Anybody cutting glass

[chris@cestrian.com]

My better half has decided that she likes stained glass work and has asked me if I can cut the stained glass pieces on the Shopbot.

Is anyone doing this?

If so what bits are used (and where from).

What feed rates, depth of z etc.

[billp]

Chris, You aren't the first person to look into this. If you type in "glass"on the keyword search you'll see previous discussions. I've always thought that the 'Bot would be a natural tool to use with glass in cutting out the actual recesses stained glass cut be inserted into. Imagine a spider web of wood with flanges so that you could just drop the cut glass into. Someone could probably have the glass pieces cut out, and then use the "edge finding"process with the probe to make cutout patterns. I know this isn't the classic "leaded bead" form of stained glass, but there are a million people already doing that...We have a tool that can let us try different techniques..Bill P.

[bjwat@comcast.net]

Geez...that's a tricky one! I've done a bit of stained glass in the past and I'm not sure that cutting the glass on the Bot would be the best way to go. I think that if I had to do it, I would make something to chuck into the router, or fixed chuck that doesn't spin, that could score the glass. Once you have the scribed pieces, lay them on a convex 'button' (sold at stained glass supply store) and snap the pieces off cleanly.

If you've done stained glass by hand, no doubt you've used one of the roller cutters with the cutting oil reservior. The key is to get the cutter to 'sing' while going across the glass. A roller cutter may not be the way to go, since there may be issues when you go to change X/Y direction. I don't recall, but I think that there may be some kind of carbide tipped scribe that you could get that wouldn't matter if you were going in the X or Y.

If you dial in the Z properly and experiment with getting the tool to scribe in just the right amount, I think that scribing glass on the Bot is a real possibility. Actually cutting the glass on the Bot is more trouble than it is worth since you will need a clean, cool supply of water to the cutting stone, which will wear down quickly...so much that it will vary the kerf and throw off your dimensions...not to mention totally screwing up your spoilboard and warping it...Throwing off your flatness. Typically, you only use the stones for edge grinding and not for actual cutting.

Hope that helps...
Brady

[bjwat@comcast.net]

Something like this:

http://www.khue.com/dept/misc/scribe.htm

[rgbrown@itexas.net]

A diamond scribe on a spring?

Just thinking out loud.....

Ron

[chris@cestrian.com]

To clarify my initial post.

We have been doing fairly well by just hand scribing however, as the pieces become more complex with tighter turns the breakage factor climbs drastically.

My initial thoughts were to use a diamond tipped router bit & basically grind through the glass following x & y repeatedly lowering z by a small amount (.001 ?) per repetition until thru the glass.

[dands50@hotmail.com]

Chris I talked this over with my Cousin Berry Dolynn He is a world class Stained glass artist and has done some of the tightest turns of anybody I have ever seen. He is very good with my Shopbot and he just doesen't think that it will work. Long sweeping turns possibly but he said he wouldn't want to try it on some of the more rare glass as even that veries so much in the perosity of the glass. He said your breakage proublem is more than likely the type of glass and not the tight turns. As I stated He is a world class artist as he does entry doors in the $20,000.00 price range and is now in the process of doing a complete stained glass and wood designed interior for the Abby Winery in Canon City Colorado it is designed to go along with the Abby's Gothic architecture. This one job is over $100,000.00 He also said to tell your wife not to give up, just to learn the tricks for different glass types.He is one hundred percent self taught. David in Wyoming.

[bjwat@comcast.net]

Chris,
I hear the voice of an old shop teacher saying, "Use the right tool for the job." The fact of the matter is you CAN cut glass on the Bot...but a rotary type cutter is not the best way to go. It's like saying that you can cut 3/8" steel with a router...no doubt you can, after a lot of headaches and bits/stones...but a plasma or waterjet is a far superior choice. If you had a WaterJet/Abrasive cutter attached to your Bot, it would cut the glass like butter with extreme accuracy and next to no breakage regardless of porosity/age of the glass. Unfortunately, a WaterJet is very expensive and it would require a ton of electrical power and at least $50k for just the WJ setup.

As I suggested before, scoring the glass is probably the best way to go on a budget. I know that the Bot is more consistently accurate on a sweeping curve or straight than a human. If you have a design with a delicate/thin section, don't scribe it so tightly to the design and leave a lot of meat around it when you make it in PartWizard. Use a grinding table or glass bandsaw to do the delicate cuts/finish work.

Again, just my 2 cents. If you have large production runs of pieces, you might want to link up with a company that does WaterJet cutting. Who knows, maybe you can trade machining time. Just a thought.

-Brady