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Old 14-09-2014, 04:29 PM
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Shiraz (Ray)
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Shiraz is offline
Join Date: Apr 2010
Location: ardrossan south australia
Posts: 4,798
Originally Posted by codemonkey View Post
Thanks everyone for your help! :-)

I tried shifting the RA axis by hand today... if there was a backlash problem should I be able to feel anything? Feels very smooth in both directions.
lock the clutches to stop the thing from moving, put on a scope and then see if you can feel any slight rocking (a sort of "clonking" feel) as you try to move the RA by pushing/pulling gently on the end of the scope. If there is any noticeable back-forth movement at all with the clutches locked, you have backlash. You need a very small amount to stop the gears from binding, but if you can feel some slop, it is too much and it would be worth tightening the worm up a bit.

If the backlash is OK, it would be worth checking that there is not too much preload on the RA bearings - which would make the movement a bit stiff - smooth, but a bit sticky to get moving. The last dozen or so panels in show what you need to do to check that - just take off the polar scope surround, loosen the grub screws and rotate the nut to tighten/loosen the axis bearings. Tighten the bearing nut until you can just feel that the rotation is stiffer and then back off the nut until the rotation frees right up. Then redo the grub screws and replace the surround.

Last edited by Shiraz; 14-09-2014 at 05:01 PM.
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