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Motor-driven mount with slow-motion controls

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#1 Classic8

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Posted 31 March 2009 - 06:07 PM

If I want a German equatorial mount for a 4" F7 refractor, and I want one that has a motor-drive (in RA at least) but also has slow-motion controls where I can switch between the two fairly easily, what are my choices?

I haven't seen much out there like that, but I was hoping someone could suggest some options. I guess I could buy 2 different mounts but I would think I could get both on one mount. Thanks for any input on this. :question:

#2 Lane

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Posted 31 March 2009 - 06:42 PM

I had that setup in the past with my old Super Polaris mount. It had slow motion controls and I bought a little motor from Orion and added it to the mount. Problem was the cluch on the motor was so tight it made moving the slow motion RA control very difficult. So I would have to use a hex wrench to unhook the motor when I did not want to use it for tracking. So just get yourself one of the manual mounts with slo-mo from Orion and then add the motor after the fact.

You could also get a Sirius mount without the GOTO. It comes with a little 4 button keypad for RA and DEC movement. Not exactly the same as manual slo-mo but maybe better since it doesn't create vibration. I assume it also tracks in RA automatically. Then you could add the GOTO controller at a later date if you decided you wanted that.

#3 Classic8

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Posted 01 April 2009 - 09:14 AM

Thanks, I might have to go that route, and add a motor to a manual mount. I was wanting a mount that could be used without power, if necessary, hence the slow-motion controls.

#4 rmollise

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Posted 01 April 2009 - 09:38 AM

If I want a German equatorial mount for a 4" F7 refractor, and I want one that has a motor-drive (in RA at least) but also has slow-motion controls where I can switch between the two fairly easily, what are my choices?

I haven't seen much out there like that, but I was hoping someone could suggest some options. I guess I could buy 2 different mounts but I would think I could get both on one mount. Thanks for any input on this. :question:


All the non go-to Vixen clones, the CG5, the EQ4, etc., etc. are set up this way. You've got clutch knobs as well as locks on each axis. Loosen the knob and you can use the slow-mo control. Tighten it and the motors engage.

#5 Classic8

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Posted 01 April 2009 - 05:18 PM

If I want a German equatorial mount for a 4" F7 refractor, and I want one that has a motor-drive (in RA at least) but also has slow-motion controls where I can switch between the two fairly easily, what are my choices?

I haven't seen much out there like that, but I was hoping someone could suggest some options. I guess I could buy 2 different mounts but I would think I could get both on one mount. Thanks for any input on this. :question:


All the non go-to Vixen clones, the CG5, the EQ4, etc., etc. are set up this way. You've got clutch knobs as well as locks on each axis. Loosen the knob and you can use the slow-mo control. Tighten it and the motors engage.


Thanks so much for the info. I couldn't tell for sure from the product descriptions whether that was all that was involved to switch to manual controls.

One more question - are those mounts reliable? I'm not mechanically inclined so really don't want to have to try taking apart and re-greasing the thing just to get it to work properly before I can use it. I've heard of some issues like that on these forums. I'd only use the mount for visual, not imaging, so the tracking doesn't need to be outstanding or anything.

#6 Mike Holland

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Posted 01 April 2009 - 06:07 PM

I don't know if the clones are reliable, but I can tell you that the genuine article is reliable. They still sell Vixen mounts at several places, so you might want to check out the Vixen GP2 mount, which runs $500 (sans the motors).

Mike

#7 Littlegreenman

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Posted 01 April 2009 - 07:07 PM

I had that setup in the past with my old Super Polaris mount. It had slow motion controls and I bought a little motor from Orion and added it to the mount. Problem was the cluch on the motor was so tight it made moving the slow motion RA control very difficult. So I would have to use a hex wrench to unhook the motor when I did not want to use it for tracking...


Something was not working correctly on that set up. All it should take is to loosen the clutch and the gear on the worm gear shaft will 'loosen' and move independently from the shaft. Maybe the clutch was a poor match, or not aligned 'just right.' Or the shaft was bent, even a tiny bit.

Here is a problem I had that was easily fixed when I figured out what was going on. I just bought a used Great Polaris DX mount, the heavier version of the Great Polaris. Loosening the clutch did not disengage the axis from the motor. In the picture below the gear in the center slips over the brass clutch 'shaft.' The brass clutch shaft slips over the worm gear and is held on by a tiny set screw. That gear is supposed to rotate freely over the brass shaft unless the clutch is tightened. But, due to sitting around unused for years, that gear was frozen to the shaft. It took a lot of elbow grease to loosen it. Other potential issues are that the motor can be mounted a little off, causing the motor gear (the gear on the right in the pic) to be pressed too tight against the other gear, or too loose, or tilted, etc. It's just a matter of futzing with the bolt holding the motor on. The clutch is chromed; you can see the bottom of it on top of the motor housing.

Reliability: Vixen generally has a good reputation. Some of the clones have had some quality control issues. I'm guessing that reliability is getting better over time. If buying used, be sure to see if either worm gear shaft for either axis is bent. Those shafts can be bent from the mount having fallen, or from stiff slow motion shafts acting like a lever. There was an interesting thread over on the Classic Scopes forum about straightening bent shafts earlier this week.

Littlegreenman

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#8 Classic8

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Posted 01 April 2009 - 07:26 PM

Thanks for the info. I did get the impression that the Vixen mounts had a pretty good reputation for reliability. They cost more too, so I guess that shouldn't be too surprising. I'll take another look at the Vixen mounts.

#9 Lane

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Posted 01 April 2009 - 07:49 PM

I had that setup in the past with my old Super Polaris mount. It had slow motion controls and I bought a little motor from Orion and added it to the mount. Problem was the cluch on the motor was so tight it made moving the slow motion RA control very difficult. So I would have to use a hex wrench to unhook the motor when I did not want to use it for tracking...


Something was not working correctly on that set up. All it should take is to loosen the clutch and the gear on the worm gear shaft will 'loosen' and move independently from the shaft. Maybe the clutch was a poor match, or not aligned 'just right.' Or the shaft was bent, even a tiny bit.

Here is a problem I had that was easily fixed when I figured out what was going on. I just bought a used Great Polaris DX mount, the heavier version of the Great Polaris. Loosening the clutch did not disengage the axis from the motor. In the picture below the gear in the center slips over the brass clutch 'shaft.' The brass clutch shaft slips over the worm gear and is held on by a tiny set screw. That gear is supposed to rotate freely over the brass shaft unless the clutch is tightened. But, due to sitting around unused for years, that gear was frozen to the shaft. It took a lot of elbow grease to loosen it. Other potential issues are that the motor can be mounted a little off, causing the motor gear (the gear on the right in the pic) to be pressed too tight against the other gear, or too loose, or tilted, etc. It's just a matter of futzing with the bolt holding the motor on. The clutch is chromed; you can see the bottom of it on top of the motor housing.

Reliability: Vixen generally has a good reputation. Some of the clones have had some quality control issues. I'm guessing that reliability is getting better over time. If buying used, be sure to see if either worm gear shaft for either axis is bent. Those shafts can be bent from the mount having fallen, or from stiff slow motion shafts acting like a lever. There was an interesting thread over on the Classic Scopes forum about straightening bent shafts earlier this week.

Littlegreenman


Unfortunately I had the original SP mount and it was not compatible with the nice motor you have in your picture. If I could have used the one you have I would probably still have that mount. I had to use the smaller electric motor that attached directly to the slow motion pin without any gears in between. So I had to loosen the hex bolt that locked the motor to that pin to free up the tension.






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