Re: [ATM] Ready for polishing?

[Bill Marriott <bmarriott@pacbell.net>]

And yes, I do know how to spell....  8+)

B.

Bill Marriott wrote:

> We rutinely have people polish with 9u finish, at the Chabot mirror 
> workshop, as going finer, especially in an open room where everyone from 
> 80grit to polishing are located (yeah, not ideal) The risk of scratches 
> is greatere than the gain in a finer abrasive.  If you can provide a 
> very clean enviroment, and proceed carefully, you may be able to knock 
> an hour or two off your polishing times, with a 6u finish. But, unless 
> you grind and completely remove damage form 9u, you will still have pits 
> from the 9u.  Lets see, subsurface damage is supposed to be twice micron 
> size, so, 18-12=6u, so in theory if you grind off 6u of stock (.00025") 
> you should be find.  That is not very much with pyprex.
> 
> BillMarriott
> 
> Rich Ball wrote:
> 
>> Mentors,
>>
>> On my way to finishing the glass-on-glass part of mirror-making I ran 
>> out of
>> 6 micron grit.  A friend gave me some 9 micron and 3 micron in its place.
>> (8" f4.5 project, Pyrex blanks).
>>
>> I have finished 8 wets of 12 micron and 8 wets of 9 micron and the finish
>> looks marvelous, lustrous and smooth.    Can I go to pitch lap at this 
>> point
>> or do I need one grade finer?  Tex says that powders as fine as 3 micron
>> will not take out all the coarser pits and will leave pits that will 
>> take as
>> long to polish out as if the 3 micron had not been employed.
>>
>> What's the voice of experience?  If I need 6 micron I'll have to take the
>> time to send away for it.
>>
>> Rich Ball
>> Oak Park
>> _______________________________________________
>> ATM mailing list http://www.atmlist.net/
>>
> 
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