Re: [ATM] Stuck 20" lap on 30" mirror

["Lawrence D. Lopez" <lopez@mv.mv.com>]

Ok, how do you get it free ?
I'm dying to know.

Scott Milligan wrote:
> Dry ice, nice touch.  Even better, next time, you will skip the first step,
> eh?
>
> Shared by one who has stuck a full-sized 32" lap to a $10,000.00 substrate
> and lived to tell the tale.
>
> Scott Milligan
>
> -----Original Message-----
> From: atm-bounces@atmlist.net [mailto:atm-bounces@atmlist.net] On Behalf Of
> Lawrence Sayre
> Sent: Friday, November 02, 2007 1:08 PM
> To: ATM List
> Subject: Re: [ATM] Stuck 20" lap on 30" mirror
>
> Ouch!  Glad to hear that it came undone.   Hope the resulting fit is a 
> good one!!!
>
> Larry Sayre
>
> Bill Prewitt wrote:
>   
>> I've been traveling a lot lately, and have only been able to work on 
>> this figuring project for a few days every month or so. Last month, I 
>> poured a fresh layer of Gugolz 55 on a 20" lap, and left it to cold 
>> press till I came back.
>>
>> Big mistake... It was stuck tight.
>>
>> To dislodge the lap, I tried bar clamps, tubular webbing with a wood 
>> lever, then plastic-sheathed steel cable with a metal lever for several 
>> days of sustained force, but nothing worked.
>>
>> So yesterday I bought 10 pounds of dry ice, layered it on top of the 
>> lap, and covered everything with towels and blankets. After 24 hours of 
>> chilling under tension, the lap separated easily from the mirror.
>>
>> The lap surface was shiny & black.
>> I had forgotten to coat the face with CeO before pressing.
>>
>>       Bill Prewitt
>> ----------------------------------------
>>           www.astrocaver.com
>>   webpage of telescope making and caving
>>       My hobbies keep me in the dark
>> ----------------------------------------
>>
>>
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>>
>>   
>>     
>
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