Just how much load can a Mesu take?

[tomato]

While waiting for the next clear night, it occurred to me that I currently have the kit to run at 3 varying image scales: Altair 102mm APO/ASI 178, Esprit 150/IMX 571 and RASA8/QHY268c, so how about running them all at the same time?

After an afternoon’s thrash, all 3 now sit on the Mesu, the Altair is riding piggy back on the Esprit atop an adjustable saddle so it is out in the breeze somewhat. Oscillations after a knock take 2-3 secs to dissipate so this may be a non starter. Getting all three scopes to point through the dome aperture is also a challenge, the dome Az rotation rate will have to be spot on. Hopefully will get first light on this set up tonight, I’ll post on the Mesu owners section if the mount is up it.

 

Edited August 19, 2022 by tomato
Duplicate image deleted

[tomato]

And ahem, no prizes for cable management…😊

[Tomatobro]

If some is good, more is better and too much is just about right.

I just watched a program on particle entanglement so I guess you are conducting research into this phe👽nomena

But if it works..........who cares!

Also gonna need a bigger aperture, right chief?

 

[tomato]

Yeah, I thought my meagre fibre glassing skills had been permanently  put to bed, last time I think I handled gel coat was sealing the wheel tubs on a certain Opel GT, but who knows?

[newbie alert]

Canons at the ready!

[Marvin Jenkins]

It’s a giant lovely mess that might work perfectly. I love it! Never tidy it up, something will stop working.

M

[Mandy D]

I thought I was looking at the large hadron collider at CERN when I saw that wiring! 🤣

[gorann]

Brave man! What is that tiny counter weight bar doing on a Mesu?

Cheers 

Göran 

[tomato]

That’s offsetting the asymmetric location of the little Altair refractor. The proper CW has a custom extended shaft with about 30 kg hanging off it…

But stop press, the Mesu didn’t let me down, running at 0.45” total RMS all night but there were other issues which I will report on tomorrow after some sleep.

[ONIKKINEN]

Im getting a third party headache trying to figure out the cabling here, but if/when this thing works its going to be epic.

[maw lod qan]

The wiring looks like one of our hurricane spaghetti models! 👍

[Skipper Billy]

You have a way to go yet !!!

mesu2.jpg.crdownload

[scotty38]

3 hours ago, Skipper Billy said:

You have a way to go yet !!!

mesu2.jpg.crdownload 1.05 MB · 2 downloads

A meridian flip would be interesting

[tomato]

Well, overall the 3 scope rig was successful, in that I got reasonable data from all three. The Mesu performed admirably, guiding at 0.45" total RMS, the Dec corrections were all on one side so my PA has drifted with all of heavy lifting on and off the mount. Gotos were OK after plate solving and syncing except I slewed to Jupiter to align the refractors and the goto was off a bit after slewing to the target at 60 degrees elevation, either due to drive slippage or scope sag?

The biggest problem by far was trying to get all three scopes to point through the open aperture, I chose NGC 7331 which was at 60 degrees Altitude, and the Altair scope being mounted so far away from the axis of the mount meant it didn't have a fully unobstructed view, you can see the diffraction spikes on the bright stars on the sample image. All you ROR observatory owners, have a wry grin!

So is all of this worth it? Can anybody suggest some targets ( currently at moderate elevation) that would benefit from data being collected at varying imaging scales? If not I think my triple rig will be no more.

RASA8/QHY268c

Esprit 150/IMX571c

Altair 102/ASI 178 (Lum only)

[gorann]

"Can anybody suggest some targets": M31 of course, you can get the core as well as the "hook" in the faint dust that @ollypenrice always gets excited about😅

Edited August 20, 2022 by gorann

[Marvin Jenkins]

I think you are slightly mad and equally inspired. I am in awe of your venture into the triple OTA world, and when I first saw you post I was musing over the idea of one day building a huge pair of binoculars from twin achromatic refractors. 
At least my idea doesn’t have any wires😂 No idea how to mount such a thing.

Your post brought back a memory of seeing a frac setup called the Dragonfly. 
I think it was eleven fracs on one mount, a Paramount I think. I have a pic somewhere but not on my phone sadly.

I presume one was for guiding the other ten for capture, (just writing that sounds nuts). Ten scopes, ten cameras! And I think you have cable problems. Can you imagine the focus issues?

Ten EAFs, ten filter wheels arrrhhhhh.

[tomato]

2 hours ago, gorann said:

"Can anybody suggest some targets": M31 of course, you can get the core as well as the "hook" in the faint dust that @ollypenrice always gets excited about😅

Thanks, that sounds like a project, and I currently stand a chance of all three scopes peeping through the aperture at M31.

[dan_adi]

On 19/08/2022 at 16:09, tomato said:

While waiting for the next clear night, it occurred to me that I currently have the kit to run at 3 varying image scales: Altair 102mm APO/ASI 178, Esprit 150/IMX 571 and RASA8/QHY268c, so how about running them all at the same time?

After an afternoon’s thrash, all 3 now sit on the Mesu, the Altair is riding piggy back on the Esprit atop an adjustable saddle so it is out in the breeze somewhat. Oscillations after a knock take 2-3 secs to dissipate so this may be a non starter. Getting all three scopes to point through the dome aperture is also a challenge, the dome Az rotation rate will have to be spot on. Hopefully will get first light on this set up tonight, I’ll post on the Mesu owners section if the mount is up it.

 

The Mesu can handle a lot. 

I have a 8 inch refractor on it with all the accessories, maybe around 50 Kg. I know for sure the counter weights are 50 kg in total.

When the weather cooperates, guiding RMS is 0.2-0.3" with this load. Also, in my case at least, with a long-ish refractor, wind-gust can screw things up for a little while, but only in winds greater than 10 miles/hour. 

To me the price/performance ratio is incredible.

[gorann]

When I visited Lucas Mesu in July I asked him about how he knows it can handle 100 kg and the answer was simple: he had tested it with 100 kg and it was fine. But he said it behaves slightly differently with a lot of weight - pure physics of the momentum of a big load.

Edited August 21, 2022 by gorann

[Taraobservatory]

On 21/08/2022 at 21:37, dan_adi said:

The Mesu can handle a lot. 

I have a 8 inch refractor on it with all the accessories, maybe around 50 Kg. I know for sure the counter weights are 50 kg in total.

When the weather cooperates, guiding RMS is 0.2-0.3" with this load. Also, in my case at least, with a long-ish refractor, wind-gust can screw things up for a little while, but only in winds greater than 10 miles/hour. 

To me the price/performance ratio is incredible.

Im getting very curious about these Mesu mounts. 

I dont see much information accept that they are very good. But what software do you use to controll the mount etc? 

As far as I can see I could easily do 10m subs with this thing without any bloadting of stars. 

Do you have any complaints ? 

 

Clear skies 

Roger 

[Louis D]

I'm thinking you could image some of the larger nebula regions like NGC 7000 and IC 5070 and take closeups of the Cygnus Wall simultaneously.  Same goes for the Veil Nebula with closeups of the Eastern/Western Veil along with Pickering's Triangle.  M16 is smaller, but has great detail up close.  You could then composite the high resolution closeups with the wide field views.  I'm not an imager myself, but there are lots of nebula regions with small detailed areas and larger diffuse areas.

[dan_adi]

On 23/08/2022 at 12:07, Taraobservatory said:

Im getting very curious about these Mesu mounts. 

I dont see much information accept that they are very good. But what software do you use to controll the mount etc? 

As far as I can see I could easily do 10m subs with this thing without any bloadting of stars. 

Do you have any complaints ? 

 

Clear skies 

Roger 

The mount uses a sidereal technologies controller. On their website you can download the software. The latest software is on sidereal technologies forum on groups.io

The mount uses friction drives, no gears, no belts. That means it is very stiff, more so than regular worm-gear mounts or direct drive mounts. It has no backlash. The periodic error is slow, easily corrected with autoguiding.

Requires no maintenance.

All this combined, in good seeing, produces autoguiding RMS around 0.2 ". 

Given the payload - performance and price, I think it is the best mount out there.

The downside is seeing. Since autoguiding performance is determined by seeing, the mount will perform according to it. But this affects all mounts. The solution is absolute encoders on both RA and DEC axes and a mount model, combined with very few guiding corrections, if any. This way you will basically guide on encoders and the seeing impact on the mount will practically be null.

[Louis D]

What are they using to transfer torque to the mount from the motor via friction?  Is it some sort of hard rubber wheel?  If so, will replacements be available as the rubber hardens and degrades with time?

[tomato]

I’ve not taken mine apart but I believe the  drive is transferred through hardened steel rollers and disks, no rubber involved.

Some Mesu mounts have been operational now for 10+ years at sites that get more than a handful of clear nights every month, mine is now 8 years old and is performing as well now as when it was new.

[dan_adi]

On 26/08/2022 at 15:06, Louis D said:

What are they using to transfer torque to the mount from the motor via friction?  Is it some sort of hard rubber wheel?  If so, will replacements be available as the rubber hardens and degrades with time?

Steel. No rubber, no belts, no gears.