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Equipment Discussions >> Refractors

Pages: 1
ponz
super member


Reged: 07/18/12

Loc: Kansas City, MO
SkyWatcher Pro 80ED Rough Spot
      #5646945 - 01/27/13 09:04 PM

Greetings!

I've been familiarizing myself with my new toys. The SkyWatcher and Atlas mount.

There's one spot on my focus tube, if you will, that hangs up when focusing and I have to help it gently pass that spot. I'm wondering if it's an issue or if I should attempt taking it apart, re-greasing it or if there's an adjustment somewhere?

I'd hate to return it, if it's a simlple fix.

Thanks
Ponz

Your additional thoughts please.


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ponz
super member


Reged: 07/18/12

Loc: Kansas City, MO
Re: SkyWatcher Pro 80ED Rough Spot new [Re: ponz]
      #5647029 - 01/27/13 09:55 PM

By the way....It has the 2” Crayford rack & pinion focuser-assembly

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Jon Isaacs
Postmaster
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Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: SkyWatcher Pro 80ED Rough Spot new [Re: ponz]
      #5647054 - 01/27/13 10:12 PM

Quote:

By the way....It has the 2” Crayford rack & pinion focuser-assembly




Ponz:

Is it slipping at that one spot?

Jon


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ponz
super member


Reged: 07/18/12

Loc: Kansas City, MO
Re: SkyWatcher Pro 80ED Rough Spot new [Re: Jon Isaacs]
      #5647082 - 01/27/13 10:27 PM

Quote:

Quote:

By the way....It has the 2” Crayford rack & pinion focuser-assembly




Ponz:

Is it slipping at that one spot?

Jon




Yes Jon. Slipping at just one spot


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Jon Isaacs
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Reged: 06/16/04

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Re: SkyWatcher Pro 80ED Rough Spot new [Re: ponz]
      #5647440 - 01/28/13 05:59 AM

Quote:

Quote:

Quote:

By the way....It has the 2” Crayford rack & pinion focuser-assembly




Ponz:

Is it slipping at that one spot?

Jon




Yes Jon. Slipping at just one spot




Crayford focusers can be quite finicky. If the scope is under warranty I would be worthwhile contacting the seller and discussing this with them.

That said, in my experience, Crayfords eventually need some attention, whether it is just cleaning the drawtube flat and pinion, adjustment or even modification. A common fix for the Synta Crayfords has been to carefully stone the drawtube flat so it is actually flat. But I wouldn't go there yet.

First I would inspect the drawtube to see if there is any problem. Then I would wipe it down with alcohol. If that didn't solve the problem then I would more carefully clean the pinion and the flat. I recently discovered this trick:

Cut a strip of standard, white computer paper the width of the drawtube and the full 11 inch length. Then with the drawtube fully extended, slip the paper into the focuser so it slips under the pinion shaft. I then run the focuser back and forth and clean the pinion by letting it slip.

There is also an adjustment screw that adjusts the load on the pinion, some scopes have a thumb screw for this, some do not. The screw is next to the focuser lock thumb screw. Increasing the "tension" can help with slippage but one has to be careful...

Jon


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Scott BeithAdministrator
SRF
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Reged: 11/26/03

Loc: Frederick, MD
Re: SkyWatcher Pro 80ED Rough Spot new [Re: Jon Isaacs]
      #5647478 - 01/28/13 06:43 AM

Jon gave good advice. Check with the seller if possible.
If that isn't an option, then adjust as he instructed.
If that doesn't solve the problem to your satisfaction:

Get a Moonlite focuser and never worry about it again.


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Chuckles34
member
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Reged: 08/03/11

Loc: San Antonio, TX
Re: SkyWatcher Pro 80ED Rough Spot new [Re: Scott Beith]
      #5649276 - 01/28/13 09:15 PM

Slipping or binding? The coarse focus knob on my Skywatcher 100ED needed ever so slightly loosened because the inside edge of the knob would rub during a certain point in the rotation. Bad tolerence in the knob, not mounted on spindle perpendicular, other...I don't know, but it came from factory like that.

-Chuck


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ponz
super member


Reged: 07/18/12

Loc: Kansas City, MO
Re: SkyWatcher Pro 80ED Rough Spot new [Re: Chuckles34]
      #5649312 - 01/28/13 09:37 PM

Slipping. And I really have to tighten it down, BIG TIME, in order for it to hold steady while pointing straight up with my DSLR attached.

I've been told, by a reliable source, that's about as good as it gets with this focuser.

Celstron sent me a return auth for a replacement, but I don't think I'll bother with a replacement, since I'll just inherit the same condition/focuser again. It would be a real pain to pack eveything up too.

I guess I'll save for a better focuser.

If anyone can suggest if taking it off/apart to rework it for the better, I'd give that a shot.

Ponz


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Jon Isaacs
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Re: SkyWatcher Pro 80ED Rough Spot new [Re: ponz]
      #5649770 - 01/29/13 07:04 AM

Quote:

Slipping. And I really have to tighten it down, BIG TIME, in order for it to hold steady while pointing straight up with my DSLR attached.

I've been told, by a reliable source, that's about as good as it gets with this focuser.

Celstron sent me a return auth for a replacement, but I don't think I'll bother with a replacement, since I'll just inherit the same condition/focuser again. It would be a real pain to pack eveything up too.

I guess I'll save for a better focuser.

If anyone can suggest if taking it off/apart to rework it for the better, I'd give that a shot.

Ponz




In the past there have been several discussions of reworking the Synta Crayford focusers. I have done a few myself. If you post a photo of your focuser, I can probably tell if it is basically the same focuser as the ED-80/ED-100s..

Jon


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ponz
super member


Reged: 07/18/12

Loc: Kansas City, MO
Re: SkyWatcher Pro 80ED Rough Spot new [Re: Jon Isaacs]
      #5655847 - 02/01/13 09:00 AM

I managed to take the focuser apart and tighten things down quite nicely. It was actually pretty darn easy. Now, I can hold the scope by the focus tube and jiggle it without any slipping at all!!

Check this out. A must do for anyone with focuser issues!

http://www.astronomyshed.co.uk/forum/viewtopic.php?f=43&t=4932


Ponz

Edited by ponz (02/01/13 09:02 AM)


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Jon Isaacs
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Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: SkyWatcher Pro 80ED Rough Spot new [Re: ponz]
      #5656270 - 02/01/13 12:30 PM

Quote:

I managed to take the focuser apart and tighten things down quite nicely. It was actually pretty darn easy. Now, I can hold the scope by the focus tube and jiggle it without any slipping at all!!

Check this out. A must do for anyone with focuser issues!

http://www.astronomyshed.co.uk/forum/viewtopic.php?f=43&t=4932


Ponz




Ponz:



That is a somewhat unusual design, good to know about it.

My favorite design is the JMI, instead of a friction block to provide the load on the pinion shaft, they have a ball bearing that pushes directly on the shaft... no added friction.

Jon


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oo_void
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Reged: 11/13/09

Loc: San Francisco, CA
Re: SkyWatcher Pro 80ED Rough Spot new [Re: ponz]
      #5656272 - 02/01/13 12:30 PM

The optics on the SkyWatcher are great, but the focuser leaves a lot to be desired. There are a couple of articles (including the one listed above) that might help. When I had my 80ED though, I finally settled on an after market upgrade after much, futile, fiddling.

One thing I didn't try was adding some teflon tape to flattened surface of the draw tube.


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ponz
super member


Reged: 07/18/12

Loc: Kansas City, MO
Re: SkyWatcher Pro 80ED Rough Spot new [Re: Jon Isaacs]
      #5656291 - 02/01/13 12:41 PM

Quote:

Quote:

I managed to take the focuser apart and tighten things down quite nicely. It was actually pretty darn easy. Now, I can hold the scope by the focus tube and jiggle it without any slipping at all!!

Check this out. A must do for anyone with focuser issues!

http://www.astronomyshed.co.uk/forum/viewtopic.php?f=43&t=4932


Ponz




Ponz:



That is a somewhat unusual design, good to know about it.

My favorite design is the JMI, instead of a friction block to provide the load on the pinion shaft, they have a ball bearing that pushes directly on the shaft... no added friction.

Jon




Thanks Jon. I was tickled pink not having to return the scope! It took about 5 minutes of tweaking the see-saw screws and center tightening screw to achieve the correct level and tension.

I imagine that's exactly what they would have done if I returned the scope!

later
Ponz


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ponz
super member


Reged: 07/18/12

Loc: Kansas City, MO
Re: SkyWatcher Pro 80ED Rough Spot new [Re: oo_void]
      #5656295 - 02/01/13 12:43 PM

Quote:

The optics on the SkyWatcher are great, but the focuser leaves a lot to be desired. There are a couple of articles (including the one listed above) that might help. When I had my 80ED though, I finally settled on an after market upgrade after much, futile, fiddling.

One thing I didn't try was adding some teflon tape to flattened surface of the draw tube.




Wouldn't adding some teflon tape to flattened surface of the draw tube knurl up?

I did notice some teflon lubricaion the axle (for lack of better terms)


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Jon Isaacs
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Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: SkyWatcher Pro 80ED Rough Spot new [Re: ponz]
      #5656340 - 02/01/13 01:11 PM

Quote:


Wouldn't adding some teflon tape to flattened surface of the draw tube knurl up?




That is where you need the friction so Teflon would be the wrong thing. Crayfords use friction between the pinion and the drawtube flat instead of gears so one want's as much friction between them as possible.

Jon


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ponz
super member


Reged: 07/18/12

Loc: Kansas City, MO
Re: SkyWatcher Pro 80ED Rough Spot new [Re: Jon Isaacs]
      #5656373 - 02/01/13 01:32 PM

Quote:

Quote:


Wouldn't adding some teflon tape to flattened surface of the draw tube knurl up?




That is where you need the friction so Teflon would be the wrong thing. Crayfords use friction between the pinion and the drawtube flat instead of gears so one want's as much friction between them as possible.

Jon




I should have included that in my inference Jon.

I noticed a tiny bit of teflon tape assisting the axle between the knobs, which makes sense. Since I tightened it up really good, I suspect that tape will begin to wear more quickly. But I'm not worried about that because I can, now, get in there very easily.


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Fogboundturtle
professor emeritus


Reged: 05/20/09

Loc: Burnaby, BC
Re: SkyWatcher Pro 80ED Rough Spot new [Re: ponz]
      #5656376 - 02/01/13 01:33 PM

after using a FT focuser of my other scope, There is no way this SW focuser will do the trick for me. Its hard to go back after using the best.

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