I wonder what torque setting on the drill would do to work out when the worm is getting too tight?
By hand - motor removed. That's how you feel it best. If you can't turn it with your fingers, no good. It's not that hard. I run my index on the side of the oldham coupling. If it can't turn this way then I relax the worm.
I agree Marc, for final adjustments, but just to be able to wind the gears through a couple of cycles to bed them in would be a definite advantage.
I'll let you know how I go. Its raining here and I've got little more interesting to do.
You guys are lazy bums. You've got to put your backs into it. No pain - no gain. I want to see those blisters on those fingers Nah... seriously it has to move pretty freely. Hard to judge with the drill even with very little torque. I tried it both ways.
Lazy bums?? I've never pulled a mount apart in my life and between last night and today I've completely stripped and rebuilt this GM8 twice, I've cleaned god knows how many threads and gear teeth with toothpicks, I've polished every surface of the mount, I've been working on this worm alignment....
Well I gave the drill a go and it was great. I set the worm where I felt it needed to be (either Dec or RA) and then ran it at a moderately slow speed with the torque set at the 4th lowest setting. I went back and forward a few times, loosening off the worm each time it bit. Once I got a free run I lowered the torque again and repeated. Each time I checked by hand that the area that was tight was free enough to turn by hand with just a little bit of pain. Now it only jams on torque 2 and I can move that quite easily by hand. Too easy. I'd better check that my mounting blocks are aligned before I jump too much for joy
I'd better check that my mounting blocks are aligned before I jump too much for joy
Use the angle cover as a traverse to keep them square in relation to the worm axis (i.e. traverse pushing the front of the blocks toward the gear while you squeeze the two blocks together with your fingers.)
Yep they look pretty good. I've just completed a couple of revolutions in Dec using the stick method (still get sore fingers) and a few rounds of RA+ &RA- with the stick as well. Feels great. Now all we need are some clear skies.
Hey - I've hit a snag here guys... one of the bolts on my dec motor has something jammed in the hex head, I can't pull it off... hence, I can't adjust the dec worm and then re-attach the motor? Any thoughts?
The RA one is done, I can rotate the RA axis with my fingers, no tight spots... smooth as silk. the dec worm I got smooth, but then in order to reattach the motor, I needed to undo the worm blocks..
Is it possible for me to use the Dec motor in order to adjust it, start with it really loose and slowly tighten it until its tight enough?
Hey - I've hit a snag here guys... one of the bolts on my dec motor has something jammed in the hex head, I can't pull it off... hence, I can't adjust the dec worm and then re-attach the motor? Any thoughts?
Just losen the oldham coupling and remove the central plastic link. As long as the motor is not coupled you can turn the worm.
Paul.. If I loosen off both of the worm bolts, I can remove the worm by sliding it out of the plastic coupler between the motor and the worm shaft.RA is all sorted now.. Just need to do the Dec..
Dave - The hex socket is glugged up with something metallic that will not come out... My guitar does get glugged up hex bolts too.. I know what you're talking about
On the bright side, I was able to remove one bolt from the RA motor, and rotate the motor around on the other bolt, allowing the plastic coupler joining the motor and the worm to come free, and I was able to adjust the RA worm... It is now silky smooth in both RA and DEC, feels to be very little backlash.... I am really happy I was able to get this all sorted myself.. I was going to pay to send it to NSW and get Mr. Ward to service it for me, as I feared pulling it apart... Seems my metal working background and the wealth of information on IIS has seen this job done for a grand total of $10 worth of grease (which I may have used 0.05c worth on this service)
Bargain! And satisfying too...
Can't wait to get this out under the sky!!!
Thanks everyone for your help and contributions to the thread... Very helpful bunch!
pfft.... do what ever I damn like, the dog doesn't care. And it was an old sheet (from somewhen in the late 70's early 80's by the look of it ), not a table cloth. Long been relegated to the roll of paint drop sheet.
Paul - I am lucky like that too... My dog, lizards and snakes rarely complain about what I decide to do with sheets/towels etc... Nobody even complained when the degreaser got onto the floor yesterday... I cleaned it at my leisure and the world did indeed go on.
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.
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You guys are lazy bums. You've got to put your backs into it. No pain - no gain. I want to see those blisters on those fingers 
Nah... seriously it has to move pretty freely. Hard to judge with the drill even with very little torque. I tried it both ways.
