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Crayford Focuser Tension Adjustment Help

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#1 Peter A.

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Posted 21 February 2019 - 12:26 PM

I just received an ED66 CF from Orion (their CF equivalent of the discontinued AT66 ED, I believe). While the focuser is buttery smooth, it is quite stiff. The instructions say that the tension can be adjusted with the "drawtube tension thumbscrew," however, this is already loosened all the way. I called Orion and the rep wasn't quite sure. (He seemed more willing to let me figure it out, and exchange the whole thing if I couldn't get it, which I thought was a bit silly.)

 

I've never messed with a focuser before, so before I start playing with allen keys, can someone advise me on what all these screws do? I labeled them to make it easier than saying the "larger silver one" etc. grin.gif

 

 

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#2 SeattleScott

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Posted 21 February 2019 - 01:05 PM

Usually there are four screws that can be loosened or tightened. This layout is busy so it is hard to tell which screws, but I would guess A, B, C and D. If it doesn’t work tighten them back up and try different screws. Something should work.

Scott

#3 jeremiah2229

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Posted 21 February 2019 - 01:19 PM

Try this PDF and it should get you started safely.

 

 

Peace...



#4 junomike

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Posted 21 February 2019 - 02:09 PM

"E" is what determines the focuser tension. 

The Drawtube screw merely locks the Drawtube (used mainly for AP).


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#5 Peter A.

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Posted 21 February 2019 - 02:10 PM

Usually there are four screws that can be loosened or tightened. This layout is busy so it is hard to tell which screws, but I would guess A, B, C and D. If it doesn’t work tighten them back up and try different screws. Something should work.

Scott

 

Thanks Scott. It sounds like I won't mess it up by trying at least.

 

Try this PDF and it should get you started safely.

 

 

Peace...

Thank you. I actually have this PDF, and it wasn't clear to me which screws would be "equivalent" to those in the PDF. I'll re-read it though.



#6 Peter A.

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Posted 21 February 2019 - 02:12 PM

"E" is what determines the focuser tension. 

The Drawtube screw merely locks the Drawtube (used mainly for AP).

Thanks for that. Yes, it was clear that that the drawtube screw wasn't the right choice for adjusting the tension. The Orion instructions could be more clear in that regard.



#7 Peter A.

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Posted 21 February 2019 - 07:38 PM

I just tried adjusting the focuser. Curiously, "E" was the only one that actually loosened the the feel of the focuser, however, it causes the draw tube to float freely when it's loosened, so that's not the answer. I tried A and B, and C and D in pairs, as well as F and G. None of these made any discernible difference.

I must be missing something.



#8 jeremiah2229

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Posted 21 February 2019 - 08:24 PM

A, B, C and D hold the pinion onto the focuser, keep these snug, no need to mess with unless you want to remove the pinion. Remove the large tension screw then barely back out E, this levels the pinion. Now adjust F and G slowly while checking the tension/smoothness, go slowly. Once you have it as you want then snug E back up. F and G should not be over tightened so just make "contact" with these then   b a r e l y   snug them. It will be trial and error but hopefully you will get what you want.

 

Let us know if this helps.

 

 

Peace...

 

Edit:

 

Adjust E and F the same, equally, balanced.


Edited by jeremiah2229, 21 February 2019 - 08:26 PM.

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#9 Peter A.

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Posted 22 February 2019 - 07:02 AM

Thank you all. I will try again this weekend and report back.



#10 emflocater

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Posted 24 February 2019 - 03:40 PM

A, B, C and D hold the pinion onto the focuser, keep these snug, no need to mess with unless you want to remove the pinion. Remove the large tension screw then barely back out E, this levels the pinion. Now adjust F and G slowly while checking the tension/smoothness, go slowly. Once you have it as you want then snug E back up. F and G should not be over tightened so just make "contact" with these then   b a r e l y   snug them. It will be trial and error but hopefully you will get what you want.

 

Let us know if this helps.

 

 

Peace...

 

Edit:

 

Adjust E and F the same, equally, balanced.

Adjust E and F the same, equally, balanced.

Don't you mean F & G?

 

Cheers

Don



#11 jeremiah2229

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Posted 24 February 2019 - 05:04 PM

Adjust E and F the same, equally, balanced.

Don't you mean F & G?

 

Cheers

Don

Yes, good catch. I'm a dummy. Couldn't pick the winner of a one horse race.

 

 

Peace...


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#12 Peter A.

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Posted 25 February 2019 - 10:12 AM

Adjust E and F the same, equally, balanced.

Don't you mean F & G?

 

Cheers

Don

 

 

Yes, good catch. I'm a dummy. Couldn't pick the winner of a one horse race.

 

 

Peace...

 

I figured that was the case. Either way, I've been unable to get anything but a loose drawtube or a stiff focuser feel. Seems kind of strange really. Maybe I need to mess with it some more, but I can live with it as it is if I can't get it to loosen a bit.



#13 emflocater

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Posted 25 February 2019 - 03:43 PM

Call Orion and ask to speak with a Tech. Maybe over the phone they can walk you through steps as you adjust the focuser. I did this with JMI and Explore Scientific with happy results from both.

Cheers

Don




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