Re: [ATM] Fixing Tom's oblate sphere

["Polk, Tom" <TPolk@decatur-al.gov>]

Hello Mike,


>SNIP<

   http://www.atmlist.net/contrib/tpolk-at-decatur-al-dot-gov/

and then navigate the folders you have set up.

***** Thanks, I'll use this. 

Yes, there is some progress, but it should be faster.  I think we're 
still missing something.

Questions:
What is your stroke speed?  (How many per minute?)

*****40-60 strokes per minute. Toward the end of a wet the strokes take
longer. Friction is greater. 

*****If I understand where you may be headed, I have two CEO ratios
mixed, one for polishing at three rounded tablespoons per cup of H2O
plus about 0.5 cc suds and one for cold pressing at three rounded
tablespoons per 0.25 cup H2O and 1.5cc suds. But in use the leaner mix
is rarely used. From a spray bottle a several shots are applied to the
glass and lap after a cold press and I'm underway. The sponge paint
brush that I apply the slurry with is used to apply more CEO.

How often do you have to re-channel your lap?

*****I poured this lap on 3/27, re-channeled once and it's needing a
minor one now. About 5-6 hours total wear.

Does the pitch lap feel like it's glued to the surface, or like it's 
skidding on top of the polishing slurry?

*****After a cold press, the action is fairly easy. After I water down
the slurry, the friction increases. If my stroke is too fast, it does
skid. It does not feel like it is glued to the surface, maybe 20 lbs of
lateral force is needed to move the mirror or tool sideways.

Does the friction change during polishing sessions?

******Only as described above. Friction is smooth and even but does
increase with time during a wet.

Does it feel different right after a cold press?
*****Yes

>SNIP<

Foucault, used by a practiced hand, will readily give quantitative 
data about the mirror's surface.

******I might do a Foucault test tonight. Thanks so much for the help!

Tom Polk
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