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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.
Having suffered for some while with broken teeth on my Tracelscope 70s plastic focuser rack; I finally got around to doing something about it.
First of all I cut a piece of aluminium (aluminum for our friends across the Pond 🇺🇸) the same size and dimensions as the plastic one on the focuser tube. Using the damaged one on the tube as a template, I marked out the replacement and began to file it down to size. Once this was done I copied across the positions of the valleys between the teeth onto the aluminium replacement. Using a manual mitre saw with a blade suitable for metal I cut the valleys. Some rough filing and the rack was almost complete. A hole was drilled at each end to receive a screw. I then cut off the plastic rack from the focuser tube, filed the cut flat and the glued and screwed the replacement into position.
Due to the rough hand marking, cutting and filing it is not 100% smooth running, but at least it gives me full travel.
A couple of pics:
Broken plastic rack (removed). New aluminium rack glued & screwed in place
I am selling my Moonlite installation kit for 8" newtonian focuser as shown here
The installation kit was fitted on my 8" dobson in Italy and used very little (it is essentially new). I no longer need it as the focuser now sits on my 12" dob.
New £58, my price: £40 (including RM 1st class signed-for). PayPal (pay as a friend) or direct bank transfer.
Also advertised on ABS.
Thanks for looking,
I've upgraded my focuser so have a Skywatcher Dual-Speed Low Profile 1.25/2" Crayford focuser for sale £70 delivered to UK only.
Bank transfer or Paypal F&F preferred.
I just installed this Lacerta 1:10 Micro Transmission focuser on my 8” Skywatcher Dobsonian. It is a direct replacement for the stock focuser and works extremely well. I was surprised at how easy it was to install! Ordered it from 365Astronomy and got fast shipping.