ATM Polishing goof of the week

[Buck Childers <buckchil@sound.net>]

Hello all,

I'm working on a 10".  I polished it out with pads for as far as I
thought I could go with them and it set idle for two lunar cycles
waiting for me to get down to tackle the pitch lap and figuring. 
(During the mean time we did get some stunning views of the moon :-)

Ok, There's good news and bad news.

First the good news.  I poured my first, and second <grin> pitch laps
last weekend.  On the first attempt I realized that the work table I was
using was not at all level.  I found this out as I was pressing the
grid.  I peeled, and/or chipped the lap off and threw it back into the
pot for the second try.  The second try went much better.  I now have a
good looking lap.  I used a 1/4" wet dowel to press the grid.  Even
doing it twice, the whole process was much simpler, easier and quicker
than I expected.  Seeing it done in the Dobson vidio really helped.  I
should not have put it off.

Now the bad news.  In getting the pitch off the tool after the first
attempt I had to chop away at the lap.  I tried to contain little pitch
flakes but some bits got away.  A few bits ended up on a squirt bottle
with my cerium oxide solution.  I was using a turpentine dampened rag to
clean up and, not thinking, I used this rag on the CeO bottle.  I
started polishing the next day after pressing to get good contact. 
Things seemed to be going fine.  I stopped and left the mirror on the
tool overnight.  The day two the mirror was nearly stuck to the pitch
lap.  I pushed the mirror off the tool, poured on a bit of CeO solution
and polished a bit more.  I noticed that the lap smelled like
turpentine.  I smelled the solution.  It smelled like turpentine. 
Somehow I got turpentine in the solution!  Maybe I'm imagining things. 
I stopped and left the mirror on the tool overnight.  today it was
nearly stuck to the lap again and took even more force to slide them
apart.  I cleaned the lap and mixed up a new CeO solution.  I'm letting
the lap uncovered for tonight.

I think the lap will be ok.  I couldn't have gotten much turpentine in
the water but a diluted half drop was probably enough to give the lap a
slightly sticky surface.

Any recommendations/comments?

By the way, the pitch is Gugolz 73, good hard stuff.  I used an electic
2-burner "Buffet Range" to slowly heat the pitch in my garage.  I used
covered pot that I found at a yard sale for 25 cents.  Even though I
feel confident that I can now melt, pour, and work a pitch lap without
creating a mess, I wouldn't try this in *my* kitchen.

Although I have a goof at least once a week only a few of them are ATM
related so they won't all show up on the list ;-)
  
Have a great day,
-Buck
-- 
  Buck Childers     email:  mailto:buckchil@sound.net