RE: ATM 4" ronchi, day 4

["Mel Bartels" <mbartels@efn.org>]

Very nice smooth surface with no TDE!  Good job!  Those ronchigrams
are a great way to do virtual figuring via the WWW!

>>>
Something very interesting -- after the 1/3 COC strokes (mirror on
top) when I put it on the tester I could practically see the pitch
squares on the mirror (in the ronchigram) -- it took a 10 minute
session with standard W stroke to remove these 'artifacts', which by
the way, scared the sh*t out of me ;-)

I'd appreciate any feedback... I have another 4.25 sitting there
through fine grinding waiting for it's turn on the lap (which reminds
me, my pitch is hard, which I like, and I think I can just plop this
second mirror on the current lap after a little trimming, give it a
good warm press, and hit it, no?)
<<<

Ok, you don't need to channel except for the initial gross pressing
into shape.  Let the squares close naturally.  You will get a smoother
surface.  Yes, you can reuse pitch laps.  But the pitch may become
'used' over time, so pouring a new thin layer on top to renew it will
be the order of the day.

Mel Bartels