Losmandy G11 non gear related backlash issue.

[White Rabbit]

Hi Guys.

I seem to have a bit of backlash in my RA axis and it's not gear mashing ralated.
If I grab the counter weight bar and rock it back and fourth there is about 5mm of play. Any idea how I would rid my mount of this.

Thanks.

[dcalleja]

There is a small amount of play on both my g11 axes. I'm led to believe this is both ok and needed to prevent the worm from binding.

I have no issues with tracking that I can see as a result.

Dan

[peter_4059]

It is probably end play in the worm. You need to squeeze the worm blocks together and then tighten the mounting bolts.

[multiweb]

Hi Sandy, maybe there is a little play between the bearings. Make sure the blocks are tight against the sides of the worm.

[rat156]

Hi Sandy,

Firstly, you mean meshing, mashing your gears is not good for them!

Now, I hate to get picky, but by what do you mean 5 mm of play? Do you mean that the end of the CW bar moves in an arc about 5 mm long? You are talking about a rotation axis, 5 mm of movement near the axis would translate to something much greater at the other end. Probably best to estimate the movement in degrees, or arc seconds. Now, how do you know it's not the gear backlash? The design of the G11 mount requires that there be some backlash in, not only the worm to main gear, but in the reduction gearbox as well. My Paramount MX removes most of this by using a belt drive to act as a reduction gearbox, but the G11 doesn't do this, so there must be backlash in the gear train or the would bind.

If you're talking about 5 mm deflection of the end of the CW shaft back and forth I would suggest that this seems like normal backlash in the gears, the G11 is a good mount, but it will have some backlash which is why most people who use them run them unbalanced with a sleigh excess on the eastern side to keep the gears meshed when tracking.

Cheers
Stuart

[White Rabbit]

Ok, yes meshing not mashing ipad auto correct there, and the play is 5mm on the rotation axis.

I remeshed the worm today just to be sure that it wasnt that and it isnt. I lossend the worm off and pushed it up tight then worked it back to stop the binding. It's definitely not the worm/gear mesh.

I dont have any play in dec.
If it's supposed to be there then there isnt much I can do then.

It doesnt effect tracking or pointing I'm just concerned that is is effecting my guider calibrations as I seem to be having a hell of a time getting TSX CAO to calibrate for guiding. I'm just trying to eliminate all the variables.

Thanks guys.

[rat156]

Hi Sandy,

There are settings for backlash in TSX in the auto guider tab I think, maybe under the calibration settings. Try calibrating for longer periods to over-run the backlash. Try putting in a delay before the auto guide calibration image is taken, these things should help.

Cheers
Stuart

[White Rabbit]

Thanks, I've tried all of that but to no avail. The weird thing is that I have no problem with phd. I'm considering going back to maxim for automation with ccdap5.

Thanks
Sandy

[alistairsam]

hi,

I have a similar problem with my neq6. the play in my case is gear meshing which I'm fine tuning, but I have a tough time getting maxim to calibrate, however I ran 20 min subs last night with phd and that had no problems at all.

Cheers
Alistair

[peter_4059]

Have a look at this:
http://www.wilmslowastro.com/tips/images_g11/G11_Bearing_Block_Problem.gif

http://www.wilmslowastro.com/tips/g11gemini.htm#bearing_block