[ATM] Re: Sub-Diameter Lap?

[Ray at J-Engineering.com (Ray@J-Engineering.com)]

Hi Tom and All,

I have fresh Gugolz, 64 and 73.  Room temp is about 70 degrees F.  My 
plan will be to mix about 50:50 and not overheat it.

Two 8" f/6.3 mirrors.  One with a bad edge.  I was using a 6" rather 
hard lap.  While taking a break during final figuring, I read that a 
good way to get a smooth finish was to push hard and slow.  I tried it 
and promptly trashed the edge.  I should have know better!  Nothing I 
could do with this lap would get the edge back.

So here I sit.  I have ordered a mold from pitchlaps.com. My first 
thoughts are two laps, a 6" and a 8.8".  The oversized lap worked great 
when getting them spherical.  Someone suggested using an 8", but seems 
to me a 6" provides more local control.

Ray J


tkrajci@san.osd.mil wrote:

>>From: "Ray@J-Engineering.com" <Ray@J-Engineering.com>
>>
>>I need to make an new lap anyhow.  Might it be easier to figure 8"
>>mirrors with a 6" lap, 8" or slightly bigger?  If I go with the 6", is
>>it worth channeling it?
>>
>>Can one recover from a turned edge with the 6" lap?  I am looking for
>>the path with the best chances of success since I'm a first-timer.
>>
> 
> Have you measured the hardness of your pitch and determined that it is 
> within the proper hardness range at your workroom's temperature?
> 
> What f/ratio mirror are you figuring?
> 
> Tom Krajci
> Tashkent, Uzbekistan
> 
> 
> 
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