Re: ATM cutting glass

[astillma@nit.AirTouch.COM (Anthony Stillman)]

Jerry Upchurch wrote:

Can anyone offer suggestions on cutting glass circles.  The only power
tools I have are a variable speed hand drill, hand circular saw,
grinding wheel, with two wheels rough and not so rough.
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I assume by circles you mean disks.  Depending on the size there are a varity of
methods.  For small thin circles (<1" dia.) first I mark the glass with permanent
 marker.  Then I rough in the the shape with a daimond saw I made from a old
 sewing machine motor and a grinding wheel adapter I got at the hardware store.
  Last, I round the glass up on a grinding wheel.  Both the saw and the gringing
 wheel have a supply of water to cool the cutting surface and remove the waste.

For larger sizes I use the core method, I haven't done for a while.  Basically,
 you need a metal cylinder, perferably steel, into which you can cut notches.
  Somehow attached to this cylinder is an axle coincident with tha axis of the
 cylinder which you can install into somthing like a drill press.  Next you need
 grit and water.  Some people use course grit as it cuts faster, but this also
 chips the glass.  I suggest 220 for most of the work then switch to 360 for the
 last few 100ths.  It takes longer but it leaves a nicer finish. For pieces less
 than 2" I used (this is ten years ago) one of thoes wood disk cutters.  The
 process distroys the teeth quickly, so from then on I would file a few notches
 in the metal.  These are to help hold the grit.  Earl Watts told me onece that
 they weren't necessary.  For larger disks I make a wood form put a bolt through
 the center, the kind that has a square section under the head and then lock it
 down with one of thoes gripping washers and nuts.  Make sure you center it well
 and don't crush the wood so that the bolt becomes can't.  Its also a good idea
 to seal the wood (paint whatever) as the water slurry can soften things up.
  Next I wrap a piece of sheet metal about 3 inches wide around the disk to form
 a cylinder (length=pi*diameter + thickness of metal).  I screw this in place with
 sheet metal screws. Notch the end assembly, add grit and water and go to work.

You have to keep an eye on the slurry.  Don't let it go dry.  Keep even pressure
 on the glass, I used a weight tied to the handle of the drill press.  Also adjust
the drill press for fairly slow, you are grinding not drilling.  Then sit back and
 read a book, or your back issues of S&T.

Anthony