Cutting remarks (cutting glass with a tile saw)
February 13, 2012 by Cynthia
It’s all in the way you slice it. And the way you slice it is, apparently, profoundly affected by a good blade.
Check any glassmaker’s forum and you’ll probably find someone with glass cutting issues, usually stemming from a tile saw that’s more like a Cuisinart than a slicer. I don’t claim any special expertise at this stuff, but I do have a decades-old, cheap, badly made, out-of-true tilesaw that reliably cuts amazingly thin murrini cane* slices.
Shown below, top to bottom, for example: A piece of thin (2mm) Bullseye Gold Purple, a piece of 3mm Bullseye Marigold Yellow…and then a series of pattern bar slices I’ve tried at various thicknesses. The thinnest (sixth from the top) is 1.5mm thick.
I do this a lot. So I must be doing something right…right?
Apologies for what’s probably a boring (and redundant) subject to most glassworkers, but this post is about how to cut glass with a tile saw. There are already some excellent tutorials and videos on using tile saws to cut glass. I STRONGLY urge you to buy Jonathan Schmuck‘s excellent book on coldworking and ask some real experts. And HIS Glassworks has a number of videos on coldworking and glasscutting, like this one:
During the 15 years or so I’ve been coldworking glass, I’ve ruined a LOT of things with a tile saw. I think/hope I’ve also learned from all those mistakes, so here are my rules for cutting glass with a tile saw:
Caveat–this is what works for me; as usual, your mileage may vary. If you have additional tips, please, please chime in by commenting below.
1. The most important part of my tilesaw is the blade.
My tilesaw came with three cheap, thickish (2mm, or about .085 inches, thick) diamond blades. I was happy to get them, they’re great for making rough cuts in the glass that you plan to coldwork later, and probably work well for cutting ceramic tile.
However, those blades take a huge kerf (the gap created by the saw blade) with each slice, which wastes material.
Worse, if I’m very careful, I can get them to slice the glass to about 3/8 inch with only a little breaking or chipping…but no narrower.
I complained about that to expert coldworker Marty Kremer and he said “You need a decent blade.” He was right.
On his recommendation I chose a 10-inch Result blade from HIS. It’s half the thickness of those old blades–0.04 inches or a little more than 1mm thick–and makes a huge difference in the quality of my cuts. I have much less chipout (the chunks that fly off the edges of the cut). Kerfs are less than half the previous size so I waste less glass.
The best part: Thin slices. I can slice a 2 inch thick block of glass, 10 inches long, into slices between 1mm and 2mm thick. That’s thinner than a US dime.
Thinner slices mean I can get more slices per block of glass. It also means I can put a lot of detail in the block with darker frits and powders without worrying that they’ll look black in the slice…and THAT gives me a much wider color palette when working on murrini cane. And, interestingly enough, this blade cuts about twice as fast as the old blades.
2. I must control blade wobble.
There’s probably an expert term for “side-to-side movement of a saw blade on a fast-moving spindle” but I just call it wobble. A saw blade can wobble because there’s some play in the way it’s attached to the spindle/axle-thingy (the nut’s not firmly tightened, or has vibrated loose, for example). Or, as might happen with the thin Result blade, the blade can be thin enough that it flexes at high speed.
A wobbly blade can widen the saw kerf, make a rougher, wider cut that wastes glass, and is also more likely to chip or break the glass.
Obviously, tightening the nuts that hold the blade on the spindle is part of the solution, but I also invested in blade stabilizers from HIS (I think they call them “wheel stiffeners.”) The stabilizers look like great big washers–I suppose if you could find great big washers they’d work as well–and they go on the spindle on either side of the blade to prevent wobble.
They definitely make a difference–less chipout. The downside is you lose some depth in your cuts–without stabilizers, my 10-inch tilesaw can cut a maximum depth of almost 4 inches (although that’s puuuushing it). With the new stabilizers, I have a tiny bit more than 2 inches. But the cuts I can make are almost exactly the width of the blade, without chips.
3. The deeper or thinner the cut, the more water I need.
A moderate trickle of water against the blade suffices when I’m cutting flat (6-9mm) pieces of glass. I find I must really pile on the water, however, when cutting thick pattern bar, castings or murrini slices.
I invested in some Loc-line hoses (left), one for each side of the blade. I aim one at the blade that’s in the cut, right at the base. The other I position so it’s shooting water into the cut, almost on top of the front edge of the blade. Then I attach the garden hose and turn on a nice stream–if I’m not getting drenched, I can’t cut as thin. (Again, experts may have a better way to do this).
The loc-lines make it easy to position water exactly where I want it. I adjust the water position every time the cutting depth changes, which is why the easily adjustable loc-lines are so important.
I do NOT recirculate water from a pump in the reservoir–it doesn’t work all that well on my saw anyway, and when the water clouds up my cutting action seems to suffer. So I use fresh water all the time now, and accept that I’ll be sending a stream of water down my driveway (where it excites comment from my water-conserving neighbors).
4. I use sacrifice glass to prevent losing corners.
A traveling saw blade puts a lot of pressure on the last little bit of glass going through the saw and it’s easy to break off the bottom corner of the slice. This is a problem in woodworking, too, and they solve it by putting a piece of scrap wood behind whatever’s being cut. I do the same on my tile saw, and any breaks happen in the sacrifice piece, not the real thing.
5. I ensure my feed table is straight and true to the blade.
Yeah, right. To put it bluntly (hah!), mine isn’t true and it isn’t adjustable, which is a big headache. At best, it can cause my slices to get fatter or thinner as I move along. If I’m not careful, it also can put pressure on one side of the slice, and cause it to break.
I compensate by making my own jigs to line up the glass. I true THOSE to the saw, which sorta works. I fully intend to use my el-cheapo saw until it dies…but if anything could make me break down and buy a good saw before that, that daggone feed table would do it.
6. I don’t mess around.
I use my cheap blades for freehand carving in the glass, kinda like chainsaw sculpture in wood. You bring the glass to the bare, moving blade and dig into the glass to rough out shapes. I do NOT do that with the Result blade. It probably wouldn’t hurt anything, but it’s possible to torque a thick piece of glass when you’re in the middle of a freehand cut, with an outside chance that it would damage the blade. So I don’t.
I don’t depend on my ability to hold an uneven piece of glass perfectly straight and steady as I’m feeding it into the saw, either. If it’s wobbling on the table I shim it up and stabilize it before I cut, so that I’m holding it to keep it from straying, not to keep it upright. The issue here isn’t damaging the blade as much as damaging the cut–if the glass is wobbling on the feed table you increase the chance of chipping or breaking your slice.
7. I take CARE of that blade.
Result blades aren’t cheap. I clean off the glass particles, dry the blade and periodically clean and lubricate it. I never push a cut. If it changes noise/pitch in unexpected ways while I’m cutting, or I start seeing a lot of chipping in the glass, I stop and figure out what’s going on before I proceed. I may beat that saw to death…but the blade gets gentle treatment.
If I’m hacking through a lot of glass fast and don’t need the thin, smooth slices, I swap out the Result for one of the old diamond blades–no need to waste a fine blade on thick cuts. I also dress the blade when it appears to be slowing down. HIS and other places sell dressing sticks for this purpose; I use broken mullite kilnshelves to expose fresh diamond in the blade, and it seems to work fine.
And that’s it. Nothing magical, and I’m probably doing something I shouldn’t, technically speaking. But it makes some pretty fine slices.
*Technically, what I’m making is pattern bar, i.e., stacked or dripped glass block that makes beautiful, Rorschach-like patterns when sliced open and combined. I call what I’m making “murrini cane stock,” essentially pattern bar with a small repeating pattern, designed to be sliced into bars (cane) and then chopped like murrini.
Last year about this time I dove into them with abandon and made and hundreds hundreds of cabochons for buttons, pendants, earrings and rings. Roughly 95 percent of what you see at left is made from slices that measure 6mm or less in thickness. (and I still have enough bar left to make about twice this much)
If you’d like to see how these were made, check out these posts–the “sandwich” post talks about the bars:
- Murrini cane in a kiln: Sandwiches, Part I
- Murrini cane in a kiln: Jellyrolls
- Kilnformer’s murrini you can buy
- Murrini cane in a kiln: The rod pod