[Phoenix (Steve)]

Hi Folks

Really interesting thread Alex - thanks. I too just serviced my GM-8 with advice from JohnG and Bird (many thanks) and help from Mischa's links of course:
http://www.astro.uni-bonn.de/~mischa/mounts/g11_disassembly.html
and
http://www.astro.uni-bonn.de/~mischa/mounts/g11_tuning.html

I picked up my mount second hand recently, which was purchased new in 2005 from another IIS member - I didn't know the service history of the mount so though I would pull it apart. I'm not usually hesitant in pulling things apart but I read so many posts about worm block adjustment difficulties that I decided to clean the worm shaft and gear insitu.

The mount was actually in pretty good nick but I decided to service it anyway. Once removed I cleaned all of the clutch washers and their roller bearings using isopropyl alcohol (bunnings) as well as all shafts. The centre RA and DEC shaft needle bearings were a little difficult to get at and clean properly, but I found a thread on CN that recommended CRC Brakleen, which cleans grease, oil, etc and is supposedly non-corrosive and leaves no residue - "cleans without disassembly". Well, I purchased it but didn't use it in the end - thought it would be a little too aggressive - but I did use CRC CO Contact cleaner:
http://www.crcind.com.au/catalogue.n...r?openDocument

This stuff is excellent and is safe to use (low toxicity) and is used on electronic circuit boards to clean them with no harm. It comes in a spray can with nozzle so you can direct the spray accurately (areas where you don't want it to go protect with a rag). The old grease and oil just pored out of the mount. Turn the needle bearing using your finger, spary a little more, turn again, spray, etc. until it runs clear and there is no oil/grease residue when testing it with a rag.

The general consensus on the Losmandy user group is to use slick 50 (PTFE) grease for the shaft bearings but I found this a little difficult to get hold of so I used the 'similar' SuperLube multipurpose grease with PTFE (SUP21030) for both bearings and gears/worm. Apparently only a very small amount should be used on the shaft bearings (thanks JohnG) and after working a small smear of grease on the end of my finger into the bearings I found that the bearing was a little harder to turn. While this was concerning, once the shaft was replaced it turned buttery smooth. My only concern about using the CRC CO contact cleaner is that it completely cleans the needle bearings DRY! So I am concerned the superlube has not worked its way into the needle points - ie. the location within the bearing where there is likely to be ware. Now I see the logic in Marc's suggestion to use the aerosol version of this grease which is:

"temporarily thinned with a solvent that cleans and penetrates the components to be lubricated, carrying the grease to those components. After a short time, the solvent evaporates, leaving behind a thin film of grease that provides long term lubrication that does not evaporate, dry or wash out"

Very cool - provides a solution to my concerns about the tube version of the grease - should I clean out the grease I have just applied and re-do with the aerosol? Particularly because I have used the CRC CO contact cleaner?

Anyway, I also used the isopropyl alcohol and toothbrush to clean the worm gear in place as well as the worm shaft - I also use the CRC CO cleaner on the worm shaft, which blasts out any contaminants - make sure to protect the worm bearings from the CRC CO cleaner at the end of the worm shafts with rags. With the motors removed and a notched piece of wooden dowel to spin the worm shaft I went round with my toothbrush and cleaned all gears and worm - applied superlube grease and rotated the gears several times to work in the grease.

Re-assembled everything and she seems nice a smooth. I'm very keen on the rumored one-piece Losmandy worm block (about time) so I thought I would remove the gears properly once I get my hands on one of these to clean a re-grease the gears. Perhaps I will use the aerosol on the needle bearings when I take the mount apart then.

Thanks again Alex

nix