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Intes mk-67 focusser help needed

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#1 Nebula27

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Posted 24 August 2019 - 07:38 AM

I just received my "new" intes mk 67, which I bought used for a very good price, but the focusser isn't working properly. When I turn the focusser, the  inner tube moves, but with almost no force. So I guess I need to adjust the tension of the teflon bearing on the inner tube. Can anyone help on on which screws I need to adjust?

Attached Thumbnails

  • 20190824_143643.jpg
  • 20190824_143804.jpg

Edited by Nebula27, 24 August 2019 - 07:40 AM.


#2 luxo II

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Posted 24 August 2019 - 08:46 AM

Sounds like you have not used a Crayford focusser before - that’s exactly how they’re supposed to work - ie next to zero force.

The real question is whether it holds an eyepiece without slipping. If so, it is correctly adjusted.

In the second photo I’d suggest the two larger screws are the ones to tweak - and note they have knurled heads suggesting they should be finger-adjustable.

Do not overtighten these unnecessarily - all that is needed is enough force to hold an eyepiece.

If you overtighten you risk creating a groove (bump) in the surface of the drawtube.

Edited by luxo II, 24 August 2019 - 08:50 AM.


#3 Nebula27

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Posted 24 August 2019 - 09:16 AM

Sorry for poorly explaining the problem. I meant there is not enough friction to hold an eyepiece. The screw to the side of the mirror seems to lock the inner tube and the other screw to the side of the diagonal seems to adjust the friction like you said. If that screw is tightened, there is still not enough friction to hold my somewhat heavier eyepieces(diagonal+eyepiece is about 1.5-2 lbs max). It seems that there is some space bewteen the inner tube and the top of the focussing tube. So maybe I need to tighten a screw on the top of the focusser to press the inner tube against the teflon bearing, or would I just have to tighten the big screw on the side of the diagonal even more?

Edited by Nebula27, 24 August 2019 - 09:19 AM.


#4 luxo II

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Posted 24 August 2019 - 09:23 AM

Ah ok understand.

Experiment. If you figure which screw is the one that locks it, ie all-or-no drag, consider replacing a steel screw with a nylon screw which will give you adjustable drag.

I did that to mine and the result is nirvana. I also found a UK source of nylon screws.

Edited by luxo II, 24 August 2019 - 09:24 AM.


#5 Nebula27

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Posted 24 August 2019 - 09:36 AM

It's not really all or no drag(I just eddited my previous post because I said it wrong, sorry my Englisch is not that good). I can't get enough friction to hold my somewhat heavier eyepieces. Do I need to tighten the screw even more, with the risc of damaging the inner tube's surface, or can I do something else?

Thanks for helping, now I can at least use my 1.25" eyepieces.

Edited by Nebula27, 24 August 2019 - 12:48 PM.


#6 TomTTuttle

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Posted 27 August 2019 - 09:53 AM

I just got a MK-67 as well, and the focuser is a bit more finicky than the others in my not very broad experience.  I don't remember which, but yes it did seem like 1 locked the barrel and the other was the tension. The slightest bit of turning on the lock screw stopped the movement completely. On the tension screw it was very fussy - too little and it would just slip; too much and it was dragging.  I was able to play with it until I got it going just right. It was part of the reason for my wanting to upgrade the focuser  (Feather Touch on it's way :) ) - back travel is the other reason. Wish I could be more help... 




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