41 replies to this topic

[Waldemar]

Can you recommend that oil also for bushing mounts?

I superlubed (with grease) my GP-DX some time ago, but got no improvement at all.  That was DEC as a start, but I didn't do RA after the weak result.

(I think it's not a real issue for guiding, but balancing is basically impossible...)

Very often the bushingsurfaces are so course that they need to be polished before relubing to get any improvement.
You will have to take it apart again, clean it and polish the bushings with very fine waterproof sanding paper until the surface starts to shine, then apply a very thin layer of grease and a drop of superlube oil. It will take a bit of time and patience, but the results are rewarding.

[Stevegeo]

Another note on grease ..

We haven't hit on any ptfe greases ...main ingredient polytetrafluoroethylene, trade name Teflon.

Mainly used now in auto bearing cartridges where the bearing is actually two , inside \outside used in most front and AWD cars ..these bearings have a teaspoon of grease in each ..

If you come across this type of grease ...and think you may want to use it ...it will be white and very creamy..

A few things to warn you of ...

You should not mix ptfe grease with any other grease ...it will break down loose lubricity .

Never ..and I mean Never heat ptfe or ptfe grease to high temperature.. this will give off fumes that can KILL...no joke.

Brake cleaner will not remove ptfe grease .. only mechanical methods work. ( Wiping with a rag )

Finally if you decide to use a ptfe grease ...wear nitrile gloves ...ptfe will mess up your liver as it can be absorbed in pores of your hands .

[macdonjh]

While it won't hurt anything to pack an axis ball bearing completely, it will stiffen things up.  It might not matter, but it could end up making balancing more difficult.  The situation in these mounts is that the bearing components need only enough lubricant to thinly coat them and keep them from corroding.  This goes equally for the open axis taper bearings.  Like I said earlier, the only bearings that I have ended up replacing have been contaminated so that when turned they felt like they had sand in them.  This certainly has the potential of impacting the smooth turning of the axis and when we are dealing variations of small movements with a telescope mount that can be important.  In over 600 mounts I have replaced less than 10 axis bearings and probably fewer taper bearings (which can end up corroded).  I have worked on some of the oldest Atlas mounts out there without feeling the need to replace axis bearings regardless of what it going on inside them.  I don't even look inside them (I have in the past but have not done so for many years now after my initial experimentations).  As long as the sealed bearing turns smoothly, there is nothing that needs to be done.  I hadn't thought of that and had never experimented with different fill percentage.  I guess next time I clean and regrease a mount I'll see the effect of less than 100% fill for myself.  The Atlas I recently stripped did feel like it had grit in the bearings; it was rough.  That, and the damage to the seals made me think I'd be replacing the bearings initially.  However, after doing what you just said not to do ( ), the bearings cleaned up nicely (at least compared to their initial state) and the mount's operation is improved.

 

I have had to replace the axis need roller bearings on a number of Losmandy mounts over time.  But those mounts were pretty severely abused.  The bearings are very difficult to remove from the mounts and sometimes simply can't be in which case they have to be cleaned in place to remove whatever gunk it is that Losmandy uses that does drive out over time and leaves the bearings completely solid.  I've also worked on an old, unloved Losmandy, a G11.  I had to use brake cleaner to get the dried grease out of the roller bearings.  Since then, though, it's been a fine performer for visual.  A bargain, too, since it was sitting in the previous owner's closet.

 

The only bearings that I routinely replace are worm bearings.  I replace those because they are often damaged by over-preloading and they directly impact the random and periodic error of a mount.  Those are usually lubricated with a fine oil that does not need to be messed with.  I understand.  The worm bearings in the MI-250 I bought might need replacing sooner rather than later.  

 

Shielded bearings like those in the MI-250 are not very likely to need replacing and they certainly should never be opened up.  Removing a shield (as opposed to a seal) will ruin it.  If there is a chance that a bearing might dry out and be a problem, it is with a shielded bearing since they are not sealed.  That's another reason to replace the worm bearings in the Atlas type mounts since they a shielded, not sealed.  

 

Depending on the type of grease used in a bearing, a little bit of light oil may help to loosen the old grease back up.  This will likely work best with a petroleum based grease rather than a synthetic grease.  That makes sense.  On thing to never us is white lithium grease.  It will dry out and make a mess of your bearings.  I have to clean out taper bearings that people have used this stuff on and it is a mess.  Agree, my experience was the same the first time I rebuilt a mount.  I thought I was doing myself a favor by using light-weight grease.  Oops.  If someone put white lithium in a sealed ball bearing, I would simply toss it.  White lithium grease is the soap-type grease you are thinking about.  I thought the thickener in petroleum greases was considered a "soap" as well.

 

When it comes to re-greasing bearings (including taper bearings), just about any bearing grease will work, but petroleum based greases tend to break down a lot quicker and in higher temperatures they separate and run out of the mount.  Some people advocate using really expensive greases in telescope mounts and in some high-end premium mounts that might be justified, but in the average non-premium mount, Superlube is all you need.  Another reason I use it is because it is basically non-toxic so that when you end up with it all over your hands you aren't poisoning yourself.  Contact with toxic grease is a small price to pay for the night sky. 

Thanks again, EFT.  Some comments in red above. Thank you for the tutorial

[macdonjh]

 

Never ..and I mean Never heat ptfe or ptfe grease to high temperature.. this will give off fumes that can KILL...no joke.

 

I'll go out on a limb and say "high temperature" is less than 400F.  That's the design temperature (my personal rule of thumb is 350F) we quit specifying PTFE in gaskets and valves because it starts losing it's strength and starts to creep/ flow.  

 

I didn't know that about PTFE gassing, but it makes sense, fluorine can be nasty.

[Tom Zaranek]

Look if you are doing a Bearing..you need only a fingertip worth .just enough to coat the bearing rollers or balls .unless it's for wheels or constant working bearing .

For shafts with bronze or brass a SMEAR....wipe a fingertip on the surface . Slide the shaft on and wipe excess off ..and some bronze bearings can be warmed up, placed in oil (10weight) let cool ..making the bronze lubed for life ...this is old school.

 

Sealed bearings if they feel stiff can be brought back with a DROP of oil at seal lifting the seal with a jewlers screwdriver . Some times the lube in sealed  bearing get dry and a tiny drop of light machine oil will revillitate this ..

Do not ever Spin a bearing with air ..high speeds will destroy bearing surfaces , and centripetal force can explode a bearing.

Finally and I'm dead serious about this next tip...

Do not EVER strike the race with a hammer ...this will distort the race AND put tiny flat spots in the balls or rollers ..if it does not go on ( slip or press fit)  warm it up.or tap it with a mallet .

This will kill a bearing quick...50 yrs experience speaking here .

Yeah, I agree on the bearing extraction/insertion.  At worst, I tapped it gently on the outer ring only.  It is very easy to get it stuck because it is not flush with the hole one is inserting it into.  What I've done is made really sure that the inner/outer rings are super clean and a very tiny bit greased/oiled and then put the bearing on a flat (clean) surface and, in the case of the brass worm cylinder I put it down against the bearing.  I found this to be more flush than me trying to put the bearing by hand into the cylinder.

If gotten it stuck, super carefully hit the outer (not inner) ring to get it unstuck.

[Tom Zaranek]

...

Finally if you decide to use a ptfe grease ...wear nitrile gloves ...ptfe will mess up your liver as it can be absorbed in pores of your hands .

That's weird.  If this is the case why is SuperLube where PTFE is an ingredient non-toxic and food safe? 

[Stevegeo]

There are many different grades of ptfe lubricants.  Some.. (usually high temp applications) are hazardous. One grade is under the trade name of KRYTOX, which is a blend with other additives  and processed .

I suspect these additives are the real Hazzard... But like I stated, I'm not a chemist,  but I do have a couple degrees in engineering and materials science...

Where I work, we have a few grades with ptfe, some food grade, and some strickly industrial.

I'm not a chemist, and don't claim to be, however like many chemicals you should protect yourself from the unknown.

 

Not like the old Western days when greasing wagon wheels was done  with LARD,  from meat....most greases are NOT edible dispite the claims...

[Jon Isaacs]

It doesn't really matter if they do not turn freely as long as they turn smoothly.  The axis bearings in these mounts have virtually nothing to do with the typical stiffness of the axes.

 

 

  

 

- The axes are being driven by massive amounts of gear reduction.

 

- Spinning freely with no load is different than spinning freely with a load even though they're preloaded..

 

- Mention was made of a 25 year old Atlas.  My recollection is the Atlas was introduced about 2003..

 

Jon

[EFT]

I don't know when the Atlas or EQ6 came out, but I have certainly worked on some of the oldest, black glue mounts out there.  Once they are cleaned up, regreased and adjusted they still do pretty well.

 

There are a lot of greases out there that can be toxic.  The might be OK if you are using it once with gloves, but I work in this stuff all the time so I specifically chose Superlube about 10 years ago in order to not poison myself.  I recommend it to others and use it in kits for the same reason.  While it is possible that some expensive, exotic lubricant might work a little better, particularly in high precision mounts with very tight tollerances, the difference is wasted on a mount like the Atlas.

 

macdonjh - If the bearing felt rough and the seals were damaged, then they had been opened up and contaminated.  Your cleaning them out probably did help them.  The races and balls are probably damaged to some extent, but again, the axis bearings don't have much effect on anything. 

[daquad]

The movement in my 1992 Losmandy GM 100 was getting stiff, so I completely disassembled the mount and removed all the old hardened grease.  I washed all the bearings, axles and bearing surfaces  in lacquer thinner.  After everything was completely dry, I regreased all bearings, axles and relevant surfaces with super lube.

 

The mount now moves so easily that the OTA balance must be spot on to keep the scope in any position without locking the clutches.  I leave the mount outside with a Telegizmos 365 cover.  After two years the motion is still buttery smooth.

[EFT]

That is the beauty of the Losmandy mounts.  They are mechanically pretty bullet proof.

[Tom Zaranek]

Thanks, this is a lot of interesting experienced-based information.

 

Since I've already opened the bearings I have nothing to lose by experimenting with different things and in worst case if they end up getting worse over time it'll cost $70 CAD to replace all 3 including shipping with exact same ones. However, I know that in a few years I'll probably have the same problem so I first want to see if I can make things better with existing ones.  As it is, I've repacked it very lightly with Superlube again and it's super stiff.  So next I'll add small amounts of Superlube oil (will have to wait till it arrives in the mail) to dilute the grease, alternate plan is to re-grease with grease+oil mixture to increase viscosity.  I'm trying to match up Superlube grease & oil so they are as compatible as I can make it be.  Plus the oil will be useful in the future and it is the same non-toxic stuff as the grease. 

 

I see that most of the Losmandy bearings are needle bearings so are they not significantly different from the sealed race bearings in CGEM?  There is a bearing on CGEM that is a tapered bearing and that one looks ok with the grease applied.  It's just those sealed race bearings that become very stiff (and yeah, I see how they mostly impact balancing and it was a small problem for me and now it will become even more so if I leave it the way it is now). 

 

Slightly off topic: how fluid/stiff should the worm shaft be? Freely spinning multiple revolutions if lightly pushed or is half a revolution ok? Once I have the Superlube oil, I intend to put a drop or two on the sealed worm bearings to see if I can make them move more freely (they don't seem bad right now but they don't spin full revolution).

 

 

While it won't hurt anything to pack an axis ball bearing completely, it will stiffen things up.  It might not matter, but it could end up making balancing more difficult.  The situation in these mounts is that the bearing components need only enough lubricant to thinly coat them and keep them from corroding.  This goes equally for the open axis taper bearings.  Like I said earlier, the only bearings that I have ended up replacing have been contaminated so that when turned they felt like they had sand in them.  This certainly has the potential of impacting the smooth turning of the axis and when we are dealing variations of small movements with a telescope mount that can be important.  In over 600 mounts I have replaced less than 10 axis bearings and probably fewer taper bearings (which can end up corroded).  I have worked on some of the oldest Atlas mounts out there without feeling the need to replace axis bearings regardless of what it going on inside them.  I don't even look inside them (I have in the past but have not done so for many years now after my initial experimentations).  As long as the sealed bearing turns smoothly, there is nothing that needs to be done. 

 

I have had to replace the axis need roller bearings on a number of Losmandy mounts over time.  But those mounts were pretty severely abused.  The bearings are very difficult to remove from the mounts and sometimes simply can't be in which case they have to be cleaned in place to remove whatever gunk it is that Losmandy uses that does drive out over time and leaves the bearings completely solid.

 

The only bearings that I routinely replace are worm bearings.  I replace those because they are often damaged by over-preloading and they directly impact the random and periodic error of a mount.  Those are usually lubricated with a fine oil that does not need to be messed with.

 

Shielded bearings like those in the MI-250 are not very likely to need replacing and they certainly should never be opened up.  Removing a shield (as opposed to a seal) will ruin it.  If there is a chance that a bearing might dry out and be a problem, it is with a shielded bearing since they are not sealed.  That's another reason to replace the worm bearings in the Atlas type mounts since they a shielded, not sealed.

 

Depending on the type of grease used in a bearing, a little bit of light oil may help to loosen the old grease back up.  This will likely work best with a petroleum based grease rather than a synthetic grease.  On thing to never us is white lithium grease.  It will dry out and make a mess of your bearings.  I have to clean out taper bearings that people have used this stuff on and it is a mess.  If someone put white lithium in a sealed ball bearing, I would simply toss it.  White lithium grease is the soap-type grease you are thinking about.

 

When it comes to re-greasing bearings (including taper bearings), just about any bearing grease will work, but petroleum based greases tend to break down a lot quicker and in higher temperatures they separate and run out of the mount.  Some people advocate using really expensive greases in telescope mounts and in some high-end premium mounts that might be justified, but in the average non-premium mount, Superlube is all you need.  Another reason I use it is because it is basically non-toxic so that when you end up with it all over your hands you aren't poisoning yourself.

Edited by Tom Zaranek, 20 October 2019 - 10:51 AM.

[EFT]

Don't judge the stiffness of the bearings by how they turn in hand.  Once you put them in the mount you probably won't notice it.

 

An oil will definitely loosen things up and if the seals are still good, they will hold the oil in well.  But you are a bit more likely to have to do more maintenance on them down the line, particularly if the seals are not in good shape.  Like I said before, the only bearings I have replaced have been ones that have been played with or damaged.  That includes bearings from the very easily EQ6/Atlas mounts.  As long as the seals are in tact, the stock grease works just fine.  Something to remember is that the rubber seals with cause some drag and as a result, these bearings do not spin freely.  Replacement bearings will be even more stiff, but once they are in the mount it is not noticeable (the axis may be stiff but it is for other reasons).

 

The Losmandy shaft needle roller bearings are similar to the taper bearings but have much thinner rollers and become clogged up much easier.  The taper bearings do not need to be packed.  Think about it as needing enough grease to coat the rollers and the race plus a little bit more.  These bearings are exposed and can be contaminated because of that, but a more critical problem is corrosion.  A grease like Superlube helps protect the bearing from corrosion. 

 

The rule I use for the worm bearings preload is that the worm should spin a few turns but that is about it.  Tighter and you risk damage and looser you have end play.  But the bearings used for the worm do not need to spin freely at all as long as they are new and turn smoothly.  Spinning is not the point, preload is.  If your worm doesn't spin a little more, then my concern would be the preload, not the bearings.  Again, if they are sealed (not shielded), then don't open them up to add oil.  It's not necessary and you run the risk of damaging the seal on these much smaller bearings.

[macdonjh]

I don't know when the Atlas or EQ6 came out, but I have certainly worked on some of the oldest, black glue mounts out there.  Once they are cleaned up, regreased and adjusted they still do pretty well.

 

There are a lot of greases out there that can be toxic.  The might be OK if you are using it once with gloves, but I work in this stuff all the time so I specifically chose Superlube about 10 years ago in order to not poison myself.  I recommend it to others and use it in kits for the same reason.  While it is possible that some expensive, exotic lubricant might work a little better, particularly in high precision mounts with very tight tollerances, the difference is wasted on a mount like the Atlas.

 

macdonjh - If the bearing felt rough and the seals were damaged, then they had been opened up and contaminated.  Your cleaning them out probably did help them.  The races and balls are probably damaged to some extent, but again, the axis bearings don't have much effect on anything. 

I certainly understand protecting yourself from toxic stuff, even irritating stuff, if you are in contact with it daily.  My comment was supposed to be a joke. 

 

The Atlas I worked on was definitely opened at least once before.  Bearing seals were damaged, I saw two kinds of grease, etc.  Whoever did it before me didn't have the benefit of this forum, otherwise at least there would have been only one kind of lubricant in there.

[macdonjh]

alternate plan is to re-grease with grease+oil mixture to increase viscosity.  

Increasing viscosity will make the lubricant thicker/ stiffer.  Decreasing viscosity will make the lubricant thinner/ "looser".  Milk is not very viscous, peanut butter is viscous.  Not to be confused with lubricity, which describes how slippery a lubricant is.  A viscous lubricant may still have high lubricity and vice versa.

[Tom Zaranek]

Firstly, yeah, I'm trying to eliminate that stiffness so I can balance the mount better.

 

Ok, got the Superlube oil and it worked exactly as I thought. It diluted the grease and the bearings and results are quite good. 

 

However, in the process I discovered that the main reason for the stiffness was due to the grease in between the housing and the brass ring gear (I think that's what this thing is called: https://farm6.static...98f751bfb_z.jpg; not my pic btw, just found one while googling around). So a bunch questions:  Can I/should I sand it with a superfine sand paper?  Would a tiny amount of grease be enough instead so I wouldn't have to sand it? That brass looks shiny and smooth and I don't really see anything wrong with it.  Same for the housing.  It all looks in good shape its just that it is a bit tight and any amount of grease (even the oil) makes the whole thing stiff. 

 

Thanks for describing the preloading, I kinda noticed and guessed at this part but it was very useful to see a written confirmation.

 

Don't judge the stiffness of the bearings by how they turn in hand.  Once you put them in the mount you probably won't notice it.

 

An oil will definitely loosen things up and if the seals are still good, they will hold the oil in well.  But you are a bit more likely to have to do more maintenance on them down the line, particularly if the seals are not in good shape.  Like I said before, the only bearings I have replaced have been ones that have been played with or damaged.  That includes bearings from the very easily EQ6/Atlas mounts.  As long as the seals are in tact, the stock grease works just fine.  Something to remember is that the rubber seals with cause some drag and as a result, these bearings do not spin freely.  Replacement bearings will be even more stiff, but once they are in the mount it is not noticeable (the axis may be stiff but it is for other reasons).

 

The Losmandy shaft needle roller bearings are similar to the taper bearings but have much thinner rollers and become clogged up much easier.  The taper bearings do not need to be packed.  Think about it as needing enough grease to coat the rollers and the race plus a little bit more.  These bearings are exposed and can be contaminated because of that, but a more critical problem is corrosion.  A grease like Superlube helps protect the bearing from corrosion. 

 

The rule I use for the worm bearings preload is that the worm should spin a few turns but that is about it.  Tighter and you risk damage and looser you have end play.  But the bearings used for the worm do not need to spin freely at all as long as they are new and turn smoothly.  Spinning is not the point, preload is.  If your worm doesn't spin a little more, then my concern would be the preload, not the bearings.  Again, if they are sealed (not shielded), then don't open them up to add oil.  It's not necessary and you run the risk of damaging the seal on these much smaller bearings.

Edited by Tom Zaranek, 25 October 2019 - 09:24 PM.

[Tom Zaranek]

To keep the thread complete with post-tuning feedback, my update after a few months and warmer weather to re-calibrate without losing my fingers to frostbite:

 

I only cleaned and regreased DEC axis as I wasn't sure if I'm doing it right.  Results are in and it is way better than before when I got it new.  I'm getting RMS in DEC between 0.35" and 0.70" compared to before of around 1 - 1.5 when the mount was new and recently it was just horrible 2-3.5" and completely unpredictable (likely some of this was due to poor balance because of stiffness).  So a huge improvement.

 

I was very worried about the stiffness in the movement of the axis once everything got put back together but it was not warranted.  Once the mount got a load on the axis, it was way smoother than when I got it new.  Balancing it was more sensitive, much better.

Now it is time for RA as it is in the 1.3-1.7" range - I rarely had issues in the RA axis but I think with time, that factory grease combined with dust needs to be cleaned.  At least now I will not be afraid to take the mount apart. 

 

What I ended up doing: cleaned and regreased the worm gear + cylinder, repacked the bearings with a mixture of Super-lube grease + Super-lube liquid to lower viscosity (not sure if this was needed, I was just trying reduce stiffness). I used 1500 and 4000 grit dry/wet sandpaper to lightly polish the brass cylinder and then applied Super-lube. After putting it back together I also adjusted the O-ring so that when slewing around, there is uniform and satisfying sound of movement (no  coffee grinder noises) while keeping it snug.