Ovision worm for Losmandy G11

[multiweb (Marc)]

Originally Posted by rat156

He may have, I bought the mount secondhand from here, so I don't know the age.

The Ovision worm works in two ways, the mounting removes the 76 second error, but the worm is a really high precision part.

Cheers
Stuart

What's the difference between the ovision and the losmandy high precision worm? Machining tolerances? Material used? Or is it the fact that the meshing area is narrower? Would that make a difference?

[multiweb (Marc)]

Hi Stuart, I finally managed to get some data on my G11 tonight.
I couldn't figure out what camera to use as I only have a QHY5 and a QHY8 but I don't have Maxim or CCD Soft, etc... but I did have a Nexstar imager and it worked as a VGA-USB cam
Here's the result of 4 worm cycles on achenar so I'll be able to compare when I've replaced my worm block.
How do you load the PEC back into the mount with the gemini to smooth things out?

[netwolf]

Marc
The Ovision is a single block with worm and bearings encased within. One of the problems with the Losmandy g-11 desing is that there are two independant block in which the worm sits and they can be out of alignment.

Interestingly the HGM Titatn i belive comes with a single block design. Why Losmandy has not done the same with the G-11 is anyones guess. The issue has been raised a lot in the Losmandy users yahoo groups. The first working solution i saw was developed by Rainer who i think is a member on these forums. He created modifications to his mount and that in turn i think has led up to these commercial single block developments.

There has been further discussions on replacing the couplers to also enhance performance further. Also there is the McLennan Gearbox which also have shown to provide further enahncment in performance.

This is not to say that the G-11 out of the box is not a good mount, it is a very good mount. However as always we can tweak it to perform even better, and many have achived fantastic results.

[rat156]

Hi Marc,

When you setup PemPro, specify your mount as G11 with Gemini (if you have it) then another tabe appears in the software which allows you to program the mount directly.

Looks good though. From my experience invert the curve before sending it to the mount.

Cheers
Stuart

[multiweb (Marc)]

Originally Posted by rat156

Hi Marc,

When you setup PemPro, specify your mount as G11 with Gemini (if you have it) then another tabe appears in the software which allows you to program the mount directly.

Looks good though. From my experience invert the curve before sending it to the mount.

Cheers
Stuart

Thanks Stuart - yeah I realised that after chatting with Ray on the CCDware forums. I chose the wrong type of mount. I picked G11 instead of Gemini Lvl 4 which has the dialogs to upload PEC data. I'll have to do another PEC data run. It turned out better than I thought though, +/-4 arcsec out of the box and that's the standard SS losmandy worm. And I didn't get the 76s problem. I have one of the HP losmandy worm that I'll swap and see if it makes a difference.

I understand from the PEMPro docs that the PEC data is dependent on the guide rate used. What's the recommended guide rate? I think I use 0.5 sidereal from memory but I'll have to check. The range is from 0.3 to 0.8 I believe. What do you use?

[multiweb (Marc)]

Originally Posted by netwolf

Marc
The Ovision is a single block with worm and bearings encased within. One of the problems with the Losmandy g-11 desing is that there are two independant block in which the worm sits and they can be out of alignment.

Yep, I'm aware of that. The one block set-up takes the standard two end block mis-alignment out of the equation and makes meshing way easier. Although you can use the aluminium cover as a traverse when aligning those blocks. That's what I did and they must be pretty well inline because my PEC data didn't show any bearing popping. Still the one aluminium block is the ONLY way to go IMHO.

Originally Posted by netwolf

Interestingly the HGM Titatn i belive comes with a single block design. Why Losmandy has not done the same with the G-11 is anyones guess. The issue has been raised a lot in the Losmandy users yahoo groups. The first working solution i saw was developed by Rainer who i think is a member on these forums. He created modifications to his mount and that in turn i think has led up to these commercial single block developments.

They sure learnt from their G11 experiences There is actually a one block worm design from Losmandy. I've seen it and touched it but it's not commercialised and I'm not sure when it will.
Rainer has been of a tremendous help to me. I have based all my new blocks design on a lot of the work he had already done on his two mounts. He knows what he's talking about.

Originally Posted by netwolf

There has been further discussions on replacing the couplers to also enhance performance further. Also there is the McLennan Gearbox which also have shown to provide further enahncment in performance.

Yeah I saw that on the internet. Not convinced. I reckon changing the Oldham coupling for something more rigid is more beneficial than playing with the gearboxes.

Originally Posted by netwolf

This is not to say that the G-11 out of the box is not a good mount, it is a very good mount. However as always we can tweak it to perform even better, and many have achived fantastic results.

It is an excellent piece of engineering very well designed. Every time I pull it apart and play with it I'm always amazed at how well thought it all is.