From: "James Lerch" 
To: "ATM List" 
Reply-To: "James Lerch" 


----- Original Message -----
From: "Vladimir Galogaza" 

> Hi Michael,
>
> >My plan for grinding two blanks with it is to proceed with wets on an
> >A-B-B-A basis.
>
> Consider efficiency of this scheme. Tool and blank tend to follow
> the same curve generated by grinding. Using this tool for another blank
> will first regrind them to conform. So it seems to me that certain part
> of efforts will be devoted to constant mutual adjustments of tool and
> blanks.
>
> Maybe for hogging it will not matter. But at later grinding it is required
> that spherical shape is generated and for this sharpie test is used to
> be sure that tool and blank are well matched. Proposed plan
> will ensure just the opposite, constant unmatching of tool-blank.
> If this will nevertheless be possible
> with one tool  and two blanks scheme remains to be demonstrated.

Hi Vladimir,

One tool used on two blanks in an A-B-B-A fasion works just fine
(amazingly!)  I did my best to document and demonstrate this on my webpage
for my Bino-scope.  (http://lerch.no-ip.com/atm Items #5  - 9)

In hind site the only thing I would have done differently is use a tile
tool instead of a Glass tool (or channeled the glass tool somewhere around
120 - 220 grit level)

BTW, this same method was used on the pitch lap during initial polishing.
Again it worked really well.  It wasn't untill figuring time that the two
mirrors stopped sharing the pitch lap.  (Each mirror was figured seperatly)

Take Care,
James Lerch
http://lerch.no-ip.com/atm (My Telescope building, testing and coating site)

--- BBBS/NT v4.00 MP