Jump to content

Banner.jpg.b6007b69ccdf5c69bf18273ddfe023df.jpg

Mesu mount (all versions) owner's thread


Jonk
 Share

Recommended Posts

7 hours ago, dan_adi said:

Have you tried asking mr. Mesu if he has your dat file? 

I have been emailing Lucas for 3 months now - I don't think he has kept the dat files from the Servocat/ArgoNavis versions of the mount. This is why I am asking elsewhere as there are many enthusiastic users out there and I don't think a 10 year old high value mount is that old yet.  I have a 20 year old AP1200 and any requests to AP for help get answered immediately. Try getting any support for a 5 year old Chinese made mount - it puts issues with other mounts into perspective.

 

Ian B

Link to comment
Share on other sites

5 hours ago, astronomer2002 said:

I have been emailing Lucas for 3 months now - I don't think he has kept the dat files from the Servocat/ArgoNavis versions of the mount. This is why I am asking elsewhere as there are many enthusiastic users out there and I don't think a 10 year old high value mount is that old yet.  I have a 20 year old AP1200 and any requests to AP for help get answered immediately. Try getting any support for a 5 year old Chinese made mount - it puts issues with other mounts into perspective.

 

Ian B

I see from your signature that you use a MI250 mount with Sitech controller? I thought it was a Mesu mount ... my mistake. Did mr.Mesu fit the controller to the mount? Otherwise I don't see how he should have a dat file for that mount. Did you contact Mathis Instruments? Maybe they can help

Link to comment
Share on other sites

On 26/06/2022 at 21:05, dan_adi said:

I see from your signature that you use a MI250 mount with Sitech controller? I thought it was a Mesu mount ... my mistake. Did mr.Mesu fit the controller to the mount? Otherwise I don't see how he should have a dat file for that mount. Did you contact Mathis Instruments? Maybe they can help

Dan,

I have a mi250 with original Gemini 1 controller and motors. Never had any trouble with it. I also have a 2002 AP1200, no unsolved issues and excellent support from AP even though this is also a s/h mount.

 

I do also have a Mesu 200 which I am struggling with.

 

I purchased a second hand Mesu 200 after hearing all the good reports about the mount and support for it. I contacted Lucas before the purchase and he assured me he was happy to support the mount. It's carrying capacity is supposed to be higher than the Mi250 and as I wanted to put multiple scopes on the mount I decided to try a Mesu.

A previous owner of the Mesu seems to have changed the configuration of the Servocat and so I am trying to correct it. I lost the ArgoNavis setup during a software upgrade, but that seems to work fine now.

I am now suspicious that the axes are slipping or snagging during goto operations as they always come up short. If I use the hand controller from the Servocat to move the mount until the ArgoNavis display suggests the object is close I invariably see it in the field of view. The ArgoNavis uses its own shaft encoders, of course, so as long as the mount is roughly polar aligned any object can be found in this way.

I have run tests for Gary Myers, the builder of Servocat and the conclusion he has come to is that the rollers are slipping or binding during goto's. This is based on the 2-3 step goto code he wrote for Servocat. Given a goto instruction by the ArgoNavis he says the first course step should drive the mount to within 2-3 degrees of the target. The slew speed is then reduced to run a residual move and if necessary a final step to centre the object. On the test I ran I used the hand controller to move the mount to the object position to prove polar alignment. Then I drove the mount 55 degrees from the object in RA only. Now I issued a goto which should have driven the mount back to the object. Whilst it did alsmost achieve this the first stage only achieved 50% of the move (it stops between stages for a second or two) and according to Gary Myers even on the   worst Dobsonians the first stage move goes at least 90% of the way. I believe there is handshaking at the end of each of these move steps between the AN and the Servocat, though I may be wrong.

This may be the issue I am seeing as it explains why after a supposedly successful goto the ArgoNavis suggests the object is still some degrees away. Repeatedly pressing 'goto' does get the object in the field so I am minded to blame the odd performance on the rollers slipping or maybe binding.

There is no sound change during a goto or slew so I have been progressing with setup of the Servocat.  The way I understand goto's working is that the AN tells the Servocat how many ticks to drive each axis by. If it is always short then maybe the parameters are wrong. I am now not sure this is the issue but until I have the correct gear ratio and motor encoder resolution in the Servocat I am not 100% sure.

I have been unable to get the original Servocat parameters from Lucas, though he has offered to check out and fix the mount if I take it to him. If he was in this country I would take the mount to him now. Taking it to the Netherlands is a long and expensive commute, which I would have to do twice.

Mesu mounts may be excellent, but a small niggle in one can be extremely difficult to solve, as I am finding out.

 

Ian B

 

Link to comment
Share on other sites

7 hours ago, astronomer2002 said:

Dan,

I have a mi250 with original Gemini 1 controller and motors. Never had any trouble with it. I also have a 2002 AP1200, no unsolved issues and excellent support from AP even though this is also a s/h mount.

 

I do also have a Mesu 200 which I am struggling with.

 

I purchased a second hand Mesu 200 after hearing all the good reports about the mount and support for it. I contacted Lucas before the purchase and he assured me he was happy to support the mount. It's carrying capacity is supposed to be higher than the Mi250 and as I wanted to put multiple scopes on the mount I decided to try a Mesu.

A previous owner of the Mesu seems to have changed the configuration of the Servocat and so I am trying to correct it. I lost the ArgoNavis setup during a software upgrade, but that seems to work fine now.

I am now suspicious that the axes are slipping or snagging during goto operations as they always come up short. If I use the hand controller from the Servocat to move the mount until the ArgoNavis display suggests the object is close I invariably see it in the field of view. The ArgoNavis uses its own shaft encoders, of course, so as long as the mount is roughly polar aligned any object can be found in this way.

I have run tests for Gary Myers, the builder of Servocat and the conclusion he has come to is that the rollers are slipping or binding during goto's. This is based on the 2-3 step goto code he wrote for Servocat. Given a goto instruction by the ArgoNavis he says the first course step should drive the mount to within 2-3 degrees of the target. The slew speed is then reduced to run a residual move and if necessary a final step to centre the object. On the test I ran I used the hand controller to move the mount to the object position to prove polar alignment. Then I drove the mount 55 degrees from the object in RA only. Now I issued a goto which should have driven the mount back to the object. Whilst it did alsmost achieve this the first stage only achieved 50% of the move (it stops between stages for a second or two) and according to Gary Myers even on the   worst Dobsonians the first stage move goes at least 90% of the way. I believe there is handshaking at the end of each of these move steps between the AN and the Servocat, though I may be wrong.

This may be the issue I am seeing as it explains why after a supposedly successful goto the ArgoNavis suggests the object is still some degrees away. Repeatedly pressing 'goto' does get the object in the field so I am minded to blame the odd performance on the rollers slipping or maybe binding.

There is no sound change during a goto or slew so I have been progressing with setup of the Servocat.  The way I understand goto's working is that the AN tells the Servocat how many ticks to drive each axis by. If it is always short then maybe the parameters are wrong. I am now not sure this is the issue but until I have the correct gear ratio and motor encoder resolution in the Servocat I am not 100% sure.

I have been unable to get the original Servocat parameters from Lucas, though he has offered to check out and fix the mount if I take it to him. If he was in this country I would take the mount to him now. Taking it to the Netherlands is a long and expensive commute, which I would have to do twice.

Mesu mounts may be excellent, but a small niggle in one can be extremely difficult to solve, as I am finding out.

 

Ian B

 

Friction drive mounts do slip, you can not eliminate it. Well u can but with Renishaw absoulte encoders on RA and DEC...

I usually run my mesu mount with the acceleration and speed at the lowest setting to reduce the slip possibility.

Overall, my guiding RMS is between 0.15" and 0.3" in seeing conditions of about 1.8-3 ".

For gotos I use platesolving.

Did you do your tests with a ccd/cmos camera attached to the scope?

Do you initialize the mount before gotos?

Edited by dan_adi
Link to comment
Share on other sites

On 29/06/2022 at 00:46, dan_adi said:

Friction drive mounts do slip, you can not eliminate it. Well u can but with Renishaw absoulte encoders on RA and DEC...

I usually run my mesu mount with the acceleration and speed at the lowest setting to reduce the slip possibility.

Overall, my guiding RMS is between 0.15" and 0.3" in seeing conditions of about 1.8-3 ".

For gotos I use platesolving.

Did you do your tests with a ccd/cmos camera attached to the scope?

Do you initialize the mount before gotos?

Dan,

Thankyou for the information on how you use your mount. I have left the default slew speed at 4 degrees per second, which might be higher than yours. What ramp up/down rate are you using? In the Servocat I have set 3 seconds. I assume you have a Sitech Controller rather than a Servocat, but the parameters ought to be similar. Your guiding figures are the best I have ever heard of.

I have run a number of tests with Gary Myers that indicates there is a varying amount of slippage in both axes during goto's.  It isn't predictable, except that the mount always comes up a bit short. This is why I thought the 2000:1 gear ratio may be wrong.

I hear what you say about friction drives, but if goto's cannot get you even close to where you want them to then it would make it frustrating to try and run the mount entirely remotely. Plate solving returned images may help to determine where the mount is pointing, but it does seem a retrograde step to have to do this every time.

Having now spoken to Lucas he tells me that every mount is configured with slightly different gear ratio's which he calculates whilst the mount is on his test rig. This probably explains why he couldn't provide a generic Dat file but general advice that the ratio is around 2000:1

Unfortunately it appears previous owners have not only messed with the software loaded on the mount but also the friction adjustment. After talking to Lucas I agree with him that the best course of action is to get the mount to him to apply any mechanical corrections needed. At the same time he will change the ArgoNavis/Servocat system for a Sitech controller. I had planned to do this myself, but it would be prudent to get him to do it. After it returns, which could be months away due to supply issues, it will be fully operational for the way I (and most other people) want to use it, be fully serviced by Lucas, and so be functionally as good as any Mesu mount out there.  I shall then have to consider whether to keep it or move it on.  The after affects of Covid have left both my wife and myself with long term issues so plans made when Covid was just getting started are having to change.

Having said the mount potentially may need some mechanical adjustments I have to add that with ArgoNavis and Servocat in unison I always know where the mount is pointing and have been able to use Stellarium to drive it through the ArgoNavis serial interface as well, so not a disastrous situation at all. I guess I was expecting a mount that was over £4K new back in the day, and now running at £6.3K new, to be perfect from day one and exhibit better goto performance than lower cost mounts. One thing that must be said in favour of the Mesu is that the electrical and electronic parts are readily available and that they are supported by the manufacturer who you can talk to. Neither of these points is true for most 10 year old budget mounts.

 

Ian B

 

 

Link to comment
Share on other sites

On 25/06/2022 at 13:19, astronomer2002 said:

Olly,

I connected the Servocat to my PC via a standard USB cable (the Servocat has a USB port on the front)

If you had a copy of the original dat file that Lucas should have included with the mount that would be a good starting point for me.

Here's a screenshot of what I have set up

image.thumb.png.ed3f77deb9ab26e21cd02a4fb4649bdb.png

 

Have you tried using the setting in the quoted post above? 

Peter

Link to comment
Share on other sites

  • 2 weeks later...
On 01/07/2022 at 20:20, astronomer2002 said:

Dan,

Thankyou for the information on how you use your mount. I have left the default slew speed at 4 degrees per second, which might be higher than yours. What ramp up/down rate are you using? In the Servocat I have set 3 seconds. I assume you have a Sitech Controller rather than a Servocat, but the parameters ought to be similar. Your guiding figures are the best I have ever heard of.

I have run a number of tests with Gary Myers that indicates there is a varying amount of slippage in both axes during goto's.  It isn't predictable, except that the mount always comes up a bit short. This is why I thought the 2000:1 gear ratio may be wrong.

I hear what you say about friction drives, but if goto's cannot get you even close to where you want them to then it would make it frustrating to try and run the mount entirely remotely. Plate solving returned images may help to determine where the mount is pointing, but it does seem a retrograde step to have to do this every time.

Having now spoken to Lucas he tells me that every mount is configured with slightly different gear ratio's which he calculates whilst the mount is on his test rig. This probably explains why he couldn't provide a generic Dat file but general advice that the ratio is around 2000:1

Unfortunately it appears previous owners have not only messed with the software loaded on the mount but also the friction adjustment. After talking to Lucas I agree with him that the best course of action is to get the mount to him to apply any mechanical corrections needed. At the same time he will change the ArgoNavis/Servocat system for a Sitech controller. I had planned to do this myself, but it would be prudent to get him to do it. After it returns, which could be months away due to supply issues, it will be fully operational for the way I (and most other people) want to use it, be fully serviced by Lucas, and so be functionally as good as any Mesu mount out there.  I shall then have to consider whether to keep it or move it on.  The after affects of Covid have left both my wife and myself with long term issues so plans made when Covid was just getting started are having to change.

Having said the mount potentially may need some mechanical adjustments I have to add that with ArgoNavis and Servocat in unison I always know where the mount is pointing and have been able to use Stellarium to drive it through the ArgoNavis serial interface as well, so not a disastrous situation at all. I guess I was expecting a mount that was over £4K new back in the day, and now running at £6.3K new, to be perfect from day one and exhibit better goto performance than lower cost mounts. One thing that must be said in favour of the Mesu is that the electrical and electronic parts are readily available and that they are supported by the manufacturer who you can talk to. Neither of these points is true for most 10 year old budget mounts.

 

Ian B

 

 

Sorry for the delayed response, haven't checked in for a while.

It's good that mr. Mesu will take the mount and service it. No doubt someone messed with it. 

The mount autoguides very well, as well as more expensive mounts, but they are small cut-corners if you will, in order to make the mount more accessible-price wise. For example I didn't like the wire connections and the servos exposed to the elements, a nice aluminium case to cover them would be nice and also protect the sensitive electronics.

Other than that the mount is really good for the high payload. 

The only time I see the autoguiding deteriorate to 0.5 " RMS or 0.7" is in windy conditions. But in windy conditions I also have worse seeing, so I don't image anyway in such a night.

In my routine I unpark the mount, so it starts tracking, I focus, then do a platesolve - offset init, then a goto to my target. The target is usually less than 1 arcminute away. I do another platesolve-offset init, goto target, and start autoguiding - imaging. So it would not take more than 2-3 platesolves to get things going. 

With regard to remote use, I wrote a little tutorial you can find here on the forum, in order to control the mount through a local area network. It is not hard but it takes a little DIY to make a serial cable and a small investment in a serial server dongle. This is how I control my mount now, and it works reliably, something I cannot say about using USB cables in general .. 

I am confident mr. Mesu will get your mount in order.

Link to comment
Share on other sites

  • 2 weeks later...

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.