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Cutting glass


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I sent the StewMac 16" sanding bar back, because it wasn't as flat as my old 'donnell fret and fingerboard plane'. But this fingerboard plane is only 13.5" long.

I have a bunch of 1/4" thick glass that turns out to be very flat (even a little more flat than the ground surface of stewmacs sanding bars). I want to make my own stewmac style sanding bars by gluing glass to a piece of wood or something.

I need to cut pieces of this thick glass to 18"-19" long and 1" wide.

Can't get a piece that long to turn out. I got a nice 8" long x 1" wide, so far.

I have a glass cutter, and have had luck cutting small pieces of this thick glass, but no luck getting an 18" long piece to turn out. It ends up breaking in half, etc.

I can't figure out how to cut off such a narrow strip of glass off the bigger piece.

Not even expecting any help here with this, because it's unlikely that most of you have even cut glass this thick.

I found some sites, that have a few different methods, but so far no luck when I try myself.

So, any advice is appreciated.


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Cutting glass is easy... in theory. I could tell you all the stuff you probably already know, just score, tap and snap. 1/4 inch clear glass should snap clean in any length depending on it's properties. Old glass and poorly annealed glass can cause problems but 1/4 inch clear should be the easiest glass to cut. Try cutting inside curves on 1/2 inch tempered glass, now that is fun. A good cutter and lots of practice to get the feel of cutting is all you need.

I've cut miles of glass and used to be able to cut complex curves in even the most temperamental pieces. But now after being away from it for years I would consider taking it to a good local mom and pop hardware store to cut rather than try and get back into the swing of things. They have that nice straight edge cutter that makes scoring a breeze.

Backing up the glass with wood or something is a must. 18 inches of glass that thin will flex way more than you would think. Make sure that the board you're gluing it to is perfectly true or the glass will bend to it's shape when you glue and clamp. You will also want to grind the edge down and round the corners a bit.

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yeah. buy a regular plexiglas cutter at your hardware store/ they're about 5 bucks. just score the line for about 20 minutes. then just set the line on the edge of a table. Glass will not snap clean unless you set the exact line on the edge of a table. Simply press down on the end you need to snap off. and if you scored enough it should be quite clean.

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Sorry to disagree Snork but the plexi cutter won't cut it. :D

Use a good glass cutter, the cheap ones in the store are OK if they are new.

The tabletop idea is a great one, thanks for pointing that one out Snork. Give it one good score with a smooth motion and a medium firm pressure, just enought to get the little chips started along the line. There is no need to dig in deep, that will cause little fractures to start away from the line. Then put it on the edge, grab the middle and give it a good, firm snap.

You can also tap on the backside of the cut to get the crack started but the quick snap will give you a nice clean cut much easier.

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Hey thanks guys, I wasn't even expecting so many replies about glass cutting here at the projectguitar forum. It turns out that a good friend of mine is married to a lady who has been cutting glass for several years and has all kinds of tools for doing it, such as a $30 oil filled glass cutter, and special rounded pliers or something like that. I'm going to go there and see if we have any luck.

When I was 12, I used to have this thing you would put a bottle or jar on, and turn the bottle or jar, and it would scribe a line around the glass. Then I would use a candle to heat the scored line, then after a while dip the glass into cold water, and 90% of the time, it would snap off right on the line.

So earlier today, I thought maybe something like that would work with this 1/4" glass. I took a frozen jug of ice out of the freezer and beat the hell out of it with a hammer, letting the ice chunks fall into an old coleman cooler. Then I filled the cooler with about 4 gallons of water. Then got the torch and heated the glass on the scribed line for about 3-4 minutes, then dipped it into the ice water. WHAT A FREAKIN' WASTE OF TIME ! B) Didn't work right.

Not to mention there are glass fragments all over my shop, with customers guitars in the shop too. :D

I finally had blood running out of my thumb, without even knowing exactly how it happened.

But if I end up with some 18" long, very flat sanding bars, it'll all be worth it.

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  • 2 weeks later...

Drew. Snork, you guys were right. But it took the right tools. Went to my buddy's today, used their $35 wheel, oil-filled, glass cutter, to score the lines, then we used their "running pliers" or whatever they are called. They are curved face pliers. You line up the little line on the pliers over the score, and then with some moderate pressure squeezing of the pliers handles, the glass snaps apart perfectly on the scored line. The special pliers also have a screw to adjust them so they don't get squeezed more than they should.

I got some great pieces of 1 1/4" x 19" strips to make an even better sanding bar than the Stew-mac one I had. The glass is flatter than the surfaces of the StewMac bar, it's longer and CHEAPER!. I can sand all the frets at once from side to side on a strat neck. None of that 16" long crap, that was probably designed so it could be used on an LP fret-board where you don't want to remove the neck p/u.

I'll be gluing the strips to a thick piece of dense fiber-board tomorrow.

I had doubted those special pliers would work on 1/4" thick glass. They worked great, and it was quite easy. From doing this myself (with a little help), I can now imagine a glass shop probably wouldn't charge much to do this.

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Hmm... what kind of glass did you start with? I'm looking at some prices for 1/4" and 3/8" glass shelves and they're very cheap! Even factoring in tool costs like oil-filled cutter and the pliers (or having it done at a glass shop,) it'd probably be much cheaper than a set of the StewMac's levelers (I'm assuming you mean these.) If it works out well for you, maybe it should be added to PG.com as a tool tip :D.

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Yes, I am talking about the tools in your link. The glass I used is actually 1/4" thick mirror. I had these 2 big mirrors in my garage and they ended up getting broken, which left me with several, still sorta big pieces, that I was planning to throw away. After not being satisfied with the flatness of the stewmac bar I had, I then checked out these mirror pieces and found them flatter than the damn bar ! I used my 24" precision straight-edge and feeler gauges to check the flatness. That's the key. You need a really good, REAL straight-edge and feeler gauges to check any glass you are thinking about using for a precise tool like these leveling bars. Not all glass is this flat. I have often checked all kinds of glass I had got from here and there, and never found any of it to be dead flat. So I just assumed these mirrors couldn't be so flat either. But they sure are. B)

I looked up info on glass related sites about cutting glass. Like this one:


(the tech-tips box on the right side )

Then after reading that, I told my buddy I could just try it myself with his tools. He helped me a little anyway. (His wife was supposed to do it, but she was sick for a while)

I'm also going to make an 8" one for the hell of it.

I also cut a few 16" long ones, in case the vintage LesPaul situation would ever come up :D

If I was buying glass to do this, I would check around to see if any places can say how flat their glass is. Using glass for stuff like this is nothing new, so there should be some places that offer really flat glass.

Make sure you don't use some kind of "safety glass" , which some shelf glass might be. It will just break into little squares when you try to cut it.

I think buying the tools and glass would actually be more expensive than buying the 16" bar from stewmac. But if you use glass that's as flat as mine, and make more than one bar, I guess doing it my way might be worth it.


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