Re: [ATM] Polishing stroke

[William Marriott <bmarriott@pacbell.net>]

Hello;

In my experience, using polishing pads can make life
more difficult instead of easier, often leaving zones
that take away the time advantage of using pads. Start
with a very spherical fine ground surface, and a good
pitch lap, (Gugloz 64), and just dig in and start
polishing, 1/3rd stroke, center over center, alternate
MOT TOT, and you should be fine, & this is one
reporter's opinion only.

Bill Marriott
VA Optical Labs






--- "Polk, Tom" <TPolk@decatur-al.gov> wrote:

> Hello,
> 
> Thanks and I agree on the importance of fine
> grinding. This is my first
> time to use polishing pads and I'm finding out they
> polish different
> from pitch laps.
> 
> The mirror central hole matches the central area of
> the tool where the
> excess pad that was trimmed from the edge was placed
> in the voids
> between pads. The 1/4 "W" TOT hope caused the TUE
> (?). The tool is full
> sized and the edge pads were not trimmed that well.
> My course of action
> is to trim the edge pads better, remove the extra
> pad pieces at the tool
> center and polish for ~2.5 hours longer. Fingers
> crossed on this being a
> good course of action.
> 
> Tom Polk
> 
> -----Original Message-----
> From: atm-bounces@atmlist.net
> [mailto:atm-bounces@atmlist.net] On Behalf
> Of Mike Lockwood
> Sent: Monday, January 09, 2006 3:22 PM
> >SNIP<
> 
> Let's keep in mind that polishing with pads is very
> different, in 
> terms of correcting asphericity, from polishing with
> pitch, which 
> Charles was doing.
> 
> A mirror polishing unevenly is a sign of one of two
> things - either 
> more polishing action is occurring in one region due
> to the technique, 
> lap, stroke, etc., or there was asphericity after
> fine grinding.  For 
> the former, the stroke may be adjusted to speed up
> polishing, but care 
> should be used.  For the latter, there is no way of
> getting around 
> polishing away the errors (short of regrinding).
> 
> The importance of thorough fine grinding is often
> underappreciated.
> 
> 	Mike Lockwood
> 
> 
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