Re: ATM Driving a scope questions

[Andy Saulietis <iss@pvtnetworks.net>]

John Sherman writes,

>I put a Dob Driver on my old 17". It was troublesome. I took it off and
put on
>the early DSC unit from Lumicon. It was wonderful.
>Sure, a drive is nice. And Mel's system is way better than the Dob Driver.
But
>me, all I need is a DSC. Actually, I now REQUIRE a DSC. Lumicon seems to have
>the best encoder hardware (JMI the worst). I highly recommend spending the
extra
>and getting the DSC computer with at least 10,000 objects in memory. My
last top
>of the line Lumicon unit came with encoders, hardware and everything for
around
>$450. For me, it's the way to go. With a DSC you will likely see thousands of
>objects you would never see otherwise. More important to find an object,
than to
>guide on it.
>
>>Has anyone made a scope drive that is dual purpose,
>>that is can be used manually with the teflon/formica
>>bearings or the drive type bearings?
>
>Yes, my Dob Driver was set up that way.
>One big problem with having an Alt/Az drive is that lots of people will
assume
>your scope is a dob and that they know how to work it. I used to have to
babysit
>my scope constantly. No matter what I would say, many obnoxious people would
>still move the scope by hand. At Mt Pinos there are always a few
inconsiderate
>morons masquerading as AA's. After they damaged my drive I have
>not had one since. I considered an EQ platform, but then you have to
>reinitialize the DSC every hour. A split ring might be the way to go, you can
>put a clutch on the drive.

I have retrofitted several dozen alt-az scopes with simple alt-az > polar
drives,
of 16-36" aperture, which used the Tangent microprocessor controller. This
system
provided true polar rate alt-az tracking and used encoders to compute the
drive rates required to track. It did not provide high speed slewing (as
does the
Bartel's system) but did have  0.3 and 12x sidereal guide/point rates. The
mounts
had to be modified to eliminate the usual teflon/formica bearings to reduce
the
friction load seen by the drive motors, and had adjustable friction
clutches to
allow moving the scope manually, like the usual Dob, except than when
released, the
scope would track. It also had a field rotation port, several scopes using
this system are being
successfully used to do CCD imaging (Al Kelly's 17.5" and 32", for example,
see
http://www.ghgcorp.com/akelly ).

The Tangent controller is being discontinued by the mfg so any future
alt-az > polar
tracking scopes I build will use the more complex & capable Bartels system.
I'm currently
building a 36" scope/mount for a customer who wants to do CCD photometry
with it.

 
Andy Saulietis
ISS Enterprises
39 Silver Fox Trail
Mayhill NM 88339
505-687-3067 voice
505-687-3021 fax, call voice or e-mail to set up
e-mail: iss@pvtnetworks.net