Tight Dec axis (hypertuning EQ6)

[traveller (Bo)]

Seeking comments from others that done hypertune of EQ mounts.
I replaced the bearings on my dec axis last night, a huge improvement in free rotation on the worm carrier.
However, my dec axis is still very tight and only moves with hand pressure similar to turning on a tap. This was no different to the dec axis movement before the tune.
When I looked at the mount closely, I realised that the tapered bearing at the end of the Dec axis shaft (at the counter weight bar end) may be the problem. In fact, I had to twist and turn the dec axis in order to push it back into the bearing. This causes the bearings to expand slightly and therefore push tight against the mount housing and making it difficult for the Dec axis to "free wheel".
Is this normal?
The tapered bearing I am referring to is on the bottom left hand corner of the photo. The green bearings are the new ones and the silver ones are the original ones.
Thanks
Bo

[Shiraz (Ray)]

Had the same problem - backing off the weight bar collar a little to reduce the preload on the tapered roller bearing fixed it and improved the guiding.

[traveller (Bo)]

Got it, thanks Ray.
Will have another play and and loosen off the collar and see how I go.
I have not done the RA axis yet, but my RA guiding seems doing well, even on my ST80 (FL 400). But judging by the improvement to the dec axis, I can't see any harm in replacing the bearings.
Bo

[Solitarian]

Grab some emery paper and rub the machined facings on the shaft down, my Dec was fine but the rough machining of my RA shaft didn't allow easy dismantling.
It's worth the time and effort to do, my bearings fit perfectly now.

Like Ray said, watch the preload on the tapered bearings, the Dec is easy to adjust, so you can tighten or loosen if it needs a tweak . I think I saw on one of Astrobaby's (forgive me if it wasn't hers) guides, she gave a specific position for the weight bar lock, doing that disregards the preload of the tapered bearing under the collar, the preload has to take priority.

They're a solid mount, well worth the effort to spruce them up with a few minor tweaks .