Supertune the EQ6 -Addendum

EQ6 super tune guide

Supertuning the Synta / Skywatcher EQ6 / Orion Atlas

This procedure is an addendum to the main strip down guide located HERE and will guide you towards Super-tuning the mount to get better results. This guide needs to be read in conjunction with the main strip down guide and shows how to get better tuning with the RA and DEC worm gears by using additional shims to set the worm gear to worm roller more accurately.

This guide also includes a shim calculator so you can automatically calculate the shim sizes required when rebuilding.

I am going to break with convention for super-tuning in this guide and NOT replace the main bearings. Much discussion about these has taken place in various guides and forums but the fact is the main bearings are perfectly adequately engineered for a mount like the EQ6. The only bearings I changed in this guide were worm roller end shaft bearings because these are generally pretty poor quality from the factory. The other bearings are more than adequate as the mount does not need high speed bearings and ceramic bearings are prone to potential problems in cold weather.

The super-tuning element is concerned with the setting of more accurate worm gear alignment. Its assumed if you are carrying out this process you will have carried out all steps for improving the mount in the strip down and rebuild guide with regards to cleaning and de-burring components and replacing the factory lubricant with a lithium type grease.

The EQ6 mount used for this guide was a new model and was probably manufactured around 2009. The overall machining was far better than on the earlier mount used for the strip down guide and engineering tolerances were significantly better. The mount showed a better quality lubrication although it was almost dry in places and a generally ‘cleaner’ level of engineering with none of the swarf and drek found in the earlier generation Synta mounts I have disassembled.

Replacement parts required for this guide:
The only parts acquired for this guide were the worm roller end shaft bearings and some additional shims. Details of these are as follows along with a complete bearing list if you find any of your bearings have been damaged or are unfit for use.

Pack of Delrin shims in assorted sizes. These can be acquired from;

These are fairly standard bearings and can be acquired almost anywhere. Mine were acquired from ebay relatively cheaply. A complete list is supplied for your information although for tuning only the worm roller end shaft bearings are worth replacing in my opinion. There are very many manufacturers of bearings, SKF bearings are relatively common in the market place and these were used. Other manufacturers part codes may differ slightly – if in doubt check with your supplier.

 QTY Application Manufacturer SKF Product Code  Replaced in this Guide
4 Worm Roller
End Shaft Bearings 
SKF  608 2RSH  YES 
6 Main Shaft
Bearings (3 per axis) 
SKF  6008 2RSH (Equivalent 6008 2RS1) NO 
1 DEC Shaft
Taper Bearing 
SKF  30206 J2/Q  NO 
1 RA Shaft
Taper Bearing 
SKF  32208 J2/Q  NO 

Tools required for this guide:
In addition to the tools required to do the mount strip down for supertuning you will also require the use of a digital caliper. These can be acquired readily at reasonable prices from sources such as Amazon from around £10 upwards.

Shim Setting/Calculations
Shim Calculator

Enter your A, B, C, D measurements into this table to calculate the correct shim to place between the worm gear and the bearing face. Note: When you click SUBMIT the page will reload and you will need to scroll down to the table to see the result.

 Measurement  Values

The EQ6 used to create this guide actually needed no shims applied to the RA axis as it was perfectly well set-up, the large amount of play in the RA axis was tuned out just through a rebuild and relubrication and careful setting of the worm gear during the worm tuning stage.

The DEC axis however was rather challenging and this is described with pictures below…..

What this problem indicated to me was that to some extent these mounts need a sympathetic tune rather than a strictly scientific one. It can often be an art more than a science and requires a certain ‘feel’ to weigh up whether a shim is too much or too little. If you are facing this kind of problem after supertuning read the shim washer considerations at the end of the EQ6 Case Study HERE

The mount used in this guide was over time tuned to a much higher degree than when it left the factory and after the stages described in the EQ6 strip down and rebuild guide and the supertune guide it operates far more quietly with no play in either axis.

My thanks to all the people who have encouraged me to create this guide and who have offered help and support in the making of this guide.
You know who you are and you have my gratitude.