any advice on how to stop the humming and shuddering?

[prefetch]

so here i am on my first non-cloudy night to test out my mount.  very exciting!  

 

i thought i had it balanced pretty well.  the red lines were at or near overlap on both RA and DEC, and then i proceeded to do an auto-tune.

 

it ran through it's paces, and said that it found some better variables and whatnot, and i moved on from there.

 

anyway, i started to slew around and get images of stars in my camera, which is refreshing about every 1/2 second and the stars are all "warbly" - zigzaggy and scribbly.  my mount is vibrating.

 

i can move it a little here and a little there and get it to stop, but then if i slew it again it will find some odd harmonics and begin to vibrate again.

 

not exactly sure how to resolve this.

 

i'm using a C11HD with the stock finder scope and a dew shield.  again, balance appears to be okay.

 

any advice?  i can't seem to get the hums and shudders to subside.  

[MarkS]

Usually that is a sign that the tuning is too hard. Try backing off the PID numbers a little and see if that helps.

 

Regards,

Mark

[Jay]

Hi

 

Vibration is almost always caused by balancing problems and/or tuning issues. Make sure that your mount is balanced well in all different positions not just in one place. Automatic tuning is pretty good but there might be a need to adjust some parameters manually. 

Jay

[Jay]

One more comment about balancing... move your mount around and check the balancing with software in different positions. I'd be surprised if you got it right with one go.

Jay 

[lukepower]

One more thing that comes to mind is the rigidity of the setup. I tried once to run everything with my bend pier not firmly tightened to the ground, and that caused (or allowed?) more vibrations. Tightening the screws helped alot.

[prefetch]

thanks everyone.  i'll spend some time today working on balancing some more in different positions.  my permanent observatory is still under construction, so for now the mount is on a CGEM tripod which is on a wheeled platform - perhaps that structure is contributing to the problem.

 

i'll keep working at it.

 

some additional questions though: did it take you guys a while to get it tuned correctly?  about how many hours did you spend on the initial balancing and tuning?

[lukepower]

Prefetch,

 

the heavier my scope became, the more time it took to balance it And well, the tuning became easier with the autotune feature in Autoslew (even if I still work on it manually, as I feel the automatic settings are not always that good).

[prefetch]

so lukas, should i think something is wrong if it takes an hour or two to tune and balance my C11 for the first time?

 

i spent about 20-30 minutes and it still had problems shuddering, and i adjusted my PDI like the manual suggested, and it still hummed and shuddered so i keep freaking out hoping that my mount isn't somehow defective.

 

but if it takes a long time by balancing the RA axis, repositioning, balancing again, moving it back, balancing again, and then switching to DEC axis, repositioning, balancing again, moving it back, then going back to RA and starting over again...if this is just how it works, then i'll feel better and keep working at it. 

[Waldemar]

Prefetch,

 

In AS under the tuning settings are a few factory settings as well: Low, medium and high weight.

I choose the medium weight PID settings.

They were a lot softer than the automatic PID settings I got from the automatic tuning.

For my TEC140 the medium settings work nice without any vibrations or sounds.

but in your case they may need some adjusting as well.

It took me some time to get things right in the beginning as well. Patience and Perseverance are the key words here.

The better balance and tuning the better results. So, the invested time will pay off :-)

 

Regards,

Waldemar

[Roger]

As a systems engineer, a wheeled base will almost certainly mean you need to back I (of PID) way down.  I stress I do not (yet) have one of these mounts, but that is what I'd first try.

[Jay]

It's very normal to spend 2 hours and more for the balancing and tuning for the first time. Next time will be a lot easier if need to do it again. RA axis is usually more difficult (and crucial) when trying to get good balance/tuning results.

[prefetch]

okay, i just spent about 2 hours balancing and tuning.

 

i'm down to 1 little noise when i cross the 'top' of the rotation right near the meridian.  

 

RA at sidereal rate is

DE at sidereal rate is

 

RA at medium speed is

DEC at medium speed is

 

my "Autofind quality" (not really sure what that even means) is 76% in RA and 52% in DEC.

 

what do you guys think?  does these readings seem reasonable?

[MarkS]

thanks everyone.  i'll spend some time today working on balancing some more in different positions.  my permanent observatory is still under construction, so for now the mount is on a CGEM tripod which is on a wheeled platform - perhaps that structure is contributing to the problem.

 

i'll keep working at it.

 

some additional questions though: did it take you guys a while to get it tuned correctly?  about how many hours did you spend on the initial balancing and tuning?

I've been off the air for a few days,so I've just seen this.

 

I gave up on the CGEM tripod - I couldn't stop it vibrating with any reasonable PID settings!

 

Regards,

Mark

[Wojtek Gdańsk]

Welcome. I DDM60 but I think the PID is the same as DDM85 . On my DDM is installed DDM C14HD but still copes with such a heavy burden . At the beginning I also had problems such as tremors DDM , it took me quite some time before the DDM started going to watch = ) . The first thing I did to DDM do not run in the tremor and no humming .

1 ) balanced the DDM using the built- in autoslew electronic tool .

2 ) I ran the auto-tuning PID - autoslew pre- configured PID but DDM is still not functioning as it should so the auto-tuning PID ran further manual tuning , and he tuned PID . As I wrote above, it took me a lot of time. Now DDM performs well .

As for the filter axis RA and DE . I do not know with you but in my ED axis I rather high set PID parameters so that the axis of the DE from the filter I am very pleased. Unfortunately, the RA axis when I turned on the filter I can not quite high set of PID parameters - practically you do not hear any engine operating in the RA axis I PID parameters set to low ranges - I do not know if it's good . Are you also in the RA axis is a problem with the filter.

Regards

Wojtek .