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testing mount without load

Linda Thomas-Fowler
 

I¡¯m working on getting my GM811 set up with software and I had a question about what was the appropriate way to run the mount without any OTA. Should I remove the counterweight shaft or leave the shaft attached but without any counterweights?

If I do¡¯t hook gemini up to the mount it complains about stalls I guess since it¡¯s not getting any signals from the Dec or RA axes.

What¡¯s the right way to go about this?

Thanks!
 

You can set the Gemini Tracking rate to Terrestrial mode (not sidereal, lunar, solar,...etc).
This stops the RA worm and tells Gemini not to expect any ticks from the optical encoders.

As for the counterweight... it is not so heavy as to cause any problem for the mount.? The top dovetail does have some weight to it, so I'd just leave the counterweight shaft in place... with no weights on it.

Best,
Michael


On Tue, Dec 12, 2017 at 12:39 PM, Linda Thomas-Fowler linda@... [Losmandy_users] <Losmandy_users@...> wrote:

?

I¡¯m working on getting my GM811 set up with software and I had a question about what was the appropriate way to run the mount without any OTA. Should I remove the counterweight shaft or leave the shaft attached but without any counterweights?

If I do¡¯t hook gemini up to the mount it complains about stalls I guess since it¡¯s not getting any signals from the Dec or RA axes.

What¡¯s the right way to go about this?

Thanks!




--
Michael Herman
mobile: 408 421-1239
email: mherman346@...
 

Linda,

As the shaft weighs over 2 kg, I suggest you
remove it also. There should be no problem in running Gemini without a load.

David

At 21:39 12-12-17, Linda Thomas-Fowler linda@... [Losmandy_users] wrote:


I?€?m working on getting my GM811 set up with
software and I had a question about what was the
appropriate way to run the mount without any
OTA. Should I remove the counterweight shaft or
leave the shaft attached but without any counterweights?

If I do?€?t hook gemini up to the mount it
complains about stalls I guess since it?€?s not
getting any signals from the Dec or RA axes.

What?€?s the right way to go about this?

Thanks!
 

Hi Linda,

My old G11 was a 15 year old mount that had a new Gemini 2-mini w/HT-motors and HP worms on both axes. I had Scott rebuild this old G11 as a fully optioned current spec. G11G - Gemini 2-mini w/HT-motors, new design OPWs, tucked-in motors, RAEXK etc. I also own and love my classic GM8G with HP worms that remains un-updated but will will get the tucked-in motors once there is room in the schedule at the shop. I have not worked with the? GM811G, I've watched all of the various prototypes being developed in Losmandy's shop but I don't know if they are being specified and shipped with the RAEXK installed or if it's simply being offered as an option.?

So with that said, if testing with an empty saddle I prefer to?leave the counterweight shaft on the mount because this prevents a worse imbalance than taking the counterweight shaft off. If you do remove the counterweight shaft the saddle side of the head will be much heavier and will rotate surprisingly quickly if a clutch is loose or loosened. If your GM811G has the RA extension kit installed it should not hit any other parts of the mount as long as the saddle is completely empty. Even so, with the counterweight shaft in place the imbalance will favor the CWD position and there will be no surprises if a clutch is let loose as the counterweight shaft will always rotate to CWD. Don't worry about the servomotors, even my very first generation Gemini 1 motors will handle this load no problems, the later high-torque motors will have no issue used this way either.?

Chip?
Linda Thomas-Fowler
 

¿ªÔÆÌåÓý

Thanks to everyone for your answers. I actually just set the mount on the table and ran it without the CW shaft and everything seemed fine.?

Software seemed to connect and control properly. The only odd thing was Sky Safari on an iPad Pro (10.7¡±). Sky Safari was quite sluggish when connected. Lowering the readout rate to 1 or 2 per second (from the default of 4) improved things but it was surprising. Looks like the software is polling the mount in its main loop which is a bad idea for responsive user interfaces. Even at the lower rate there were periodic UI freezes as it polled the mount. Other than that everything went smoothly.

Unless you count the awful weather and cold I got since the mount arrived. I¡¯m now two weeks in and still haven¡¯t been able to get outside. Hopefully by the weekend!

typos courtesy of iPad

On Dec 13, 2017, at 12:29 PM, chiplouie@... [Losmandy_users] <Losmandy_users@...> wrote:

?

Hi Linda,


My old G11 was a 15 year old mount that had a new Gemini 2-mini w/HT-motors and HP worms on both axes. I had Scott rebuild this old G11 as a fully optioned current spec. G11G - Gemini 2-mini w/HT-motors, new design OPWs, tucked-in motors, RAEXK etc. I also own and love my classic GM8G with HP worms that remains un-updated but will will get the tucked-in motors once there is room in the schedule at the shop. I have not worked with the? GM811G, I've watched all of the various prototypes being developed in Losmandy's shop but I don't know if they are being specified and shipped with the RAEXK installed or if it's simply being offered as an option.?

So with that said, if testing with an empty saddle I prefer to?leave the counterweight shaft on the mount because this prevents a worse imbalance than taking the counterweight shaft off. If you do remove the counterweight shaft the saddle side of the head will be much heavier and will rotate surprisingly quickly if a clutch is loose or loosened. If your GM811G has the RA extension kit installed it should not hit any other parts of the mount as long as the saddle is completely empty. Even so, with the counterweight shaft in place the imbalance will favor the CWD position and there will be no surprises if a clutch is let loose as the counterweight shaft will always rotate to CWD. Don't worry about the servomotors, even my very first generation Gemini 1 motors will handle this load no problems, the later high-torque motors will have no issue used this way either.?

Chip?

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