ATM [Fwd: BOUNCE atm@shore.net: Non-member submission from [Bjørn Sørheim <bsoerhei@online.no>]]

[Mel Bartels <mbartels@efn.org>]

owner-atm@shore.net wrote:

> To: atm@shore.net
> From: Bjørn Sørheim <bsoerhei@online.no>
> Subject: Re: ATM Re-coating mirrors
>
> At 08:39 03.09.97 -0500, Dave Parker wrote:
> >Just a quick question. How do you remove a mirrors coating to have it
>
> >re-coated? Is it done chemically? Does it require reworking the
> surface?
>
> I have an additional question here, really a horror-story.
>
> I read about the advantages of having a mirror-spot in the center
> of the primary (and a small one on the secondary), using a sighting
> tube for alignment.
> So I made one from some piece of red plastic. To make it stay in the
> right place for a while I thought that it would be best to use a
> strong
> glue, so I didn't fall off in the end - and _stayed_ in the very
> center.
> I therefore chose Araldit epoxy! Not thinking anything about such
> thing
> as a recoating!
>
> I made a centering mask with a hole (made of a washer) having a
> slightly
> bigger diameter for placing/centering the spot. Well, I tended to put
> on too
> much of glue, so the superfluous made a rimmed ring around the spot,
> while also some long thin hairlike strings of glue was made when I
> tried to lift
> off the mask, and some glue had come under the washer! These strings
> of glue
> was of course impossible to remove, the result would have been a
> disaster.
> The mirror is performing pretty well anyway, the area of the glue is
> very small.
>
> My reccomandation: Don't use Araldit, don't use a centering washer
> (the glue
> will come under it)!
>
> So my question is: Is this Araldit glue (with spot and glue-strings)
> possible
> to remove when I come to the recoating process?
>
> Bjørn Sørheim
>
> --
> - Bjørn Sørheim



--
Clear skies, Mel Bartels    Programmer/Analyst, amateur astronomer
Eugene, Oregon, USA         homepage: http://www.efn.org/~mbartels
mailto:mbartels@efn.org     atm, atm-digest list-owner
Motorize A Dob: http://zebu.uoregon.edu/~mbartels/altaz/altaz.html