[ATM] Fixing edge zones

[Francis J. O'Reilly]

Said authoritarian elitist literature from the 1930s being what I keep at my 
bedside, right next to Malacara.

Francis J. O'Reilly
----- Original Message ----- 
From: "Richard Schwartz" <richard1941 at gmail.com>
To: "Mel Bartels" <mbartels at bbastrodesigns.com>
Cc: <atm at atmlist.net>
Sent: Friday, October 09, 2009 5:07 AM
Subject: Re: [ATM] Fixing edge zones


>I think the problem is one of visualizing the error and modifying the 
>stroke to correct that error.  If you have a null test for the desired 
>shape, the error visualization is not a problem, so there is no reason  to 
>go back to a sphere.  Getting to the desired surface is no more  difficult 
>than getting a sphere with a primitive tester like those  described in the 
>authoritarian elitist literature of the 1930's.
>
> Sent from Richard's iPhone
>
> On Oct 8, 2009, at 19:21, "Mel Bartels" <mbartels at bbastrodesigns.com> 
> wrote:
>
>> I consider this good advice because often, in the end, you get to the
>> finished figure quicker if you start with a spherical smooth  beginning.
>> Going back to spherical is always good advice because you can't go  wrong
>> with this approach.  Continuing to fix a figure with major problems  can 
>> be a
>> black hole that will suck your enthusiasm across the event horizon!
>>
>> Mel Bartels
>>
>>
>>
>> -----Original Message-----
>> From: atm-bounces at atmlist.net [mailto:atm-bounces at atmlist.net] On  Behalf 
>> Of
>> Mike Coslo
>> Sent: Thursday, October 08, 2009 6:09 PM
>> To: atm at atmlist.net
>> Subject: Re: [ATM] Fixing edge zones
>>
>>
>>> I'm in the final stages of figuring my first 8" mirror.  I first  over 
>>> shot
>>> the parabola by quite a bit, but with some help from the experts, I  was
>> able
>>> to get close to a parabola using COC strokes.  Using figureXP, my
>> wavefront
>>> error is about 1/3 wavelength.  I need to increase the ROC of zones  3 
>>> and
>> 4
>>> (I'm using a 4 zone mask). My question is what type of stroke do you
>>> recommend using to knock these zones down? Any help would be awesome!
>>
>> This is non-standard advice, but you may want to go back to a sphere,
>> and then take it to a parabola. Occasionally a mirror can be  overworked.
>>
>>     - Mike -
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