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Question M Uno loose dec axis, bearing noise on both axes

  • aenglish
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18 Nov 2022 04:36 #1089 by aenglish
Hi, I have had my M Uno for a few months now. I have used it maybe 5-8 times. When I received it, I noticed some minor bearing noise when manually moving the RA and dec axes -- I figured this was normal. Now, the sound has turned crunchy -- as if either there's no grease in the bearings or they're contaminated. I've only used the mount a handful of times, it has only accumulated some light dust from sitting inside my house. I have noticed also that the dec axis is loose... if you put your hand on the Losmandy plate and another on the bottom of the dec axis, you can move it up and down ~2 mm. I have noticed when imaging past the meridian (no meridian flip) that my guiding seems to randomly go from acceptable (0.5"-0.7") to very poor (1.5"+); I attribute this to the looseness in the dec axis. I have also noticed my guiding seems to fluctuate inconstantly throughout the night -- not just normal atmospheric fluctuation, but on a night of good seeing for example, it will go from 0.3" to 0.8" by the end of the session (the telescope is balanced and the mount is not pointing close to the horizon or anything); I am wondering if this, too, has to do with the bearings but I haven't verified that yet.

I am mechanically inclined and willing to strip the mount down to investigate, but I also don't want to void my warranty so I haven't done that yet. I did remove the dec clutch housing (4 bolts) to see where the movement was coming from -- it appears the entire composite? gear moves up and down inside the housing; again it feels like 2-3mm of play. So when a telescope is mounted, when the mount is flipped upside-down, it slips down the dec axis 2-3mm. Not good with $15k+ of equipment attached!

So far I've used this mount with mainly a 72mm petzval refractor, total weight with camera around 15-20lbs.

I have attached videos showing the bearing sound and the play in the axis. There is also similar bearing noise on the RA axis. Let me know if there's any other info I can provide. Thanks!

Bearing noise: youtube.com/shorts/hxr_e9yDQDA
Dec axis looseness:

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  • Stefano82
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22 Nov 2022 15:20 #1094 by Stefano82
Replied by Stefano82 on topic M Uno loose dec axis, bearing noise on both axes
Hello

We will provide you via mail within few days, the instructions to check and perform safely the DEC axis adjustment.

Best regards

Stefano
Avalon Instruments Team

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  • aenglish
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23 Nov 2022 15:11 #1096 by aenglish
Hi Stefano, thank you. I will wait patiently for it.

What do you think of the bearings? It does not sound good to me but I’m not sure if it’s a problem or not.

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