was temperred. Didn't break when I threw it in the dumpsters, so is pretty tough stuff, but that sand sure cut into it a long ways in a hurry!

CB

 

[putz]

I wonder if a waterjet could do it?Guess not just found this from wikipedia
Materials commonly cut with a water jet include rubber, foam, plastics, composites, stone, tile, metals, food, paper and much more. Materials that cannot be cut with a water jet are tempered glass, diamonds and certain ceramics.[sup][5][/sup]

 

[Corley]

I know that side and rear windows on cars are highly temperred, but I thought windshields were not temperred, just two pieces of untemperred glass sandwiched around that gooey plastic. Is that right or are windshields temperred too? If not, then maybe there is hope to either sand blast a hole or water jet a hole through it. Just curious, don't actually have an application at hand... Maybe when I get back to Battle Ground I'll dig that temperred piece out of the dumpster and try sand blasting a hole clear through it just to see what happens. I hate it when temperred glass breaks though, it makes such a mess...

CB

 

[409T]

For sandblasting a pattern we mask off the area with a product called butter-cut, use an Exacto knife to cut out the design and then blast away. How much glass is removed will depend on the media, pressure, nozzle size and so on. Acid etching is another way to accomplish nearly the same thing. All this, as well as drilling, edging and what-have-you has to be done before sending the glass out to be tempered.

Jeff

 

[Don'tCallMeJimmie]

I know that side and rear windows on cars are highly temperred, but I thought windshields were not temperred, just two pieces of untemperred glass sandwiched around that gooey plastic. Is that right or are windshields temperred too? If not, then maybe there is hope to either sand blast a hole or water jet a hole through it. Just curious, don't actually have an application at hand... Maybe when I get back to Battle Ground I'll dig that temperred piece out of the dumpster and try sand blasting a hole clear through it just to see what happens. I hate it when temperred glass breaks though, it makes such a mess...

CB

Corley, you are right on the money. Side glass is tempered so that when it breaks it shatters into tiny, less dangerous pieces. Windshield glass is untempered and laminated so that it WON'T. They cut down windshields by blasting so I don't see why you could not sandblast a hole but the stress released might cause cracking - quite different making a hole vs wearing surface or an edge off of plane of glass.

 

[ruggs]

Corley and Don'tcallmejimmie are both right, windshields are untempered laminated glass. We have had them drilled for years but, the trick to it is let the glass company do it. That way they cut and drill until they get you a good one. You only pay one time
As far as sandblasting a hole, I sure wouldn't know but you could always try on an old piece.......ruggs

 

[Ted Brown]

The glass man came out to replace a tempered glass in an office door, full door glass top to bottom, he walked up and walked right through where the old glass window was, just a second ago, and not a sound was made... He told us that is how people break into office buildings without making any noise and looking from a distance like they had a key to enter... He just uses a snap punch, the point shatters the glass in a million pieces instantly... You can drive over that same glass (a brick at each end) and it will not break, tempered glass breaks mostly from the edges, like regular safety glass in windshields. is very easy to break starting at the edge, that is why the edges are sealed in a special compound..

 

[T-Test]

Don't know about tempered glass, but I drill holes with the glass bits and running water to cool it. The headstone makers use a rubber pad that sticks to the marble/glass with the pattern cut in it and then sand blast at medium pressure to engrave with. Don't need much blasting to etch glass.