[ATM] Figuring nightmare I need your help - part II

["Brent Russell" <brussel@bpc.org.za>]

Hi Folks,

Here is my progress so far. Cleaned the lap and pressed well. I have
done about 30 minutes of polishing with a COC stroke with the tool just
getting to the edge of the mirror. The center 70% (approx) of the mirror
is now as near as dammit to a sphere. There is a slight tool pattern
because I am doing such COC strokes but that will dissapear later with a
small amount of W stroking or some chordal strokes so I am not worried.
However the edge is still focusing too far. 

Total deviation has dropped from 15mm at my last measurement to 13.7mm
now so the overcorrection is slowly being removed, but the edge is still
hyperbolic.
At this rate I would have to continue for 5 more hours to get a
parabola... 

So do I lengthen the strokes slightly and still stay COC? Or continue
like I have been and the edge will eventually come round? Any other
ideas. I just want to get back to a sphere. I know now how to get the
correction into the mirror, just having problems removing it :-)

Brent



-----Original Message-----
From: system user for apache-conf [mailto:apache@think.localshops.org]
On Behalf Of Ken Lowther
Sent: 03 October 2004 06:19 AM
To: Brent Russell
Cc: atm@atmlist.net
Subject: RE: [ATM] Figuring nightmare I need your help


I have seen this work for others.  On the way back to a sphere they 
stumbled on
a parabola. ;)

Ken

Quoting Brent Russell <brussel@bpc.org.za>:

> Hi Ken
>
> That is my next plan. I have been thinking that I am doing the right 
> strokes but obviously not. So I will use COC strokes and perhaps 
> shorten them slightly and see how I go...I'll let you know
>
> Brent
>
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Hermit, holed up in Youngstown, Ohio

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