ATM Have trouble polishing down a hill in the center.

[Arni Ingimundarson <arning@itn.is>]

Hi all...

I started polishing my 8" f7 after some break now.

I am using an elgin type machine (ala Tom Waineo) MOT and have been 
polishing for 5-10 min and then cold pressing for 5-10 min.

But I can't get rid of that hill in the center.  I longened the stroke
when I started now (I had an oblate spheroid) and it looks to me now
that I have a quite OK sphere from edge to about 2" radius then there
is hill to about 1/2"radius and then there is a small hole in the center.

An coarse mesure og the hill's ROC is about 1,5 cm longer than the
sphere zone (from 2" radius to the edge).     ((1,5 cm is ca 19/32"))

The lap is W-B pitch on a flat plywood circle with the pich wearing
a little thin on the edge.

What do you think I should do ???

--------------------------------
Arni Ingimundarson
arning@itn.is
Electronics Technician
Amateur Telescope Maker
Iceland.