Re: [ATM] mirror grinding

["Jeff Baldwin" <bald@olypen.com>]

I've used professional sand blasters for generating curves in large fast
mirrors.  If you have 436 cubic inches of glass to remove it does the trick.
Using a template you can control your progress.  The project should be in an
enclosure so you aren't breathing that nasty stuff.  If you have the dough
to have it curve generated you will have a nicer result, but if not, you can
make it happen.  When finished you have a huge probability of the curve not
being oriented with the back (wedge), so expect hours of fixing that.  If
you have a mirror that isn't a 40" f/3.6, then you probably won't have 436
cubic inches of glass to remove, and you might consider not sandblasting.
JB

Jeff and Glenda Baldwin
Beaver  WA
bald@olypen.com
glendabaldwin@olypen.com
http://olypen.com/bald

----- Original Message -----
From: "Bob May" <bobmay@nethere.com>
To: <atm@atmlist.net>
Sent: Monday, July 04, 2005 10:56 AM
Subject: Re: [ATM] mirror grinding


> I've heard rumors of using a sandblaster for getting a hole done for a
> mirror but haven't heard much about it.  Brave people to do a curve that
> fast in the glass as you can eaisly overdo it in an area and then have to
> drop the rest of the surface down to compensate.  However, that would
indeed
> be a nice fast method of removing a lot of material.
> A lot better is the using of a long arm with a toolgrinder or other drive
> for a 4" diamond blade of the $10 for 3 blades that HF often has on sale
to
> swing back and forth and do the ROC pregeneration that way.  No need to
put
> the mirror on a lathe although turning it on a MOM turntable would make
the
> curve a bit more even wedgewise than just putting the glass in a fixture
at
> the working end of the long spar.
> There's really a lot of ways to skin a cat!
> Bob May
> bobmay@nethere.com
> http://nav.to/bobmay
> http://bobmay.astronomy.net
>
> _______________________________________________
> ATM mailing list http://www.atmlist.net/

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