Grease for gears on GPDX mount

[Ludd]

I'd like to refresh the grease on my recently acquired GPDX. The gears are quite dry and chattery, and I understand that a fairly silicone grease is considered suitable for this purpose. But does anyone know of any shops where I can buy this stuff? Maplin only seem to have the aerosol stuff, and DIY superstore places seem to have buckets of the gloop that builders use to fit waste pipes. Any suggestions would be gratefully received!

[E621Keith]

You need some really thick grease for the worm so they don't get rub off in use.

Don't use light lithium grease and certainly not aerosol stuff. Ideally the grease should match the static friction with the dynamic friction of the worm.

Quoting Pete_Gamby (Vixen UK) and Peter Drew from this thread - http://stargazerslou...-polaris-mount/

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.

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

[Ludd]

THanks, and yes, I saw the reference to glutinous malt-sugar when I was googling earlier today. I may have to buy some of the relevant gloop online, as I don't seem to be able to track down any actual real world shops that sell the stuff. Having said that, I did a while ago have a tiny pot of the stuff that came with a bicycle bottom-bracket - it was almost like lip-balm.

[Ibbo!]

i did mine before xmas

the stuff I was given (secret stuff from a friend he wont tell me what it is) is great for the worms but far too viscous for the internal bearings and will have to be redone, esp in this colder snap.

If I get motivated it will be done tomorrow and will report my success or failure.

Steve

[Carbon Brush]

I use something like this...

http://uk.farnell.com/servisol/200002000/grease-silicone-50g/dp/3821559

Works nicely on gears, plain bushes and bearings.

A tiny smear on screw threads prevents binding.

Go sparingly with it as you don't want it finding it's way onto any 'glassware'.

[stevieR]

I have a heq5 mount. What grease should i use for my mount?

[E621Keith]

I have a heq5 mount. What grease should i use for my mount?

Is it in need of regreasing? If not then it's best to leave it alone.

Finding the right grease can be very difficult, and you risk damaging your mount if you used the wrong type of grease.

[Astro_Baby]

Superlube for the HEQ5 is oft recommended.

http://uk.rs-online.com/web/p/greases/1847967/

Personally,

I use TF2 which is a lithium teflon mix which you can get from any decent bike shop. I have rebuilt quite a few mounts with TF2 includinag two of my own. Both were improved hugely from an overall clean out of the goop and regreasing. After paranoia posts on here some time ago about lithoum greases I took one of the mounts I rebuilt about 3 years ago to bits to examine it. Its a mount which is obs based and not well cared for. I found no problems in the lithium based TF2 after 2-3 years. I also strripped my own HEQ5 for a check and found no problems in that either. Spur gears still had a gopd coating of grease and so did the worm gears.

Word of warning here if you lack mechanical nous, dont have a good set of tools etc then dont even think about taking a mount to bits. I see far too many threads on forums whereele have busted stuff througj lacl of machanical ability. Usually screws and threads being stripped and I have also seen a fair few mojnts taken to bits where previous owners have busted stuff and not been honest when they sold the mount which shows that taking these things to bits, while not hard, does carry its risks.

[stevieR]

Thanks. Im an eletrician by trade with good mech skills (automation engineer/panel builder)and have already stripped it to have a look and see how it all works. The mount is fine for grease at the moment i was only asking for future reference. Cheers

[Ludd]

To my surprise and delight, my local Maplin had Servisol-branded silicone grease for sale, so I now have enough for the gears on about 300 equatorial mounts. Oh, and I picked up one of their 7A bench power supplies while I was there.

[cantharis]

Again, the usual load of confusing and conflicting opinions. Firstly, the gears in your mount are very LIGHTLY loaded at all times, and when it is just tracking are experiencing close to a zero load - after all, we are just rotating a tube that is balanced and only masses a few kilos. So the manufacturers can make the bearing surfaces out of soft, easily machinable metals like brass and aluminium and even plastics.

Our cars have wheel bearings which operate under the most gruelling conditions, high rotational speeds, continuously loads of hundreds of kilograms and shock loads of thousands of kilograms, all happening at high temperatures. For these harsh conditions a lithium based grease is invariably that of choice. I find that this high performance lithium grease is more than adequate for our lightly loaded mounts, and recommend its use. I would indeed recommend that anyone buying a mount made by Synta clear out the stiff glop that the makers put in - mostly to disguise the sometimes large clearances that can occur, and rebuild it carefully using a lithium grease. I have done this with all my mounts with total and lasting success, and an immediate improvement in how the mounts function.

I have found that Synta´s stiff glop can make balancing the scope in the mount a most imprecise operation - basically preventing the mount from achieving an important design function.

[Ludd]

OK, that's us told.

[Astro_Baby]

I agree, the thock synta goop is principally there to make the mount shut up and to hide imperfect tuning at the factory. Like above ai cannot believe that these mounts are under any sort of load. If they were the manufacturers would up the bearings in stuff like the CG5. The average mount is carrying a few kilos and moving at very slow speeds carrying a balanced load.

You could probably run them with no lube at all perfecly well and your onl problem would be rust rathe than friction issues.

Theres no great engineerng requirements in the average mount and its under nothing like the stresses of car compnents. Heck I ran a ford escort years ago for 50 plus miles on cookimg oil and it was fine afterwards...just had a pong like a bad fry up

[billhinge]

Theres no great engineerng requirements in the average mount and its under nothing like the stresses of car compnents. Heck I ran a ford escort years ago for 50 plus miles on cookimg oil and it was fine afterwards...just had a pong like a bad fry up

I was in London today for an exam, dropped into a greasy spoon for a cup of tea beforehand , now I realise what you mean, smelling it all afternoon

[E621Keith]

Again, the usual load of confusing and conflicting opinions. Firstly, the gears in your mount are very LIGHTLY loaded at all times, and when it is just tracking are experiencing close to a zero load - after all, we are just rotating a tube that is balanced and only masses a few kilos. So the manufacturers can make the bearing surfaces out of soft, easily machinable metals like brass and aluminium and even plastics.

Our cars have wheel bearings which operate under the most gruelling conditions, high rotational speeds, continuously loads of hundreds of kilograms and shock loads of thousands of kilograms, all happening at high temperatures. For these harsh conditions a lithium based grease is invariably that of choice. I find that this high performance lithium grease is more than adequate for our lightly loaded mounts, and recommend its use. I would indeed recommend that anyone buying a mount made by Synta clear out the stiff glop that the makers put in - mostly to disguise the sometimes large clearances that can occur, and rebuild it carefully using a lithium grease. I have done this with all my mounts with total and lasting success, and an immediate improvement in how the mounts function.

I have found that Synta´s stiff glop can make balancing the scope in the mount a most imprecise operation - basically preventing the mount from achieving an important design function.

I agree, the thock synta goop is principally there to make the mount shut up and to hide imperfect tuning at the factory. Like above ai cannot believe that these mounts are under any sort of load. If they were the manufacturers would up the bearings in stuff like the CG5. The average mount is carrying a few kilos and moving at very slow speeds carrying a balanced load.

You could probably run them with no lube at all perfecly well and your onl problem would be rust rathe than friction issues.

Theres no great engineerng requirements in the average mount and its under nothing like the stresses of car compnents. Heck I ran a ford escort years ago for 50 plus miles on cookimg oil and it was fine afterwards...just had a pong like a bad fry up

It's apples and oranges. A car uses spur gears that is continuously lubricated with oil whereas a mount uses worm gears doesn't get re-lubricated at all. Furthermore, you can have a lot of wear in a car transmission and the car will still run, but a slight wear on a GEM worm will introduce a lot of error. If you ride a bike then you will know the sprocket teeth can lose half their height and you may not even notice.

Worm gear works on a different mechanism to normal gears. The contacting surfaces in worm gear slide across each other rather than roll across each other, which make it harder to maintain the lubricant film and avoid metal on metal contact. As such worm gear box generally use much more viscose oil than the one use in spur gear box. If you have a apple vs apple comparison, the typical car engine oil has iso vg under 46, whereas a typical worm gear box uses oil above iso vg 460. Thick and sticky lub is even more important for a low speed worm gears that doesn't get re-lubrication at all and have to rely on sticky grease that will stay on the worm for years.

Finally, this thread is about Vixen's GPDX's lubricant, not Synta EQ5. While one may get away with accusing Synta using sticky grease to cut cost, I'm sure Vixen chose the sticky grease for a reason. If you follow the other lubrication thread then you will know Vixen keeps their grease formula secret even from Vixen UK.

[Planetesimal]

I used "carlube" lithium grease for my Dec worm gear and rack & pinion focusser assembly - the yellowish translucent stuff you squeeze out of a tube. Seems fine so far!

[cantharis]

I used "carlube" lithium grease for my Dec worm gear and rack & pinion focusser assembly - the yellowish translucent stuff you squeeze out of a tube. Seems fine so far!

Absolutely - that will lube your EQ mount fine!!!