Vixen GP Goto Conversion Using Meade DS Motors by wt808

Last crawled date: 3 years, 3 months ago

Brackets and adapters for installing Meade DS motors on a Vixen Great Polaris telescope equatorial mount. May fit other Vixen equatorial mount models and clones such as:
Vixen SP, SP-DX, GP-E, GP-DX
Celestron CG-5
Synta EQ-4, EQ-5
Skywatcher EQ-4, EQ-5
Orion SkyView Pro
Jinghua HD (Apogee Inc.)
Or make your own brackets for your mount to fit the motor adapter and ring.
Installation on a Vixen GP
Remove the lock ring and threaded collar from both DS motors. Thread on the 3D-printed motor ring until nearly fully seated on the motor threads.
Note the orientation of the ring with the 3D-printed mounting bracket and where the M3 nuts will need to go. Turn the ring as needed until the holes of the ring and bracket line up properly. Make note the holes on the ring where the M3 nuts need to be pressed in.
Remove the ring, press in the three M3 nuts, and reinstall the ring in the proper orientation again.
Press a MF85ZZ bearing into the recess inside each motor. Finger pressure should be enough to seat both bearings.
Press a 635ZZ bearing into each end of the 3D-printed nose piece adapter.
Cut a small flat into the 5mm shaft for the set screw of the 22T gear to prevent the gear from rotating on the shaft when locked. I allowed 4mm of the shaft to protrude from the bottom of the gear to fit in the MF85ZZ bearing in the motor.
Install the 22T gear on the shaft lining up the set screw with the flat. If the underside of the gear is hollow, 3D-print the gear spacer and press it into the gear. This prevents the MF85ZZ bearing from unseating from the motor housing during operation.
Slide the longer end of the shaft through the nose piece and attach the 40T 5mm ID pulley. Check for free rotation and excessive play.
Apply grease to the 22T gear and carefully slide the nose piece into the motor. Note the alignment nubs on the nose that mate with the notches on the motor. Rotate the pulley/gear as needed to align the gear teeth with the nylon gear in the motor as you slide the assembly into the motor.
Fasten the motor assembly to the 3D-printed mounting bracket using three M3 screws and washers. Press an M6 nut into the base of the bracket.
Repeat for the other DS motor. At this point, you might want to connect both motors, power supply, and the Autostar controller to the jack panel, power the system on, and test for proper operation.
Install the 40T 6mm ID pulleys on both worm screws of the mount. Do not tighten fully yet.
Carefully install the belt simultaneously as you position the bracket for installation. Once the bracket is positioned properly, insert an M6 bolt through the corresponding opening in the mount and tighten to secure the bracket.
Verify the belt alignment and tighten set screws on the mount pulleys. If the belt alignment cannot be corrected by adjusting the mount-side pulley, you can also shim M5 washers between the motor-side pulley and outboard 635ZZ bearing. Note that you will have to remove the motor from the bracket to access the pulley set screws.
Install the 3D-printed jack panel housing on the RA motor bracket using the two M3 wood screws. Install the jack panel with the 4 screws provided with the panel, or use 4 more wood screws like the ones you used to mount the housing.
Connect the motors and Autostar hand controllers to the jack panel, connect the power supply, and verify proper operation. Note positions where the motor might hit the other motor, mount, jack panel cables, or where the telescope might hit either motor or jack panel.
Notable Autostar configuration parameters
Telescope - 4504/114EQ if FW patched, otherwise DS-127
Alt/Dec Ratio = -03.28533 (1:144 worm ratio)
Az/RA Ratio = +03.28533 (1:144 worm ratio)
Alt/Dec Percent = 75%
Az/RA Percent = 75%
Parts list
2x Meade DS motors (492 or 493)
1x Meade Computer Control jack panel
1x Autostar hand controller (495 or 497) + coil cable
1x 5.5x2.5mm 12VDC power supply, center-positive, 1.5A minimum (preferably with a right-angle DC connector)
1x Meade 505 RS-232 serial interface (optional, RJ11 on handset end, DB9 or USB on computer end)
2x 22T pinion gear, mod1, 5mm ID bore (used for RC cars)
4x 635ZZ ball bearing, double shielded, 5x19x6mm
2x MF85ZZ ball bearing, flanged, double shielded, 5x8x2.5mm
2x 5mm OD x 60mm L stainless round shaft
2x GT2 timing belt, 180mm circumference, 6mm width
2x 40T GT2 timing pulley, 5mm ID bore, 6mm width
2x 40T GT2 timing pulley, 6mm ID bore, 6mm width (I bought four of the 5mm ID pulleys and reamed two to 6mm)
6x M3 x 20mm bolt
6x M3 nuts
6x M3 flat washers
2x M3 x 8mm wood or self-tapping sheet metal screws (6x if the jack panel didn't include screws)
M5 washers (optional, for spacing timing pulleys for belt alignment)
1x M6 x 20mm bolt
1x M6 x 45mm bolt
2x M6 hex nuts
References
"Retrofitting Autostar GOTO control to the Vixen SP and GP style GEM mounts using Meade DS-Series motors", v1.2 2/14/2003https://www.cloudynights.com/ubbthreads/attachments/677648-Retrofit_v1.2.pdf
"Adding Autostar GOTO functionality to your existing telescope", Christopher Ericksonhttp://data-plumber.com/autostarupgrade.htm