Re: ATM Chipping and polishing

[Anthony Stillman <atmer@flash.net>]

>Hi! I'm new to the list.
>Can I manage to polish the mirror correctly with such a chip at the edge





Frode,

Welcome to the list.

The chip you describe sounds like an orientation mark for alligning the
mirror with the clips you will use to retain the mirror in its mount.  A
number of my mirrors have such orientation marks.

As for polishing, yes pitch will flow into the depression durning pressing
and result in a turned edge from polishing.  To deal with this, the
protrusion of pitch must be removed.  There are all sorts of ways to
approach the problem.  You already mentioned the approach I perfer.  Namely
orienting the lap such that a lap low is coincident with the chip.
Sometimes its necessary to removes some of the lap with a blade.  Also it
helps for pressing allignment if you mark both the back of the mirror and
the tool.  Lastly, after a press, feel the edge of the pitch around where
it was close to the defect to make sure there isn't a bit of raised edge.
If so, scrape it down with a blade.

Good luck

Anthony