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Equipment Discussions >> Mounts

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PJ Anway
Double-Star Observer
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Reged: 06/04/03

Loc: North Coast
DSC's on a GM-8 ??
      #6024661 - 08/14/13 08:59 AM

I am considering putting digital setting circles on my Losmandy G-9 (GM-8). I mean push-to like Skycommander, not go-to like the Gemini system. Anyone using these? If so, what are you using and what are your thoughts?

Thanks for any help


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hottr6
Carpal Tunnel
*****

Reged: 06/28/09

Loc: 7,500', Magdalena Mtns, NM
Re: DSC's on a GM-8 ?? new [Re: PJ Anway]
      #6024697 - 08/14/13 09:23 AM

I bought the JMI kit and had my friendly tame machinist modify the RA slip-ring per the Losmandy clutch design. Works as you would expect it to. The Losmandy installation instructions suggest grinding a flat for the no-slip-ring, but I did not bother and find that the grub screw finds plenty of purchase; this is not a highly-torqued piece that needs the flat.

The add-on does look a little cheesy. The G8 is a handsome machined mount, and the little nylon gears for the DSCs are definitely after-thoughts.


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PJ Anway
Double-Star Observer
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Reged: 06/04/03

Loc: North Coast
Re: DSC's on a GM-8 ?? new [Re: hottr6]
      #6025966 - 08/14/13 08:46 PM

Thanks Shane.

I am looking at a Sky Commander computer and he suggests using the JMI encoder kit (Sky Eng. only makes a kit for dobs). I would hope the JMI gears are acetal (Delrin) rather than nylon, it's a much more stable and durable material. Though I wouldn't think the stress on DSC's gears would be much.


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Jason B
Proud father of 5!!
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Reged: 06/21/04

Loc: Mid-Michigan
Re: DSC's on a GM-8 ?? new [Re: PJ Anway]
      #6026597 - 08/15/13 07:32 AM

PJ,
Kevin has a Sky Commander on his GM8 so you can contact him or see him at GLSG for a close up...


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hottr6
Carpal Tunnel
*****

Reged: 06/28/09

Loc: 7,500', Magdalena Mtns, NM
Re: DSC's on a GM-8 ?? new [Re: PJ Anway]
      #6027037 - 08/15/13 12:08 PM

Quote:

I would hope the JMI gears are acetal (Delrin) rather than nylon, it's a much more stable and durable material. Though I wouldn't think the stress on DSC's gears would be much.



I'll be honest and state that I don't know what the gears are made of. They are a dark color, not pale like "typical" nylon. And you are correct, there is almost no stress on these gears...... gravity probably being the biggest source.

I do note that nylon is used a lot in automotive valve timing gears, so it cannot be all that bad.


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tomcody
Pooh-Bah
*****

Reged: 07/06/08

Loc: Titusville, Florida
Re: DSC's on a GM-8 ?? new [Re: PJ Anway]
      #6027272 - 08/15/13 02:06 PM

PJ
I am also considering going with a GM8/DSC combo if I can locate a GM8 with the Losmandy kit on it?
If You do get one I suggest you go with the Nexus system
web page
As it is less expensive than a Sky Commander and a Sky Fi units to connect to an IOS Skysafari app and a lot cleaner simpler install.
PS : I used a Sky Commander with a SkyFi unit to connect to my IPad and it worked well on my Diskmount DM6, but I think the Nexus would be simpler cheaper and better.
PPS Losmandy may be coming out with the DSC's again as I noted on a Japanise web site a picture of a new GM8 with the flats machined on the mount body for encoders ( as I understand, Losmandy stopped putting the flats on in 2002, but it is rumored that encoders are " in the works" to interface with the new Gemmini II controller) .
Rex


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dobsoscope
sage
*****

Reged: 05/24/06

Re: DSC's on a GM-8 ?? new [Re: tomcody]
      #6028422 - 08/16/13 01:45 AM

The Nexus system seems to be very interesting indeed - but cannot find that much GEM using it , at all...! Maybe it is only because it's still relatively new. But, I would say, just as good as Argo Navis or Sky Commander. I am tending to go towards push-to as I live in a very urban area and having motors running at 3am would wake up the neighbours..!

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Falcon-
Post Laureate
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Reged: 09/11/09

Loc: Gambier Island, BC, Canada
Re: DSC's on a GM-8 ?? new [Re: dobsoscope]
      #6028428 - 08/16/13 01:55 AM

I am using a NGC-MAX with JMI's encoder kit on my CI-700.

At first I was somewhat disappointed after my previous experience with the CG-5/Nexstar go-to accuracy when it comes to finding objects, but now that I have a better handle on how to do the initial align with the NGC-MAX I am getting fairly decent results.

I should note that I use the mount for imaging so my definition of decent result is if the target is at least *partially* on the DSLR's sensor so that I do not need to do a whole lot of hunting about to get it framed correctly. The NGC-Max system does that most of the time (more often with better polar alignments) vs the Nexstar goto system being dead-center every time (with proper 2+4 star goto calibration). With a wider FOV (wide field eyepiece, finder scope, etc) I would expect the NGC-Max to be not too bad visually.


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RAKing
Postmaster
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Reged: 12/28/07

Loc: West of the D.C. Nebula
Re: DSC's on a GM-8 ?? new [Re: PJ Anway]
      #6028797 - 08/16/13 09:43 AM

Quote:

I am considering putting digital setting circles on my Losmandy G-9 (GM-8). I mean push-to like Skycommander, not go-to like the Gemini system. Anyone using these? If so, what are you using and what are your thoughts?

Thanks for any help




PJ,

I have one of the older Losmandy DSC kits installed on my GM-8 and it works great. I have the original Losmandy computer - but it's a clone of the Sky Commander and the DSCs should also work with a new SC box. The system is easy to use as a "slip the clutches and push to" or you can drive the mount with the Digital Drive System.

In my case - I plug the DSCs into my Gemini box and use them as a feedback loop. This is especially helpful at public outreach sessions. If someone bumps or moves the scope accidentally, it does not lose its alignment and I can quickly recover and carry on.

You could possibly find a Losmandy kit for sale on A-mart - or you might even be able to get the hardware from Losmandy. It would definitely be worth a call. The kit is well-designed and an easy install.

Cheers,

Ron


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PJ Anway
Double-Star Observer
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Reged: 06/04/03

Loc: North Coast
Re: DSC's on a GM-8 ?? new [Re: RAKing]
      #6030056 - 08/16/13 10:55 PM

Thanks for all the suggestions. I will probably go with the Sky Commander. I called Losmandy and they are putting together an encoder kit for their mounts and they said it should be ready in a couple of weeks. I'll either wait for them or go with the JMI kit.

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Rocky68d
member


Reged: 11/01/09

Loc: Anacortes, WA USA
Re: DSC's on a GM-8 ?? new [Re: PJ Anway]
      #6030248 - 08/17/13 01:42 AM

PJ,
Did whoever you spoke with at Losmandy say if the new kit would work with all their mounts, even older ones? Thanks.


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PJ Anway
Double-Star Observer
*****

Reged: 06/04/03

Loc: North Coast
Re: DSC's on a GM-8 ?? new [Re: Rocky68d]
      #6030399 - 08/17/13 07:15 AM

Keith,

He said they would work with both the GM-8 and G11.


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hottr6
Carpal Tunnel
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Reged: 06/28/09

Loc: 7,500', Magdalena Mtns, NM
Re: DSC's on a GM-8 ?? new [Re: PJ Anway]
      #6030561 - 08/17/13 09:40 AM

Quote:

I will probably go with the Sky Commander. I called Losmandy and they are putting together an encoder kit for their mounts and they said it should be ready in a couple of weeks. I'll either wait for them or go with the JMI kit.



Be aware that unless JMI have changed their design, their kit does not use the 6 transfer dowels as shown on this Losmandy schematic. These dowels enable one to move the 'scope and still retain encoder positioning. I had to modify my JMI kit to accommodate for these dowels.

The Losmandy kit used to be supplied with delrin gear covers, but I understand that they are NLA.

The Losmandy kit is waaaay expensive. The JMI is a lot cheaper, and if you have access to a machine shop, is the way to go.

One last plug for the Nexus/Sky Safari combo. This is state-of-the-art planetarium software on a wireless hi-res tablet. The hand-held units used by Sky Commander, JMI and goto offerings of commercial 'scopes are so very 1990s: Quaint.


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RAKing
Postmaster
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Reged: 12/28/07

Loc: West of the D.C. Nebula
Re: DSC's on a GM-8 ?? new [Re: hottr6]
      #6030603 - 08/17/13 10:06 AM

Quote:

One last plug for the Nexus/Sky Safari combo. This is state-of-the-art planetarium software on a wireless hi-res tablet. The hand-held units used by Sky Commander, JMI and goto offerings of commercial 'scopes are so very 1990s: Quaint.




My Losmandy encoders work very well with Sky Safari on the iPad. It's another reason I like to use my encoder mount for public outreach.

Cheers,

Ron


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PJ Anway
Double-Star Observer
*****

Reged: 06/04/03

Loc: North Coast
Re: DSC's on a GM-8 ?? new [Re: hottr6]
      #6030974 - 08/17/13 01:27 PM

Quote:

Be aware that unless JMI have changed their design, their kit does not use the 6 transfer dowels as shown on this Losmandy schematic. These dowels enable one to move the 'scope and still retain encoder positioning. I had to modify my JMI kit to accommodate for these dowels.





Shane,

Unless I'm reading it wrong, from the schematic it seems the only purpose of the thick gear and 6 pins(dowels) it to get the motion of the telescope axis through the gear cover (because the gear cover does not move). If you did without the gear cover it seems these "tranfer" dowels would not be needed and it looks like the JMI kits do not have a gear cover. Am I reading this wrong?


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astrodevices
Vendor-Astro Devices


Reged: 10/26/07

Loc: Sydney, Australia
Re: DSC's on a GM-8 ?? new [Re: dobsoscope]
      #6031692 - 08/17/13 08:25 PM

Quote:

The Nexus system seems to be very interesting indeed - but cannot find that much GEM using it , at all...! Maybe it is only because it's still relatively new. But, I would say, just as good as Argo Navis or Sky Commander. I am tending to go towards push-to as I live in a very urban area and having motors running at 3am would wake up the neighbours..!



When Nexus is used together with SkySafari Plus/Pro any telescope mount can be used - GEM, Alt-Az, Equatorial fork, Equatorial platform. The same applies to other planetarium software - if the planetarium software supports a certain mount type then Nexus can be used with that type of the mount.

Best regards,
Serge.


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Ed Wiley
scholastic sledgehammer


Reged: 05/18/05

Loc: Kansas, USA
Re: DSC's on a GM-8 ?? new [Re: astrodevices]
      #6031714 - 08/17/13 08:39 PM

I had Losmandy DSCs on my G8 and transferred them to my G11. Used with a Sky Commander. No problems, worked perfectly before I retrofitted a Gemini II. I am keeping them on in expectation of integration. If Losmandy is in the process of offering these again it might be good to await their appearance simply because the originals were so well integrated with the mounts.

Ed


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hottr6
Carpal Tunnel
*****

Reged: 06/28/09

Loc: 7,500', Magdalena Mtns, NM
Re: DSC's on a GM-8 ?? new [Re: PJ Anway]
      #6032484 - 08/18/13 09:35 AM

Quote:

Quote:

Be aware that unless JMI have changed their design, their kit does not use the 6 transfer dowels as shown on this Losmandy schematic. These dowels enable one to move the 'scope and still retain encoder positioning. I had to modify my JMI kit to accommodate for these dowels.





Shane,

Unless I'm reading it wrong, from the schematic it seems the only purpose of the thick gear and 6 pins(dowels) it to get the motion of the telescope axis through the gear cover (because the gear cover does not move). If you did without the gear cover it seems these "tranfer" dowels would not be needed and it looks like the JMI kits do not have a gear cover. Am I reading this wrong?



Hey PJ,

If you tighten the JMI encoders onto the shaft you will not be able to tighten the clutch and if you leave the encoder loose (even with the set screw against the flat side of the shaft, as JMI suggests) it is certain to slip. It takes only a very small amount of slippage to totally ruin your pointing accuracy.

Losmandy solved this with the transfer dowels. What is happening here is that the encoder disc is now firmly attached to the shaft, but the clutch pressure is relayed through the dowels without affecting the disc.

It works for me, though I guess a call to JMI would explain their reasoning for why they do not use dowels.


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PJ Anway
Double-Star Observer
*****

Reged: 06/04/03

Loc: North Coast
Re: DSC's on a GM-8 ?? new [Re: hottr6]
      #6034142 - 08/19/13 08:48 AM

Shane,

Now I understand, that makes sense.

PJ


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Gil V
sage


Reged: 09/09/12

Re: DSC's on a GM-8 ?? new [Re: PJ Anway]
      #6075395 - 09/11/13 03:39 PM

Knex rollercoaster building sets have the plastic gears. They fit perfectly on a 1/4" encoder shaft. We happened to have a few of those around. Haven't tried encoders on my GEM yet, but that's what I'm using when I do.

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