[ATM] Generated Tool does not Match Mirror Blank

["Dave Jack" <dave.jack@glass-beads.net>]

Hello all;

First off I would like to say that I have been reading this list with some
interest for a while now and have been really pleased to see the level of
enthusiasm and knowledge that its members have and share on a regular basis.

I decided to grind my own mirror having never owned a telescope before and
thought I would start with a generated 8" f/6 kit so as to make my first go
of it a bit easier. Call it a safer bet or a bit of laziness I thought a
generated curve would be easier to work with  my first time.

So here is the rub: after waiting 5-1/2 months for the kit to arrive I now
have a great looking mirror blank ready for fine grinding but the tool is a
bad fit. The tool has a 1/4" dia. flat spot in the middle. If you place the
tool on the mirror you can spin the tool like a top (it makes an awesome top
btw). For those who have seen curve generating done I think this means the
blank was not centered prior to generating the curve so I have a flat spot
and probably the curve of the tool is slightly different from the mirror.

Given that I have waited 5-1/2 months for the kit to arrive I would rather
fix this than send it back. Do I need to go back to rough grinding or will
this sort itself out with a normal W stroke at #220 grit(my corsest grit)? I
have a fear that this would create a mirror with two radiuses, would I be
best to go center over center until the tool and the mirror appear to mate?
Will I need to find some corser grit? Newbies always have so many questions
so thanks for your suggestions and patience.


-Dave Jack



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