[ATM] Whiffle Tree mirror edge support help needed

[rguinamard at infonie.fr (Raphaël Guinamard)]

I'm always confused about the term "whiffle tree" and I don't have "whiffle"
in my dictionnary.
By "whiffle tree", do you speak about the arrangement of triangle/bar in a
cell or about a type of edge support with no sling like piano wire or
others.
So what is whiffle tree?
Rapha?l Guinamard
----- Original Message -----
From: Mark Suchting <masuch@cia.com.au>
To: Lawrence Sayre <lsayre@neo.rr.com>; The Amateur Telescope Makers List
<atm@atmlist.net>
Sent: Tuesday, February 24, 2004 9:29 AM
Subject: Re: [ATM] Whiffle Tree mirror edge support help needed


> At 07:56 PM 2/23/2004 -0500, Lawrence Sayre wrote:
>
>
> >Can anyone point me to good examples of Whiffle Tree based mirror cells?
> >Sites containing pictures would be great
>
> Judging from your subject line, I take it you are asking about edge
supports
>
> There is an example at:
>
> http://www.nightskyscopes.com/site/std_mirrorcell.shtml
>
> Click the small image of the edge support for a larger one.
>
> These manufacturers are using a layout favored by Pegasus optics for
> testing large thin mirrors.  The fulcrums of the two wiffle-tree bars are
> at 60 degrees apart , and the pads on either end of each bar span 30
degree
> apart. This leaves 30 degree gap between the inner two pads . Adding
> another four bars in this layout ( for an equatorial mounting layout )
> would give 12 pads at 30 degree spacing, something which George Ritchey
> seemed to favor in his famous essay.
>
> I've tested this layout with 20" X 1.6" with horizontal axis and the
mirror
> figure held very good.
>
> For edge support in the telescope I'm more in favor of the piano wire edge
> support at 90 degree because it works and is so simple to make . Have
> tested these on a 16" X 1" thick mirror.  I don't see any good reason to
> use slings anymore.  Theres not much practical information on the Piano
> Wire supports on the WWW yet.   Check the archives,    also :
>
> http://www.astrosurf.com/altaz/lateralsupport.htm
>
> In truth these supports  can either be a `machinists wonder' or a short
> length of 1.5mm piano wire poked into a wooden block with a little teflon
> pad on the end.
>
> Hope this helps.
>
> Mark Suchting
>
> _______________________________________________
> ATM mailing list http://www.atmlist.net/


---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.593 / Virus Database: 376 - Release Date: 20/02/04