[ATM] creative lap choices - what has been tried?

[Dominic-Luc Webb]

I am not sure what your question is after. These are very
fast mirrors by most ATM measures: slowest is F/3. All are
spherical.

Dominic


On Mon, 30 Jan 2012, Paul A. Valleli wrote:

> Yes, Dominic, all of the materials you listed have
> been used for one purpose or another, but most cause
> the glass to flow, covering up pits and defects and
> leave an orange-peel finish that is unacceptable for
> astronomical use. Additionally, Teflon sheet has
> been tried ( extremely slow), paper, and
> Polyurethane foam pads (PUCO). Some are available
> already loaded with cerium during the manufacturing
> process.
>  Synthetic Polycrystaline Diamond powder from DuPont
> is currently the fastest know agent and is used for
> military projects or anyplace where delivery time is
> critical. The material is available in a variety of
> micron and sub-micron grades, some are pre-mixed
> slurries.  Hard materials such as ruby, sapphire,
> ALON, and Spinel require its use.  VEERY EXPENSIVE
> for the amateur to consider.
> The diamond slurry is used with copper matrix laps
> for grinding and good-old Gugolz pitch for polishing
> and figuring. Burgundy Pitch, Coal Tar/Rosin and
>  similar resins work and must be flexible enough to
> follow the extreme asphericty of the mirrors.
>
> Are these mirrors going to be crude light buckets ?
> Starman Paul
>
>
>
>
> ---- Original message ----
>
>   Date: Sun, 29 Jan 2012 10:14:49 +0100 (MET)
>   From: Dominic-Luc Webb <dlwebb at canit.se>
>   Subject: [ATM] creative lap choices - what has
>   been tried?
>   To: ATM Superheros <atm at atmlist.net>
>   >>Hi,>>I now have a couple of mirrors to polish
>   and a couple in>line after that. They are all fast
>   mirrors, like: F/0.37,>F/1.0, etc with F/3.0 being
>   the slowest. The F/0.37's are>currently convex
>   (thick with flat back). We could
>   separately>discuss the cool things one could do
>   with these, but at>this moment, while a lot of
>   polishing is ahead of me, I am>wondering what
>   kinds of laps the more creative people in>here
>   have tried?>>Some know I have used bee's wax in
>   the past. This was>so-so, but can be used OK if
>   you do not have pitch. The>CeO tended to get
>   embedded into the wax too easily and>seemed to use
>   up too much CeO. I have not done enough with>my
>   own pitch collected from various conifers, but
>   probably>competes well with commercial pitch once
>   the thickness/density,>etc get sorted out. Pitch I
>   collect is initially way too soft,>but probably
>   works OK. Then I have tried commercial
>   polishing>pads like the white wooly ones often
>   sold with drill>attachments. Like bee's wax, the
>   ones I used might have>worked, but used up so much
>   CeO that it was not very>efficient. CeO is a bit
>   hard to come by here, so I put>some priority on
>   low CeO consumption.>>What are used in gem making
>   that could be tried:>>1. felt>2. leather>3.
>   cork>4. cloth>5. wood>>Reflecting back, I wonder
>   if anyone on the list has tried>any of these?>>To
>   this, I could add linoleum flooring. I have some
>   left>over from a renovation I will try. No big
>   expecations,>but what the heck, it happens to be
>   sitting right next>to the mirror I need to polish
>   and its
>   tool.>>Dominic>>_______________________________________________>ATM
>   mailing list http://www.atmlist.net/
>