Re: [ATM] next mirror .. hand grind or build a grinding machine??

["tony gondola" <acgna@comcast.net>]

I think that if it's just for one mirror I'd just build it as you've 
suggested, just the basic turntable with an adjustable but not driven 
overarm. That will allow you to take a lot of the labor out of the process. 
You can do the fine grinding and polishing using the spin technique so the 
machine will do all the work there. Then just finish up smoothing and 
figuring by hand. I have the feeling that more then a few M.O.M. owners do 
this anyway.

Tony



----- Original Message ----- 
From: "Robert OToole" <polaris@gsinet.net>
To: <atm@atmlist.net>
Sent: Saturday, August 05, 2006 4:24 AM
Subject: [ATM] next mirror .. hand grind or build a grinding machine??


> I'm working on a 6" f/8 mirror for my son right now, all by hand.  I've
> done a few mirrors, all modest in size.    After this I have my sights on
> some aperture and I want to grind a mirror in the 14" - 18" range.   I
> don't expect to do more mirrors after that.
>
>  Anyway, I've heard that a grinding machine is the way to go on bigger
> mirrors.  However, somehow I question putting the time, money, and
> energy into building a grinding machine   for just one mirror! It would
> become yet another project to complete.
>
>  Instead, I'm thinking of forging ahead and just spending the effort on
> the mirror itself.  I've ground a 16" mirror before, all the way to the
> polishing stage. However, it's the polishing stage which will be a
> "bear" methinks.
>
>  Another half-way idea I had was the following:
>  build a simplified machine ...  just a motor-driven turntable with a
> pivoting overhead armature.   This would be for TOT work.  The turntable
> would be for  just slowly spinning the mirror while I would manually
> move the tool back-and-forth using the armature.  I would also be able
> to stack weights on the arm to apply necessary pressure.
>
>  This idea isn't too bad since it takes most of the grunt work off my
> shoulders.  It would be a lot simpler to build than a full grinding
> machine.
>
>
>
>  Anyway, I want to solicit opinions and thoughts on this before moving
> forward.
>
>  Thanks,
> Rob
>
> -Robert OToole
>
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