Rotatable UTA

rmcpb (Rob) · #1 17-09-2006, 09:08 PM

In my quest for a collapsible split ring mount I have found, as expected, the eyepiece to end up in totally unacceptable positions as the mount is moved to point at varying objects.

I have seen designs that involve rotatable telescopes in the mount but I was wondering if anyone has ever seen an example of a rotatable UTA to allow the repositioning of the focuser regardless of the position of the telescope.

Sounds like a challenge worth taking up.

Any thoughts??

ballaratdragons (Ken) · #2 17-09-2006, 09:17 PM

Not to sound dumb, Rob, but what is a UTA?

Astroman (Andrew Wall) · #3 17-09-2006, 09:36 PM

Upper tube Assembly Ken.

I have seen something for a UTA, its a bit hard to describe but uses small rollers. There is a seperate ring section where the truss tubes attach to and the UTA sits on top of this ring in a recess. The rollers help the thing rotate about it's centre so no matter where you rotate it its still optically aligned, also stops it from falling off when at weird angles.. Where the UTA and truss ring meet you can either use teflon and ebonystar or roller bearings. As I said its a bit hard to explain.

ballaratdragons (Ken) · #4 17-09-2006, 10:11 PM

Thanks Andrew.

Seen one???

Yep! Used them!

The 8" EQ Reflector and the 26" Relflector at the Ballarat Observatory both have a rotatable UTA. Although a little stiff on the colder nights the 8" worked quite well. The 8" is the scope that Junior members were trained on. 16 years ago I used it as regular as possible and found the rotatable UTA VERY handy. The times I got to use rotatable UTA on the 26" it was hard to use.

Those that came to Camp last November went to see them. Here are some pics of the scopes. You can see the handles to turn the UTA's.

rmcpb (Rob) · #5 18-09-2006, 09:02 AM

Thanks Ken, Any idea on how the UTA was actually attached to the scope?

Merlin66 (Ken) · #6 18-09-2006, 09:25 AM

I successfully used one for many years on a 12" f5. ( Now with Peter Nelson in Vic) Made up a top hat which ran on 90 4mm ball bearings held in a "cage" between the bottom race ( mounted on tube) and the edge of the top hat.
Another popular design in South Africa in the 1970's was to have a flange running on three axial points and three edge points( teflon) and a couple of small clamps on the top ring to hold it together. Worked on a couple of 10" and 12" telescopes.
Maintaining optical alignment is always interesting??!!

Rotating the whole tube can be done just as easily, using a clam shell "box" with a circular hole to suit the tube. I used some felt seal around the edge as the bearing. This is used on my 13"

rmcpb (Rob) · #7 18-09-2006, 11:56 AM

Yeh, the more I think about it the more I am leaning toward rotating rings or the system in this setup.

Would be really cool to set up the rotating UTA but collimation has me a bit rattled

Lee · #8 19-09-2006, 11:28 AM

You would really need to be spot on, wouldn't you.... I have just started to think of rotating rings for my Newt, as I contemplate EQ mounting it.....

OneOfOne (Trevor) · #9 19-09-2006, 01:19 PM

Have a look at Antares tube rotators

http://www.scopestuff.com/ss_arrs.htm

I have put in an initial order, but haven't heard anything for more than a month. Antares are just starting production so they custom make each one. They are not cheap, but it is easier to buy a finished article some times than to try to develop something yourself.

I think they also have a high "cool" factor, especially for those who know of the problems with EQ mounts!