I’d like to re-use a 24 x 28″ piece of 1/8 glass but need to shorten one side by 1/16-1/8″. The archives seem to indicate it’s possible to use a belt sander to do this but I had no luck with 80 (old) and 120 grit belts. Is there a better way?
Thanks.
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Replies
No reason the 120 won't do a fine (literally and figuratively) job, I've done it many times. A fine flat file will also work but very slowly.
Perhaps the glass is tempered? Would that make a difference?Thanks.
Borrow a glass grinder used for stained glass.
Mike
or if there are ANY stained glass hobbyists...or shops in his area, they'll at least have a grinder like this (bottom end basically cheaper version) that would make quick work of what he needs done.
View Image
I can slice a sliver of glass off of a pane like he's got, with my diamond band saw - stained glass hobbyist version...but of course, is uneconomical for him to send that pane to me! Still, anybody who's an SG hobbyist in his geographic area could get the task done for him on their eqpmt in less than 5 minutes...DUM SPIRO SPERO: "While I breathe I hope"
diamond band saw?
well, la dee dah
I've gotta make due with a plain old cast iron one
<G>
2 actually...but they're just tabletop hobbyist's size for use doing SG.
so no basis to be impressed! <g>DUM SPIRO SPERO: "While I breathe I hope"
Glass is so cheap, it's not worth the bother.
$12 isn't a fortune, but is worth saving, to me. Your wallet may differ. <G>Thanks.
A good belt for the sander can cost that much.
Go slow because if you overheat the glass, it is all time wasted
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Some one told me I couldn't trim Neo-ceram glass for a coal stove door..after I did .
I busted a pane with the handle of the grate shaker at 200AM...3' of snow still falling and I had a house down the road that I used to live in that had a door with intact glass ( no one was living there), so I went and swiped the door, cut the glass with a regular glass cutter, nad beltssanded the arch...worked just fine.
Short time later a helper stuffed a bunch of trash cardboard in a customers fireplace..fire it up and busted the glass door, I went to a glass shop and they informed me, it was impossible to cut after "treating"...new to me.
I have also cut tempered and ground the edges for sharpening plates...never problem unless I got it too hot and it chipped.
Gimme a heat gun and a window pane and a putty knife tho' and I am buying a pane, I break at least one reglazing a 6 over 6.
Spheramid Enterprises Architectural Woodworks
"have the cold, comfortably numb"
For Darcy.
Glass-ceramics of the type sometimes used for wood stoves can be cut or ground. Tempered glass is impossible to cut by any method whatsoever.
How much you betting?
I'll cut temp and show ya, for a price (G).
Spheramid Enterprises Architectural Woodworks
"have the cold, comfortably numb"
For Darcy.
I'll go with you, Sphere. I have seen tempered rear window glass (backlite for those in the autoglass business) that was cut down when chopping the top on 60's and newer cars at car shows.SO, it can be done, just not sure how....Frank DuVal You can never make something foolproof because fools are so ingenious.
Diamond wheel, cuts about anything.
But Safty glass as in an auto, is also laminated which makes it a bit easier to cut.
The other tempered glass I have cut was 3/8th thick glass shelves, and yup, I broke some getting the hang of it.
Spheramid Enterprises Architectural Woodworks
"have the cold, comfortably numb"
For Darcy.
>But Safty glass as in an auto, is also laminated which makes it a bit easier to cut.
Just the windshield - all the other glass is tempered.
Don
True.
Spheramid Enterprises Architectural Woodworks
"have the cold, comfortably numb"
For Darcy.
Hot rod shops cut tempered auto glass with sand blast equipment. Mask off what you want to keep with rubber, or duck tape.
I was able to cut about 3/16 off one piece of glass, the 'regular' way, then used the sander to clean up a couple of irregular spots on the cut line. Worked well.Tried the belt sander on a piece of scrap glass that I'd scored and cut, easily. I guess it works, but to take off 1/16 x 20+ inches would take quite a while.In the end, to use the piece I had, that was 1/16 too wide, I used the router to enlarge the opening. Quick and easy. <G>Thanks for all the tips!
Oh no Mister! After all that you cant take the easy way out. Cut the glass dammit!
if he's only allowing a 16th of an inch play..
he'll be back later to make another when that one cracks..
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Forget the primal scream, just ROAR!!!
If you ever need to belt sand the edge of tempered glass in the future, please wear goggles! I once was trying to shave an eighth or so off of a shower panel about 24 x 72. I was 90% there and the whole thing exploded!!! Yes, billions and billions of glass pieces all over my garage and quite a shock to my nervous system.
Be carefull our there!
Fred
Hey Sphere- been there, done that too, and no waterjet cutter was needed. Shouldn't be able to, but you can. When it's free, there's no harm trying! Needed some smaller pieces of thick glass to glue sandpaper to for sharpening plane blades etc., so the need was there. And the glass was free- a store remodel was tossing sheets and sheets of it. Definitely tempered, as they were used for dividers and shelves. Nothing magic: just a good quality glass cutter (i.e. the stained glass variety: very small diameter carbide wheel), good bottom support and lots of force. And both pieces came out fine.
LOL.
That is exactly what I did it for, and where I got the glass.
I was too stupid to KNOW ya couldn't cut it, so I did.
Spheramid Enterprises Architectural Woodworks
Go away rain.
I tell you what I do, and it is ghetto! I carefully scribe my cut line with a standard cheapo cutting wheel. This gives the glass a relief line to break to. Then I take some crappy tile nibbler pliers that I have (also use 'em to pull out nails) and go to town. Takes a while, and the edge looks like crap, but it's pretty accurate and it's all covered with putty anyway. Take your time and go slow...
That's funny- I knew you couldn't do it and I tried it anyway!
It was a keep versus throw decision- if I couldn't cut it, there was no need to keep it!
Who knows- maybe the store was just using 1/2" thick float glass for its shelves and dividers, but that would be pretty unsafe and no doubt break some code or another. Guess I'll have to find an off-cut and smash it to see how it breaks to know for sure. This stuff cut without exploding into millions of little crumblies like I expected. Maybe it's just surface-tempered and the score line went through the tempering. I don't know- I just know I cut it, multiple times, with no problem, and my tools have never been sharper. I can't sharpen a chisel on an oilstone worth beans, but sandpaper on glass and a Lee Valley sharpening jig keep my cutting tools keen. All thanks to glass that you ain't supposed to be able to cut!
I wouldn't even try to nibble off 1/8" or even 1/2" of this stuff, though- bet that would cause big problems. You can get away with that with float glass if you're careful and have a very good score line, but I wouldn't bother- I have a diamond wet grinder for stained glass work. Much less risky.
Glass shelving is not supposed to be made with tempered glass. It is highly unlikely anyone who thought they were working on tempered glass because it came from shelving was.
That's strange: I thought that any glass which was load-bearing, and which might injure someone if it fractures under load, was to be tempered. Maybe that stuff I have IS just really thick float glass. That would make sense. Definitely have to smash some to know for sure.
The store where my wife use to work was remodeled a few years back. They had tons of full length mirrors on the walls, which I pulled off for future projects. The mirrors were 9' tall. I cut about a foot off most of them. I was told they were tempered and could not be cut! I cut them with a standard glass cutter. The edges came out a little jagged and you could see the black(mirror)stuff in the edges. I covered the edges with wood trim. Still on my bathroom walls and neighbors walls looking great!!
Simple reason - whoever told you they were tempered was mistaken - they were not tempered glass.
Glass for shelving is very rarely tempered.
Nope - you can't cut heat-tempered glass - period. Physically impossible because of the nature of the beast.
You may have cut glass that you thought was tempered, but it wasn't.
Glass is tempered by taking the core of the lite to 940 degrees F. To do this the tempering oven will heat the lite to about 1100 to 1200 degrees F.
When the glass has reached the desired temp, it is blasted with cool air (quenched) until the exterior surface temperature is lowered to 900 degrees F. Since glass expands when heated, the outer surface of the glass shrinks during the quenching process causing a compressive surface layer.
The inner portion of the lite is still expanded and it is still in a semi-molten state. The inner portion of the lite cools much more slowly and this induces a tension layer.
When completely cooled, the compression layer comprises the outer 21% of the volume of the lite completely surrounding the inner tension layer.
If you pierce the 21% layer the tension in the inner portion is released and BANG lots of little pieces of glass...NO exceptions.
Doesn't matter if you cut it with the best diamond saw in the world, or a water jet, or by hand...the glass WILL burst if it was tempered.
You can shave a small amount from the edge of a tempered lite - as long as you don't contact the tension layer - otherwise - buy a new sheet.
Laminated glass can be cut using a diamond saw, a water jet, or by hand - although by hand it does take a little experience.
Chemical tempering occurs when the glass is suspended in a bath of liquid potassium nitrate at about 800 degrees. At that temperature the glass "relaxes" and expands slightly.
Once the glass is relaxed it releases sodium ions to the bath and these are replaced by potassium ions from the bath. Since potassium ions are larger than sodium ions this places the surface of the glass in tension once the glass is cooled and resumes its "normal" size. The depth of this tension layer is only a few molecules thick though so only the surface of the glass is affected.
Chemically tempered glass is not considered a safety glazing product since it doesn't shatter into tiny pieces when broken...but the surface tension can be many times that of heat tempered glass.
But, chemically tempered glass can be cut using any means that will cut annealed glass - however, cutting chemically strengthened glass "removes" the tension for about 1" or so from the edge of the cut.
OT, but I don't believe what you cut was fully tempered glass. Fully tempered glass resists impact because it has huge internal stresses put into it with heat treating. Cut into it or catch it on a corner with a sharp object and the whole pane blows into a zillion fragments instantly. There is something called chemically tempered glass that can be cut, but I don't know anything more about it. Laminated automotive safety glass is a sandwich of glass and plastic that can be cut or ground.Pete
Edited 10/18/2006 7:30 pm ET by PeteBradley
Chemically tempered glass cannot be cut, either. I work for a company that used to make it.
I've cut tempered glass too. Not easy to cut but it can be done! The REAL trick is to cut it into usable sized pieces... mine were about 1/4 inch diameter and smaller. That is what you get when you cut tempered glass... UNLESS you were to heat treat the glass, basically reversing the tempering process. This could theoretically be done, though it is hard to imagine a scenario where it would make economic sense.
You could take a 'crack' at it with an angle grinder if you have one. Yes the pun was intended. ;-) Discs for masonry should work. Cheap imported diamond wheels 4.5" dia are about Can$12 around here.
Well, I definitely got nowhere with a brand new 120 grit belt on the sander--and I had it on there long enough I was worried about overheating it. (Just occurs to me I should try a piece of glass I have that I KNOW isn't tempered.) I do have a masonry disc for the angle grinder. I'm guessing you'd want the glass well clamped, very close to the edge you'd be working on? I'm also going to guess you two can't both be right about whether tempered glass can be cut or not?? <G>Thanks again.
Too bad it's sunday nite...
I mean, you could go to virtually any garage sale, pic up a cheapo picture with same kinda glass ya need but larger dimensions, buy yourself a std glass cutter at the box stores to score/cut it down, and be done with this for under $5 and a lot less time!DUM SPIRO SPERO: "While I breathe I hope"
Try a Silicon carbide belt, much harder than aluminum oxide abrasive used for wood working. As last poster indidacte, protect your lungs. Grinding glass or stone is typically done under a mist of water to precipitate the dust, and keep things cool, need to protect against electrical zap however.
try the blue belts and clamp the glass between wood strips at your cut line
Tempered glass is regular glass that's heated to some high temperature and then quenched. This cools all 6 sides faster than the center, and they shrink, creating an outer tension layer that lends amazing strength to such a fragile substance. If you cut, or in some cases nick, an edge of a piece of tempered glass, the tension goes out of balance, usually shattering the glass. Just how Sphere got away with it I'm not sure.Andy
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Ive trimmed panes that little by scoring with a glass cutter and nibbling and I've trimmed panes with a tile saw. Neither method is great and if it was me I'd get a new pane. I own the glass grinder type pictured but I'd still spring for the right sized pane or cut one down from a larger size.
Tom
Just a note of caution: When sanding/grinding glass, be sure to wear a good respirator. Silica dust + lungs = not good.
Mike Hennessy
Pittsburgh, PA
I once had a glass shop increase the four radiused corners of a 30" X 60" X 1/4" safety glass from 5/16" to 5/8", and they used a belt sander. Which is obviously a good tool for the job. My suggestion would be to use an aluminum oxide 100 grit cloth backed sanding belt and a very small amount of Bee's Wax directly on the belt; and as one replier previously stated "go slow". Of course, the guy in the glass shop did it as quickly as we would sand wood. My understanding of "go slow" is to use a light touch.
That's like a crooked nail, that you have to try and straighten out!