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Author Topic: wrong angle  (Read 2223 times)

dragonlost

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wrong angle
« on: August 17, 2016, 00:37:37 »
Hello.

I have a problem angle applied by astroEQ.

I have a GP2.
stepper motor 400 steps
pulley 1: 4
Worm: 1: 144
mega 2560 r3 + 2x drv8825


when I move the axis of declination (or ascention right) of 90 ° according EQmod, the shaft rotates 110 ° (measured on the frame).

I have verified the number of turns per revolution calculated in the interface and is well calculated.

By introducing an angle 3.23676323 pulley ratio is nearly equal to 90 °.

I do not understand why I have this error? Thank you for your help.
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TCWORLD

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Re: wrong angle
« Reply #1 on: August 17, 2016, 00:54:53 »
If there is a mismatch, it means on of three things:

  • There is some gearing or step angle difference that you aren't accounting for
  • There is a loose connection causing the motors to skip steps
  • You are trying to run the motors faster than they are capable and so skipping steps

Which option it is, I can't say. You can try running the mount at a lower slew speed and see if the issue persists. If it does, then it is likely one of the first two options.

The calculations done by the configuration utility and in the firmware shouldn't be at fault as they work for other mounts.

Kind Regards,
Tom.
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Tom Carpenter (AstroEQ)

dragonlost

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Re: wrong angle
« Reply #2 on: August 17, 2016, 10:52:59 »
Thank you for the quick reply !

I tried to very low speeds and the angle remains strictly the same.
For jumping steps of stepper motor I do not think that's it because the actual angle have to be smaller than the angle required.

I'll check the gear pulleys
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