Re: [ATM] 12.5 inches BVC advice for parabolizing

[hermit <hermit@outofoptions.org>]

RM L wrote:

>Hello again,
>
>I'd love some advice as what approach to take when I continue the work, on another day. I do not want to mess up, and you may see allready a bad tendency in my images... that I wouldn't see.
>
>I update my site with the last photos for the day.
>
>http://www.axeinformatique.com/temp/Mirror/BVC_Mirror.html
>
>The zoning is allmost gone now. 
>
>I'm using standard parabolizing W stroke, going up to 1,5 in of the border, with the center of mirror.
>
>Should I keep doing the same thing ? It's the edge that scares me a little... Is it parabolizing quicker than the rest ? Am I worstening the TDE ?
>
>I don't want to waste energy curing the TDE, but I would'nt want to make it worst.
>
>Thanks all for your time, patience, and help.
>
>  
>
I like to keep a spread sheet and graph my results as I go.  I put in 
the tolerance envelope and watch the change in the graph.  For me, it is 
really nice feed back on my progress and to see where/how the line 
moves.   My last mirror had a turned edge before I started to parabolize 
and it was gone by the time I was finished.  You take down the edge 
during this process.   I was using a subdiamer lap, mirror on bottom.  
My machine had turned the edge, but if you think about it, you are 
taking glass away at the edge any how.    If you are careful, for me 
that meant keeping the weight away from the edge, you don't touch the 
edge, just the 'high zone' inside of it.  Good luck.  If things show 
improvement, don't second guess it. 

Ken
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