DIY rotating tube rings?

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DIY rotating tube rings?

Postby rene-gedaly » Mon Nov 27, 2017 5:39 pm

Hey, ATMers

​I'm putting my 7.5" Mak-Newt on a CGEM​/pier​ and don't want​ to pay $500 for professional rings so I can get the eyepiece where I need it.

The observatory f/5 reflector uses them. Anyone know who made them? Also Allen says we have a Newtonian with "poor man" rotating tube rings in the loaner program.

So, has anyone actually made rotating rings or know of someone who has? Cloudy Nights has examples, of course, but I'd love to discuss this with someone, especially since I have a non-standard tube diameter.
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Re: DIY rotating tube rings?

Postby rene-gedaly » Wed Nov 29, 2017 7:51 pm

From email list [email protected]:
Ed Fraini
Nov 27 (2 days ago)
On my Outreach DOB I put a system on for about $20 bucks, Involves a piece of L shaped plastic and a large, really large band clamp. Works really well. You would have to see it to understand how it works. I will talk in person with you about it.

Marty Levine via HAS <[email protected]>
Nov 27 (2 days ago)
7.5” is big, but I have accomplished this sort of thing with a slice of a large PVC pipe fitting and as Ed suggests a bracket made from aluminum, plastic or steel. I like to go prowl around ACE hardware for this kind of stuff.

Melanie Black via HAS <[email protected]>
8:53 AM (9 hours ago)
ACE is a REAL hardware store. Not "Home improvement" stores like home depot and lowes. or tool stores like harbor freight.
Plus the people there usually really know what they are talking about, unlike the above places.

Sarah Silva via HAS <[email protected]>
Have you tried Bering's Hardware?

Bram Weisman via HAS <[email protected]>
The Atascosita Ace is probably a good one for ya. The past owner was into Astronomy, but sadly he did pass. In general, the older the hardware store, the better. You could try Southland in the Montrose area on your way to the meeting.

John Haynes via HAS <[email protected]>
I’m a little late to the party on this one, but I’ve mocked-up a solution in Sketchup.

It requires 4 hose clamps that are large enough to fit all the way around comfortably. You probably want to add some kind of padding (felt or rubber?) to prevent scratching the OTA. Basically, you place one clamp on either side of each of your dovetail rings, maybe 1mm away. You then loosen your dovetail rings JUST a bit, just enough that the tube can rotate freely. You might consider removing the felt from the rings and putting in some strips of PTFE (the same stuff that a lot of Dob bearings are made of) along with a little silicon lubricant. This would allow the tube to rotate freely in the rings, and the hose claps would prevent the tube from sliding up or down. It might not be a perfect solution, but I think it would probably work out ok and not permanently affect the OTA itself. The design might need a little modification, but I think the basic concept is sound. The PTFE you’d probably have to buy online (I don’t know anyone in the area that carries it), but the whole thing shouldn’t cost more than $20-30 I imagine.

image005.jpg


Buster Wilson via HAS <[email protected]>
7:26 PM (10 minutes ago)

to Buster
Lots of messages and different sizes in them. IF you have rings like mounted on the scope pictured it can be simple ATM stuff to do what you want. Make a phone call tomorrow and get one ring the same as what you have. Pieces of Teflon or other material is easily found local. And yes, nice rotating rings can be $500 and the standard ones $200. And then there are others. . . . like what you already have. It all depends on how much effort you want to do. Thanks. *BW*

Bram Weisman via HAS <[email protected]>
AttachmentsNov 30 (2 days ago)

I'm like to suggest a modification to John's idea. The house clamps alone are thin and may want to work their way under the factory rings. You could feed some PEX tubing over the hose clamp first, which would make the effective clamp height taller. Then it would bear against the side of the tube rings.

Plastic channel would be better than the PEX, if you can find the right size.
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