Re: ATM Advice with Flexing a 16"

["Ken Hunter" <kb7h@onemain.com>]

Unless you have a LOT of experience in optical fabrication and at least a few mirrors under your belt, it's best to keep
both sides of the glass at the same grit level. Nothing brings tears quicker that a #80 scratch on a finished surface.
If you keep the wedge within a couple thousandths at #80 and bring it closer with each abrasive size (it's hard to make
wedge change if you are smoothing a spherical surface). You should not have to worry too much after the first coarse
abrasive sizes.

Ken Hunter


----- Original Message -----
From: "Peter" <peter@kitgear.com>
To: <atm@shore.net>
Sent: Friday, January 17, 2003 5:55 PM
Subject: ATM Advice with Flexing a 16"


Hi,

I don't seem to be able to get much direct info on the flexing process. I just wanted some advice regarding the best
order things should be done for a shaped back flexed mirror project. My mirror is 1" thick so I need to get the order of
events correct.

Should I grind the front surface to the correct sagitta then grind the back to the same ROC and then finish the front?
Or, should I finish the front to the polishing stage then go and rough grind the back?

There must be a defined method somewhere which yields the best results and least amount of dewedging.


Thanks,


Peter