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With Astro dark in Central Scotland now gone for a few months, I’ve turned my attention to improving the tracking accuracy of my EQ6. There is a well documented way to do this, and is commonly called “Hypertuning”. I already stripped the mount and changed the stock grease with white lithium grease when I bought it last summer, so now to properly tune it I need to very accurately set up the worm gear spacings and also deal with a few issues with the stepper motors. I can then start to use Periodic Error Correction to improve the accuracy even further. Like a lot of the things on the EQ6, the stepper motors can be quite troublesome. A lot of users report rattling noises as the motors spin up, and there can be quite a lot of backlash between the motor itself and it’s transfer gear. I bought the Synscan upgrade kit for this mount so these motors are only a few months old and have both these problems. There is a nice video showing the problem here:

The rattling noises made by the motors comes down to how the transfer gear is held in place. It is held on it’s shaft by two brass washers and the shaft itself it’s then held in place by two grub screws. Putting excess pressure on the shaft to stop the rattling causes the brass washers to start to clamp the gear to the point it’s slowing it down. The ideal thing to do here is to replace these washers with something low-friction. After much searching I found these panel mount phono plugs from Maplin. They have Teflon washers that are exactly the right size.

These then allow the transfer gear shaft to be put on really tight, without causing friction on the gear itself. So long rattling noise! So, the next thing is the backlash adjustment. At this point someone gave me a really good tip here. Because of the minute tolerances in the manufacturing of the gears, simply messing the two hard against each other makes them start to bind at certain points of the rotation. By putting a piece of doubled up tin foil sheet through the gears, I was able to get them close enough to eliminate any backlash, but also far enough away to avoid them binding.

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