I am making a cabinet. I would like to glaze the cabinet doors and put a mirrored back in it. Normally I just buy the stuff ready cut. I found a piece of mirror at the dump and brought it home.
I have some of those old fashioned metal glass cutters. I scored each line about 20 times. Then I tapped several times. Gentle pressure did nothing. Saveral taps with a rubber malett . . . was a stupid thing to try.
So how do you use those little glass cutters properly?
Firstly, you should only score the line once-if you go over it repeatedly you damage the tungsten edge-it is brittle, then that cutter is history. Secondly glass becomes harder with age-makes it more difficult to cut.
If you get new glass, new cutter and some kerosene you will soon see the difference: score once against straight edge, support the edge under the cut and snap it off.The scoring takes a firm hand, and you can hear the sound of an effective cut. Philip Marcou
Edited 4/21/2007 10:38 pm by philip
If I may ask a related question that you may have experience in -- how do you cut a right inside angle in glass? Some years ago I built a grandfather clock with instructions from Mason and Sullivan. The glass over the face had two such angle cuts. I took it to glass cutter that probably tried half dozen times before he made a half acceptable one. There must be a way as that is what the blueprints called for. I have wondered if one could drill a hole in it while submerged in water, then cut the lines to the hole. Would like to build some more of those clock cases but that is one of the problems.
I have limited experience of glass cutting, only simple stuff. Your plan sounds workable, but having the correct drill bit and method should not require that you submerge the glass. I have drilled a few holes by using a special carbide bit, with a ring of putty to hold the kerosene around the hole- slow revs with good support under.
There are belts available for use in a belt grinder to sand the edge- Klingspor do them, so if you needed to fair the areas adjacent to the hole they would work. Also the very useful diamond plate works the edges of glass easily.
I am willing to bet that there is a more cunning way , though.Philip Marcou
Like any cutting tool, glass cutters need to be sharp. Normally, a lubricant like kerosine is used. It's important that you make ONE, firm, steady pass. You will be able to hear the wheel making the score, the sound is distinctive. You know that the cut has been made. It's a good idea to have a padded surface to work on, safety goggles and leather gloves. After scoring, you can lift up the cut end a few inches off the table, like opening a door just a little. Place a stick or rod, like a 3/4" dowel, flat and length ways under the sheet on the keeper side, an inch behind the cut, and just drop the glass on the dowel. The cut will snap off. To get a clean cut, you need to make a good score from start to finish. You don't have to score deeply, just evenly. The teeth on the side of the cutter are for breaking off small areas that may not have broken off cleanly. It doesn't take much to break thin glass like a mirror. You have to be careful about putting any stress on the sheet by twisting or hitting. If you have ever snapped a sheet of sheetrock, glass is similar. The snap has to be quick and abrupt. Dropping it on the stick applys the right force. Easier to show than explain.
Beat it to fit / Paint it to match
Along with the excellent advice so far, I would add tapping on the back side of the cut after you have scored it. In fact, that's what that little ball on the end of the glass cutter is for.
Such tapping is not really necessary with single strength glass, but it does help with tougher materials -- like a mirror.
I'm assuming your mirror is 1/8".
The score is everything: apply enough pressure across the cut, so you hear a consistent cracking sound. Practice on scrap will help you get the pressure/technique right.
I use 6-10 sheets of newspaper under the glass, which provides just a little padding, but a firm surface to snap the glass. I also use a couple of spring clamps to hold the glass in place when I snap it.
"It is what we learn after we think we know it all, that counts."
John Wooden 1910-
Thanks all for the great advice. As I suspected, I was all wrong. Also this advice seems sounder then using the table saw (10 year old's suggestion).
Cutting glass ..............in actuality you are controlling the brake.Type of glass should be identified. As you indicated the glass is mirror, no big deal. mirror face side up.
The correct glass cutter must be chosen. The cutter thats most often available should do. The wheel must be chip and nick free, clean of contaminants, spin freely. Most often glazers would just leave the cutter sit in the tin with the kerosene. Wheels can get dull from use and from corrosion. The newer version cutter have fluid reservoirs in the handles.Place your wooden straight edge, draw a brush full of kerosene along side it and holding the cutter vertically, press down and score the glass. (only once) Practice so you get "the sound" down before the important cut. Don't cut to close to the edge or braking away from the sheet is problematic and less than desirable. You should be able to cut single and double strength glass 1/4-3/8" from an edge. Larger is better. Never re-score.
Thicker glass has wider requirements or distances from the edge.
Cutting "so called stained glass" presents a few differences. Harder, softer, thicker, thinner, hard spots, tight inside radius, soft curves. Equals different angled wheel and smaller diameter.Don't tap straight line cuts, place a wooden pencil under the score line and gently push down, on the end nearest you to the outside of the score line. (I'm a right handed)
I prefer to hold each side of the score line at the nearest edge to me. index finger and thumb. Make a fist thumbs up. thats how to hold the glass. Just twist them simultaneously thumbs roll to the outside, down wards (slightly ) folded index finger supports and slightly moves up. All done, ready for next cut.I hope this helps.
Lube is the trick with glass. WD40 works in a pinch. Cutter should sound like a light sizzle as you run it across the glass. This is a controlled break and the "cut" induces a stress line. As others have said lift the glass a little and have the "cut" on the outside of the break.
There is a glass cutter that is made specifically for mirror glass - I believe the angle of the cutter was slightly different. I found it at Hobby Lobby I think.
Listen to the others, kero lube, firm pressure, one pass. Also listen ! A good score will sound like tearing paper. Try this experiment, score a scrap piece of glass and quickly hold it up to your ear. You should hear a very faint crackeling sound, wait till you hear the sound stop and then try to break the glass, you'll find it much more difficult to break that way. Try again and immediately try to break the glass while it's still making it's crackeling noise. Bingo a nice clean break.
My prefered method for holding the glass is as follows. Make two fists with your thumbs parallel to the first two joints of your index fingers(thumbs on top). After scoring the glass, place it under your thumbs quickly and with one quick motion rock your thumbs appart keeping your little fingers together as a hinge . It works for me.
Work Safe, Count to 10 when your done for the day !!
Edited 4/22/2007 1:06 pm ET by BruceS
Possibly you may have a piece of tempered glass. (It was in the dump, unbroken.) If so, there is no way to cut it.
Here are a couple of sites that I found helpful when I was learning to cut glass.
For snapping the scored glass I've found a glass pliers gives more consistent results than other methods but YMMV.
Just to let you know, your 10 year old son was NOT that far off. If you go to places that make larger stained glass assemblies, they DO have a bandsaw that cuts glass. It looks like a 9" table-top saw with a 3/16" (tungstin coated) blade, the lower guard being a water tank so the blade is always wet. You use it just like you'd use a bandsaw on wood, cutting curves, straight lines and yes, even the 'ell' shaped notch for the clock face. You've just got to feed it slightly slower than you do with wood.
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