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ICR_2019

Sloppy rack and pinion focuser fix

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Hi All

I thought I would share how I fixed my sloppy rack and pinion focuser on Skywatcher 130p.

The issue? When using or collimating the slop in the focuser would put the target or centre dot way out of line.

With the tube tilted downward I removed the 4 screws/nuts  of the focuser to remove it from the OTA.

Loosen the lock  and 2 adjusting screws, I used a small torx screwdriver as i did't have an allen key small enough.

Remove the 4 screws holding the adjuster bar in place, and remove the adjuster.

Note: Be careful to avoid the very sticky grease used on the drive!

Remove the draw tube assembly, remove the lock/adjusting shim located at the top of the main body.

There were 2 plastic shims 1 each side of the drive I removed both of them.

 Thoroughly clean everything with degreaser and isopropyl alcohol except the drive itself.

I cut 2 plastic shims from food packaging, cleaned them, and using 50mm double sided tape I lined out the main focuser body. Be careful to cut to the correct size and shape before installing and don't cover the drive or lock/adjusting shim areas.

Next using teflon tape purchased from eBay I covered the draw tube exterior.

I then did the same covering the plastic shims in the main body.

It was still a little loose so I doubled the teflon tape at the top of the tube either side of the adjusting shim.

Next I added a plastic shim onto the adjuster shim and covered with teflon tape.

Put it all back together and almost no slack!

I can now move the focuser from fully in to fully out without the collomation moving out of the centre ring on the primary.

Complete success I think.

 

 

 

 

Edited by loft_boarding
Better wording of sentence
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