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PMC-Eight for other mounts?


Charles Botkin
 

I am looking at getting the PMC-Eight to convert a non go-to mount into a go-to.
From what I have read it seems this would be a nice solution compared to building an on-step, but can encoders be used with the PMC-Eight ?


Skull HQX
 

I believe ES has a kit to upgrade a Losmandy G11 with PMC-Eight GoTo capabilities. It’s not cheap, but that’s relative. Maybe you could use that?

To be honest, what you want to do might be more trouble than it is worth. Unless that is something you will enjoy?

Clear skies!



Op vr 7 feb. 2020 om 21:47 schreef Charles Botkin via Groups.Io <charlesbotkin=yahoo.com@groups.io>

I am looking at getting the PMC-Eight to convert a non go-to mount into a go-to.
From what I have read it seems this would be a nice solution compared to building an on-step, but can encoders be used with the PMC-Eight ?


Wes Mcdonald
 

The PMC8 is not integrated to encoders....have to ask Jerry if that is in the cards.  The losmandy upgrade employs a TDM to manage the velocity of the shaft and has its own high res encoder not interfaced to the PMC8.


At least I believe all of the above is correct.

The only magic about putting in a PMC 8 on another scope would be working out the drive chain.  

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


Charles Botkin
 
Edited

I believe that the drive pulses and gear ratios can be adjusted to match almost any mount ? Or did I read the information wrong?
Doing atm work is something I do enjoy, but why would I buy the G-11 kit and not the EZOS2-GT and supply my own motors and brackets ?

 


Wes Mcdonald
 

Charles

You change the number of pulses per revolution in the app and I think in the ascom driver too....

Why would you buy a exos2-gt and put stepper motors on it and then try to purchase a PMC and interface it etc, when you can purchase the exos2-gt PMC8 as a package?  Btw I don't think ES has or sells PMC8 controllers stand-alone.

Tell you what.  If you want to build something sweet, get yourself an exos2-gt PMC8 and build you and me the spring loaded worm modification I have designed?  With that we can reduce the backlash to about zip and probably reduce the PE also.  You could source kits for the community.  The idea is you modify the existing worm block and machine two slides.  The springs and things come from McMaster Carr.  It's a snap.  If you have a mill.

You should probably go private on this if you are interested.  

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


Steve Siedentop
 

The PMC Eight will bolt on to a G-11 with the included mounting plates.  If you’re getting a second hand G-11, do yourself a favor and get the one piece worm blocks.  You will eventually have to adjust a G-11 and the two piece worm block will be exercise in frustration.  The RA extension is really nice also as it lets you separate the mount into two pieces for easier transport.

As far as other mounts go, you’ll need to figure out how to secure the motors to the mount.  There will be other settings to configure, but I’m not at my desk right now and can’t give you any screenshots.  Perhaps Jerry can chime in.

A TDM is nice to have but not required.  However, if you’re going to do long exposure astrophotography, you’ll need to use an autoguider or a TDM.  If your setup will be portable, stick with autoguiding.

-Steve



On Fri, Feb 7, 2020 at 6:05 PM Wes Mcdonald <wesmcd6@...> wrote:
The PMC8 is not integrated to encoders....have to ask Jerry if that is in the cards.  The losmandy upgrade employs a TDM to manage the velocity of the shaft and has its own high res encoder not interfaced to the PMC8.


At least I believe all of the above is correct.

The only magic about putting in a PMC 8 on another scope would be working out the drive chain.  

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


--
Mounts: ES PMC-8 G11 with Ruland Couplers and One Piece Worm Blocks, Skywatcher NEQ-6
Scopes: ES ED127CF FCD100, Orion 6” Mak, Stellarvue SV80EDT, Coronado Solarmax 40
Cameras:  CentralDS CDS-600, CentralDS Astro 60D, Orion Starshoot SSAG
Msc: Moonlite Focusers, Astrozap Dew Straps, Pegasus Ultimate PowerBox
Software: PixInsight, Cartes du Ciel, BackyardEOS, SkySafari


Jerry Hubbell - Explore Scientific VP Engineering
 

On Sat, Feb 8, 2020 at 01:36 AM, Charles Botkin wrote:
I believe that the drive pulses and gear ratios can be adjusted to match almost any mount ? Or did I read the information wrong?
Doing atm work is something I do enjoy, but why would I buy the G-11 kit and not the EZOS2-GT and supply my own motors and brackets ?

Hi Charles,  thanks for your question. Yes, the PMC-Eight can be configured and used on any mount as a DIY project.
The PMC-Eight Programmer's Reference provides a lot of good information you would need:
http://02d3287.netsolhost.com/pmc-eight/PMC_Eight_ProgrammersReferenceManual_Release2_2019_March_07.pdf

The retrofit for the G11 is only for those that have a G11 that they want to upgrade, it includes shipping the mount back to us for the mechanical upgrades and for servicing. We also test the mount and bring it up to the level of the new G11 PMC-Eight mounts that we sell. We install and test everything and you get a like new updated G11 PMC-Eight mount back. That is why the cost is more than you might spend if we just offered it as a DIY kit, which we do not do.

There are a couple of things you can do since we do not sell the controller boards separately and that will save you quite a bit of money compared to the G11 PMC-Eight upgrade. I think it is important to state that if you go the DIY route we would not provide any warranty for the PMC-Eight system installed on your DIY mount.

Depending on the size of the mount you want to add the PMC-Eight system to, you can either buy an iEXOS 100 PMC-Eight mount with the small controller board (Model 1A-01C) and NEMA 11 motors or the EXOS 2 PMC-Eight with the large controller board and the NEMA 11 motors. If you opt for the EXOS 2 PMC-Eight, then you can buy your own larger NEMA 17 motors and use it with the large board controller (Model 2A-06B). Either way you would need to purchase your own belt/pulley system or you could use the ones provided if it would work on your DIY mount.

The basic equation for calculating the total motor counts which is the main value needed to scale the gear train correctly is:

Total Motor Counts = Ring Gear Teeth x Pulley Ratio x Motor steps/rev x 32 microsteps/step

So for the G11 this is:  360 x 1 x 400 x 32 = 4,608,000 total counts. The arcseconds/microstep = 1,296,000 / 4,608,000 = 0.28125 arcseconds/microstep
For the EXOS 2 this is: 144 x 4.5 x 200 x 32 = 4,147,200 total counts. The arcseconds/microstep = 1,296,000 / 4,147,200 = 0.3125 arcseconds/microstep

The only other thing to set is the motor current. This is not user configurable, but I do provide versions of the firmware that set different motor currents. You can use those to select the motor current and then set the total motor counts in the ASCOM driver (it is hardcoded for our mounts, I would need to update the driver to support custom motor counts, or you could change the driver yourself) or the ExploreStars application which allows you to set the motor counts.

I have built a prototype Celestron CGE PMC-Eight mount for a friend of mine that we are using at our MSRO Observatory. It works very well. 


  
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!


 

Jerry,
 
That's an interesting picture.  I was trying to figure out why the worm pulley was so small, and then realized that that mount's tooth count explained it.  :-) 
 
I would think that selling DIY PMC8 kits for refurbing select mounts from other mfrs, could be a good idea, down the road.  Perhaps someday move the motor counts out of the source code and into an external .xml file for both ASCOM and INDI, to facilitate?  
 
- Bob
 
--
Mounts: ES PMC-8 EXOS2
Scopes: SV 102EDT, ZWO 60/280 Guide
Cameras:  Nikon D5300, Altair GPCAM2-IMX224C
Software: ASCOM, CdC, AstroTortilla, BYN Pro, Sharpcap, PHD2
Computer:  Thinkpad x230, Win7Pro/64


Jerry Hubbell - Explore Scientific VP Engineering
 

On Sat, Feb 8, 2020 at 01:34 PM, Robert Hoskin wrote:
I would think that selling DIY PMC8 kits for refurbing select mounts from other mfrs, could be a good idea, down the road.
Hi Bob,

I can say a couple things about that, as I had the same view when I started this project 6 years ago. After numerous discussions with Scott Roberts over the years, as far as the business model that Explore Scientific has pursued in the past and our plans into the future, I can say that we have no plans to create any type of DIY kit to sell for people to retrofit other manufacturer's mounts. Being a small company, there currently is not a large enough market to sell DIY kits for the astronomical community.

We will help those who wish to use their purchased systems for their own DIY projects though, and encourage this work. Our future business plan does not support the DIY market and are geared toward selling complete systems.

The CGE PMC-Eight mount was an experiment to see what was involved with designing a retrofit drive system. We have it in service and the initial measurement of the native PE is very good at around 3 arcseconds RMS. 

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!


Charles Botkin
 

Well I'm not planning on getting a small G-11 . I am getting a second Byres Series II that will be converted to GoTo..
From what I have seen the max current limit is 2A so I just need to choose a motor that is under that as to not pop a fuse.
If I really want encoders I'm sure I could find some way to get that to read out on a computer/tablet/phone

On Saturday, February 8, 2020, 12:51:30 PM CST, Jerry Hubbell - Explore Scientific VP Engineering <jrh@...> wrote:


On Sat, Feb 8, 2020 at 01:34 PM, Robert Hoskin wrote:
I would think that selling DIY PMC8 kits for refurbing select mounts from other mfrs, could be a good idea, down the road.
Hi Bob,

I can say a couple things about that, as I had the same view when I started this project 6 years ago. After numerous discussions with Scott Roberts over the years, as far as the business model that Explore Scientific has pursued in the past and our plans into the future, I can say that we have no plans to create any type of DIY kit to sell for people to retrofit other manufacturer's mounts. Being a small company, there currently is not a large enough market to sell DIY kits for the astronomical community.

We will help those who wish to use their purchased systems for their own DIY projects though, and encourage this work. Our future business plan does not support the DIY market and are geared toward selling complete systems.

The CGE PMC-Eight mount was an experiment to see what was involved with designing a retrofit drive system. We have it in service and the initial measurement of the native PE is very good at around 3 arcseconds RMS. 

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!