Celestron CGX (new) vs CGEM (hypertuned) un-clutched movement

Fresh out the box CGX vs Hypertuned CGEM
Testing the free, un-clutched movement in both mounts.
Had issues with my new CGX mount. RA spikes and DEC backlash. Also sticky DEC axis.
Shared with Celestron support to describe issues with a sticky DEC axis.
Receiving good feedback and support from Celestrons support team.
Issue still ongoing.

[@gothicm3rcy426]

loosening the bearing on the RA shaft a tiny bit oftem helps. they set the bearings too tight most of the time. though i do recommend hypertuning

[@astroboden]

Hi! Cheers! That's precisely what I did. Along with that was a much needed clean of the gears, they were in such a poor stat I don't know if this was a refurbish, or a brand new mount. The is a whole video series here on the subject... but long story short: I got it to a state where I have been using it for some time with quite nice result. Now the electronics(sensor boards I hope, ordered from deepspace....) are shit with a whole new set of issues(other video). The tripod and wedge are only good parts to this mount if you ask me now, and are used where they are more useful(yet another video ;) )!

[@johnathanedwards8706]

I bought a CGX 1 year ago and the DEC axis was extremely stiff right out of the box. Celestron refused to help me and of course PHD2 will not guide correctly because of the DEC stiffness. It was my fault though for not using the mount right after I bought it...had to travel for business-long trip..anyway High Point would have replaced it but too much time had passed. Too bad because now I am ready to upgrade and the CGX-L will most likely not be chosen..it depends. This time I know to use the mount within 30 days- High Point is very good about replacing items, but not after 2+months. Anyway I'm thinking seriously about getting the CGX hypertuned when I upgrade. Thanks for the video.

[@astroboden]

Hi Johanthan, Sorry to hear you had the same experience I had. Seem like a thing that has been going on for a while. Bad that they haven’t a better response made up then. I’m making a little review of my CGX experience so far, but I’m struggling to get it politically correct. I bought mine and pretty much immediately sent in for service just before the Christmas holidays. By the time there was clear skies to properly test it ones returned, months had past. The really worrying thing was that my supplier opened at least 2 more from different batches and they were all the same. Is proper balancing no longer a requirement? They would have invented a seriously fabulous mount then. The dirt in the gears was also something that made my stomach turn. After less than 30 hours it looked like I would have expected it to look after a year at least: kzbin.info/www/bejne/mpjXmoJul9hqaZY When I’m on the ranting topic… Have you read the manual? Is that a joke? No wonder they removed the section on worm gear meshing when it was all backwards. They are also referring to the atl/az system and other completely wrong details. It’s a copy-past job. And for equipment in this price range - NOT acceptable! The only good thing about it is that I now feel comfortable about servicing and hypertuning it myself. With all this said, with the small service I have done so far, I now have it guiding with accuracy up to

[@johnathanedwards8706]

I'm thinking about just going for it and getting a Software Bisque with absolute encoders.

[@astroboden]

@@johnathanedwards8706 Yeah, I thought I went all in, but still within budget. I like the way you think. Screw the budget. Go all in! ;)

[@bobafiatcoupe]

Ensure you update with the latest handcontroler and Mount firmware. All those weird noises disappeared after upgrading . Guiding works great, I made a photo with 10' exposure for fun and guiding was good as well as the stars are rounded properly.

[@astroboden]

Hi bobafiatcoupe, thanks. Good to hear that the update did the trick for you. I did the update on request by Celestron tech support and it did do difference, but some noise is still there. I'm not too concerned by them at the moment however. More so the sticky axis which even Celestrons support agreed was too excessive and required service. The mount is with the supplier now and I'm waiting to hear their response. Cheers!

[@timdennis3300]

@@astroboden Any updates on this? I'm trying to decide between a CGK and an AZEQ6 Skywatcher.

[@astroboden]

Hi Tim! Just uploaded a video of how it looks atm. kzbin.info/www/bejne/mKe9pqONrryrjcU Still have not tested it fully since I have had issues with my power supply recently, not to mention weather. I really want to like this mount. I think it has some great potential. The NexStar+ hand controller is great in my opinion and with the spring-loaded worm gear meshing and belt drive I was hoping for an instant success, ha ha. With the price tag in mind, I was also looking at the EQ6-R from skywatcher, and iOptrons CEM60. I don’t want to be looking back yet, but at the moment I really can’t say “Get the CGX!”. I can’t advertise for the others though.

[@possisvideos]

for me the upgrade in 3-2020 did not change anything. The loud noise stay, the additional laud cracking noises around +-10° from upright still there, guiding of my expensive CGX-L is still totally crab. I tried several worm backlash adjustments in RA and DEC, still I have a +-3" guiding.

[@phillipwatson810]

So between the CGX and the CGEM II the CGEM win's? The CGX is 700.00 more here in the US on Celestron website. I'm looking at the 11" EdgeHD and was thinking about going the CGX being more money and a better mount. Maybe not so. Thanks for the side by test.

[@astroboden]

Hi Phillip, This video was made to fault find calibration issues with the CGX. First it was made for the technical support, then for the community to provide some insight and suggestions. There is also a “review” video that I made after I fiddled with it, and used it for a couple of months. I still use the CGX mount as my main mount and it works alright. My very personal impression is that the Celestron mounts might have been better in the past. Maybe it’s changed since I bought it, but it’s a feeling I get when I read reviews and compare the two. I have the EdgeHD 800 and it’s great, so I’m not saying Celestron equipment sucks, I’m just not happy about how the CGX landed in my lap. All I can say is that I’m not alone about that, but I’m sure many are getting a great experience as well. Hope you find what your looking for! Thanks for watching!

[@fabienlouvel5536]

the "clutched" position of declination clampiong knob is too close from maximum left position. You need to unscrew it from clutched position , remove the piece from its nut base, and place it more on the righ. Then when you unclutch it'll have more range to release.

[@astroboden]

Hi Fabien, very good suggestion! I did find this suggestion, and it was the first thing I tested before sending it in for service. It would have been soo nice if it was the cure. Sadly, it did no difference. Neither did the service. Some "warranty void operation" or "Open heart surgery", did however solve much of the issues. Have not yet made any video documentation official of this since I want more time on it first...

[@astroboden]

Update: According to Celestron the movement of the un-clutched axis is normal. The only question left is the "sticky" DEC axis. If this is indeed an issue? If it performs alright - it's good. - If it works, don't fix it. Update: The mount was returned to the supplier for service as per recommendation by Celestron support. Will update further when I get the mount back! See you all in 2020! Update: See: kzbin.info/www/bejne/mKe9pqONrryrjcU For an update on the dec axis after service. The axis is slightly easier to balance than before. The service staff at the supplier said that 2 other CGX mount from different deliveries had the same "stiffness". Does this mean that this is how they should be? If you can't see an imbalance, is it good enough? I'm use to use the imbalance to counter backlash in DEC, so I naturally want it to be easy to see. It feels like it's the bearings that stands for most of the resistance, but could also be contributed by the internal wiring that you can hear moving when turning the mound by hand. I just had the "spikes", or "binding" issue possibly resolved, so now I can begin to test it properly.

[@jmustoe]

Astroboden. Check my recent 3 vids on youtube. For me the stickiness created awful guiding. The Ring gear when unclutched allows the whole axis to rotate. When clutched the motor drives the axis around the ring gear. You can take the plastic motor/worm gear block off to see this in action. With all the stiffness in the DEC axis (note mine was RA too) it becomes almost impossible to balance, that's the first issue. Then the second issue is the amount of torque needed to drive the worm around the ring gear as the axis is so stiff, this created an issue where I could not do a calibration in PHD2 as it kept on reporting a backlash of nearly 4750ms!! I thought I should have hung onto my Hypertuned CGEM as it appeared to be better than the CGX. Because I did my own CGEM hypertune I remembered over tightening the tapered bearing at the bottom of each axis this on the CGEM created the same effect as these out of the box CGX's......so i decided to open the bottom of my CGX, and check the tapered bearing. Indeed I appear to be right, after backing the retaining ring off for the DEC axis (remember to re-apply thread lock) it became nice and free and easy to balance. I've not had a chance to test the guiding due to clouds but I'm sure it will be fine now. Have a look at my vids, and check out my cloudy nights post. Hope this helps you...these CGXs should be good mounts, but the out of the box experience is not good. I have seen some youtube vids where owners CGXs are perfect out of the box, yours looks exactly as mine did, not so good. www.cloudynights.com/topic/686498-something-for-cgx-owners/

[@astroboden]

jmustoe: thanks for your reply! Seems like we have the same issue indeed. Kinda wish I found your post before. I honestly believed that the hypertune requirement was going to be worked out by now. I would call the CGX a high(er) end mount from a price point of view and that QC would follow that. Celestron did acknowledge that the mount requires repair and I'm sending it back to supplier for service. Hope they will do what should be done(that you did yourself) so that it's kept it in warranty. Cheers again for the link to your post! Will see how it ends out.

[@sly9263]

@@astroboden please update here with the results from Celestron on this mount. I was going to pull the trigger on the CGX-L today but will hold off. Glad I found this.

[@astroboden]

@Bobby very long reply to follow... sorry about that! I will try to be diplomatic… My take on the CGX has been very cold to say the least. From day one I had the “sticky” axis in Dec, which I send it off to the supplier for. It seems like they are all like that, so if that’s how they are suppose to be, I can’t say. It does make balancing hard. Specially the fine tuning the DEC axis to counter backlash. And there is backlash. PHD2 couldn’t even measure a consistent result with Guiding Assistant at first. After service and tweaking the meshing I was able to make it work, but still with ≈2000ms of backlash. And it was binding! In both axis. Almost didn’t think that was possible. Feels like I have been barking up every tree in the woods here, to get on top of it. My current path is the guide computer. An issue that started with the CGX, but I’m not leaving any stone unturned now. I'm collecting PHD2 graphs for a more in-depth analysis, but I don't know if I can hand it back on warranty anymore. Would I buy the CGX today? - Absolutely Not! Would I buy it when I know the cause of the binding/spiking issue? It might even be the guide computer. - Maybe! I’ll make a full review of how my CGX experience has been when: I have resolved the issue, OR surrendered to defeat. The quick version is that I think the CGX mount is a very good design. I would love for it to work as intended. It would solve a lot of possible issues. I don’t feel 100% on the assembly or parts involved however. After some 20-30 hours of runtime I just cleaned the worm gear grease that was completely grey, hoping that would have been the problem, just to mention one. The manual is not helping out either. When adjusting the worm meshing you have to do the exact opposite to what they say, but you have to figure out where and how yourself. -Terrible! By the time you realise, the factory setting is long gone. They also reference to the Alt-Az coordinate system for the motor slewing, and with wrong speed table (I suppose it’s a copy-paste from another mount manual). It just feels like they didn’t care. Might be different for the CGX-L, but I would search for “issues with CGX-L”, or similar first to get that part of the story. I was very biased for CGX when I compared products before buying. Hope that helps somehow. I'll be updating as I progress, but there is so few clear nights that it takes some time.

[@sly9263]

@@astroboden thanks for the details and taking the time to reply. I'll stay tuned here.

[@lancewilliams8732]

This is scary stuff, as I was considering the CGX with it's higher payload capacity vs EQ6-R Pro, especially considering all of my AUX equipment is Celestron. The EQ6-R won't handle CPWI and ASPA. Recommendations if any ?

[@astroboden]

Hi, Sorry for taking so long to reply. I have never used CPWI, but I do love the All-Star Polar Alignment feature of the Nexstar hand control. I believe there is some similar alignment feature with SynScan, but I don’t really know how it compares with the ASPA. I had my first observation session after midsummer a few days back with my Star Adventurer and my old EQM-35. Both where very satisfying. I might check if how the polar alignment feature works on the EQM-35 later. Anyway, the CGX mount was, last time I used it, not an unpleasant experience. There are things I must get to business with (like a 34s periodic error which I have heard more people are having issues with). I think it’s coming from the tension, or meshing of the worm gear, but we’ll see. At the moment, I don’t know about any other system too well, and they might have their own issues that one must learn and deal with. Now that I’m getting the hang of the CGX (I think!) I don’t think I’d like to change it out. The devil you know... The EQ6-R was one of my options when selecting a mount however.

[@doccortex1203]

@@astroboden Well, I have the CGX, and the results have been pretty poor, I can get around 3 min subs, then the movement is so bad that stacking simply fails. Like you, the axis are very very stiff. I have sent my PHD2 files to Celestron, and their advice is simply what I have already tried! I will try to have it hypertuned somewhere, if I get the same result, I will selloff all my Celestron equipment, and move elsewhere

[@astroboden]

Hi, Sadly I no longer get surprised when I hear about others having similar issues with this mount. What I did was a small “hypertune” of my own by “simply” disassembly the axis and loosening the retaining ring clamping the axis to the bearings. Then cleaning this, applying new lock-tight and reseating the ring with just as much force that I could not feel it restricting the axis motion. It is not super trivial and will absolutely void you warranty. Proceed with caution if you want to do this yourself. I also worked on the meshing with the spring loaded system they’ve got, and got a few surprises. As I mention in my review video I found that the gears were super dirty, though brand new. I think the mount can be good, but I also believe it might involve making it your own by getting your hands dirty. Unless you are lucky and get a well assembled and QC setup and then only sending it off for service when needed at a high cost. Anyway, I can now do 5-10 minutes exposures with not too bad result. I wish you the best of luck hyper-tuning it, and hope get it working swiftly.

[@andrewbrunson8382]

How much of a guiding improvement did you see after hypertuning?

[@astroboden]

Hi Andrew. I didn't do the hypertuning on the CGEM, so I cannot say honestly. The previous owner ensured that it made a big differences, specially with stiction between the moving parts that could be a thing in the past. However, I can't give you a personal opinion here.

[@user-ux4wq2zu2l]

What is the sound the cgem mount makes when tracking ??

[@astroboden]

Hi! The hypertuned CGEM is completely silent when tracking. Slewing produced a bit of noise depending on the speed selection. Can't tell you what it sounded like before hypertuning, but if it was anything like the CGX there is a bit of noise. Not terrible, but audible.

[@possisvideos]

My CGX-L has exactly the same problem. sticky as hell on RA and DEC, guiding is a mess (+-3' normally). I guess the gearing is crab. It also produces horrible cracking sound when moving. 3 month old. My cheap ioptron CEM25 is MUCH better in guiding and not sticky. My seller is not helpful. Celestron Service here in Germany is by Baader Planetarium. They have a lot of work an the technician told me its an excellent mount...

[@possisvideos]

ist here any data what exact is the gearing dimensions? Maybe I can change them agains high quality German or Japanese gearings. These Chinese gearings seems to be crab.

[@astroboden]

Hi Possi! Sorry to hear that you have the same issue. As you might have seen in the videos, the RA in my case was not as bad. Do you mean that your guiding it +-3’(arcmin), or 3”(arcsec)? The former would be absolutely crazy. The cracking sound could be/should be, the cable harness that runs up the axis. They sit with some plastic clips to stop them from moving too much. What I did (however not made a video on it yet), was to loosen the retainer nut at the end of the DEC shaft. It did make a difference. Sadly, I didn’t take the measurements on the bearings, since I didn’t have the sealed bearings out enough to measure them. The thing I noticed was that when the retainer nut was fully loosen, it was still not perfectly spinning. All that held the shaft then was the bearings and the cable harness that runs up the axel. You can actually hear the cables (crackling sound might be a good description), when turning the mount by hand, and I think they will restrict motion somewhat, but the main thing must be the sealed bearings. In your case though the cables might be more restricting then they should. Make a video for us! The DEC is still sticky, but it’s much better than the RA because of some 34s periodic error (check out that video if you got the time: kzbin.info/www/bejne/l4vRcmeraMipjbc). That said, I’m guiding with about 1” rms on RA and 0.5”-1” on DEC. And my polar alignment is not perfect. ≈1’ at the best. Just out of interest, on another topic concerning the CGX. Do you have “user objects” in the main menu tree in the Nextar+ hand controller? It should be there, but I have a different set of options. Also, and even more worrying, I now have issues connecting with the CFM software to re-flash the firmware. I’m sending a ticket so Celestron about this, so we’ll see what’s coming out the other end.

[@possisvideos]

@@astroboden anyway the guiding is crazy bad, its normally 2..3" RMS. (not arcmin of course, sorry for the typo...). My tiny iOptron has normally 0,8...1" RMS error. I will check again the harness, but I did not find anything there last time when i dissasebled the whole thing. The sound is mainly when tilting CC wise near the verticale. Both axis are affected. I am still fighting, maybe I should get a CEM120 or 10micron, but they are more expensive. I use a 11" RASA, nice scope and only 620mm focal length. I would like to buy a 1500...2000mm 14" scope, but not with this mount - if I cannot fix.

[@astroboden]

Still, 2-3" is RMS is not working. I was considering the CEM60 instead of the CGX. I guess the CEM120 is a good replacement spec wise for the CGX-L. I believe the CGX is a good design, but the assembly (QC etc) and part selections might leave room for improvement. Some might get very nice builds, and some of us does not... But if the not too much is shit in the build, I guess you should be able to get it to a good working condition. I though that a RASA however, with that short focal length, would be very forgiving. How does the guiding error precent it self? Is it spiking/binding? Overshooting? Too slow? I had something that looked like binding on both axis, but it ended up being the a communication related error(USB cables). Got another video on how I analysed that, if your interested in perusing that path: kzbin.info/www/bejne/mpjXmoJul9hqaZY