The Starfinders' RA-Drive doesn't need any tightening screws as its equipped
with a quite sophisticated clutch, wich seperates the axis from the drive unit itself.
It is, roughly spoken, a quartz controlled dc drive. Angular speed is sampled via a
sliced wheel running with the motor
Figure 1 shows the worm gear's big wheel, wich directly connects to the main axis. Furthermore
You can see the motor working via a small gear onto the worm. The angular rate sensor is shown
in Figure 2.
Also one can see - in the black housing on the main axis' end - the incremental sensor for the digital
RA-setting circle of the Magellan Computer. The big black screws is for tightening the setting circle.
The worm is to be seen, as well. The angular rate sensor is the golden disc with the two black
wires sitting on the motor's axis.
Figure 3 shows more details. 1 are two of the three screws for the adjustment of the clutch,
2 is the incremental sensor for the setting circle, 4 its tightening screw. 3 is the motor itself.
Figure 4 shows the metal block containing the worm. On its face side, left to the incremental
sensor's cable, You can see a hole with a screw in it. This is for adjudsting the worm gear.
Attention: Don't tighten it too fast, otherwise the gear can run so hard, that anything might
Figure 5 shows all parts of the RA drive as You should find it when disclosing the mount's housing.
Tuning the mount:
As mentioned above, two parameters can be adjusted: the worm gear and the torque of the clutch.
The clutch should, in doubt, be tightend a bit too fast than too lose as it should guarantee a secure
and backlashfree transport of the telescope. Normally, when the clutch is adjusted quite well, there is
no delay when speeding up the scope to let's say 32x sideral speed in either direction.
The worm, however, should be tightened so, that the gear isn't too loose, but NEVER too fast!
The motor itself is powerfull enough also for the 10" scope with additional photographic equipment.
It should run nearly quiet and also 32x sideral speed should cause only a decent whiz.
It should run quite fast at a constant speed, which gives a very stable control loop with the additional
gear between motor and worm. If the motor is running unsteadily, this might have several reasons:
First there could be some mechanical parts be stuck. Or second, the electronics could have a problem,
but this is the least probable case. Also, a partially dirty speed sensor wheel would cause unsteady
movement of the motor.