Re: ATM Non-rotating Helical focuser

[andydtg@phoenix.net]

Re:

>>Is there any of you who knows of a good design for a solid, low-profile,
>>non-rotating helical focuser ?
>
>A _non_rotating_ helical focuser? Is there such a beast?

I've built a couple of these, they have an inner sleeve with threaded
outer sleeve which can rotate but not move axially relative to the inner
sleeve. The inner sleeve is kept from rotation by a radial pin at
its lower end which engages a slot in the focuser body. The threaded
sleeve is turned by a ring at its top & as it moves axially it
carries the inner sleeve/eyepiece/camera with it. They're more
complex than a simple helical & not quite as rigid because of 
the additional sliding interfaces. They will carry a *lot* more
weight than the typical spring loaded Crayford focuser.

Andy Saulietis / DTG Alt-Az-Fp Drive Systems
HDPE Worm Gears, Custom designs & Machine work
12617 Harriet Ln
Santa Fe, TX 77510 USA
409-925-8854 Voice/Fax
e-mail: andydtg@phoenix.net