RE: [ATM] More Mirror Disasters! Pitch movement

[GARY FUCHS <gary@rcn.com>]

Thomas,

Thanks for the detailed explanation. Interesting things to consider...

Looks like you probably have some exquisite viewing conditions. Good wine too.

Gary Fuchs



---- Original message ----
>Date: Wed, 8 Jun 2005 21:01:52 +1000
>From: "Thomas" <tomjan@ozemail.com.au> 
>Subject: RE: [ATM] More Mirror Disasters! Pitch movement  
>To: "'Gary Fuchs'" <gary@rcn.com>, <atm@atmlist.net>
>
>Gary, 
>
>This advice is only pertinent to the final figuring stage, as the amount
>of "wear" of the lap in this final stage is quite small. 
>
>Besides most of the pitch lost from a lap isn't lost in a manor similar
>grinding glass, it's lost through trimming the lap, where the surface
>layer remains relatively unchanged, but the material supporting it moves
>outward from the centre of each facet/tile. Therefore if there is a
>piece of micro grit say 1mm below the surface and 5mm from one edge of
>the facet it will move towards the edge of the facet, but it's relative
>position to the working surface of the facet will not change much.
>Eventually it will reach the edge and be trimmed with the excess pitch.
>This is why laps get thinner with use.
>
>Clear skies,
>Thomas Janstrom
>http://www.tjanstrom.com
>http://www.norsewines.com.au
>"Your nobody until you've been ignored by your seventh cranio-facial
>nerve."
>
>
>-----Original Message-----
>From: atm-bounces@atmlist.net [mailto:atm-bounces@atmlist.net] On Behalf
>Of Gary Fuchs
>Sent: Wednesday, 8 June 2005 9:45 AM
>To: atm@atmlist.net
>Subject: Re: [ATM] More Mirror Disasters!
>
>
>I don't mean any disrespect, but it doesn't sound right to bury 
>something that might scratch in the pitch. At some point, if your 
>polishing/figuring continues, that contaminant is going to become 
>exposed - isn't it? Shouldn't you rather remove the contaminant, or 
>remake the lap with clean pitch?
>
>Gary Fuchs
>
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