Nema 17 slipping

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999dom999
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Nema 17 slipping

Postby 999dom999 » Tue Jul 29, 2014 4:09 am

I'm using a RAMPS controller and a NEMA 17 motor.

When its connected to the z-axis spindle and I try to move it 1mm it just slips and vibrates.

Without it connected to my Z axis spindle and I hold it with my fingers and move 1mm, it turns fine both directions. If I apply a small amount of pressure with my fingers then it slips.

Any ideas why this appears to have such little power?

Finhead
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Re: Nema 17 slipping

Postby Finhead » Tue Jul 29, 2014 10:09 am

What are your stepper motor specs? Have you adjusted your stepper driver properly?

999dom999
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Re: Nema 17 slipping

Postby 999dom999 » Tue Jul 29, 2014 10:38 am

I'm starting to get somewhere. I adjusted the pot on the stepper driver and it increased the power. I also noticed the spindle was a little tight when the top plate was tightened and also when the linear block is screwed into the spindle. I loosened these and it worked fine. I will try to add some washers to adjust the height and the distance of the blockl and tighten to see if this allows it to move freely.

adambx
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Re: Nema 17 slipping

Postby adambx » Tue Jul 29, 2014 10:41 am

maybe the motor current of your microstepping driver is just way too low. Check with the motor data sheet and adjust accordingly.

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cncbasher
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Re: Nema 17 slipping

Postby cncbasher » Sat Nov 08, 2014 9:16 am

stepper motors slipping or not moving or irratic etc , is mostly down to either trying to run the stepper at a higher speed than it's capable of
this can manifest it's self in many ways .

such as low voltage , not enough current , incorrect setup between what you have the stepper driver set for and the actual step pulses
i.e setting the software for for say 1/8 step and having the actual hardware set for 16 microsteps .

ideally for steppers you want the highest voltage for the stepper driver spec and around 3A for each stepper your using
most stepper drivers can accept upwards of 24v , and with the advent of modern stepper drivers they take care of the current rating
put very simply voltage gives you speed , amps gives you holding torque for the position .

however there is a trade off the higher the microstepping the lower the torque available ,to overcome z axis forces of gravity etc
this will show it's self as slipping downwards , especially if a fast move or high acceleration

if ever your faced with a stepper that seems to slip , modify your step rate and acceleration , by reducing by 50 % and try again
once you have it working correctly then you can bring the speed up in stages

hope this helps people understand steppers a little bit more


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