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CEM40 mechanical issue

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#1 erlab16

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Posted 27 September 2022 - 08:16 AM

Hi there,

 

  I recently noticed some sort of a loose with the RA gear box - see attached picture  - of my CEM40 which might have contributed to the DEC backlash of 2400ms recently reported by PHD2.  It used to be well fixed on the mount but it is now moving eastward or westward by about two milimeters.  In fact, everytime I change the RA direction from east to west and vice-versa there is a 2mm delay between the command and the response.  Obviously the hex bolts holding the case on the mount have become loose, most probably through vibration.  I tried to screw them tight but I have no idea how to access them (they seem to be located behind the gear).

 

  I informed iOptron of the issue but I have received no answer yet.

 

  (Customer service seems to be swamped).

 

  Has anyone ever run into this issue before?

 

Thanks!

 

Regards,

 

EL

Attached Thumbnails

  • IMG_20220926_194924066-3.jpg

Edited by erlab16, 27 September 2022 - 08:19 AM.


#2 dx_ron

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Posted 27 September 2022 - 09:01 AM

I have attached iOptron's guide to tracking down sources of play in the CEM40. Good luck!

 

Attached File  CEM40_GEM45_PlayFixing_1_.pdf   340.14KB   36 downloads



#3 erlab16

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Posted 27 September 2022 - 11:05 AM

Hi Appolo,

 

  Thanks for the document.  

 

  Obviously there is a play with the whole gear case, and I have to remove the ring gear in order to tighten the hex screws (see picture below).

 

  However, this is exactly my problem: I had no luck at all trying to pry this ring out of the gear box (of course after removing the six screws).

 

  Since it seems to be rather easy - at least according to the document -, I will try again this evening using some other tools. 

 

  (Maybe two flat-head scrwedrivers?)

 

  Thanks again!

 

Regards,

 

EL

Attached Thumbnails

  • ring gear.jpg

Edited by erlab16, 27 September 2022 - 11:05 AM.


#4 eddyGorsuch

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Posted 27 September 2022 - 12:49 PM

Check the bolts on the other side of the RA axis. I had noticed some play in my RA axis, and fixed it by tightening the bolts that are accessible after removing the plate with the iPolar port. There are 4 bolts, and I can see them when I take out the plastic cover on the RA axis. 



#5 eddyGorsuch

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Posted 27 September 2022 - 12:52 PM

I have attached iOptron's guide to tracking down sources of play in the CEM40. Good luck!

 

attachicon.gifCEM40_GEM45_PlayFixing_1_.pdf

Ahh, I just saw this document. Check out pictures 7.4 to 7.6.



#6 erlab16

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Posted 27 September 2022 - 02:22 PM

Hi Eddy,

 

  Good idea for the rear pannel on picture 7.4 - 7.6.  I will check this one as well.

 

  However, I am quite sure there is a play with the gear case (figure 7.1-7.2), and I really couldn't pull out the ring gear.

 

  (Maybe I was too scared to scratch it).

 

  EL



#7 eddyGorsuch

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Posted 27 September 2022 - 06:15 PM

 

  However, I am quite sure there is a play with the gear case (figure 7.1-7.2), and I really couldn't pull out the ring gear.

 

  (Maybe I was too scared to scratch it).

 

  EL

I think I was able to pull off the gear by using a couple of hex wrenches to hook behind the gear and pull it out that way. 



#8 erlab16

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Posted 28 September 2022 - 08:25 AM

Hi Eddy,

 

  Guess what, I managed to pull the ring gear out of the gear box using flat-head screwdrivers and hex wrenches!  It took me about 20 minutes but I managed to do it.

 

  The 3 hex bolts begind the gear were completely slacked.  

 

  The RA case is now solidly fixed to the RA arm.

 

  I can't wait to measure the new backlash on PHD2!

 

  EL

Attached Thumbnails

  • ring gear pulled out.jpg

Edited by erlab16, 28 September 2022 - 08:25 AM.


#9 fmendes

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Posted 28 September 2022 - 08:42 AM

  However, this is exactly my problem: I had no luck at all trying to pry this ring out of the gear box (of course after removing the six screws).

 

  Since it seems to be rather easy - at least according to the document -, I will try again this evening using some other tools. 

 

  (Maybe two flat-head scrwedrivers?)

 

 

No screwdrivers!

 

Three of the holes on the gear are threaded. If I remember right, the screws are M3 but the holes are threaded with M4. Get three M4 screws and use them to jack the gear out of the shaft, tightening them evenly, little by little.

 

EDIT: now I see, it is already done. Next time, M4 screws are the right tools for the task.


Edited by fmendes, 28 September 2022 - 08:49 AM.


#10 erlab16

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Posted 28 September 2022 - 12:22 PM

Ok thanks!

 

EL



#11 fmendes

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Posted 28 September 2022 - 03:51 PM

One more thing I forgot to mention: There's a hole on the side of the mount where you can insert the Allen key to lock the RA shaft in place for service.




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