[ATM] Preparing to trepan for the first time

["Chris Dalla Piazza" <dalchri@hotmail.com>]

I have created a biscuit cutter by wrapping 22GA steel sheet metal around a
round wood block.  I pretty sure the bolt through the wood block is at the
exact center because I spun it using a drill and sanded the edge to the
correct diameter.  Visually, the outside diameter of the edge does not
appear to wobble much as the cutter is spun.

 

Although I got it close, bottom of the cutter edge does not line up exactly
where the end meets the beginning as the sheet was wrapped around the wood
block.  This means that the end of the edge will be cutting deeper into the
glass as it spins than the beginning of the edge.

 

Also, I have not cut teeth into the cutter yet.  The cutter is about the
exact diameter of the hole desired.

 

I will be cutting two BK7 lenses and I have a practice Pyrex disk available.
I'm thinking of making a paper cutout to layover the disk to center the
trepanning cutter.  I plan to come in from both sides and meet in the
center.

 

I am considering using Silicon to glue the core back into the disk afterward
and I am currently on 120 grit with the BK7 disks.

 

Can I go without cutting teeth into the cutter?  After all, the carbo is
doing the cutting, not the cutting head right?

 

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?

 

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?

 

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."

 

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

 

Should I try to meet in the center of the disk since both surfaces will be
optical surfaces or is it better to try to go almost the whole way through
one side so it is easier to line up the opposite side to complete the cut?

 

Is it ok to use Silicon to cement the core or is there too much flexibility
in the bond?  I was thinking Silicon would not be water soluble like the
plaster that I usually see recommended.

 

Any other suggestions before I embark on this adventure?

 

Any ideas are appreciated!

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