Re: [ATM] need help with an altitude bearing problem

["Lawrence D. Lopez" <lopez@mv.mv.com>]

Dominic-Luc:

You have too little friction.

The idea behind teflon formica was to have
Dynamic and Static Friction the same not
to eliminate it entirely.

You can increase the overall friction by
increasing the load on the bearings
by adding weight, by use of a spring,
or by moving the bearing blocks farther
apart.

If the dynamic friction is higher than
static friction then you will have to resort
to clutches and so on because if you
increase the static friction the dynamic
friction will go up and the scope will
be hard to move.

Larry


Dominic-Luc Webb wrote:
>> I have a telescope that was made for me by a friend. The altitude
>> bearing surfaces are highly polished stainless steel against Teflon.
>> This results in extremely smooth motion with hardly any "stick-tion" at
>> all. This makes the scope very sensitive weight to changes at the ep and
>> difficult to counterbalance (ie, a counterweight that will keep the
>> scope from plunging downward when I add a 2" ep will also cause the
>> scope to swing toward the zenith once I pass the midpoint going
>> upwards).
>>     
>
> I have never been especially good at translating written words to
> a mechanical device, but I am guessing you are wanting something
> like a clutch. I have used greased cork and a tensioner for this.
> If a clutch sounds like something you are after, you could have
> a look at the higher end Manfrotto tripod heads. I finally got
> round to buying one (a tad expensive). My different cameras and
> spotting scopes have different weights and weight distributions
> and the tensioners and locks on the Manfrotto heads made a real
> easy task of switching cameras and lenses on the same tripod.
> This was actually a surprising and pleasant bi-product of my
> purchase. I wanted the Manfrotto for the very stable, long (~2
> meter), tripod legs so I could stand upright (much easier on
> the back than bending down). I think the clutch (adjustable)
> arrangement is pretty simple. It definitely works well and
> moving up and down to point at different altitudes gives
> essentially constant tension, which again, is adjustable.
>
> Dominic-Luc Webb
>
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>
>   

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