Strange issue with Quark T Thread adaptor

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Strange issue with Quark T Thread adaptor

Post by PDB » Tue Aug 23, 2016 6:22 pm

Hello,

together with my Quark, I ordered a Quark T-Thread adaptor. When I wanted to use it a few days ago, it did not fit as it should. Unscrewed the eyepiece holder then putting on the T-thread adpaptor I could screw it 1/4 to 1/2 turn, and then it is completely stuck. On another forum i found the thread should be something like 1.375" x 24, which is 3,49cm x 27 TPI. TPI i can't measure so i measured the outside diamer of the thread on the adaptor: 3,49 cm. That looked ok (seems to be the same a the old celestron visual back, so tried it on the old C8 tele-extender, perfect match)

Then i measured the Quark eyepiece holder: 3,45 cm. So a difference of 4 mm. This makes that the adaptor does not fit in the thread on the Quark (measured the same on the female thread in the Quark)

I called my supplier and he did some tests with the same type of adaptor on his quark. Fits perfect. He measured the outside diameter of the adaptor: 3,49 cm. Exactly the same as mine.

So we both are confused. (we do some more tests next week) If anyone had similar problem, or could measure the diameter of the thread on their quarks with a slide caliper I would very much like to know the results.

Kind regards,

Paul

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Re: Strange issue with Quark T Thread adaptor

Post by marktownley » Thu Aug 25, 2016 9:54 am

Is there any swarf blocking the threads?
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Re: Strange issue with Quark T Thread adaptor

Post by PDB » Thu Aug 25, 2016 9:57 am

Hi Mark,

nothing blocking it (at least nothing that I can see). Just a little bit smaller. The EP holder fits very smooth.

Rgrds,

Paul

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Re: Strange issue with Quark T Thread adaptor

Post by _Zakalwe » Wed Aug 31, 2016 8:08 am

The Quark thread (where the eyepiece holder fits) is not a T-Thread. It's some obscure imperial thread (1.375"...Celestron used the same thread on some ancient eyepiece projection adapters).
A T-thread will engage, but will foul quickly. I'm betting that your adapter is a standard T thread.
You need one of these:
https://www.firstlightoptics.com/adapte ... quark.html

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Re: Strange issue with Quark T Thread adaptor

Post by PDB » Wed Aug 31, 2016 9:25 am

I have this adapter http://www.rowanastronomy.com/productsa4.htm. But that does not fit on on the Quark. The Quark thread differs with 0,4mm from 1.375"x27TPI. I have the old C8 Visual back that is indead the same thread, but does not fit the Quark either. (What i mentioned in the message)
Looks like the Quark I have has sightly different thread (3.45cmx27TPI or 1.358x27TPI?) Same adapter seems to fit on other Quarks.


Paul

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Re: Strange issue with Quark T Thread adaptor

Post by _Zakalwe » Wed Aug 31, 2016 9:32 am

Hi Paul,

I have the Rowan Astronomy one too. It sounds like a machining error on the Quark, unless they've changed the thread pitch?

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Re: Strange issue with Quark T Thread adaptor

Post by PDB » Wed Aug 31, 2016 9:38 am

That is what I am trying to find out ...

Rgrds,

Paul

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