Re: [ATM] Harry's 14-inch Sandwich Dob ready

["Peter" <peter@kitgear.com>]

Very nice work Harry!

Thanks Stathis for sending this.

Harry would you please tell us what adhesive you used to laminate the wood
to the styrofoam?
Your lateral edge support appear to be teflon pads. Do you have any problems
with astigmatism when moving from the vertical to horizontal positions?

Great looking scope.


Peter

-----Original Message-----
From: atm-bounces@atmlist.net [mailto:atm-bounces@atmlist.net]On Behalf Of
Stathis Kafalis
Sent: May 23, 2006 1:39 AM
To: atm@atmlist.net
Cc: harald.feigel@gmx.net
Subject: [ATM] Harry's 14-inch Sandwich Dob ready


Hello list members,

let me introduce you the latest baby, that Harry, a member of our mirror
making workshop in Munich/ Germany, just finished:

http://www.astrotreff.de/topic.asp?TOPIC_ID=41869

Harry started the mirror during telescope meeting Vogelsberg (ITV) exacly
one
year ago, working under the tent, as it was raining (like almost allways at
ITV). Tomorrow ITV starts again. Weather forecast: lots of rain!

The text is in German, but the pics shoud tell 90% of the story:
- 14" f/4.6 mirror made of 25 mm Schott Borofloat (this stuff became "THE"
mirror making glass in Germany)
- collapses into a box whre all parts fit nicely into each other
- almost all woodparts of styrofoam/wood sandwich
- one upper ring sandwich with 40 mm "Styrodur", a stiff styrofoam, cut with
a hot wire.
- Guitar string wire spider in X pattern - very stiff configuration!
- Filter weel made af a computer hard disk drive
- all in one 8-pole truss. Connenctions with bicycle quick fasteners - very
fast setup!
- Total weight just over 20 kg (~ 41 lbs)

The wohle thing feels like a high quality racing bicycle frame: lightweight,
extremly stiff, and works like a perfect machine.

Even before the 14" was finished, I had to get him a 22" borofloat for his
next project. It seems, that he can't live without ATM-ing anymore.
See some pics as I ground the back flat against a 24" (absolutely nessesarry
for the large extrathin discs to prevend astigmatism):
http://www.astrotreff.de/topic.asp?TOPIC_ID=39398
click to second page as well to see all pictures

Harry is not on the list. If you have questions you can contact him by mail
directly. As I followed most of the making process, propably I can reply to
some comments as well.


Stathis Kafalis
T: 089 / 62 42 01 71
www.stathis-firstlight.de

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