Plate groove in glass

[rayman]

I need three plate grooves put on 3 glass shelves 1/4" ..(glass co. wants $200 a groove ) Has anyone here ever performed such a trick on their CNC? If you have could you share you technique?????

Raymond

[coryatjohn]

If the shelves are tempered, you can forget about it.

[bleeth]

Even if they are not this is not a bot project.
It takes diamond bits, and water and a different type of mill.
I would call different glass people. Prices for this kind of thing can vary quite a bit.

[jerry_stanek]

How about Plexi or Lexan

[dana_swift]

Raymond- first to be clear this is one of the materials I have never machined!

John is correct, if its tempered, dont even think about it. The glass will shatter violently at the first attempt of machining.

However its clearly on the list of materials I have thought about machining. There are two approaches that may do what you want, first is a cork or similar shaper with diamond polish. The cork "bit" would have to spin at about 2k rpm to keep the cork from flying apart. A constant flow of diamond paste abrasive and water is required.

Another option is to use a Poly Crystalline Diamond bit (PCD) and water.

In either case your feed rates will need to be extremely low, probably slower than the shopbot can move. First check this one. Can you set a feed rate in the order of of one inch per minute? (Or slower)

I have drilled holes in window glass successfully using a standard drill bit, water and a hand drill turning about 300 rpm. Much patience is required, but you can drill a quarter inch deep hole in about a half hour. Dont even think about using a center punch!

Also you are probably talking about lead "float" glass. It comes in various thicknesses and is the stuff most likely you are being asked to machine. However, there are more kinds of glass than there are kinds of wood. It pays to read up on glass and know a bit about the topic. In the daily world we encounter two types of glass regularly. "silica" glass formed with the lead float process, and "borosilicate" glass (often referred to by the Corning trade name Pyrex). The machining strategies are different for the two common families of glass.

Most likely you are not dealing with borosilicates but be knowledgeable enough to tell the difference. Lead float glass absorbs the lead from the float process and (usually) looks green when viewed from the edge. Borosilicates (usually) look clear when viewed from the edge. Colored glass is fairly easy to make (if anyone cares to bother) by doping the glass ingredients with small quantities of metal, and metal oxides. Gold turns glass red, cobalt-blue, lead-green, etc.

Glass is really interesting stuff. I used to have a home-made glass kiln and have made glass from scratch. The "hard" material we put in our windows is actually a viscous liquid, not a solid. The difference is not important to know, but helps explain some of its bizarre properties.

Good luck with the grooving project! I will be very interested to know how it goes with the shopbot- especially what works!

D

[Keyco Wood]

Have u considered LEXAN

[rayman]

I probably would not try even if you could, anyway thought I would ask, I have the shelves on order should be here Tuesday, thought I would see if they could cut me three square 1/4 x 1/4 pieces 20 inches long and glue them to the shelf.

[myxpykalix]

Why don't you take some 3/8" thick wood material the length of your shelf, and cut your grooves in that and put it up there? Or do the same with some lexan?

[steve_g]

Raymond...

I found that a raised section of glass or other material bonded to the glass works as well as a grove. Where this doesn't work is when the customer was just looking for flexibility and they really want to put books on the shelf...

SG

[Bob Eustace]

I need three plate grooves put on 3 glass shelves 1/4" ..(glass co. wants $200 a groove ) Has anyone here ever performed such a trick on their CNC? If you have could you share you technique?????

Raymond

Raymond you can get a table type wet diamond tile saw for under $100. Just make up a sled to protect the surface.