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New Mesu MkII With Modifications


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Hello Everyone, 

This is my first post on this forum (although I've lurked in the shadows for a while). So I thought I'd share some of the modifications that I've had done to the new Mesu MkII I received last week in case someone can benefit. Sadly I haven't tried it imaging yet only balanced, slewed it around and read the Sitech documentation to make sure everything is functioning.  The day it arrived we plunged into sub-zero temps and snow 😫

The mods include an extended wedge for some limited imaging past the meridian, and an angled counterweight bar for clearance in the tight space.  Some have commented in other posts on the long Mesu CW bar but its necessary to balance the weight of the head (unloaded) and to accommodate counterweights for the significant payload. Once tested I'll be loading this bad-boy with a number of different focal length scopes as changing equipment at 25C below is not fun. I lasted one winter doing this and the automated ESO (Exceedingly Small Observatory) was born.

Has anybody with this mount installed homing switches? The Sitech1 controller has an aux port for this purpose. For me this would be for integration into the ROR control system to prevent an expensive mistake.  Eventually the goal will be to monitor for inclement weather and shut down the system safely or automate parking and calibration frames at the end of a normal session. This is a work in progress as I only completed the ROR roof upgrades this summer. 

Thanks

Gary.

PS That flats panel needs moving. It was ok with the old mount but every inch counts now! 

 

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1 minute ago, Ships and Stars said:

Hello and welcome. I'm a visual astronomer, but the Mesu has an excellent reputation. That looks like an incredible set-up! Hoping you have clear skies soon.

Thanks! I've been doing astrophotography for about three years.  It's become an obsession! 

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Hi, 

Your ESO naming is definitely appropriate and your innovative solutions to enable this mount are Impressive. My Mesu Mk 2 with it’s CW bar fit snugly into my 2.2M Pulsar Dome so I am not dependant on a home arrangement just yet, but will be very interested in any solution to support such an arrangement for my ROR observatory.

I operate my Mesu using only plate-solving and it guides great using PHD2 without the need for a Sky or PEC model. How are you planning to operate your mount?

 

Edited by Xsubmariner
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6 hours ago, Xsubmariner said:

Hi, 

Your ESO naming is definitely appropriate and your innovative solutions to enable this mount are Impressive. My Mesu Mk 2 with it’s CW bar fit snugly into my 2.2M Pulsar Dome so I am not dependant on a home arrangement just yet, but will be very interested in any solution to support such an arrangement for my ROR observatory.

I operate my Mesu using only plate-solving and it guides great using PHD2 without the need for a Sky or PEC model. How are you planning to operate your mount?

 

Thanks for the comments!

The ROR is partially automated and I have magnetic switches that detect when the mount is not parked. This kills power to the opener so the ROR can't decapitate the scope. The current weakness is if the roof is closed, unparking could result in a collision. The home sensors would be used to inform the control system an unsafe state exists. Another way I've been mulling over is to use an Arduino to sense roof state and the mag switches on the mount. I have to learn how to program it though. 

I'll operate as you do with a plate solve. On my CEM60 the only time I use the handset is to polar align; I don't even have a finderscope attached anymore. Setting the home position, slewing to the target and platesolving does the trick.  The Mesu I think operates a bit differently requiring acquiring the target manually and syncing to initialize the mount. Regardless a near platesolve should still work (If my eyeballing is off then a blind solve in APT and sync would work). 

As I said I haven't tried any of this yet due to the weather so let me know if I'm wrong. 

Gary.

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  • 2 months later...
On 20/10/2020 at 00:24, astrophoto_canada said:

Hello Everyone, 

This is my first post on this forum (although I've lurked in the shadows for a while). So I thought I'd share some of the modifications that I've had done to the new Mesu MkII I received last week in case someone can benefit. Sadly I haven't tried it imaging yet only balanced, slewed it around and read the Sitech documentation to make sure everything is functioning.  The day it arrived we plunged into sub-zero temps and snow 😫

The mods include an extended wedge for some limited imaging past the meridian, and an angled counterweight bar for clearance in the tight space.  Some have commented in other posts on the long Mesu CW bar but its necessary to balance the weight of the head (unloaded) and to accommodate counterweights for the significant payload. Once tested I'll be loading this bad-boy with a number of different focal length scopes as changing equipment at 25C below is not fun. I lasted one winter doing this and the automated ESO (Exceedingly Small Observatory) was born.

Has anybody with this mount installed homing switches? The Sitech1 controller has an aux port for this purpose. For me this would be for integration into the ROR control system to prevent an expensive mistake.  Eventually the goal will be to monitor for inclement weather and shut down the system safely or automate parking and calibration frames at the end of a normal session. This is a work in progress as I only completed the ROR roof upgrades this summer. 

Thanks

Gary.

PS That flats panel needs moving. It was ok with the old mount but every inch counts now! 

 

IMG_1233.jpeg

F9157BF1-64C9-4ABF-A9BA-376EAAA80E83.jpeg

IMG_1234.jpeg

IMG_1236.jpeg

IMG_1235.jpeg

Looking great. Where did you source those black counterweights from?

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Congrats on the mount!  Like a shortened bent pier 👍

On 20/10/2020 at 15:23, astrophoto_canada said:

 The Mesu I think operates a bit differently requiring acquiring the target manually and syncing to initialize the mount. Regardless a near platesolve should still work (If my eyeballing is off then a blind solve in APT and sync would work). 

I'm not sure what you mean exactly about the manual bit - I turn mine on, connect to SGPro, and the SiTECH panel opens.  Once I click 'unpark' the motors tracking at sidereal rate, and when I start the imaging sequence in SGPro, it slews and platesolves.

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Manufacturer's claimed load capacity of 100kg. Very few users would ever remotely need this capacity.
Counterweight shaft needs a max 30kg to balance 100kg given the [roughly] 3:1 balance ratio. [Moment = M x L]

So why supply a "scaffolding pole" for an average user? What were Mesu thinking?
That "protrusion" has to be avoided by every user. Often in the dark and totally regardless of their actual instrument load.

Your bent shaft is an interesting mod but potentially changes the dynamics of the mount.

I just hope you avoided potential bearing damage during the exercise. Is the Dec countershaft removable?
The risk of putting a bend on the active length inside the Dec housing is terrifying!
I'd have taken a hacksaw to the offending shaft on Day 1.5.  :icon_clown:

 

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I briefly had ~75 kg of scopes and gear on a MkI Mesu and that necessitated either some bigger weights or a longer CW bar, and it was easier and cheaper to machine up the latter option. The extended bar just fitted inside the confines of a 2.2m Pulsar dome and worked a treat, it will be put back into service when the dual rig goes back on for galaxy season.

And the “bang my head on the counter weight bar” score stands at 2:0 to the shorter bar.🤕

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22 minutes ago, tomato said:

I briefly had ~75 kg of scopes and gear on a MkI Mesu and that necessitated either some bigger weights or a longer CW bar, and it was easier and cheaper to machine up the latter option. The extended bar just fitted inside the confines of a 2.2m Pulsar dome and worked a treat, it will be put back into service when the dual rig goes back on for galaxy season.

And the “bang my head on the counter weight bar” score stands at 2:0 to the shorter bar.🤕

Hmm. I had another look at Gary's images. The centre of mass of the OTA is really quite far away from the PA axis.
I may have misjudged the counterbalance: OTA balance ratio. Larger diameter weights make sense in an observatory setting.
Though that makes an even bigger target for the user's head and would be very unpleasant to manage in a mobile set-up.

It's not as if the moment would be much reduced from his moving the guide scope to the side of the main OTA.
When I removed my 7" refractor from its side-by-side bars with the 6" I instantly rewarded myself with the shorter Dec shaft.
The few inches difference in Dec length made a huge saving in the number of head injuries despite needing more weights.
Painting the weights bright white helps too if there is enough light. There ought to be a ring lighting with tiny LEDS for night use. B)
 

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