Re: [ATM] Preparing to trepan for the first time

[Daniel Fundo <fundo@bellsouth.net>]

<<  Should I grind down the bottom of the edge to make it level rather
than risk throwing the glass because of unbalanced grinding force or
will it do this itself as the glass is ground quickly enough?  >>

Chris,  Yes, there will be less of a chance to throw the hole off-center
if the bottom is flat to the surface your cutting.<<

<<  Does the glass disk need to be clamped down or should the cutting
forces be gentle and balanced enough that I am doing something wrong if
the disk is pushed around?  >>

Its always a good idea to secure whatever your are drilling, wood,
metal, or glass.  I don't know what size we are talking about here, but
you can get circle cutters that will cut up to 10".  A jig made this way
will be centered under the quill, and will guarentee centering when you
flip the disk over to cut from the other side.  Just bolt the jig to the
table before you go at it with the circle cutter. (One thing you learn
the hard way in building stuff is that the time and material used in
making a jig MORE than pays for itself in ease and accuracy!!)

<<  Is it realistic to think I can widen the hole cut if necessary using
something like a Dremel sandpaper bit?  I am thinking of the phrase "You
can always cut too much but you can never cut too little."  >>

Unless you have a source for diamond coated sleeves for the Dremel, the
answer is "NO"  (If you do, let the rest of us know!!! <G>)  Dremel does
have several SiC grinding stones, but unless you are just talking a few
thousandths, the enlarging would take longer than retrepanning.

<<  Is there a better way to center the trepanning bit than using a
paper cutout?  >>

Make a jig as I suggested above.  

Best of luck

*****-----
Dan F.
Memphis, TN
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