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SiTech CGE-Pro conversion

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#1 freestar8n

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Posted 24 January 2020 - 09:04 PM

Hi-

 

I mentioned a while ago that I was converting my CGE-Pro to SiTech motors and controller - and I will provide here a short summary of how it went. 

 

I am now using a CGX-L and the conversion of the CGE-Pro was mostly to give it new life and also just as an interesting project to see how it would work.  As it happened, a friend was suddenly in need of a new mount, so as soon as it was working I lent it to him and he has been using it ever since.

 

The conversion makes direct use of all the switches on the mount: for homing, axis limits, and the PEC index with no additional electronics.  I just needed to make simple connects to connect the original wires to the SiTech controller.  The controller is set to receive those signals with no pull-ups or anything - and the software can be configured to use them directly.

 

The main challenge I did not expect ended up being mechanical.  The motors have screw holes that are directly compatible with the original motors, but the gearbox and electronics connector on the SiTech motors is on the wrong side and cannot attach directly.  This means either machining a whole new way to attach the motors - or to create a bracket to offset the motors and drive with a belt.  I chose the belt approach - and for the bracket a friend designed and created a 3D printed plate with holes of the right spacing.

 

Getting the orientation and spacing of those holes was quite challenging and required some trial and error.  The end result shown below ended up being too tight and close - but it seems to work fine.  But if anyone does this themselves I would use a longer belt so there is less conflict of the motor with the worm bracket.  I was concerned about possible flexure of the 3D printed plate, but it is thick enough and short enough - and has some reinforcement - that I think it is fine.  But if you have a machine shop aluminum might be better.

 

I chose to use a 1:2 reduction pulley to match the original spur gears - but you can use any ratio you want and configure the SiTech driver appropriately.  The pulleys and belts are from sdp-si.  The shaft on the motor and the shaft for the worm appeared to be English in one case and Metric in the other - so for a tight fit I got the exact one for each.  I forget what size they were but I can look it up if there is interest.

 

The software and documentation for the controller and software are somewhat idiosyncratic and you may need to look in multiple places - but it does make sense and there are tons of features.  Once you have it configured properly you shouldn't need to alter it.  You end up with a full software suite for building pointing models of the mount using the same PointXP software that comes with Mesu mounts.

 

I wasn't able to test guiding and tracking in great detail - but from all I could tell there was no change from the original CGE-Pro.  The ASCOM interface works fine for both control and guiding.

 

Here is a picture of how it looks - showing the adapter plates and pulleys.  Note that the motors are oriented so the wires feed out more cleanly in a downward direction.  There are a few wires leading to each motor and I wrapped them in a cable housing that is thin and flexible.

 

Overall I think this is a good way to get more life from a mount that may have problems with motors or controllers but is otherwise mechanically fine.  It isn't cheap since the controller, motors, and handcontrol end up just over $1k - but in many ways it is an improvement over the original.

 

I'm happy to answer questions if there are any.  I assume a similar approach would work for other mounts.

 

Frank

 

SiTechCGEProFinal.jpg

 


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#2 freestar8n

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Posted 24 January 2020 - 09:25 PM

Here is another view showing some testing at an early stage.  I was able to attach the motor in a usable way just with one screw.  By pivoting around that screw I could set the tension on the belt - and it all held in place to allow control of a small telescope for testing.

 

So - technically I was able to get it all working without any machining at all.

 

Note that with one screw the motor can somewhat torque and make an angle with the worm shaft.  So it is very hard to translate the spacing you measure there to the spacing needed in a bracket.  So I would plan for some slop and use slots for holes where the motor attaches.

 

Frank

 

MotorWithOneScrew.jpg


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#3 Michaeljhogan

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Posted 25 January 2020 - 06:51 PM

Can you show us the video or something I had the CGE Pro and I believe it was the best mount Celestron ever made it never gave me one days trouble and with these motors the same ones used in AP mounts this is what they should of done to the CGX-L that I got a refund with.

#4 Michaeljhogan

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Posted 25 January 2020 - 06:52 PM

Can you show us the video or something I had the CGE Pro and I believe it was the best mount Celestron ever made it never gave me one days trouble and with these motors the same ones used in AP mounts this is what they should of done to the CGX-L that I got a refund with.

#5 freestar8n

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Posted 25 January 2020 - 08:12 PM

Can you show us the video or something I had the CGE Pro and I believe it was the best mount Celestron ever made it never gave me one days trouble and with these motors the same ones used in AP mounts this is what they should of done to the CGX-L that I got a refund with.

I'm not sure what your interest is but I'm well aware of your cgx-l story since you tend to bring it up in most every thread related to celestron mounts.  I'm glad your mount was refunded and good luck with your next one.  My cgx-l has been performing with no issues and there are many design improvements over the cge-pro.  The cge-pro worked very well but some of us had problems with the motors - and replacing them is a challenge since it is hard to find them and expensive if you do.  I don't anticipate any issues after this conversion to SiTech.

 

I'm also not sure why nowadays there is a desire to get information from video rather than text or text combined with a few images.  If you want a video - picture the images above but with the belt and pulleys turning.

 

Frank


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#6 Michaeljhogan

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Posted 26 January 2020 - 07:05 PM

I'm not sure what your interest is but I'm well aware of your cgx-l story since you tend to bring it up in most every thread related to celestron mounts.  I'm glad your mount was refunded and good luck with your next one.  My cgx-l has been performing with no issues and there are many design improvements over the cge-pro.  The cge-pro worked very well but some of us had problems with the motors - and replacing them is a challenge since it is hard to find them and expensive if you do.  I don't anticipate any issues after this conversion to SiTech.

 

I'm also not sure why nowadays there is a desire to get information from video rather than text or text combined with a few images.  If you want a video - picture the images above but with the belt and pulleys turning.

 

Frank

Forgot still sore are we cause i told the truth anyway the only reason the CGE Pro was any good was Rick Hedrick of PlaneWave Instruments built it then left Celestron every mount since was POS

the Chinese took out the American motors to cut costs and put in Chinese dirt thats why they blew up anyway roll on may till i have my GM 2000 HPS II then it will be all one bad dream.


Edited by Michaeljhogan, 26 January 2020 - 07:40 PM.


#7 DuncanM

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Posted 26 January 2020 - 10:44 PM

The CGE-Pro uses US Made Pittman motors.



#8 freestar8n

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Posted 26 January 2020 - 11:32 PM

The CGE-Pro uses US Made Pittman motors.

Yes - I don't know who makes the motors in the CGX-L, but the only problem I had with the CGE-Pro, which is also the reason for this thread, is its American-made Pittman motors that failed.

 

You can use your choice of motors if you do the SiTech conversion, but I went with the ones sold by SiTech - which are also Pittman, but a different model - and much cheaper than the CGE-Pro ones - if you can find them.  The SiTech ones are $155.

 

Frank


Edited by freestar8n, 26 January 2020 - 11:36 PM.



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