Re: ATM which one first

[Robert Duvall <rduvall@jlc.net>]

At 6:06 AM -0700 6/14/98, Gary Heiner wrote:
>Tim-
>
>There is what appears to be an excellent design of a
>Crayford-style focuser at
>
>http://atmpage.com/mech.cgi
>
>
>BTW, has anyone made one of these? Should a bit of rubber
>hose or heatshrink go over the focuser shaft?

Yes a friend of mine on this list made me one. He incorporated a helical
piece in it at my request. I think it's a superb combination. A HeliCray.
I'll have to take a photo and add it to the page. He outdid himelf and
turned a round piece of stock down to make it look like the pro's instead
of the angle piece.

I thought of rubber over the focuser shaft to help prevent slippage, but
haven't tried it. It really would need to be thin, or wobble and other
undesireable behavious will result, I'm sure. I'm thinking of it becuase
I'll be adding a camera to it and the weight may cause it to slip. Only
those nice big Naglers might make it slip otherwise ;) My eyepieces
certainly pose no problem and the friction is adjustable.

The advantage I see to rack and pinion is the ability to add heavy loads
without slipping. But they don't have the smoothness of fine focus (unless
of very fine quality gears, I haven't seen them in commercial units).



Robert Duvall
Force5 Telescope Making Resources

Software Engineer, Amateur Astronomer (TN),
and General Scientist (according to my son)
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