Losmandy single worm block

[multiweb (Marc)]

Recently got two of those. How do you guys work out the tight spots manually? In the old system you could decouple the gearbox from the oldham coupler but with this one there's no access to release the coupler from it unless you remove the whole worm. So what's the trick?

[adman (Adam)]

I know what you mean, the new design has its ups and downs.

I found that mine was ok. I got the one-piece blocks on both axes with high precision worms in both also. Did you go the worm upgrade, or just the blocks?

Adam

[multiweb (Marc)]

Originally Posted by adman

I know what you mean, the new design has its ups and downs.

I found that mine was ok. I got the one-piece blocks on both axes with high precision worms in both also. Did you go the worm upgrade, or just the blocks?

Adam

I already had precision worms so I just bought two blocks.

[adman (Adam)]

hmm..you'd kind of hope that with the high precision worms that there shouldn't be any spots that bind?

Adam

[multiweb (Marc)]

Originally Posted by adman

hmm..you'd kind of hope that with the high precision worms that there shouldn't be any spots that bind?

Adam

The one block ensures alignment between the motor/gearbox and worm and decouples the gearbox from the mount plate but you still need to get a correct meshing. (i.e up/down). Sideways is taken care of by the little threaded knob.

[adman (Adam)]

Originally Posted by multiweb

... but you still need to get a correct meshing. (i.e up/down).

do you mean by shimming under the worm block?

[multiweb (Marc)]

Originally Posted by adman

do you mean by shimming under the worm block?

Yes. If you mesh the worm carefully against the gear until the radius of the worm meets the radius of the gear face you'll see that there maybe a small gap between the block and the mount plate. When you tighten the hex heads you'll bring the whole block down. If you shim the block then it won't go down when you tighten it and you'll get better/smoother meshing.

[adman (Adam)]

I find it interesting that the lateral adjustment screw doesn't move the block as a whole further / closer to the main gear - rather it makes the worm act like a swing-arm with the part of the worm closest to the screw moving further than the opposite end. Doesn't seem quite right to me.

I hadn't actually looked that closely at the meshing to see whether the worm was being pulled down too far when you tightened the mounting screws - on the other hand, it does seem to be working pretty well as it is, and I am reluctant to go messing with it. Next time I have to take it apart to regrease I will make sure to check that.

I am not sure there is any easy answer to your question in the OP. The design simply does not allow you turn the worm directly once it is in place. You could try doing it through the gearbox - but you wouldn't get the right 'feel'.

Adam

[multiweb (Marc)]

I'll work something out. Maybe drill a small hole under the mount plate big enough to slide an Hex key in there.

The idea of feeling the binding over a whole revolution of the gear is that the gear is not perfectly cylindrical and also not perfectly orthogonal to the shaft axis so it slightly goes up and down and also in and out. The aim is to compromise between the hardest spot and the least backlash possible. When you get those two down to acceptable results your tracking will be a lot better.