Doing a tuneup on a G11

[pmrid]

My G11 isn't running as smoothely as I would like. Despite having the Dec and RA worms adjusted fully, there is still a fair amount of slop in both axes and the guiding takes sudden and seemingly unprovoked leaps. S.oO it's time for a strip and rebuild with new shaft bearings.
I wonder if anyone else has done this and has any hints, tips, etc

Peter

[blink138]

have you tried the losmandy users group peter?
whatever in the world has been done to a g11 is on that site
pat

[2stroke]

http://public.beuth-hochschule.de/~goerlich/cg11tune.html
http://www.astro.uni-bonn.de/~mischa/mounts/g11_experiences.html

also deepspace products sell there "hyper" tune dvd and bits

[Poita]

Are you sure it is not a slipping clutch? The clutch on mine was terribly machined and I had to mill it flat.

The G11 and scitech yahoo groups are great, lots of g11 rebuild projects in there.
Are you using an ovision worm?

[pmrid]

On RA - yes. Didn't help. I'll do a strip and grease first and have a look at the clutches when I do. I've ordered some new bearings from the states just in case.

Peter

[multiweb]

IMHO it's pretty unlikely the bearings are the cause unless they're badly corroded I wouldn't bother. Meshing the worms too tight could be one cause but the next culprit is probably the plastic gear boxes. Stiction on the clutches is another important factor. As they get greasy they tend to stick and give causing jumps.

[pmrid]

We'll soon see. It's another high 30s day here today and this is a job for 'later' I'm afraid.

What's the answer to the gear boxes? I haven't gone into that area of possibilities yet. Better do it now I guess.
Peter

[multiweb]

I'm not sure if the new losmandy gearboxes are better. I hear they come with the new high torque motors. If they have aluminium cogs instead of plastic ones I guess they're better. McLennan (http://www.wilmslowastro.com/tips/mclennan_gbox.html)used to do some but the shaft diameter was different.

When I changed both my worms to the one block worm arrangement things got worse. When I placed the old gearboxes back it improved significantly. So I guess not all gearboxes are equal.

[jjjnettie]

Ponders is the one to talk to. :)
He knows the G11 inside and out.
Slip him a pm. :)

[pmrid]

G'day JJJ. I had Paul take a squiz at it a few months back - he came down for something else so I grabbed him then. He thought it was bearing play and so that's why I'm inclined to start there first.
I just ordered a pair of McLennan gearboxes too - might as well do that while I'm at it.
It looks a bit fiddly but should be OK. Apparently the McLennans turn in the opposite direction to the original Losmandy gearboxes.

Peter

[multiweb]

They're available here (http://australia.rs-online.com/web/p/gearboxes/0336444/?searchTerm=336-444&relevancy-data=636F3D3126696E3D4931384E525353 746F636B4E756D6265724D504E266C753D6 56E266D6D3D6D61746368616C6C26706D3D 5E5C647B337D5B5C732D2F255C2E2C5D5C6 47B332C347D2426706F3D313426736E3D59 2673743D52535F53544F434B5F4E554D424 552267573743D3333362D3434342677633D 4E4F4E4526). Check with Losmandy first. The new ones might just as good mechanically.
PS: cogs are bronze so should be fine.

[Poita]

I'd be surprised if it was actually the bearings, especially if swapping out to an ovision worm didn't change the symptoms...but it is possible I guess.

This is the clutch issue I had:
http://www.helixgate.net/g11.html

http://www.helixgate.net/G11opw8.html

I'd be betting on the clutch or the gearboxes. There is some interesting gearbox tests and thoughts here.
http://www.helixgate.net/G11opw3.html

[astroboy]

It may well be the motors my G11 never tracked right till I replaced them after years of frustration of being told everything Losmandy makes is perfect in every way .
Don't bother talking to Losmandy or the dealers its a waste of time .
Sorry if I sound bitter but I've gone though this myself and I'm tierd of S**T service.

[pmrid]

My McLennan gearboxes arrived today. My next step is to find a pinion puller and source some 3/16" x 0.014" thick alumiium or brass tube. Anyone got a bit? All it needs is about an inch or so for a bushing to step the gearbox shaft up to the Oldham coupler - there's a small diameter difference between the two.
Peter

[Tandum]

Pete, I got a bit of 7/32" x 0.014" brass tube here, but I want to get down to small parts and bearings tomorrow for grub screws and they might have it.

[Rosebud]

Pete, I've some brass tube for your gearbox upgrade that you can have.
I found a suitable pinion puller from an online hobby shop. Don't think I'll need it again , so your welcome to it.
Phone me on 0438 075 973

[pmrid]

Thanks Wally. I'll give you a ring later this morning.
Peter