The EQ6 Belt mod replaces the brass gears with a timing belt to reduce errors and remove backlash.

The EQ6 has standard brass gears on the stepper motor and worm gear, with a ‘transfer’ gear to translate the stepper motion to the worm gear.

These gears introduce errors and backlash, the belt drive mod is designed to replace these gears with a timing belt


The old and new parts

Replacement of the gears for a belt drive is straightforward but will take a day to do properly. Instructions are provided with the kit from Rowan Astronomy and another useful resource is the hyper-tune instructions from astro-baby.com

There are a couple of tricky steps

  1. Removing the adapter at the bottom of the polar scope shaft – you will need a steal belt, oil filter wrench (from Halfords)
  2. Removing the worm gear caps and the worm gear retaining ring, these can be removed using pointed pose plyers, but you risk damaging the caps if you slip, a better approach is to use the specially designed tool (available from Rowan Astronomy)
  3. The bolts holding the mount together are steel bolts with M6 threads tapped into the aluminium body – it is very easy to strip the threads be vary careful – if you do strip them you can repair them easily with a Helicoil thread repair kit.


Some of the tricky steps


Threading the belts through the guides can also be tricky, locking tweezers help a lot!

Fitting the belts is easier if you have locking tweezers, but it can be done with your fingers – if you are nimble – there is not much room to manoeuvre inside the mount.


The disassembly required to fit the belt mod.