Re: [ATM] balancing a serrurier truss

["Andreas Derwahl" <andreas@duda-derwahl.de>]

Thanks all for your input.

>From your replies I get the feeling that it is very hard to design a
lightweight scope that stays put in every situation, i.e. changing back and
forth from leightweight to heavyweight eyepieces during observing.

I very much like Scotts idea of using the 2" to 1 1/4" adapter as a
counterweight, that way I only need to use the suggested altitude break.

As the scope will only stay put when the torque of the unbalanced scope does
not exceed the torque imposed by the teflon/ebony star bearings, I now see
it will be very difficult to anticipate the behavior. The bearing torque
depends on altitude ring diameter and sticking force of the teflon/ ebony
star pairs, which depends on the contact pressure, bearing area and sticking
coefficient of these pairs, right?

So I will make the rockerbox and see, how much torque the altitude bearing
can cope with. That will then give me an idea on where to place the alt axis
and if I can do without alt break or counterweights.

Andreas


----- Original Message ----- 
From: "Scott Ewart" <scott.e@quicksurfer.com>
To: <atm@atmlist.net>
Sent: Thursday, December 16, 2004 6:39 AM
Subject: Re: [ATM] balancing a serrurier truss


>
> ----- Original Message ----- 
> From: "Jay Kirkland" <jaykirk2@compusmart.ab.ca>
> To: <atm@atmlist.net>
> Sent: Wednesday, December 15, 2004 5:55 PM
> Subject: [ATM] balancing a serrurier truss
>
>
>     It's been my experience that the lighter the telescope, even with a
> heavier mirror, the more susceptable it is to imbalance, especially from
> Mr Nagler's or Mr. Pentax's heavy pieces of glass. There is no way to go
> from a 1 1/4" eyepiece to one of the bigger Nagler's and maintain a
> balance point in a lightweight scope.
>
>
>     Sure there is.  Just use a really heavy 2" to 1 1/4"  adapter.  I made
> mine out of brass.  It weighs about a pound.  The TeleVue Equalizer
> (SchwarzeNagler) weighs about 12 oz.  With an 1 1/4" eyepiece, it's pretty
> close to most heavy 2" eyepieces.
>     This won't help when changing eyepieces.  It's pretty light when
there's
> nothing in the focuser.  But if the scope will hold, or you can hold the
> scope, while changing, then the feel won't change much at all.
>
> Scott Ewart
>
>
>
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>


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