Lubricating old Vixen Polaris Mount?

[Steve Wright]

I have an old Vixen GP Polaris mount which I am guessing is about 30+ years old, what I am wondering is if it would improve its smoothness when tracking for imaging if I apply new lubrication to the gearing from the RA motor drtive, if anyone has any experience I would be most gratefull, otherwise I might leave it alone?

[Dipper]

One way to go is to follow the "don't fix what ain't broken" way, but on the other hand the lubricants that were applied to the mount when it was made probably lost all/most of their properties after thirty years.

[Peter Drew]

We always regreased Vixen Polaris mounts with a 50/50 mix of Castrol LM grease and Rocol Kilopoise. The Rocol gave great load bearing capacity, important as they are aluminium gears and the Castrol prevented the Rocol going too stiff in very cold weather.

[runoffshed]

Rather late to this post...apologies...but I regreased my ancient Vixen Super Polaris earlier this year and used Weldite Lithium grease as recommended on various sites (Astronomy Boy EQ 5 re-grease).

Some have spoken of these old mounts being difficult to disassemble, with a very tight ring nut being a particular problem, but mine came apart very easily and was a joy to work on.

The re-grease made a HUGE difference.

Hope this helps

[E621Keith]

The grease needs to match the static and kinematic friction of the mount, it also needs to be load bearing and won't rub off during operation. Re greasing the mount with the wrong type of grease can potentially ruin it. It's best to contact Vixen UK about what grease to use. You should not re-grease the worm with white lithium grease or oil, there are many reports of the mount tracking error increase by several times after people re greased their mount with the wrong type of grease.

[cantharis]

Rather late to this post...apologies...but I regreased my ancient Vixen Super Polaris earlier this year and used Weldite Lithium grease as recommended on various sites (Astronomy Boy EQ 5 re-grease).

Some have spoken of these old mounts being difficult to disassemble, with a very tight ring nut being a particular problem, but mine came apart very easily and was a joy to work on.

The re-grease made a HUGE difference.

Hope this helps

I am currently doing this job on my EQ5 (with the help of Astronomy Boy´s excellent notes). I am using a general purpose lithium based grease which gave good results in my Astro_3 mount.

[runoffshed]

The grease needs to match the static and kinematic friction of the mount, it also needs to be load bearing and won't rub off during operation. Re greasing the mount with the wrong type of grease can potentially ruin it. It's best to contact Vixen UK about what grease to use. You should not re-grease the worm with white lithium grease or oil, there are many reports of the mount tracking error increase by several times after people re greased their mount with the wrong type of grease.

You may well be right - and I hope I haven't stored up trouble for later - but all I can say is that are plenty of examples on the web of people using this (or similar) White lithium greases with- seemingly excellent results - , including Carsten Anholm who is very experienced and knowledgable about these mounts. As the Weldite grease is specifically for use in wheel bearings, I hoped that would mean that it has quite a high load bearing capacity. As to tracking, it is now vastly improved, although I am all too aware that I am comparing this to how it was in a thirty year old mount with original grease so stiff it was getting to be an effort to balance the mount properly.

I will email Vixen for their take on it...probably want me to send it back to Japan.

[cantharis]

As to tracking, it is now vastly improved, although I am all too aware that I am comparing this to how it was in a thirty year old mount with original grease so stiff it was getting to be an effort to balance the mount properly.

The grease in my EQ5 was like that when it was brand new.

[skybadger]

My view on the worm wheel grease is that it should be stiff since it has a high load and high friction to handle. Goose fat or even candle wax seems to be the consistency to aim for here, which seems to line up with sticky gunge...

The bearing grease should be the much more mobile LM or E2000 grease most of us have in the garage,

Mr Arnholm provides a very nice blow-by-blow of a Polaris strip down but I would not necessarily follow the LM grease everywhere maxim.

Mike

[runoffshed]

My view on the worm wheel grease is that it should be stiff since it has a high load and high friction to handle. Goose fat or even candle wax seems to be the consistency to aim for here, which seems to line up with sticky gunge...

The bearing grease should be the much more mobile LM or E2000 grease most of us have in the garage,

Mr Arnholm provides a very nice blow-by-blow of a Polaris strip down but I would not necessarily follow the LM grease everywhere maxim.

Mike

Interesting, Mike. I have now seen a couple of posts on other sites saying that Vixen use two different lubricants on the bearings and worm - which certainly supports what you and Keith are saying.

[cantharis]

I don´t think that a worm drive that you slowly turn with your fingertips (or with a very low-powered electric motor than will run for hours on a few dry cells) can ever be regarded as a high load-bearing application. I have previously used a general purpose lithium grease for all parts of a Astro-3 mount with excellent results - a vast improvement on the factory-filled sticky glop.

[skybadger]

Any worm driven gear is a high load application - the friction between worm and wheel is so much higher than for direct gearing and it occurs at the pressure point between worm crest and tooth wall over a small area. Check out how much of your Lm grease stays in the wheel teeth - not much after the first few revs.

IT might feel easy to your fingers but the wear rate without the proper grease will be significant.

Mike

[Peter Drew]

+ 1 for Skybadger's comment.

[cantharis]

Rather late to this post...apologies...but I regreased my ancient Vixen Super Polaris earlier this year and used Weldite Lithium grease as recommended on various sites (Astronomy Boy EQ 5 re-grease).

Some have spoken of these old mounts being difficult to disassemble, with a very tight ring nut being a particular problem, but mine came apart very easily and was a joy to work on.

The re-grease made a HUGE difference.

Hope this helps

I have just finished regreasing my EQ5 - much of the internals is the same as your Vixen - I found one of the ring nuts a bit hard to move initially but an overnight soak in light oil soon shifted that. Now it has been lubed with some proper lithium grease, not that Chinese glop, it feels just so much smoother, and you can actually balance the counterweights without masses of stiction.

[Peter Drew]

I'm not surprised that a mount feels smoother with less stiction when the lighter lithium grease replaces the original which is far too "stiff" for our Winters. A caveat however, when I was "in the the trade" we had to repair several mounts that had eventually seized after the owners had regreased with an unsuitable product, the OP's mount had survived for 30 years with the original glop, says it all.

[runoffshed]

I'm not surprised that a mount feels smoother with less stiction when the lighter lithium grease replaces the original which is far too "stiff" for our Winters. A caveat however, when I was "in the the trade" we had to repair several mounts that had eventually seized after the owners had regreased with an unsuitable product, the OP's mount had survived for 30 years with the original glop, says it all.

I think I will be taking down my Super Polaris again on the basis of what you and others have said. I suspect the grease for the main shaft rotation is fine but I'm not so sure about the worm. Anyway, that's only a partial strip down but it seems a shame to take any chances with what I consider to be a really good mount...albeit with a truly awful tripod.

I have emailed Vixen to hear what they suggest for the worm and will report back if I hear anything.

[cantharis]

Any worm driven gear is a high load application

Oh dear - sorry skybadger but i must disagree that your statement that ANY worm driven gear is a high load application - without any consideration to the applied input torque. Had you made that statement in any exam in the Royal Navy´s Advanced Marine Engineering Course (in which I was a Senior Lecturer) I would have had to severely dock you marks - you too Pete Drew.

Since CNC machining techniques have been available, in the last 25 years or so, single enveloping and double enveloping worm gear technologies have have overcome a lot of earlier drawbacks of worm gears.

[pete_gamby]

In response to John's email, I asked Vixen Japan for their recommendations and received a reply which is helpful to a degree:

“About types of grease, silicon grease of high viscosity (like clear, glutinous malt-sugar) is used for worm gears. Car axle oil mixed with silicon grease (like jelly) is used for RA axis shaft and DEC axis shaft.”

Basically, they have their own “secret sauce” formula for the grease used on the mounts and clearly don’t want to disclose what it is!

HTH

Cheers, Pete

[skybadger]

Cantharis

you are going to have to tell me what double enveloping worm gears are. I should attempt to retrench to the position that I meant the gear mating interface is going to see high pressures compared to other gear types but maybe you should be telling us what grease to use?. Every piece of advice and every thing written in the manuals for grease says use thick grease to address the wear and pressure issues. what would the navy recommend and why ?

Mike

[skybadger]

OK, I looked it up.

Double enveloped is where both the worm and the wheel are curved have curved tooth forms to give greater contact surface and better torque, the wheel is curved to wrap around a straight worm, the worm is curved to greater diameter at either end for maximum contact.

Have you seen any double enveloped worm drives on a telescope ? Sometimes single-enveloped is a big leap forward.

Mike

[Peter Drew]

I was posting, as usual, based on experience rather than any academic qualification and as such am always happy to stand corrected. I have, however, made hundreds of worm and wormwheel drives for astronomical telescope mounts which earned a decent reputation for performance and longevity.

[Astro_Baby]

Be careful you dont wear the gears out, I mean with the high rotational speed of an astronomy mount its going to do at least a few hundred revolutions every year

Two of the mounts I have stripped were badkt abused and run for some time, in one case about 5 years, on next to no lube and neither showed any significant wear on its gears.

[Peter Drew]

I don't think that the gearing is so much of an issue, it's the heavily loaded plain bearings of some mounts that are at risk.