John Miele
professor emeritus
Reged: 05/29/05
Posts: 722
Loc: North Alabama
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I just adjusted the transfer gears (RA and DEC motors) on my Atlas mount in an attempt to get rid of the “rattle” at the beginning and end of my high speed slews.
I wanted to share one observation and then ask a question. I bought my Atlas mount less than 1 year ago. My transfer gears apparently have a new design and are mounted differently from all the pictures I have seen on the web concerning this issue. I had no hex nut to tighten or loosen and there were no O-rings. There is instead a flat headed pin passing through the gear into the housing and 3 brass washers (2 on one side of the gear and 1 on the other) and there are two set screws bearing on the pin’s shaft instead of one. So if you try this adjustment be aware you may run into this new design. My adjustment method was too simply loosen the two set screws and firmly press the pin against the gear and then tighten the screws back up. This apparently has worked and virtually eliminated all rattling noise even though this connection did not appear very loose to begin with. I also cleaned the gears and then used super lube when I reassembled them.
Now for my question. Nowhere in anybody’s write-up of this procedure is there any mention of how tight to mesh the transfer gears to the worm shaft gear when you bolt the motor assemblies back in place. There are two screws holding each motor assembly in place. The screws are in slotted holes so you can shift the entire motor/transfer gear assembly tightly or less tightly against the gear in the housing (I assume this is the worm shaft gear). How tight are you supposed to make this interface? I used what I considered moderately firm pressure but I did not wedge it in there! You can’t see anything so there is no way to visually inspect the mesh. Everything seems to be working fine. Are there any cautions to be followed here? Anything about this interface that is critical to not damage anything? Thanks.
John
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C11/Atlas Mount/Denk II BV
SV102ED/AT Voyager
DSI IIc, DSI II Pro
ST-80, Mallincam Hyper Plus B/W Video Camera
Edited by mielejr (11/18/08 11:49 AM)
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Charlie Hein
Postmaster
Reged: 11/02/03
Posts: 8421
Loc: 26.06.08N, +80.23.08W
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Quote:
Nowhere in anybody’s write-up of this procedure is there any mention of how tight to mesh the transfer gears to the worm shaft gear when you bolt the motor assemblies back in place. There are two screws holding each motor assembly in place. The screws are in slotted holes so you can shift the entire motor/transfer gear assembly tightly or less tightly against the gear in the housing (I assume this is the worm shaft gear). How tight are you supposed to make this interface?
The short answer:
Adjust them so that they seat well but don't bind the motors - if you do then the motor will "lock up" and it'll make a noise that sounds like its gears are being shredded!
The longer answer:
Same as above but if you're a stickler on this kind of thing then even though the motor doesn't bind up the gears can be meshed too far and make a contribution to your PE. The only way I know of to tell if this is happening is to record your PE, check for an event at the interval for the transfer/worm gear connection, and polish and/or adjust for a minimal contribution.
Quote:
You can’t see anything so there is no way to visually inspect the mesh.
Yes you can... there is a slotted head chromed "screw" which is actually just a cover on the side of the mount casing near where the worm gears are. If you remove this cover you'll be able to shine a flashlight in there and see what the mesh looks like.
Charlie
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"He's dead, Jim - I'll get his wallet, you get his tricorder." - Leonard "Bones" McCoy
Weston CSC:
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Strgazr27
Vendor - Deep Space Mods and Composites
Reged: 10/04/04
Posts: 6984
Loc: StonyHill Observatory
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John,
On the side of the mount opposite the control panel you'll see two small chrome plated, slotted head screws. If you remove these you can see the mesh between the transfer gears and the worm gear spur gears. I cut a small strip of plain paper, slide it between the gears, push them firmly together and than tighten everything down. Perfect mesh is the result.
Any problems drop me a PM or check my rebuild tutorial at my website link in my signature.
HTH's
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Bobby
StonyHill Observatory
Skywatcher EQ6 Pro (On it's way)
AT 130 F/6 Prototype
Royce 10" f/4 Astrograph (Under Construction)
Self Modded 40D
70-200 F2.8 L IS
SSAG
YAHOO TMB 130SS Group
Astronomy Technologies Yahoo Group
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John Miele
professor emeritus
Reged: 05/29/05
Posts: 722
Loc: North Alabama
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Great! Thanks guys.  I'll remove these screws and look in there tonight. I did make a PE recording last night but I need to get it into PEAS to look for anyhting odd.
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C11/Atlas Mount/Denk II BV
SV102ED/AT Voyager
DSI IIc, DSI II Pro
ST-80, Mallincam Hyper Plus B/W Video Camera
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Mert
Carpal Tunnel
Reged: 08/31/05
Posts: 2247
Loc: Spain, Pamplona
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John,
Check where you uploaded your PE-data, I dropped
some jpg's that might give a clue.
Regards,
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Mert
42º49"N 1º38"W
3" Polarex refractor
6" F12 SW Maksutov,CS2-S
EQ6 + EQMOD 
SPC900NC/DFK21AU04.AS
My web-page don't laugh, I should make it better! 
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Jeffrey Sugden
sage
Reged: 05/04/05
Posts: 383
Loc: Akron, OH
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Charlie:
I just installed my SynScan upgrade. The dec motor stalls briefly at time when fast slewing (speed 8) that axis. It will chatter a bit then continue slewing. I have not checked closely, but I think it is the same rotational spot. No problem at speed 2.
My first thought was perhaps I had the dec bearings too heavily pre-loaded, but the shaft rotates easy enough. I will try loosening the transfer gear mesh. I pushed both motors as firmly as I could into the worm spur gear.
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Jeff
WO ZS 80FD
Celestron FS80
Celestron FS80WA
Meade SN6
Cave Newt 6" F8 (project)
SAC 8-II
Meade LPI
Philips SPC-890
Orion SSAG
Nikon D40
EQ-6 (SynScan upgrade)
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Mert
Carpal Tunnel
Reged: 08/31/05
Posts: 2247
Loc: Spain, Pamplona
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Jeff,
I did that just to try as well and the motor
just started to make grinding noises and stalled.
Just make that mesh close but not tight!
Backlash isn't any problem at all when tracking :-)
The chatter could be just the transfer gear being
too loose on its shaft.
By the way, that upgrade, how does it look like?
Any pic you can share?
Regards,
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Mert
42º49"N 1º38"W
3" Polarex refractor
6" F12 SW Maksutov,CS2-S
EQ6 + EQMOD
SPC900NC/DFK21AU04.AS
My web-page don't laugh, I should make it better!
Edited by Mert (11/19/08 03:08 PM)
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Jeffrey Sugden
sage
Reged: 05/04/05
Posts: 383
Loc: Akron, OH
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Mert,
I already have it installed. Here's what I got:
1. Two motors, each labeled "RA" and "DEC".
2. Controller board with faceplate
3. Hand controller
4. Cable to connect hand controller to the faceplate
5. Power cable with auto cigarette light plug on the end
6. Bag with screws
a. Four motor mounting screws, four lock washers, four flat washers (the screws were too long - I used the old ones)
b. Four black screws for the faceplate. I had already replaced mine with stainless, so I re-used those.
7. Installation sheet
8. SynScan instruction manual
9. Two screwdrivers (motor mounting and faceplate screws)
10. This was shipped in a box 28cm x 21cm x 11cm. Inside the box is a block of pre-cut high density foam. Package weight was 1.8 kg.
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Jeff
WO ZS 80FD
Celestron FS80
Celestron FS80WA
Meade SN6
Cave Newt 6" F8 (project)
SAC 8-II
Meade LPI
Philips SPC-890
Orion SSAG
Nikon D40
EQ-6 (SynScan upgrade)
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Mert
Carpal Tunnel
Reged: 08/31/05
Posts: 2247
Loc: Spain, Pamplona
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Jeffrey,
Do I understand you correctly if I say that
only the motors were supplied, without mounting
plate, transfer gears etc?
So you just dismounted the "old" motors and remounted
the new ones on their place?
I found some old image on my PC, don't know anymore
where I found that one, did the kit contain what
you see here?
Kind regards,
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Mert
42º49"N 1º38"W
3" Polarex refractor
6" F12 SW Maksutov,CS2-S
EQ6 + EQMOD
SPC900NC/DFK21AU04.AS
My web-page don't laugh, I should make it better!
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Jeffrey Sugden
sage
Reged: 05/04/05
Posts: 383
Loc: Akron, OH
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When I said "motor" I meant "moto assembly" The motors look similar to those in the phot. The transfer gears, mounting plate, etc are on the assemblies
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Jeff
WO ZS 80FD
Celestron FS80
Celestron FS80WA
Meade SN6
Cave Newt 6" F8 (project)
SAC 8-II
Meade LPI
Philips SPC-890
Orion SSAG
Nikon D40
EQ-6 (SynScan upgrade)
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Mert
Carpal Tunnel
Reged: 08/31/05
Posts: 2247
Loc: Spain, Pamplona
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If you try with your fingers to make the
transfer gear "wobble" and it feels too loose,
then first loosen the grub screw on the side of the
mounting plate, then tighten the hexagonal screw
a bit, afterwards fasten the grub screw again.
That likely takes care of the rattling noise and
also improves PE a bit.
Regards,
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Mert
42º49"N 1º38"W
3" Polarex refractor
6" F12 SW Maksutov,CS2-S
EQ6 + EQMOD
SPC900NC/DFK21AU04.AS
My web-page don't laugh, I should make it better!
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Jeffrey Sugden
sage
Reged: 05/04/05
Posts: 383
Loc: Akron, OH
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The transfer gear seems tight enough. I think I have 2 high spots on the dec worm. I have backed off the worm mesh as far as the cover plate will permit and it is 99% gone at rate 8. I am replacing the worm wheel spacers soon, so maybe with a better mesh height, things will run smoother.
All that being said, I am not that concerned about this. I expect it will guide well.
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Jeff
WO ZS 80FD
Celestron FS80
Celestron FS80WA
Meade SN6
Cave Newt 6" F8 (project)
SAC 8-II
Meade LPI
Philips SPC-890
Orion SSAG
Nikon D40
EQ-6 (SynScan upgrade)
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jimguy08
member
Reged: 07/17/08
Posts: 46
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I'm resurrecting this old thread because I tore down my atlas for a re-build and am addressing these parts. I have the same tranfer gear set-up as John describes. I took the entire thing apart. I have no wobble but I still can't get rid of a tiny bit of backlash in the transfer gear. The only solution would be to re-machine parts. In my aluminum casting, there isn't enough play in the hole to allow the shaft with the transfer gear to get any closer to the drive gear of the motor.
Just something I'm going to live with...
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Astro-Tech AT111EDT w/Moonlite focuser
Celestron C102F Flourite w/Moonlite focuser
Orion 80ED w/Moonlite focuser
Astro-Tech AT66 Guidescope
Atlas EQ-G Bluetooth enabled
Orion SSAG & QHY8
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Dennis Sakva
Pooh-Bah
Reged: 10/19/04
Posts: 1330
Loc: Kiev, Ukraine
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DON'T put them too tight even if it don't bind (seems like i can tighten mine as much as I want without binding). Overtighten them and you are asking for large 10.2 sec spike in your PE which is hard to guideout with anytning less then 5 corrections/second. I was fighting it for almost a year and finally get rid of it my making both motor-transfer and transfer-worm gears a liiiiitle bit loose.
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