Re: [ATM] Fixing Tom's oblate sphere

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

Hello,

>snip<

If we define a stroke as one movement, either forward or backward, 
then that speed is OK.  If you are calling one stroke a forward AND 
back movement, then we want to be nearer 30.

****Great, stroke = one movement, we're together.

>SNIP<


For spherizing, you want the leaner mix.  In my experience that helps 
lap contact and encourages the surface to go more toward a sphere, 
provided you apply pressure properly.  

****I have not been using any pressure other than the slight downward
pressure of my heel when working TOT. MOT the downward pressure is only
enough to grip the glass with rubber coated gloves (finger tips only...
boy what a work out for the forearms!).

**** How much pressure should I apply?

>>SNIP<<

Interesting.  Do you let the slurry dry out?

**** No, but at the point where the friction is too great I break
contact and recharge with CEO. Similar to a "wet" but no washing.


I noticed above that you mentioned a "wet".  I don't think so much in
terms of that when it comes to polishing - it is really one long process
with a little slurry and water added along the way.  I want the feel of
the work to 
be consistently smooth, but not easy to move.  Friction should be fairly
uniform throughout the work.

>>moved>>Another question - does the friction vary during a stroke?

****Hmmm... I'm breaking contact... to uniformly apply CEO to glass or
tool with a couple water sprays from spray bottle. Maybe not a good
thing... When Glass/Tool is de-centered and CEO brushed on, does the
non-uniform application of CEO cause problems? My method of adding CEO
does change the force required to overcome the friction, but the change
is linear and a smooth transition. No grabbing or jerking during stroke.

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

OK, this is a clue that something is going on.  Try a leaner polishing 
mixture (you don't need the really thick stuff to press).  After 
pressing, get the tool/mirror moving, and don't separate them.  Then 
start polishing slowly, with the pressure I described.  

**** The pressure I'm applying is: "Working TOT, usually I just try to
apply slightly more pressure to the trailing edge of the lap as compared
to the leading edge of the lap.". Only enough to "grip" during MOT.

Drag should 
start out heavy and stay that way.

****Tonight I'll run a Foucault test. But looks like I need to evaluate
my polishing procedures too!! I've got about 20-23 hours in polishing
now. 

**** Thanks for the help! ****

Tom Polk
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