RA Axis Issues #EXOS2


Justin Bailo <bailo.justin@...>
 

Hello, I have a EXOS2-GT PMC-8 and it is giving me some trouble with the RA axis. My RA axis has been perfectly fine, no issues. other then when I set it up recently. I noticed the mount for some reason when looking at it from the front , it would keep bouncing back to 11:00.

I have my scope mounted and balanced to my best ability. 
I home the Dec axis, then the RA axis. Then I take the RA and turn it horizontal counterweights to one side, the scope to the other. With the CLUTCH FULLY UNLOCKED, If I let it go while holding the counterweights on the right side, the counterweights will drop to 5:00 and the top to 11:00, So then I try  taking the counterweight to the left side, and when I release the counterweights swing past, then back to 5:00 and the scope to 11:00. 

The absolute best way I can describe what it feels like is, The scope is level, then I push to the left, it's smooth, it almost pulls the scope all the way. when I push to the right, it feels like i'm pulling against a rubber band thats building up, building, then when i let go all the tension releases and it bounces back to 11:00


 

Justin,
 
Just playing this back for clarity, I think that you are saying that when you are trying to balance your mount, it does not swing freely through a full arc, with the clutch off, but instead sticks at a couple of points.  I think you are also saying that this is a new development and you had not noticed it until recently.  
 
Is this correct?

- Bob
 
--
Mounts: ES PMC-8 EXOS2
Scopes: SV 102EDT, ZWO 60/280 Guide
Cameras:  Nikon D5300, Altair GPCAM2 290M
Software: ASCOM, CdC, AstroTortilla, BYN Pro, Sharpcap, PHD2
Computer:  Thinkpad x230, Win7Pro/64


Justin Bailo <bailo.justin@...>
 

Yes this is correct. It has never happened in the past, I don't know why the scope is leaning left no matter where I put it. I can change the center of mass on the scope to the right side of it, and it will fly like it's being pulled back to that 11:00 position. The mount itself is also pretty new, within 4 months.


On Sun, Jul 26, 2020 at 1:55 PM Robert Hoskin <devonshire@...> wrote:
Justin,
 
Just playing this back for clarity, I think that you are saying that when you are trying to balance your mount, it does not swing freely through a full arc, with the clutch off, but instead sticks at a couple of points.  I think you are also saying that this is a new development and you had not noticed it until recently.  
 
Is this correct?

- Bob
 
--
Mounts: ES PMC-8 EXOS2
Scopes: SV 102EDT, ZWO 60/280 Guide
Cameras:  Nikon D5300, Altair GPCAM2 290M
Software: ASCOM, CdC, AstroTortilla, BYN Pro, Sharpcap, PHD2
Computer:  Thinkpad x230, Win7Pro/64


Mike Leemhuis
 

Justin, have you checked your cable routing?  They can tend to pull on one side and not the other depending on how you have tied everything down.  I've had that happen to me when I was first getting set up.  I ended up routing my cables from the dovetail bar and then to the weight rod near the RA pivot and then to a clamp on the north leg with plenty of slack.  The goal is to minimize cable drag.  Of course it could be something else too........

Mike
 

On Sun, Jul 26, 2020 at 3:10 PM Justin Bailo <bailo.justin@...> wrote:
Yes this is correct. It has never happened in the past, I don't know why the scope is leaning left no matter where I put it. I can change the center of mass on the scope to the right side of it, and it will fly like it's being pulled back to that 11:00 position. The mount itself is also pretty new, within 4 months.

On Sun, Jul 26, 2020 at 1:55 PM Robert Hoskin <devonshire@...> wrote:
Justin,
 
Just playing this back for clarity, I think that you are saying that when you are trying to balance your mount, it does not swing freely through a full arc, with the clutch off, but instead sticks at a couple of points.  I think you are also saying that this is a new development and you had not noticed it until recently.  
 
Is this correct?

- Bob
 
--
Mounts: ES PMC-8 EXOS2
Scopes: SV 102EDT, ZWO 60/280 Guide
Cameras:  Nikon D5300, Altair GPCAM2 290M
Software: ASCOM, CdC, AstroTortilla, BYN Pro, Sharpcap, PHD2
Computer:  Thinkpad x230, Win7Pro/64


--
Mount: Explore Scientific Exos-2
Scope: Explore Scientific ED102CF, Orion 60mm guidescope
Camera: QHY163C and QHY5L-ii
Filter: Optolong L-eNhance 2"
Software: ASCOM, PHD2, CDC, Stellarium, Sharpcap Pro, NINA, Deep Sky Stacker, Affinity Photo, Lightroom
Computer:  ASRock X570 Steel Legend, AMD Ryzen 7 3700X 8-Core Processor, 3600Mhz
Extras:  Lots of 3D printed parts I designed for improved usability


 

Ok.
 
I think it's unusual for a mount to just suddenly decide to start sticking.  I had a sticking problem, but it was right from the start - a ring gear ID tolerance problem that I was able to fix(!).  
 
But for this to come out of the blue is just odd. 

Do take a close look at Mike's cable suggestion.  Also remember that the DEC motor is offside and makes balancing fun.  Also, there's a chrome thumbscrew above the RA setting circles - check that it has not become tightened to the point where it drags on the mount's central axis.  And if that doesn't get you past it, I'd suggest you give Kent (ES Curtomer service) a call.
 
HTH...
 
- Bob
 
--
Mounts: ES PMC-8 EXOS2
Scopes: SV 102EDT, ZWO 60/280 Guide
Cameras:  Nikon D5300, Altair GPCAM2 290M
Software: ASCOM, CdC, AstroTortilla, BYN Pro, Sharpcap, PHD2
Computer:  Thinkpad x230, Win7Pro/64


Justin Bailo <bailo.justin@...>
 

It looks like the screw above the dial may have played a huge part in this, also I am going to have to guess I had my weight balance way off. I had some cables mounted to the side of the telescope into a hub, and it seems this had changed the entire center of mass to slightly over the left side. I have been able to fix this after taking the entire scope down to the OTA.

Sorry not much time I will update with more later if it for sure fixed 

On Sun, Jul 26, 2020, 4:19 PM Robert Hoskin <devonshire@...> wrote:
Ok.
 
I think it's unusual for a mount to just suddenly decide to start sticking.  I had a sticking problem, but it was right from the start - a ring gear ID tolerance problem that I was able to fix(!).  
 
But for this to come out of the blue is just odd. 

Do take a close look at Mike's cable suggestion.  Also remember that the DEC motor is offside and makes balancing fun.  Also, there's a chrome thumbscrew above the RA setting circles - check that it has not become tightened to the point where it drags on the mount's central axis.  And if that doesn't get you past it, I'd suggest you give Kent (ES Curtomer service) a call.
 
HTH...
 
- Bob
 
--
Mounts: ES PMC-8 EXOS2
Scopes: SV 102EDT, ZWO 60/280 Guide
Cameras:  Nikon D5300, Altair GPCAM2 290M
Software: ASCOM, CdC, AstroTortilla, BYN Pro, Sharpcap, PHD2
Computer:  Thinkpad x230, Win7Pro/64