bumpy east slewing

[bkm2304 (Richard Brown)]

Hello all,

I have a problem when I slew the scope east. It "stutters" and I can see it stop then shudder along in a "catchup" then smooth then stutters etc etc. Slewing west is no problem. I have tried to get the balance right as well as possible but of course as the angle of the scope changes so does the force at the end of the lever - camera, focuser etc. I have stripped the whole mechanism down, cleaned it and re - seated it without any improvement in the problem.

Any suggestions would be very greatly appreciated.

Thanks

Richard

[DavidU (Dave)]

Sounds like a balance issue. It looks like there is no lube on the worm or gear.

[mozzie (Peter)]

firstly id be addressing the gear,a bit of lube wouldnt go astray

[asimov (John)]

It looks like the setup wouldn't be dust proof, as in no airtight cover? In which case I wouldn't be lubing it anyway.

Sounds like a balance issue to me. The mount always has to be 'driving uphill' slightly which means CW adjustments need to be made between east & west.

[bkm2304 (Richard Brown)]

Thanks, guys. It's a lube free zone as i just reassembled it and got the old gunk off. It does get sticky as it's not protected so I might look at putting a dust cover over it. I've tried all sorts of permutations of balance but no luck. Could it be that the gear is worn - although why then does it go OK westward?

I'll keep fiddling!

Richard

[willow (Richard)]

From an mechanical maintenance view
Check your bearings in the end mounts
if they are angular contact type ( radial and thrust load ) then it may be a worn track ( in brgs ) if the drive shaft in not perfectly in line
or maybe incorrect preload
if they are deep groove brgs ( most common ) Replace the brgs
shaft deflection due to wear can also cause problems a deflection wedge can help

hope it may help a little

[Barrykgerdes]

Your photo shows a system of drive that should not present any real problems of balance so long as the worm, worm wheel and thrust races are in good condition and correctly pre loaded.

When moving west you are going with the track rate so acceleration is probably quite smooth but when moving east it is against the track rate particularly if you are stopping the movement and reversing the motor. This will accentuate problems of rigidity, backlash and motor directional performance.

I would be checking in this area for problems.

Barry

[bkm2304 (Richard Brown)]

Thanks Barry and Richard.

The bearings are angular contact type - thanks for the info.
Barry, I'll PM you with some questions.

Richard