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Just how much load can a Mesu take?


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I don't think that problems will arise from the mount's ability to handle the weight. I think they'll arise from differential flexure in the mounting hardware. If every OTA had its own autoguider, directly attached to the OTA in use, then I think you'd be fine using one OTA (with its own guider) at once. As soon as you try to use one autoguider to guide more than one OTA you run into the flexure problem.

My first dual rig involved 2 x Tak FSQ 106, each with Kodak 11 meg chip, imaging at (read this twice) 3.5 arcsecs per pixel. Mounting hardware was the now extinct Robin Cassady T-Gad alignment device, bought second hand but still at staggering expense. This rig worked perfectly from night one. It worked perfectly, in commercial use, for many years thereafter. This made me think dual rigs were a piece of cake.

So we tried 2x TEC 140 with cameras working at about an arcsec per pixel.  Uh-oh. We had created a monster. Last week I took the last vestiges of this infernal thing off the mount and breathed a sigh of relief at being re-united with my beautiful galaxy-busting TEC 140/Atik 460 combo, free from all the dual rig flexure issues which plagued the dual setup.  None of this was the Mesu's fault. 

Conclusion? Don't create a monster.

Olly

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I think there is a distinction to be made between multiple scopes using the same imaging scale and those with differing scales. My dual Esprit 150 rig required a number of engineering modifications, principally an adjustable bracing plate across the two scopes, to work successfully with an OAG. However, currently I have paired it with a RASA8 with a more forgiving image scale and this is working fine without the bracing plate. 

Mesu 200s certainly at lower payloads are quite tolerant on balancing, but it gets more critical as the load goes up.

I do enjoy creating and then trying to tame a monster.👹

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17 hours ago, Louis D said:

I was just trying to understand how similar it's out of balance load capacity would be to a harmonic drive.

I guess if it is out of balance it would slip(just like a direct drive), since there are no gears, too much unbalance would overcome the friction between the roller plates. Some years ago there was a US manufacturer that made big mounts with friction drive for professional scopes, but I forgot the name

Ps: https://www.dfmengineering.com/news_telescope_gearing.html

 

Edited by dan_adi
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54 minutes ago, dan_adi said:

I guess if it is out of balance it would slip(just like a direct drive), since there are no gears, too much unbalance would overcome the friction between the roller plates. Some years ago there was a US manufacturer that made big mounts with friction drive for professional scopes, but I forgot the name

Ps: https://www.dfmengineering.com/news_telescope_gearing.html

 

Certainly the first generation Mesus have no way of disengaging the drive so balance is hit and miss in the sense that you just do your best to guess when it feels about equal both ways to the push of your fingers. I've never had any issues with my guesses being outside the mount's ability to cope, though.

Thinking aloud, maybe a heavier payload will be more demanding but will also be easier to judge?

Olly

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10 minutes ago, ollypenrice said:

Certainly the first generation Mesus have no way of disengaging the drive so balance is hit and miss in the sense that you just do your best to guess when it feels about equal both ways to the push of your fingers. I've never had any issues with my guesses being outside the mount's ability to cope, though.

Thinking aloud, maybe a heavier payload will be more demanding but will also be easier to judge?

Olly

I use an amp meter with stable readings in order to balance the mount. This way I could balance fast and pretty precise. The newer mount has clutches for disengaging but even then I would use an amp meter just to double check. I've seen higher tech mounts like 10 micron or ASA that have the same amp checking routine for good balancing.

Anyway I didn't find balancing on my MK1 to be a chore. 

Besides the newer improvements the only thing I would add, as an option off course, is absolute encoders. The reliability of the mesu coupled with AE will give 10 micron a run for their money  😁

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2 hours ago, dan_adi said:

I use an amp meter with stable readings in order to balance the mount. This way I could balance fast and pretty precise. The newer mount has clutches for disengaging but even then I would use an amp meter just to double check. I've seen higher tech mounts like 10 micron or ASA that have the same amp checking routine for good balancing.

Anyway I didn't find balancing on my MK1 to be a chore. 

Besides the newer improvements the only thing I would add, as an option off course, is absolute encoders. The reliability of the mesu coupled with AE will give 10 micron a run for their money  😁

I host several Mesus and have hosted several 10 Microns. In terms of 'just working,' Mesu are way ahead. Simple as that. No grilled circuit boards, no returns for backlash adjustment, no returns for refund...  My sample is still small and, therefore, anecdotal, but there it is.

Olly

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@Tomatobro made a very sensitive load gauge to help me balance my heavily loaded Mesu 200. I could certainly get it much closer than just feeling the drag on the drives.

As Olly said, the Mk 2 can disconnect the drive but respect to Lucas to develop an engagement/disengagement mechanism that delivers the correct amount of thrust repeatedly each time.

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21 hours ago, ollypenrice said:

I host several Mesus and have hosted several 10 Microns. In terms of 'just working,' Mesu are way ahead. Simple as that. No grilled circuit boards, no returns for backlash adjustment, no returns for refund...  My sample is still small and, therefore, anecdotal, but there it is.

Olly

This is reasonable, 10 micron has more technology in it, thus more possible points of failure. I never understood why simple and efficient friction drive mounts are not the norm. They are easier to build, handle big loads, require no mechanical maintenance, and the performance is very good. In addition the cost is much lower.

A 10 micron 3000 hps, with AE and 100 kg payload is around 20k euros with all the accessories. 

A mesu 200 fitted with AE will cost around 14k euros. To me the difference is significant, for the same level of performance.

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