New Exos2 GT PMC8 grinding noise


Jorge Restrepo
 

Hello everyone,

I received today my new exos2 and set it up indoors just to make some test. After setting everything up and balancing my gear I tried a few slews to see how it was working. 
I noticed when the RA rotated clock wise (from the parked position), around 50-60 degrees of rotation the mount started to make a grinding noise. No cables were tangled (just the free weight of the cables) and the mount is balanced and using the wall power. That repeated like two or three times. Slews in the other RA direction were ok. Then the same happened in the DEC axis (attached in the video). 
After this I disengaged each clutch and moved freely each axis. DEC was fine moving 180 degrees in each direction, but RA was stuck around 60 degrees clockwise, I applied a little pressure to see if I could get it unstuck, an audible “crack” noise followed and the mount was able to continue its rotation. I did some test after that and and everything seems ok. 
Is this normal for a new mount?
https://youtu.be/TK9L8L5-kl4



regards. 
Jorge


 

Jorge,
 
Well, it sure wasn't for my mount :-)   I did have a number of mechanical issues with my EXOS2 mount head (sorted out now), but they were more in the nature of impacting performance, not stalling motors and definitely no 'audible crack's...
 
Looking at your video, your RA power train ran and sounded normal to me, until something stalled it. I think we've had a few folks here whose units came to them with a worm gear adjustment that was a bit too tight.  The gears are not perfectly circular and they don't flex (much), so there needs to be a bit of clearance to permit them to rotate past high spots. If there's insufficient clearance and high spots meet, the power train can complain.  The problem could right itself on its own, or perhaps require a worm adjustment. That seems like the simplest/most likely reason for your stall.  Not sure about that 'crack' sound... 
 
My $0.02 - call ES Customer service on Monday to get their opinion on the problem (including the 'crack' sound), and any next steps. 
 
- Bob
 
--
Mounts: ES PMC-8 EXOS2
Scopes: SV 102EDT
Cameras:  Nikon D5300, Altair GPCAM2-IMX224C
Software: ASCOM, CdC, AstroTortilla, BYN Pro, Sharpcap, PHD2


Wes Mcdonald
 

Well, that is the worst.  When the thing binds up it makes a noise something like that.  As Robert said it is caused by the gear mesh.  But the "clack" concerns me.

Send it back.  Get them to sort it out and you can start fresh.

Wes.


--
Wes, Southport NC
PMC-8, ES ED 127, 10" LX200GPS, Astro-Tech 8" Newt, ETX-90
Polemaster, Orion ST-80 and SAG
Electrical Engineer, Retired


Jerry Hubbell - Explore Scientific VP Engineering
 

On Fri, Feb 15, 2019 at 11:59 PM, <jirestre@...> wrote:
Hello everyone,

I received today my new exos2 and set it up indoors just to make some test. After setting everything up and balancing my gear I tried a few slews to see how it was working. 
I noticed when the RA rotated clock wise (from the parked position), around 50-60 degrees of rotation the mount started to make a grinding noise. No cables were tangled (just the free weight of the cables) and the mount is balanced and using the wall power. That repeated like two or three times. Slews in the other RA direction were ok. Then the same happened in the DEC axis (attached in the video). 
After this I disengaged each clutch and moved freely each axis. DEC was fine moving 180 degrees in each direction, but RA was stuck around 60 degrees clockwise, I applied a little pressure to see if I could get it unstuck, an audible “crack” noise followed and the mount was able to continue its rotation. I did some test after that and and everything seems ok. 
Is this normal for a new mount?
https://youtu.be/TK9L8L5-kl4
Hi Jorge,

Sorry you are having this binding issue. As other's have suggested, this is a gear mesh binding issue so your mount requires adjustment. We do test every mount when we receive it here in the US and adjust it as needed, but sometimes after shipping it to our customers, the adjustment gets knocked and binding can occur. There are several messages here on this forum and on the internet on how to adjust the gear system (search for LXD75 mounts also as this is the same for the EXOS 2) if you are comfortable doing that, but I would suggest you call customer service +1 (866) 252-3811 ext 2 and talk to Kent about getting an RMA to send you mount back to us for adjustment.

I apologize again, I will also pass your message onto our QA department.
 
--
Jerry Hubbell
Vice President of Engineering

Explore Scientific, LLC.
jrh at explorescientific.com

www.explorescientificusa.com
1010 S. 48th Street
Springdale, AR 72762
1-866-252-3811

Author: Scientific Astrophotography: How Amateurs Can Generate and Use Professional Imaging Data
             Remote Observatories for Amateur Astronomers: Using High-Powered Telescopes From Home


Mark Slade Remote Observatory (MSRO) IAU MPC W54 Equipment
Wilderness, VA
Mounts
: ES PMC-Eight G11 + Telescope Drive Master (TDM)
Scopes: ES 165 FPL-53 ED APO CF, ES 102 FCD100 ED APO CF
Cameras:  QHY174M-GPS + FW, QHY163C
Misc: 3-inch 0.7x Focal Reducer Field Flattener, Filters: Luminance,
Red, V-band Photometric, Diffuser, 200 lpmm Spectral Grating

Software: MaxIm DL 6, Cartes du Ciel, Astrometrica, AstroImageJ, AutoStakkert!


G-man
 

Sorry to hear about the issues. I would follow Jerry's suggestion and have it RMA.

Also, when you get it back, I suggest you leave the RA clutch always disengaged, so even if you were to grab it, or do anything the axis will simply rotate and no damage to the gear mesh will happen. It has saved my mount a few times from my 2 year old who likes to grab the weight bar... now he can grab it and move it without fear of ruining the gear mesh.

Cheers.

G.


Jerry Hubbell - Explore Scientific VP Engineering
 

On Fri, Feb 15, 2019 at 11:59 PM, <jirestre@...> wrote:
After setting everything up and balancing my gear I tried a few slews to see how it was working. 
After viewing your video again, I don't know that it is reasonable that your equipment is balanced correctly as the counterweight is all the way up the counterweight shaft. Can you check to make sure the RA axis is balanced when the clutch is completely loose and post a picture of that?  Thanks
 
--
Jerry Hubbell
Vice President of Engineering

Explore Scientific, LLC.
jrh at explorescientific.com

www.explorescientificusa.com
1010 S. 48th Street
Springdale, AR 72762
1-866-252-3811

Author: Scientific Astrophotography: How Amateurs Can Generate and Use Professional Imaging Data
             Remote Observatories for Amateur Astronomers: Using High-Powered Telescopes From Home


Mark Slade Remote Observatory (MSRO) IAU MPC W54 Equipment
Wilderness, VA
Mounts
: ES PMC-Eight G11 + Telescope Drive Master (TDM)
Scopes: ES 165 FPL-53 ED APO CF, ES 102 FCD100 ED APO CF
Cameras:  QHY174M-GPS + FW, QHY163C
Misc: 3-inch 0.7x Focal Reducer Field Flattener, Filters: Luminance,
Red, V-band Photometric, Diffuser, 200 lpmm Spectral Grating

Software: MaxIm DL 6, Cartes du Ciel, Astrometrica, AstroImageJ, AutoStakkert!


Wes Mcdonald
 

Jorge:

Upon review of your video and set up I believe you are really out of balance in DEC.  This would explain the noise etc.  I see  you have a DSLR, a guide scope, and guide camera way back on the telescope  IT appears to me there is no way the thing can be anywhere near balance.  I also note the DEC stalls when it is trying to lift the weight of all that stuff up from vertical.  

To balance the thing is DEC you set it all at home then with the RA clutch tight, and the DEC released, turn the scope to 90 degrees dec.  See if it stays there.  If it does not then things are out of balance, and you need to move the scope forward or backward on the dovetail or scope rings, or both until it is balanced.  You can also figure out how to to add some weight as needed.

What is your scope?  It looks like a 102.  It's objective weight is probably not enough to balance things.

The awful noise was the motor stalled but being pulsed.  According to Jerry it does not cause damage.

Wes.


--
Wes, Southport NC
PMC-8, ES ED 127, 10" LX200GPS, Astro-Tech 8" Newt, ETX-90
Polemaster, Orion ST-80 and SAG
Electrical Engineer, Retired


Jorge Restrepo
 

Hello Jerry, 
Thanks for your reply and active involvement in this community. 
I made another video to show why I have to put the counterweight all way to the top, otherwise there is no way to balance RA. 

https://youtu.be/5kPAQ2fjpUc


Jorge Restrepo
 

Thanks for replying Wes, 
Actually is a ED80 CF, very light. My imaging train weights around 9.2-9.4 pounds, almost the same as the counterweight, that's why I have to put it all the way up. See the video I posted in my reply to Jerry. 


Jim McKee
 

jestre,
My rig weighs 7 lbs.   Ioptron sells a 3lb counterweight, 20mm hole.  My 3lb CW sits about 3 inches from the end of shaft.  You may need two 3lb CW's. Maybe measure the force required with something like a fish weight scale pulling down on your CW bar at the far end.  That would tell you minimum CW weight required. 
/Jim
--
Mounts:      ES EXOS2-GT w/ PMC-8
Lens:          Canon EF 100-400mm f/4.5-5.6L IS II
Cameras:   Canon 6D2, Canon 7D2, Canon 1D4
Misc:          CAMRANGER Mini, USB-to- Cat6 Extender, Astromania Red Dot sight (Flash Shoe)
Software:   EXPLORESTARS IOS & WIN, Stellarium. Backyard EOS, StarTools, DSS
Computer:  2012 MacBook Pro, VMWARE, WIN 10


Jerry Hubbell - Explore Scientific VP Engineering
 

On Tue, Feb 19, 2019 at 02:52 AM, <jirestre@...> wrote:
Hello Jerry, 
Thanks for your reply and active involvement in this community. 
I made another video to show why I have to put the counterweight all way to the top, otherwise there is no way to balance RA. 
Thanks Jorge for that.   I was unsure about the total weight of your rig, It looks like you have balanced it correctly.  It looks like you are having a gear mesh issue. You should contact our customer support as I suggested previously about returning your mount for adjustment.

Thanks.
 
--
Jerry Hubbell
Vice President of Engineering

Explore Scientific, LLC.
jrh at explorescientific.com

www.explorescientificusa.com
1010 S. 48th Street
Springdale, AR 72762
1-866-252-3811

Author: Scientific Astrophotography: How Amateurs Can Generate and Use Professional Imaging Data
             Remote Observatories for Amateur Astronomers: Using High-Powered Telescopes From Home


Mark Slade Remote Observatory (MSRO) IAU MPC W54 Equipment
Wilderness, VA
Mounts
: ES PMC-Eight G11 + Telescope Drive Master (TDM)
Scopes: ES 165 FPL-53 ED APO CF, ES 102 FCD100 ED APO CF
Cameras:  QHY174M-GPS + FW, QHY163C
Misc: 3-inch 0.7x Focal Reducer Field Flattener, Filters: Luminance,
Red, V-band Photometric, Diffuser, 200 lpmm Spectral Grating

Software: MaxIm DL 6, Cartes du Ciel, Astrometrica, AstroImageJ, AutoStakkert!