Re: [ATM] questions about the condition of this mirror

["jcmulherin" <jcmulherin@opticalmechanics.com>]

Hi Roman:

If I understand correctly you started polishing the mirror without first
fine grinding it? If this is correct, then you definitely have to do some
fine grinding first. You can start with #600 silicon carbide or 18 to 20
micron aluminum oxide.

A blank that has been curve generated may look smooth enough to polish to
the naked eye but it definitely has some tool marks if you inspect it with a
magnifier.

James

James Mulherin
President/Lead Optician
Optical Mechanics, Inc.
jcmulherin@opticalmechanics.com
www.opticalmechanics.com
Tel (319) 351-3960
Fax (319) 351-3943
 

-----Original Message-----
From: atm-bounces@atmlist.net [mailto:atm-bounces@atmlist.net] On Behalf Of
Roman Toledo
Sent: Sunday, July 08, 2007 2:09 AM
To: atm@atmlist.net
Subject: [ATM] questions about the condition of this mirror

     Mark it looks like it's on the surface, that old saying "if you don't
use
it you loose it" is at work here, I forgot some useful things I learned last
year and since I put it all away for a while I forgot them.

    First mistake is I did not check the surface when I got it, mainly
because
this mirror looked so smooth, it never occurred to me to look for sleeks. I
got
up this morning and decided to polish out the back some more, and got it
looking really good but not 100%, I probably ended up adding some more
sleeks
but i was very careful, for what ever reason I took apart a eyepiece t use a
loupe glass and inspected it and sure enough the scratches specially the one
that looks like a V or Y  and bunch of others are on the top.  the scratches
look like the Grand Canyon so fine grindind looks to me like 320? or a lot
of
600?

    So my dilema is I never made a fine grinding tool, I went straight to
pitch
(73 modified with some linseed oil )so I may have to do one.

    can I do a fine grind by using pads on top of pitch?  and then discard
it
and make a new pitch lap  or should I just do what I think I know must be
done,
make a new tool, and should I buy smooth porcelain tiles ?

Mark Holm thank you.

anyone please feel free to comment

PS: Greetings go out to Richard Schwartz and David Harbour have not seen
much
in here from you gents lately

  
Regards
Roman



regards,
Roman Toledo
Celestron Nexstar GPS 9.25
_______________________________________________
ATM mailing list http://www.atmlist.net/

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