Skywatcher "grease"

[JamesF]

Ye gods! What *is* that stuff?

I took the DEC axis of my EQ3-2 apart this afternoon with the intention of cleaning and re-greasing it should that be required. It still clearly had the original SW grease in place. It really is quite horrible! It's more like glue than grease. I couldn't even remove the worm drive from its housing until I'd cleaned a load of it off because it was preventing the seal from passing through the hole. Even after taking the entire unit apart, the stuff was very difficult to get off. I was tempted to resort to petrol as a solvent. It's more like glue than grease.

All sorted now and everything is back together, regreased with something more sensible. I was absent-mindedly pondering on doing the RA axis as well, but I think I'll invest in some industrial solvents first...

James

[Parus major]

I used Isopropyl alcohol. Get the play out of the Dec, then?

[JamesF]

There's still work that could be done I think, but it's probably a case of diminishing returns. I need to see how it behaves with a scope on and motor powered up.

I'm all but done with stan26's direct drive mod (very slightly different because I happened to have a spare drive shaft connector from an EQ1 motor drive). With the motor connected up there's clearly some play in the gearbox, so I opened up the motor housing and took off the gearbox to find that it is also covered in black grease. There are five(!) sets of gears between the stepper motor output and the gearbox output. Regardless of being unable to see how to separate the two halves of the gearbox anyhow, with that many gears involved I imagine some backlash is inevitable.

Now I just need to make up a bracket to mount the motor on. Temporarily I might just use an offcut of oak.

James

[E621Keith]

The famous Synta glue.

I think they are thick and sticky in order to match the static and dynamic friction properties of the gears. The original Vixen mounts also uses thick and sticky grease, but the Vixen type is clear, not Synta black.

[Chris]

So if its thick and sticky in order to match the gears is it a good Idea to remove it and use something lighter? I've just bought a second hand black HEQ5 mount and was thinking of stripping it and regreasing it with Lithium grease.

[E621Keith]

I've read reports from other forums, that the mount got worse after the owner regreased it with oil rather than glue, because of the mismatch of the two frictions.

I don't know about Lithium grease, but I think Astrobaby used it in the HEQ5 guide so I reckon you should be ok.

[Parus major]

I've read reports from other forums, that the mount got worse after the owner regreased it with oil rather than glue, because of the mismatch of the two frictions.

I don't know about Lithium grease, but I think Astrobaby used it in the HEQ5 guide so I reckon you should be ok.

Well you should never add grease to grease if the stuff on it is a different type. You need to completely strip and clean it all off, then replace.

[Chris]

Thanks guys, I'll check out the HEQ5 guide by Astrobaby:D

[Peter Drew]

I'm not too sure about this regreasing issue, the Synta "glue" is certainly too sticky, particularly in very cold conditions, it does however, have good load bearing capacity and does not wear through easily as is demonstrated by the difficulty in cleaning it off. Some mounts, the Vixen Super Polaris for instance, have aluminium on aluminium bearing surfaces and it is vital to maintain the high load lubricant. Cleaning and replacing with oil or worse, WD40, which has been known in the past, quickly leads to seizure . Lithium and other "light" greases might not have enough loading power for the more stressed mounting components. I found a 50-50 mixture of Rocol Kilopoise and Castrol LM grease to be very effective under all conditions and requirements.

[JamesF]

I'm genuinely surprised to see WD40 described as a lubricant. It would never have occurred to me to use it as such. It is described as one on their website though, so I guess it must be.

James

[malc-c]

What about good old molly grease that use on cars ?

Castrol Moly Grease is a multipurpose grease fortified with moolybdenum

It is excellent for swivel and shackle lubrication. It also shows excellent performance in the lubrication of heavily loaded slow/medium speed bearings of all types and is particularly useful in preventing bearing damage caused by excessive vibration or shock loading. When exposed to extreme operating conditions, Castrol Moly Grease helps prevent the depletion of normal grease lubrication by a residual coating of the metal surface with molybdenum disulphide to give 'dry' or 'solid' lubrication. Castrol Moly Grease also has an application in sliding motions where the prevention of scuffing is desirable and may be used in dry or moist conditions. It is not recommended for use in small, high speed ball and roller bearings.

[malc-c]

I'm genuinely surprised to see WD40 described as a lubricant. It would never have occurred to me to use it as such. It is described as one on their website though, so I guess it must be.

James

me too - normally used as a penetration fluid for releasing nuts and to expel moisture... when it dries up it leaves no protection at all

[Peter Drew]

There seems to be a myth grown up around WD40 that it is somehow the answer to every "lubrication" problem. In reality it is more of a release agent and water repellant. Any lubrication with this product is very short term. There was, long ago, an invitation, from the manufacturers I think, for additional uses for WD40, cleaning one's teeth was one that stuck in my mind (but not on my teeth!).

Refering back to the OP, my Meade 16" SCT made some horrible screetching noises on occasions, on stripping it down enough to reveal the RA drive it turned out that the wormshaft was vibrating due to the lack of load bearing grease instead of the margerine consistancy of the original grease, it was simmilar in effect to rubbing your finger round the top of a dampened wine glass. The gear was regreased where access was possible and the noise vanished. It does appear again occasionally when the drive reaches the original grease position which was not accessible.

[coulthamst]

What about good old molly grease that use on cars ?

Molybdenum disulphide grease has the property of "plating" surfaces to which it is applied. When these surfaces are already in close contact, if they are not in constant motion there is a good chance that they will weld together. Conclusion:- under no circumstance use this type of grease on astronomical gear, especially on that contained in telescope mounts, as they have to be fitted to extremely close tolerances to reduce backlash.

[dugpatrick]

"orange" cleaners work well when removing grease. Eg, Goo Gone.

I use Superlube as a replacement grease.

Doug

[skybadger]

I Think this thread confirms for me that re-lubing the drive systems needs a good thick grease with a high pressure resistance to maintain grease on high friction surfaces between worm and wheel and less thick on the toothed gears. Goose fat was always prescribed by one engineer I know...

I did use 3-in-one once on a worm - it rapidly started squealing with friction.

Mike

[malc-c]

Molybdenum disulphide grease has the property of "plating" surfaces to which it is applied. When these surfaces are already in close contact, if they are not in constant motion there is a good chance that they will weld together. Conclusion:- under no circumstance use this type of grease on astronomical gear, especially on that contained in telescope mounts, as they have to be fitted to extremely close tolerances to reduce backlash.

Thanks for clearing that up...

So... whilst we've all agreed on that some parts need a thick grease, and some need a less viscose grease, what is the preferred thick grease then ?

[Chris]

After reading this thread will be leaving the load bearing grease in place, and only regreasing the gearing with Lithium grease for now I will avoid Moly grease for sure, thanks for the advice on this thread guys

[spaceboy]

I used white lithium grease on all bearings and gears in both my CG5 & EQ6. Opening the bearings I found there to be next to nothing in the ways of grease so the fact they now have any grease in them I consider peace of mind. FWIW I found no ill effects from using white lithium grease in the bearings. One thing I will note, just don't go crazy packing the grease in the bearing