HELP! - Losmandy one piece worm.

[adman (Adam)]

after a quick installation the other day everything seemed to be ok - but today I have been sitting down trying to get the worm meshing perfect, and I have discovered what I think is a design issue with the one piece block and my version of the G11.

If you look at the attached pictures, Image A shows the bearing blocks unscrewed from the worm cover, and the cover just sitting loosely on top of the bearing blocks. There is a 0.4mm gap measured with feeler gauge (red arrow) between the cover and the block because the worm cover contacts the main gear cover (yellow arrow). This means that when the bearing blocks are screwed to the worm cover, it lifts the bearing block up by the same amount - see Image, and doesn't sit flat on the plate.

I have taken some pictures of the lip on the worm cover (Images C and D) showing where it contacts the main gear cover (Image E)

My G11 is a late 90's model as far as I know. It was made by Losmandy for Celestron - but apart from the engraving on the side is identical to non-celestron badged G11's.

Has anyone else come across this problem, and if not, what do you think might be a solution? Should it be up to me to sort it out - or is it something that Losmandy (or Bintel who supplied the OPW blocks) should sort out?

Adam

[adman (Adam)]

once I remove the main gear cover - the block installs very nicely...but this is hardly a solution. The only other 'bodgy' solution would be to take a file to the lip on the worm cover - it only needs 0.5mm taken off.

Adam

[adman (Adam)]

well - I spent all afternoon carefully filing the ba$+@&ds down 0.5mm each, and I tell you - the aluminium they make those out of is seriously tough. Not the ideal solution, and almost sacrilege to file those lovely CNC machined bits. But when its installed you can't tell. I have waited months to get the Gemini going, and wasn't about to be held up by 0.5mm of metal.

On the plus side, they now fit like gloves, and I was able to get the mount outside to give it (and my new FS-60 reducer - thanks Louie!) a try out.

I ran the mount through a few worm cycles in PEMPro - and WOW ! - 3.56 arc seconds peak to peak periodic error!!! The best I had out of the old worms was 12 or so. Not bad for a 12 year old mount.

Took a few quick shots of the area around M7 to check out the reducer - seems to correct a lot better than the Tak flattener, and gives me about a 5x3 degree field of view.

Adam

[UniPol]

Well, you get my vote for perserverence Adam, its great to see it all up and running. I'm suitably impressed with the performance of your new one piece worm block and might enquire about buying a set for my G11. Cheers, Steve.

[multiweb (Marc)]

Keep in mind that what's important is to keep those two blocks inline so they move as one. The bottom gap just needs to be shimmed so when you mesh the whole assembly into the gear you have to make sure the whole block is not going back down on to the plate when you tighten back those two hex screws. It's very easy to see. Push the worm block against the gear. There is only one position it is going to mesh square to the gear. You'll then see how much you need to shim on both ends up or down..