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Telescope and mount balancing challenges

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#1 dchamb

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Posted 24 May 2020 - 03:42 PM

Hi,

I've been doing cable management on my Astro-Tech 14" RC with a Paramount ME II. I've run into some frustration try to achieve balance. I've move the scope dovetail back and forth on the versaplate and can't seem to find an ideal place where the scope will stay steady with the Dec lock released. When the scope points to the north with the RA axis level and parallel to the floor, it stays in place from about 15 degrees to 80 degrees. However as it approaces zenith it falls forward towards the south and comes to a rest with the front of the scope pointing towards the floor and the back slightly higher than the front.

Do I need to put some weight on the scope somewhere to correct this?

Thanks,

Dale

#2 WadeH237

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Posted 24 May 2020 - 03:51 PM

If you want to get perfect balance, the declination axis needs to be balanced in two orientations.

 

I'm assuming that you balanced declination by putting the counterweight shaft parallel to the ground and then balancing with the scope also pointed parallel to the ground so that it doesn't move with the declination clutch released.  To complete balancing declination, release the dec clutch (with the counterweight shaft still parallel to the ground) and point the scope straight up.  If one side is heavier than the other, the scope will move when released.  To finish balancing, you either need to rearrange any accessories attached to the scope so that it can balance pointed straight up.  If you can't move stuff to get there, then you could add weight to the side of the OTA to get it in balance.  You will probably need to go back and make a final tweak on dec balance with the scope parallel to the ground again.


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#3 pyrasanth

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Posted 24 May 2020 - 04:12 PM

I had very similar problems with a C14 on the Paramount MX+. The back end of the telescope is really heavy so where ever I moved the OTA it would not balance. This is what I did as my problem was front end weight required. I hung a shopping bag on the front of the OTA (one of the strong sports type bags). I then filled it with weight until the tube balanced in DEC at its current position. I then weighed the bag & ordered the equivalent weight in lead flashing. I then fabricated a ring of 2 mm PTFE and lined the ring with the lead flashing. This was able to slip over my dew shield to achieve perfect balance in DEC. This is far better than counterweights on the front as the weight can be evenly distributed around the OTA.

 

You may be able to fashion a similar solution for your equipment.


Edited by pyrasanth, 24 May 2020 - 04:12 PM.

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#4 dchamb

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Posted 24 May 2020 - 05:17 PM

Thanks for the feedback! I suspected I might need to add some weight to the scope to balance it. I do have a SkyWatcher Esprit 80 refractor to piggyback onto the AT14RC but I thought it would work best to have the 14" in balance first.

Dale

#5 dchamb

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Posted 25 May 2020 - 04:21 PM

If you want to get perfect balance, the declination axis needs to be balanced in two orientations.

 

I'm assuming that you balanced declination by putting the counterweight shaft parallel to the ground and then balancing with the scope also pointed parallel to the ground so that it doesn't move with the declination clutch released.  To complete balancing declination, release the dec clutch (with the counterweight shaft still parallel to the ground) and point the scope straight up.  If one side is heavier than the other, the scope will move when released.  To finish balancing, you either need to rearrange any accessories attached to the scope so that it can balance pointed straight up.  If you can't move stuff to get there, then you could add weight to the side of the OTA to get it in balance.  You will probably need to go back and make a final tweak on dec balance with the scope parallel to the ground again.

 

 

I had very similar problems with a C14 on the Paramount MX+. The back end of the telescope is really heavy so where ever I moved the OTA it would not balance. This is what I did as my problem was front end weight required. I hung a shopping bag on the front of the OTA (one of the strong sports type bags). I then filled it with weight until the tube balanced in DEC at its current position. I then weighed the bag & ordered the equivalent weight in lead flashing. I then fabricated a ring of 2 mm PTFE and lined the ring with the lead flashing. This was able to slip over my dew shield to achieve perfect balance in DEC. This is far better than counterweights on the front as the weight can be evenly distributed around the OTA.

 

You may be able to fashion a similar solution for your equipment.

I have solved my balancing problem by temporarily attaching some bolts to the back edge of the AT14RC and testing the DEC balance. Once I found the right weight configuration I made a permanent weight out of PVC pipe filled with BBs and ends capped so there is no rolling of the inside contents. Strapped it to the same location on the scope and it says in position no matter where I move it. Thanks for the tips!

 

Now I just need some clear skies!

 

Dale




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