Re: ATM Astigmatism on 20 inch thin mirror

["A. Suykerbuyk" <asuyker@wxs.nl>]

Hi Martti,

Very interesting system. Could you give some additional information about
your side supports? Thanks!

Adrie Suijkerbuijk.

-----Oorspronkelijk bericht-----
Van: Martti Koskimo <martti.koskimo@kolumbus.fi>
Aan: atm@shore.net <atm@shore.net>
Datum: vrijdag 27 december 2002 22:47
Onderwerp: Re: ATM Astigmatism on 20 inch thin mirror


>I was asked if I made the bullet cones myself
>
>Yes,  the' bullets' are self made. It was not difficult at all. The raw
>material
>was M8 stainless steel screw rod.
>25 mm long ( and longer) bits was sawed.  Then it was inserted to small
>lathe. A Lathe is
>not indispensable. Electric drill will do the same.
>You must only have a ' holder ' for the drill. Then you take a file and
file
>the bullet shape
>while  the rod is revolving in the drill. sounds complicated but it is very
>easy and takes no time at all.
>After there is bullet shape use a set of abrasive cloth and you get nice
>polish on the bullet tip. This certainly  while the bit is revolving in the
>drill.
>And there is the other 'screw' side of the rod for easy fastening.
>
>The Teflon side is still easier.  Just find a suitable sinking cone drill.
>
>And yes,the triangles are not attached. No need for that. There are
supposed
>to be always lateral stops (sling etc.) and safety stops to prevent mirror
>from falling.
>
>This was the only support system and the only way I was able to eliminate
>astigmatism from my 700mm Dia 30 mm thick ' bad glass' Pyrex mirror.
>Probably I just blamed too much the glass while the main blame should have
>been improper
>support and improper handling of the mirror.
>
>The worst astigmatism I have ever seen was when the mirror was policed on
>the Dental Stone table covered with pitch squares ( 10 waves or something )
>
>
>Martti Koskimo
>
>
>