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Focus rack excessive play

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#1 rob12770

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Posted 02 March 2021 - 06:43 AM

Hi all, im new here smile.gif

i recent dug my Celestron PowerSeeker 127EQ reflector out the shed and have cleaned it up, collimated it etc. 

im finding the focus rack has too much play in it, making t harder to get a stable focus ..

is there a way to "tighten" up the rack so its not as sloppy ?

 Thanks Rob from Scotland  hamsterdance.gif


Edited by rob12770, 02 March 2021 - 09:42 AM.


#2 Ulmer Spatz

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Posted 02 March 2021 - 07:30 AM

Step-by-step instructions with good photographs at the link:

https://www.cloudyni...-127eq-rebuild/


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#3 DAG792

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Posted 02 March 2021 - 07:32 AM

Hello, and welcome to Cloudy nights.

The problem you're facing is a common issue with all such focusers. First thing that you should try is tightening up the two screws on the focuser body.

If that doesn't work, you'll need to disassemble the focuser and use teflon tape as shims inside the drawtube. 


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#4 Ulmer Spatz

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Posted 02 March 2021 - 07:37 AM

First thing that you should try is tightening up the two screws on the focuser body.

Good point! You can see those two screws on the bottom of the photo showing all the parts laid out on a table. 


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#5 rob12770

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Posted 02 March 2021 - 09:32 AM

Brilliant replies guys thanks  waytogo.gif

i will look through all this and sort it out laugh.gif



#6 rob12770

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Posted 02 March 2021 - 11:32 AM

Looks like in its history, its had this job done before  ( unless this is original ?)

 



#7 Ulmer Spatz

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Posted 02 March 2021 - 11:44 AM

Looks like in its history, its had this job done before  ( unless this is original ?)

I think I've seen those strips on brand-new scopes, but I couldn't swear to it. Too many old memories floating around now, with some of them of questionable authenticity. Wish we had had cell phone cameras then, but that was unimaginable. A phone with a camera in it? What a silly idea, you'd need miles and miles of chord!  


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#8 rob12770

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Posted 02 March 2021 - 11:49 AM

im finding it impossible to source "teflon strips" they all seem to be ones for food sealer machines AFAIK..

these dont look like what i need

and i think PTFE tape would last about 2 minutes ..the plumbers stuff that is,  but i see theres other stuff


Edited by rob12770, 02 March 2021 - 12:05 PM.


#9 rob12770

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Posted 02 March 2021 - 11:52 AM

. A phone with a camera in it? What a silly idea, you'd need miles and miles of chord!  

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#10 Ulmer Spatz

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Posted 02 March 2021 - 12:17 PM

The "Teflon" strips could possibly be sold under another name since "Teflon" is a registered trademark for PTFE (polytetrafluoroethylene). One source might be an art and crafts supply store. Some of the art/craft sheets or boards they sell look and feel like PTFE. Someone here will have a better idea. Many Dobsonian telescopes rotate horizontally on Teflon strips stapled or glued to the turntable base.

 

PS. A few weeks ago, I found the exact material I needed for a project (unrelated to telescopes) when going through my garbage. Turned out that a discarded plastic food container's material had just the right thickness and could be cut easily It came from a Chinese food take-out place.


Edited by Ulmer Spatz, 02 March 2021 - 12:47 PM.

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#11 rob12770

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Posted 02 March 2021 - 01:05 PM

The "Teflon" strips could possibly be sold under another name since "Teflon" is a registered trademark for PTFE (polytetrafluoroethylene). One source might be an art and crafts supply store. Some of the art/craft sheets or boards they sell look and feel like PTFE. Someone here will have a better idea. Many Dobsonian telescopes rotate horizontally on Teflon strips stapled or glued to the turntable base.

 

PS. A few weeks ago, I found the exact material I needed for a project (unrelated to telescopes) when going through my garbage. Turned out that a discarded plastic food container's material had just the right thickness and could be cut easily It came from a Chinese food take-out place.

funny you say that, i JUST installed some plastic (cotton buds tub) Q-tips,

i did 2 layers, seems to work pretty well, tiill i can find a better solution..

given the reoccurrence of this issue, im surprised no one makes an bespoke solution.



#12 Ulmer Spatz

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Posted 02 March 2021 - 01:38 PM

given the reoccurrence of this issue, im surprised no one makes an bespoke solution.

I think there's no real demand in terms of numbers. From what I understand, 90% of these type of scopes get used once or twice, then put away in the attic or gotten rid of one way or another.. Most of these folks don't even care to find out why the scope was not a pleasure to use.



#13 rob12770

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Posted 02 March 2021 - 02:01 PM

yeah, i did the same, its been sitting the the shed for 2 years.. just decided to pull it out..i like the Idea of Astronomy, but it get too cold here at night..so my interest waned a bit..so.. round 2  tongue2.gif  

im quite into general photography, ( M4/3) and i like everything magnification.. binoculars etc.. its always interested my since i was a wee boy.. still does.lol.gif



#14 Ulmer Spatz

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Posted 02 March 2021 - 03:44 PM

Yes, same here--interrupted career. First scope was a home-made Christmas gift. I remember my father sitting in the kitchen wrapping glue-soaked newspaper strips around a dowel rod until he had the focuser insert. Never let on what it was he was making.




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