My mount squeaked a bit at one point so I dismantled the dec axis and regreased with a worm adjustment. All the bearing looked good except that I notice that the bottom taper bearing grease looked a bit brown and ordinary and also that the taper bearing itself could be dismantled with two fingers to expose the loose rollers. Is this standard? I don’t think the taper bearing in my other mount comes apart, only pops out of the cone. This one can fall into all of its individual pieces.
I’ve had my HEQ5 pro apart for tuning recently and I can confirm that the inner race of the bearing and the cage with the rollers should be in one piece. Same a a trailer wheel bearing which incidentally is what that particular bearing is. The only piece that separates is the outer race which may stay ( loosely) in the RA housing.
Thanks for that. I took a note of the number so I can go to the bearing shop and get another. The good thing about living in an industrial town. You can find parts close by.
Whilst there is absolutely no reason why you should not replace the bearing if you want to, I would like to point out that not all taper bearings are made with the rollers enclosed in a cage, just as the converse is true where needle
bearings are concerned for instance. If both races and the rollers are in good
condition, and the full complement of rollers is present, there is no reason
for replacement.
raymo
The tapered bearings used in the Skywatcher mounts should be in two pieces, the outer tapered ring that is pressed into the body of the mount and the inner race consisting of the inner ring, rollers and retaining cage. If the cage comes away and lets the rollers fall out, then it is defective and should be replaced.
When replacing the threaded retaining cone do not over tighten, firm hand pressure should be enough to take out any play, maybe a wiggle or two to make sure it is seated firmly and then tighten the 3 grub screws again .
Thanks Raymo and Jeff. I am not talking about the outer cone being separate. I am used to that and have replaced plenty of those sets. I was concerned about the inner shaft sleeve popping out of the assembly although all the cages and rollers are still there and functioning. The grease means you do not loose them on the floor. So they probably still function but I think they have lost some separation tolerance and the instructions I am following do not suggest tightening past the original retainer orientation.
I have bought two new ones at the bearing shop anyway as the Timkin Polish ones are only $12 each and it is an easy fix. I might grease the Dec also In case it squeaks too.
The worm bearings however are $25 each at the bearing shop and require ordering. Not going to replace those in a hurry but I did find some Japanese 689zz models at the online parts shop for $6.50.
Interesting that my other mount worm was regreased by a professional with white ( lithium ? ) grease but that is hard to find. So i just used the high temperature red lithium stuff which came in a screw top container.
For the conical bearing, standard high temp bearing grease seems to work quite well. On the worm drive I have tried lithium and bearing grease and although better than factory I still found that it wipes itself more than Id like. I’m currently trying engine assembly lube which is lithium based but very sticky and also contains graphite. You can get it from auto parts stores. From the initial assembly point of view I think it looks like it’s going to be a winner. Some heat cycles from inside to outside at night will be the true test though. I’ve also used some valve lapping paste to smooth out some imperfections in the worm drive but despite on assembly feeling significantly better , I’m far from recommending it at this stage because I simply haven’t given it a good test yet. All food for thought .....
Interesting that my other mount worm was regreased by a professional with white ( lithium ? ) grease but that is hard to find. So i just used the high temperature red lithium stuff which came in a screw top container.
This is white lithium grease, its an easy to find bicycle grease
/www.mtbdirect.com.au/weldtite-lithium-grease
I put slickoleum on my heq5 gears the other day, certainly not a super tenacious grease but i think probablya bit moreso than the lithium gear (which i also have and sometimes use on bikes). Slickoleum (also called slick honey) is outrageously slippery stuff and more grease-like rather than creamy. People use it on their dropper seat posts, so should also be super easy to find at bike shops.
When replacing the threaded retaining cone do not over tighten, firm hand pressure should be enough to take out any play, maybe a wiggle or two to make sure it is seated firmly and then tighten the 3 grub screws again .
There is actually a little more to it than that if you really want to set them up right. The shims in the center of the mount set up the bearing preload. The bearings should be preloaded just a little beyond the point when all the end float is gone and the shims mean you can just tighten the collar to a specified torque and know that the bearing load is right. It is a little subjective in these versus things like older car service manuals I used to have where you were meant to load up a wheel bering bearing until it took a specified amount of torque applied by pulling on the wheel stud to start the hub rotating (Versus new ones where the bearing is often a sealed part just bolted in on its own premounted flange and adjusting it is via buying a new one)
There is a shim in there although only plastic as this seems designed for almost zero(15kg) load but minimum friction.
Interesting that this is role the shim plays. I wondered about that.
I can tell you that when the conical bottom bearing is worn as this may be there is no torque at all on the retainer in the design position. One can make almost a a full turn before backing off to the correct position. I imagine that would allow a little movement if not weight end heavy.
I do remember changing those old rear wheel bearings. I am glad I can pay someone to do that now. The Celestron 1990 fork mount bearing is pretty much an automotive front wheel bearing set on a stub axle.
There is a shim in there although only plastic as this seems designed for almost zero(15kg) load but minimum friction.
.
The red shim serves as nothing more than a spacer between the outer race of the lower bearing in the brass gear and the outer race of the bearing that is mounted inside the housing. Critical to have as it stops the two bearings from binding but has nothing to do with load or pre load. The only bearing that provides load adjustment in the entire system is the outer conical bearing ad it’s tightness. Over tightening will cause drag and wear the bearing quicker. Too loose and you’ll get end float of the shaft and it won’t run true in the housing.
I saw some graphite in Bunnings and also white aerosol lithium grease. Maybe for your bike chain? A lot of unusual products including one in a tiny bottle Labeled in German . My high school German not good enough. Next time I will google translate to see what it is. Maybe I should try some super sticky worm grease . I once used sticky white marine grease for boat steering .
Probably a clean is the key thing.
Quote:
Originally Posted by bojan
Green lithium grease is OK, work at broad temperature range and the load is nowhere near the condition in car wheel bearing for example.
Long time ago I used graphite grease.... also OK but don't know where to buy it now.
New taper bearings installed on both axes before being lathered in grease.
A cautionary image about condensation and moisture in the mount. Rust spots on the worm and end bearings. When I got this mount the Polar scope cover was full of condensation water , built up over time I guess.
Interesting that with new Taper bearings a hand tight dec retainer , retaining cone is in the design position with locks lining up, almost a full turn further out . A lot of wear for few rotations but does what is required .
Astro Baby misses the requirement that loosening the retaining set screws for the retainers means a full turn and a half to clear the threads. But too many turns on the DEC and the set screws fall inside the cone and then on the floor. Too few on either and the retainer will bind on the outward thread.
Glad to hear that you have the mount sorted out, the rust on the old bearings is not a good look, must have been accidently left out in the rain or something. Makes me wonder what the RA bearings and worm may be like, have you inspected them at all.
I have dismantled cleaned and greased both axes with replacement taper bearings. The worm in the image with a spot of rust is the RA. The Dec was ok. But both taper bearings had a little surface rust. I suppose that is where the condensation dribbles to. But luckily easy to replace.
The main bearings on the brass worm gear on both axes were good.
I imagined that the worm itself would be a very high quality of stainless and unlikely get rust spots but not so.
One of the squeaks came from the Rowan nylon idler which needed a little thin grease.
Quote:
Originally Posted by Saturnine
Glad to hear that you have the mount sorted out, the rust on the old bearings is not a good look, must have been accidently left out in the rain or something. Makes me wonder what the RA bearings and worm may be like, have you inspected them at all.
I imagined that the worm itself would be a very high quality of stainless and unlikely get rust spots but not so.
Being a Chinese made, mass produced mount, though the worm will be stainless steel, I doubt it would be high quality 416 or similar. A lower grade stainless in normal conditions should still be resistant to corrosion ( rust .)
The condensation that you noticed is certainly not something that would happen in normal operating conditions, thus the squeaking and the corrosion. The TLC you've given the mount will keep it in good shape for a long while.
