I believe (and hope) that I have most of the bugs worked out with my new iOptron CEM120 mount, so I wanted to post a few pics.

This journey started three years ago when I started looking for a new mount with more capacity than the AVX. I decided to build the observatory first (2017) and then last year (2019) my Christmas present to myself would be a new mount. I bought the CEM120 on Black Friday this past November.

To install the CEM120 on my SkyShed Pier adapter plate, I removed the AVX donut adapter and took the plate off and laid out the four threaded holes. Lesson learned here: I borrowed a drill press from my neighbor, but had trouble holding the adapter plate steady in the vice. Two holes were screwed up - so I just made those through holes and bought some M8 stainless steel socket head bolts and nutted them from underneath the plate. There is not much clearance with these holes, so lay them out carefully and be sure to hold the plate very tightly so the pilot drill does not move!

I also bought an ADM side by side mounting plate. The CEM120 DEC plate is easy to remove and rotate 90 degrees (note where the dec plate clamps are in the photo -having them pointing "up" is helpful during balancing and for access to power ports). Another lesson learned here - the CEM120 DEC plate's Losmandy groove is super tight! I had to use a fair amount of white lithium grease to get the ADM side by side plate installed and "slidable" - also important for balancing. It actually fit better when inserted from one side than the other.

When I finally got to my first night of actually using the mount, it would grind to a complete stop while making a horrible noise at certain points of RA movement! I worked with iOptron support and the CEM120 user group for weeks adjusting the gear mesh, triple checking balance (which was fine), etc. iOptron took the mount back on an RMA and later told me that the ring gears in both RA and DEC needed to be tightened and the whole mount was remeshed. This whole process took 6 weeks, but to their credit, iOptron paid for the shipping both ways.

When I got the mount back, the grinding noise was fixed, and the mount tracks and guides pretty well. There is a knocking sound in DEC when the temperature gets below freezing. It does not affect anything during imaging, only when slewing. iOptron says that can also be fixed also a gear mesh tuning (there are adjusting screws for both DEC and RA). I am working through that now. A lot of people have told me that adjusting the gear meshes due to temperature changes is normal .

Overall, except for the DEC knocking, things are working well. I have a lot of people to thank for helping me through this process.

First of all, I would like to thank fellow Astorbinner, CEM120 user, and SkyShed POD owner BobJ. Bob helped me check things against his own CEM120 and also got me connected with the CEM120 user group (Rainer, George, Andrew, and many others). All of you guys really made this into a good experience , with a lot of learning for me.

Dave at Highpoint Scientific was also very supportive and helped make sure that I did not have to pay any shipping or other fees to get this fixed.

I do want to thank iOptron support also (Kevin, John, and a few others). I really do wish I could have spoken to them via phone, as I tried to, but they seemed to prefer only email. This likely made the process take longer, but I also understand that the holidays was a busy time for them. In any case, I really do appreciate all of their efforts.

If I had it to do all over again, I really don't know if I would go with the CEM120 - or choose something different. I really like the "through the mount" cable management. It's great to not have to worry about cable snags. The pointing accuracy is very good also. As mentioned, the mount guides and tracks well. Hopefully, I can get the DEC knocking fixed via gear mesh tuning.

So far, the images have been coming out great. I hope that continues and I look forward to posting more soon!

Clear skies!

Pat