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EQ5 dead zone


AustinM
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Hi guys,

This is my first post in here and apologies if someone has asked this question already but I have searched the forum for this answer and couldn't find one.

So the problem I have with my mount is that there is a few seconds lag (1-2 seconds) to control input on both RA and DEC axis when I switch the control input to the opposite direction. It happens when I use both the Skywatcher Dual Axis Motor drive kit or even the manual precise controls. There is a slight "give" in the mount when I move it by hand from side to side. It just seems sloppy, like there's too much room between the moving parts inside the mount itself.

My questions:

Is this "give" normal?

Can I fix it? 

 

Thanks for reading

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Hi and thanks,

Yes I have checked all the adjustment knobs and locks are tight. It is a second hand mount and the previous owner actually wanted to sell it instead for a Dob and I fear he was using this mount in the same manner. Slewing the mount around with the locks on and possibly causing slight damage.

I noticed it most when I'm tracking an object to be photographed. The first image can have trails where this lag occurs and then on the frames afterwards there is no trailing because the mount has "caught up". It's not a crippling fault as it tracks fine once its past the dead zone but it's one I would like to fix to save me constantly having to take a test frame before I begin collecting proper data.

Cheers

Edited by AustinM
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I think what you are describing is "backlash" which is an inherent feature of mechanisms with gears, as it is impossible to reduce the gaps between the gear teeth to zero without causing excessive stiffness. It may be possible to reduce it by adjustment, but in your case the best course would be to run the mount for long enough to take up the backlash before starting to photograph.  I get the same lag when reversing the slow motion on my mounts.

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2 minutes ago, Cosmic Geoff said:

I think what you are describing is "backlash" which is an inherent feature of mechanisms with gears, as it is impossible to reduce the gaps between the gear teeth to zero without causing excessive stiffness. It may be possible to reduce it by adjustment, but in your case the best course would be to run the mount for long enough to take up the backlash before starting to photograph.  I get the same lag when reversing the slow motion on my mounts.

Thanks! Thats exactly what it is and how I get around it. That's great news to hear because I was on the verge of buying a new one.

Thanks a lot for your responses :)

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HI I would also make sure you balance you mount slightly heavier to one side. This puts force against the gears and helps with this. I always let the mount settle once in position and guiding for a few minutes before it start imaging.

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On ‎23‎/‎06‎/‎2017 at 16:35, spillage said:

HI I would also make sure you balance you mount slightly heavier to one side. This puts force against the gears and helps with this. I always let the mount settle once in position and guiding for a few minutes before it start imaging.

Yeas Ill try that, thanks for the idea!

 

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Even with the backlash removed you can still get end float and other things going on. Loading the mount with the weight on the east side can remove the end float whilst loading the mount on the west will remove the backlash. You can adjust the worm gear for end float and gear mesh. This will then high light that the bearings are not the best either in the axels or the worms.

So with some tunning the mount can perform to a point but it does have issues. Learning to tune your mount is the way to go and it might take a while to sort things out but in the end it puts you in control.

Remember that most of this tunning can be done during the day.

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  • 1 year later...

You can adjust the mechanical backlash quite well on the eq5. BUT the motors themselves have a few seconds of backlash!!

If you unscrew the motor and run it by itself. Now set the rate to 2x on the  hand controller so the motor is running slow but you can still see it moving.

hit the left button on the dec motor and watch the cog move. Now hit the right button on the controller - you will see that the cog does not begin to move in the opposite direction for 2-3 seconds !!    So there is a large amount of backlash in the internal gears of the motor itself. I have just discovered this myself. Im thinking of looking for some replacement motors. Anyone found a solution for this??

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