CEM60EC RA balance issue

[souls33k3r]

Hi All,

Today was the first time I managed to take the mount out since the pier got in. Mission was to spend some time and get the balance right. This mount and others of its kind are a different beast and not much material put there for a few issues. 

Any way, Dec was misbehaving but managed to get that sorted but now the RA is making me pull whatever hair is left on my head out. 

I suspect I will have to use that trick where I'd need a M12 rod and some washers and stick it in the counter weight thread and balance it but I'm not sure if I do. 

Here's a video, any ideas? 

[Rainer]

Hi souls33k3r,

Difficult to understand what your problem is.

My first well meant tip is get shorter cables for that stuff on top of the scope. You have a lot of unnecessary Copper weight up there.

About your RA balancing problems it would be good to see some images how the scope is up there and how the weight is distributed. Most of the times a slight unsymettrical weight distribution makes your life hard and in many cases it is possible to avoid any additional wight by analyzing well the weight distribution,

regards Rainer

Edited August 31, 2019 by Rainer

[souls33k3r]

4 hours ago, Rainer said:

Hi souls33k3r,

Difficult to understand what your problem is.

My first well meant tip is get shorter cables for that stuff on top of the scope. You have a lot of unnecessary Copper weight up there.

About your RA balancing problems it would be good to see some images how the scope is up there and how the weight is distributed. Most of the times a slight unsymettrical weight distribution makes your life hard and in many cases it is possible to avoid any additional wight by analyzing well the weight distribution,

regards Rainer

Hi Rainer, 

Yes I understand I've got a lot of cables up there which truth be told I have never had any issues with it plus the complete top bit can be removed and placed exactly like this on my second scope. My Dec balance is perfect and all this extra copper is acting like a weight for me to do this. Any way, that's another topic. 

My issue is that I can't see to find the RA balance. The mount is balanced horizontally which on other mounts is almost always good enough with a slight few adjustments but this is not like any other mounts  

But when my RA is pointing vertically (Scope pointing to celestial North Pole and counter weights down) it wants to always move in one direction. (Counter weights will want to move towards East and scope to the West). 

I found a video last night on YouTube 

He did manage to find a solution which seems to be a solution for many who own this mount and that is the threaded rod in the counterweight, some washers and a few nuts to hold the washers down. 

After more research, another chap on CN had the exact same issue (thread: https://www.cloudynights.com/topic/621559-balancing-problem-cem60-wvideos/) and he too had the same issue (3rd video link from the first post), he too ended up with almost similar solution but rather than threading the rod in to the counter weight, he ended up using a clamp on the RA counter weight bar and then thread the rod in the clamp. 

I think I know now that this is what I need but before heading off to the shops this morning, I would like to double check with a few who do own this mount as well in case they experienced the same issue with their mounts (be it a CEM60-EC or CEM60). I know @Anne S has the exact same mount and so does @fwm891 and @Brian28(Apologies for tagging you all in here but only because I've been following your work and know you've got the same mount). 

Thanks in advance. 

 

 

 

 

[fwm891]

@souls33k3r

I don't have this problem with mine probably because my guide scope sits directly over the main scope - I do that for all scopes with separate guiders. My Edge HD8 is used with an OAG so not a problem there. Re: cables where possible I have tied my cables back along their respective tubes until they're close to the mount, there I give them some slack to allow for slews east or west of the pier. I use the 4 point USB hub which has allowed me to further shorten cables.

Edited August 31, 2019 by fwm891

[Brian28]

 

 

 

 

 

Have a look at this YouTube video , I don't think your balancing the scope correctly .. .. IMHO

I removed the polar scope on my mount and run my cables up the middle I also removed the USB sockets which are useless and replaced with power supply sockets.. 

 

 

 

 

 

 

 

 

 

 

 

[Brian28]

If you check out this guys Youtube channel he has a couple of videos on balancing .. it might just be worth a look .

i am probably not as pernickety as I should be with my balancing , I tend to get it near enough , and I seem to get good  total RMS of 0.12 - 0.15 consistently..     

here's some pics of my modified mount .. 

hope this helps ...   

Brian 

[souls33k3r]

43 minutes ago, fwm891 said:

@souls33k3r

I don't have this problem with mine probably because my guide scope sits directly over the main scope - I do that for all scopes with separate guiders. My Edge HD8 is used with an OAG so not a problem there. Re: cables where possible I have tied my cables back along their respective tubes until they're close to the mount, there I give them some slack to allow for slews east or west of the pier. I use the 4 point USB hub which has allowed me to further shorten cables.

Cheers mate. Nothing of mine sticks out from the side at all, everything sits directly on the top apart from the focuser and the fw motor sticking out. So now I'm stumped.

9 minutes ago, Brian28 said:

If you check out this guys Youtube channel he has a couple of videos on balancing .. it might just be worth a look .

i am probably not as pernickety as I should be with my balancing , I tend to get it near enough , and I seem to get good  total RMS of 0.12 - 0.15 consistently..     

here's some pics of my modified mount .. 

hope this helps ...   

Brian 

Very nice and tidy. I need to learn from this I will at some point do through the mount cabling but then I only have 2 cables that come out of it. I've been balancing my NEQ6 for years and never had this issue. So quick question, how do you balance your RA then? Put the counterweight bar and scope parallel to the ground (horizontally) and adjust the weight accorindlgy? If so, do you try to move the RA in different position to check if it moves or not? 

[Anne S]

I find it helps to have as long a dovetail as possible. I then put a weight on the end that I can move back and forwards to balance the Dec axis, both when the R.A. is horizontal and when it is in zero position. I'm using a 300mm one but I'd prefer something longer. The saddle is so long! The guider stuff needs to be on the top as said by others. I've also got my Mount Hub Pro on a dovetail on top. It's mounted slightly on one side to counter the focus motor weight.

As to the R.A. falling to one side, the threaded rod, nuts and washers did the trick and was stocked by a local hardware/decoration shop. I live in a small town! It would be nice to screw a counterweight into the normal counterweight which would make it neater. I have to be careful not to walk into the rod at night! I just need to investigate whether anyone sells a m12 threaded counterweight, or get one made. A bit like the ADM one on FLO used to balance Dec. 

[Brian28]

Hi , I do exactly as per the videos ..   then you should be able to disengage both clutched and set the scope anywhere and it stays there ..    however if mine wanders slightly i don`t bother too much ..   

[Brian28]

"I find it helps to have as long a dovetail as possible"  ANNE S -----  I couldnt agree more .. especially when i set up my Edge ..  as it is rear heavy with the focuser 

[Anne S]

37 minutes ago, Brian28 said:

If you check out this guys Youtube channel he has a couple of videos on balancing .. it might just be worth a look .

i am probably not as pernickety as I should be with my balancing , I tend to get it near enough , and I seem to get good  total RMS of 0.12 - 0.15 consistently..     

here's some pics of my modified mount .. 

hope this helps ...   

Brian 

I like your power socket mods. It's a pity Ioptron used unsuitable threaded sockets. Also, I don't fancy leaving the polarscope uncovered, I don't use it as I have a Polemaster but I like to look after my stuff. 

[Brian28]

I removed the polar scope ..  !  I use the Polemaster 

[souls33k3r]

21 minutes ago, Anne S said:

I find it helps to have as long a dovetail as possible. I then put a weight on the end that I can move back and forwards to balance the Dec axis, both when the R.A. is horizontal and when it is in zero position. I'm using a 300mm one but I'd prefer something longer. The saddle is so long! The guider stuff needs to be on the top as said by others. I've also got my Mount Hub Pro on a dovetail on top. It's mounted slightly on one side to counter the focus motor weight.

As to the R.A. falling to one side, the threaded rod, nuts and washers did the trick and was stocked by a local hardware/decoration shop. I live in a small town! It would be nice to screw a counterweight into the normal counterweight which would make it neater. I have to be careful not to walk into the rod at night! I just need to investigate whether anyone sells a m12 threaded counterweight, or get one made. A bit like the ADM one on FLO used to balance Dec. 

Appreciate your input Anne, my dovetail is plenty long but maybe it's not long enough for this mount  everything of mine stays on the top. 

Here's what my setup looks like 

I know you've got the threaded rod on tge counterweight, wasn't sure if you experienced the same issue as I am. 

24 minutes ago, Brian28 said:

Hi , I do exactly as per the videos ..   then you should be able to disengage both clutched and set the scope anywhere and it stays there ..    however if mine wanders slightly i don`t bother too much ..   

I guess i wouldn't mind as well but then again I will try to eliminate any slight movement as well. I haven't seen Dion videos for so long but will watch it again for a refresher. Maybe there's something in there that can also help. 

21 minutes ago, Brian28 said:

"I find it helps to have as long a dovetail as possible"  ANNE S -----  I couldnt agree more .. especially when i set up my Edge ..  as it is rear heavy with the focuser 

EdgeHD is a tricky scope, there's a limit to the amount of dovetail that you can use. I have not had the chance to try it on this mount yet but it sure will be happening some time soon once I get this balance sorted out on the refractor

[Anne S]

1 hour ago, souls33k3r said:

Appreciate your input Anne, my dovetail is plenty long but maybe it's not long enough for this mount  everything of mine stays on the top. 

I wanted to have my guider on the top dovetail but there's not enough length to fit the MHP as well. I need a longer vixen plate on the top (and a smaller MHP but there's nothing wrong with mine and I need to have a reason to replace it). I'm going to have to rejig it once I've some more dovetails.

[Rainer]

5 hours ago, Anne S said:

I wanted to have my guider on the top dovetail but there's not enough length to fit the MHP as well. I need a longer vixen plate on the top (and a smaller MHP but there's nothing wrong with mine and I need to have a reason to replace it). I'm going to have to rejig it once I've some more dovetails.

Hi souls33k3r,

Now after so many messages I am confused.

To which side is your scope moving when I look at your last image ?

Would you please  post some images of your set up from different angles or view points ?

I have seen nowadays that more and more people pack more and more stuff onto the scopes and then start to balancing problems and if we apply Ockham´s razor then the balance problem is just because there is somewhere a slight asymmetrical weight distribution.

Now having balanced for more then 18 years scopes I came up with the idea which could help avoid adding all those threaded rods and washers all over our scopes.

Use a SBS = Side By Side  solution. Turn your lowest saddle plate by 90°, get a dovetail and a saddle plate, somrthing like this https://www.admaccessories.com/product/cgx-sbs-celestron-cgx-side-side-adapter/

and put the scope on it. In this way you can move the scope sideways when trying to balance the vertical position of the RA axis. Just an idea ... 🤔

BTW be sure to put the tightening knobs of the counterweights directly over the counterweight shaft. Those knobs can also influence the asymmetrical weight distribution.

Thank You

[souls33k3r]

Sorry about the late reply but I went out today and bought myself a 1m M12 rod, 4 nuts and a bag of washers. Cut the rod to 1 foot first and added 20 washers and voilà, the RA came to balance straight awat, cut the threaded rod to another 3" and added a few more washers and its still balanced. Couldn't be any more happier. 

Many thanks to @Anne S and her images for that. 

[StarDodger]

10 minutes ago, souls33k3r said:

Sorry about the late reply but I went out today and bought myself a 1m M12 rod, 4 nuts and a bag of washers. Cut the rod to 1 foot first and added 20 washers and voilà, the RA came to balance straight awat, cut the threaded rod to another 3" and added a few more washers and its still balanced. Couldn't be any more happier. 

Many thanks to @Anne S and her images for that. 

You really don’t need to do that, balance on a single scope rig is only needed on 3 axis and not 4.... but if it works and you are happy..but it really does not add anything to the set up...when you balance RA it’s just the sum of one end against the sum of the other....simples...the CEM 60 counterweight shaft is angle moveable to help with this 

This bolt circled in the image below has to be loosened and the bar can be moved in the direction of the arrows to achieve balance

Now when balancing the DEC axis then you have two axis to worry about, so you may need extra weight at either the front or back of the scope or possibly on one side or the other...

 

Edited August 31, 2019 by StarDodger

[souls33k3r]

2 hours ago, StarDodger said:

You really don’t need to do that, balance on a single scope rig is only needed on 3 axis and not 4.... but if it works and you are happy..but it really does not add anything to the set up...when you balance RA it’s just the sum of one end against the sum of the other....simples...the CEM 60 counterweight shaft is angle moveable to help with this 

This bolt circled in the image below has to be loosened and the bar can be moved in the direction of the arrows to achieve balance

Now when balancing the DEC axis then you have two axis to worry about, so you may need extra weight at either the front or back of the scope or possibly on one side or the other...

 

Hang on, from the documentation of the mount that bolt thay you highlighted is to be used to move the counterweight shaft if you're living in low altitude because at low altitude there's a chance of the counter weight bar hitting the tripod. That's all, never knew that it was also used for balancing the RA too 🙄

The RA axis was balanced when the scope was in horizontal position but that's the only place it was. As soon as I move it to a different position, the RA wants to come back to horizontal position. But this threaded rod trick worked like a treat. 

[Jkulin]

Hi Ahmed,

When I had my 8" RC it had a long Losmandy Rail, I wanted the weight to be as near to the dovetail as possible, so I bought another one and using extensions fitted my UPB under the scope, I also used a losmandy clamp with weights so that I could adjust the counterweights.

[souls33k3r]

1 hour ago, Jkulin said:

Hi Ahmed,

When I had my 8" RC it had a long Losmandy Rail, I wanted the weight to be as near to the dovetail as possible, so I bought another one and using extensions fitted my UPB under the scope, I also used a losmandy clamp with weights so that I could adjust the counterweights.

Hi John, 

Thank you for the share. And you scope balanced in all 3 axis I take it? Because my scope of I leave in RA horizontally, its balanced and the same goes for the Dec but when either RA or Dec in vertical position, it just wants to swing one way or the other. Basically towards the side it reckons has more weight. Its so sensitive this mount that it's weird and getting it perfectly balanced it an art for sure. 

[StarDodger]

I just don’t get why you need to add a threaded bar onto the counterweight side like that, it’s much easier to just balance the scope end and add weight to the side of the scope that needs it to achieve balance and then slide main weight down a bit to counter it, there is no need whatsoever to add that bar with washers to the counterweight....it’s pointless and unnecessary....

[StarDodger]

15 hours ago, souls33k3r said:

Hi John, 

Thank you for the share. And you scope balanced in all 3 axis I take it? Because my scope of I leave in RA horizontally, its balanced and the same goes for the Dec but when either RA or Dec in vertical position, it just wants to swing one way or the other. Basically towards the side it reckons has more weight. Its so sensitive this mount that it's weird and getting it perfectly balanced it an art for sure. 

This is how mine looks with the extra weight, also if you can slide the main weight up the shaft as close to the head as possible but you will  need more weight, it helps as there is data to prove that it’s better for the motors as it uses less inertia to move and so improves guiding and tracking...

[souls33k3r]

49 minutes ago, StarDodger said:

I just don’t get why you need to add a threaded bar onto the counterweight side like that, it’s much easier to just balance the scope end and add weight to the side of the scope that needs it to achieve balance and then slide main weight down a bit to counter it, there is no need whatsoever to add that bar with washers to the counterweight....it’s pointless and unnecessary....

Seems like this is a common issue with many, I'm not the first one it seems and those who have had the same issue have been able to fix it. Depends on what weights you'll be adding but this threaded rod solution firstly works and secondly it cost me £7 altogether so far cheaper solution  but what's really annoying is that a LOT of people are having to use this method to balance their RA. 

49 minutes ago, StarDodger said:

This is how mine looks with the extra weight, also if you can slide the main weight up the shaft as close to the head as possible but you will  need more weight, it helps as there is data to prove that it’s better for the motors as it uses less inertia to move and so improves guiding and tracking...

I've got 2 counterweight but both are 9.5kgs. Tried to have them both on but it's was just too heavy so had to remove one. 

[JamesF]

Is it not possible to rotate the entire counterweight assembly on the RA axis slightly, so the counterweight shaft is not in line with the DEC axis?  Given the design it looks like a logical thing to be able to do and would achieve the same effect as adding weight to one side of the counterweights.  More tricky to get right, perhaps.

James

[Jkulin]

23 hours ago, souls33k3r said:

Hi John, 

Thank you for the share. And you scope balanced in all 3 axis I take it? Because my scope of I leave in RA horizontally, its balanced and the same goes for the Dec but when either RA or Dec in vertical position, it just wants to swing one way or the other. Basically towards the side it reckons has more weight. Its so sensitive this mount that it's weird and getting it perfectly balanced it an art for sure. 

Yep Ahmed, it was a piece of cake.

It was a little harder with the 120EC as I did have to think about that, but easily resolved with some threaded rod into the sides of the dovetails/weight bolt and then added washers to balance.