Re: ATM roughness

[tkrajci@san.osd.mil]

>From: mdholm@telerama.com

>...As many opticians have discovered 
>over the years, pitch laps are somewhat unpredictable beasts.

Unfortunatley there is also a severe lack of analytical approach to pitch 
lap technique among many ATM's.  How many times have you seen these 
situations come across in posts on this list, or other ATM lists?

A.  Person never measured pitch hardness at a given temperature to 
determine if pitch is too hard or too soft or just right for given 
application.  (Hint:  do archive search on Twyman viscosity tester - it is 
simple to build and use.)
http://astro.umsystem.edu/atm/search.html
http://astro.umsystem.edu/atm/ARCHIVES/JUL03/msg00278.html

B.  Person polishes in unheated room.  Temperature fluctuates over wide 
range.  Is pitch matched to any portion of the temperature range in the 
unheated room?  The world may never know....  :-(

Yes, pitch can have mysterious or weird behavior.  But you can not improve 
on that by ignoring process controls.  Understand and control every 
variable that you can...that will make the situation less mysterious.

Good luck.

Tom Krajci
Tashkent, Uzbekistan