Re: [ATM] Two mirrors on one tool

["Thomas Janstrom" <tomjan@ozemail.com.au>]

OK, I HAVE done this!

So here's how I hogged out two mirrors on the one tool, for hogging I
alternated wet for wet between the two doing all the work MOT, when I
started fine grinding I alternated MOT for TOT and swapped between the
two mirrors. I did check from time to time with my spherometer to keep
track of how things were going. 

In the end I had two mirrors (4 1/4" diam) with 127" ROC which were
within 1/2" of ROC when finished polished out and figured, so well
within my tolerances. I don't see why you couldn't get the same result
with this method on a faster optic.

Hope this clears things up a bit.

Clear Skies, Thomas,
"Who would kill for a cloudy night with some rain right now".
www.tjanstrom.com
www.norsewines.com.au


-----Original Message-----
From: atm-bounces@atmlist.net [mailto:atm-bounces@atmlist.net] On Behalf
Of Paul Bradley
Sent: Friday, 7 October 2005 8:56 PM
To: ATM Mailing List
Subject: [ATM] Two mirrors on one tool


Hi all,

I'm making 2 mirrors which should be as near identical in focal length
as I can make them
as they are to be used in a pair of newtonian binoculars.

I've read about people who have done this by using the same tool and
doing alternate wets on
each mirror. That's what I'm doing, but some people said to alternate
MOT and TOT as well.

Wouldn't this tend to keep the focal length around where it is? I've
been working exclusively MOT. 

I'm only about half way through hogging, so it's not to late to start
alternating MOT and TOT if I
need to, should I do this or will I still be keeping the focal lengths
sufficiently similar by working
MOT? If it is OK to work MOT, could I do this throughout fine grinding
too if I wanted to without
encountering problems?

Thanks

Paul
_______________________________________________
ATM mailing list http://www.atmlist.net/

-- 
No virus found in this incoming message.
Checked by AVG Anti-Virus.
Version: 7.0.344 / Virus Database: 267.11.13/123 - Release Date:
6/10/2005
 

-- 
No virus found in this outgoing message.
Checked by AVG Anti-Virus.
Version: 7.0.344 / Virus Database: 267.11.13/123 - Release Date:
6/10/2005
 

_______________________________________________
ATM mailing list http://www.atmlist.net/