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Vixen Polaris RA Drive question

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#1 terraclarke

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Posted 03 July 2013 - 08:01 AM

Does anyone know if the Vixen Great Polaris RA drive and clutch will work on an original (black 1980s) Vixen Polaris drive? My Vixen Polaris drive has the tapped hole on the right side do the drive housing for a RA drive bracket just like my late model Celestron Omni CG4 drive. The Vixen Polaris uses a 144 tooth gear for the RA drive axis. I used to have a Vixen Great Polaris mount (mint green version) but I sold it 8 years ago and all I remember was that the drive went into a little box on the drive housing, I don't remember if it had a mounting bracket. It's my understanding that the gear ratio has remained the same throughout all three versions of the Vixen mount (VP, SP, AND GP).

Thanks much,

#2 rolo

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Posted 03 July 2013 - 09:14 AM

Terra, the Vixen GP & SP can share the same MT1 motors but they will not work on the Polaris mount. The gears are the same 144 teeth but that's where the similarities end...

#3 terraclarke

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Posted 03 July 2013 - 09:59 AM

Thanks Rolo. I heard somewhere that the Orion Eq-3 RA drive will work. Perhaps I will look further into that.

Terra

#4 Bill Griffith

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Posted 04 July 2013 - 04:07 PM

Terra,

I machined an aluminum block to accept an Orion #7832 True Track R.A. motor drive to an SP.

My opinion is the drive is adequate vs cost even if the dec. drive is never used.

Someday I'll fabricate the dec. motor as well.

I've built a few for others and sent the dimensions to a few to build their own. The feedback was positive. :grin:

The cost of the True Track dual axis is less than other alternatives investigated.

Bill

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#5 Bill Griffith

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Posted 04 July 2013 - 04:10 PM

2

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#6 Bill Griffith

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Posted 04 July 2013 - 04:15 PM

3

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#7 terraclarke

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Posted 04 July 2013 - 04:33 PM

That certainly looks like a viable option Bill. I like the way that it has a clutch. The Orion EQ3 option does not. I will look into your design further. Thanks.

#8 Chassetter

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Posted 04 July 2013 - 06:50 PM

EQ3 dual axis drive with hand controller and battery case on CN here

#9 Brian Risley

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Posted 04 July 2013 - 07:28 PM

Just to keep everyone straight here, Terra appears to be talking about the original Polaris mount, not the Super/Great Polaris series which mounted drives in a different manner.
I know the Dec mounting is completely different, and from the pictures and manuals I have seen, so is the RA. There is no position to mount the motor on the mount below the worm, the only motor mount has to connect with the shaft extending away from the mount.

Brian

#10 orion61

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Posted 04 July 2013 - 07:39 PM

I have an Orion SA drive from the EQ1 mount it mounts on the Right (from front) side I had it on my SP Vixen but it tracked a bit slow but it tracked steady. PM Me!
I wonder if there is a Pot you can tweek the speed?? havent checked that far.
I hope you find a drive.

#11 Bill Griffith

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Posted 05 July 2013 - 08:28 AM

Terra,everyone,

My apologies for misreading the original post.

The Orion#7829 EQ-3M Single axis bolts right to a Vixen Polaris mount.

The Vixen MD-5 that were original to the mount will interface fine to the Orion motor. The Orion controller interfaces with the Vixen motor as well.

That said, there is a DC voltage step up with a MD-5 of 3 volts DC. The Orion # 7829 is 6 volts DC.

I will confirm sidereal.


The drive systems appear to mount identically although the Vixen bracket is slightly heavier gauge metal and the motor has (in my opinion) a smoother pulse.

The motors are offset from the EQ mount by a significant amount. I have installed a counterweight (dummy shaft) that is attached on the opposite side of the mount on the worm shaft. This eliminates a slight imbalance on the mount.

Clear Skies
Bill

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#12 terraclarke

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Posted 05 July 2013 - 09:29 AM

Yes, mine is exactly like what is shown in your last pic Bill. There is a drive bracket tapped hole on the right side of the drive housing and it looks like the drive would have to go directly on the slo-mo axle just like on my CG4 mount. It wish it were otherwise and would use a geared clutch like my great Polaris did but this is the older Polaris. I am only interested in the RA drive so the Orion EQ 3 drive would be the only easy solution. It's fairly cheap too at around 80 bucks.

#13 Astrosetz

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Posted 05 July 2013 - 10:07 AM

For my Polaris mount, I use an inexpensive Celestron "Logic Drive" that can be had on eBay for about $20 to $30 bucks. It adds solid tracking to my Celestron C4.5 :)

#14 terraclarke

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Posted 05 July 2013 - 10:24 AM

Hi Bill, do you or anyone else have a solution to a converter for my 12V power supply outputting a 6V stream to the 6V drive rather than using the 4 D-cell battery pack? I am going with the EQ3 drive as I like the hand drive controller and the 8X slo-slew.

Thanks,

Terra

#15 Bill Griffith

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Posted 05 July 2013 - 11:31 AM

Hi Terra,

I would guess a small DC transformer or resistor would work.

Sorry, that's not much help!

But...

Surprisingly, the Orion battery pack with soft case and strap hangs conveniently between the Polaris tray and the leg on the attachment and just stays there.

The Polaris mount is the grab and go for about 4 different OTAs.

Consequently, It is used almost every clear night so it stays setup in the family room.

I get many many hours out of the battery pack and just use rechargeable D cells.

Bill

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#16 terraclarke

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Posted 05 July 2013 - 05:30 PM

Then I will go with that then Bill. I have a similar battery pack to power my Omni CG4 duel axis drives and that one last a surprisingly long time. I just thought it would be nice to use the big rechargeable power supply as an alternative. My Vixen Polaris has my 76 x1218 mm "Jaegertron" on it and remains set up in a corner of the telescope room/dining room where it is easy to carry it out through the kitchen door to the deck.

#17 terraclarke

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Posted 05 July 2013 - 05:37 PM

Here's the 'Jaegertron' on its vintage Vixen Polaris mount in the corner of the room. Interestingly, this scope seems bigger than the AstroTelescopes 4 inch F11 behind it. A 4 inch Unitron would dwarf the room.

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#18 terraclarke

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Posted 05 July 2013 - 05:42 PM

The Vixen Polaris mount. The tapped hole for the RA drive bracket is on this side of the housing.

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#19 John Carruthers

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Posted 06 July 2013 - 02:03 AM

>a converter for my 12V power supply outputting a 6V stream to the 6V drive <<

I use a car audio converter, it can select 12, 9, 6 or 3 volts output. It plugs into a cigar socket and has various output plugs, cost about £5 iirc.

http://www.choiceful...urce=google&...

I found mine in Maplins (UK), I imagine Radio shack would have them?

#20 turk123

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Posted 06 July 2013 - 07:36 AM

Terra, I have several mounts using a battery pack including a great Polaris. Go with the battery pack. My hand controller flashes when batteries are low. Uses "c" cells and lasts a year. Why even think of a cord?

#21 terraclarke

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Posted 06 July 2013 - 10:31 AM

Thanks for the tip John, I'll check it out. Yes Tom, the battery packs are convenient and last a long time. Just nice to have an option when the batteries are dead. My power supply is always charged.

Terra

#22 Geo.

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Posted 07 July 2013 - 10:06 PM

The EQ-3 uses a 130 tooth worm wheel. The Polaris is 144 (RA). The Speed can be corrected by changing the crystel in the hand control. I had a couple Tasco Polaris controllers that were made by Synta, who makes most of Orion's stuff including the EQ-3 drive. The pre-digital NTSC color TV system used subcarrier for the chrominance information that when added to the luminance video signal formed a composite video baseband signal. The frequency of this subcarrier is was 3.579545 MHz. The crystal for the Polaris is the same frequency and and costs 18 cents, as no one makes analog TYs anymore.

#23 terraclarke

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Posted 08 July 2013 - 08:53 AM

Thanks George, I've already gotta handle on a supplier for a replacement diode that ups the frequency by 10 percent to compensate for the 130/144 tooth gearing difference between extant EQ3 drive and the Polaris mount. Now to dig out the soldering iron. Where did I put that darned thing. :question: :foreheadslap:

#24 Starhawk

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Posted 08 July 2013 - 08:58 AM

I adapted a CG-4 drive to my old vixen Polaris. I used a 40 tooth gear to a 44 tooth gear to get the 11:10 ratio needed to adjust the 130:1 drive to the Polaris 144:1 ratio. It works quite well, and with just a little bracket I was able to attach the DEC motor and get dual axis drive.

-Rich

#25 Bill Griffith

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Posted 08 July 2013 - 11:13 AM

Thanks George! Thanks Terra! :bow:

This drive is used on grab n go scopes. I should have stated that I have noticed this.
Quite honestly,it never bothered me enough to find where the error existed and place a quantitative percentage on the error. :foreheadslap:

I'm a lazy amateur!

The other slight anomaly is at high power 300+ range on planetary viewing, I will notice at times (new batteries) the pulse count from the motor effecting fine planetary details.

The procrastinator just uses the pause on the controller then slews over. My bad!

This was all acceptable from having RA drive vs no RA drive.

Thanks for filling me in on the mod.!

Bill






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