# Easy Driver - Stepper motor not spinning smoothly.

**URL:** <https://community.sparkfun.com/t/easy-driver-stepper-motor-not-spinning-smoothly/40839>\
**Category:** Robotics\
**Created:** [November 6, 2020, 6:16pm UTC](https://community.sparkfun.com/t/easy-driver-stepper-motor-not-spinning-smoothly/40839 "2020-11-06T18:16:11Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![jinantha](https://avatars.discourse-cdn.com/v4/letter/j/f1d935/32.png) [@jinantha](https://community.sparkfun.com/u/jinantha)\
**Post date:** [November 6, 2020, 6:16pm UTC](https://community.sparkfun.com/t/easy-driver-stepper-motor-not-spinning-smoothly/40839/1 "2020-11-06T18:16:11Z")

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Stepper motor i’m using is TWO PHASE 42-34 NEMA 17

this one [https://www.reprap.me/creality-3d-two-p … inter.html](https://www.reprap.me/creality-3d-two-phase-42-34-reprap-42mm-stepper-motor-for-ender-3-3d-printer.html)

I have connected as per the hook-up guide.

Uploaded the sketch “SparkFun\_Easy\_Driver\_Basic\_Demo”.

Powered with a bench power supply 12v 2A.

Adjusted the vref to 2v to give 333mA of current.

But the stepper does not spin smoothly, but rather is spins in a jerking motion back and forward.

What might I be doing wrong here?

Kindly help.

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<div class="post-metadata">

**Author:** ![jinantha](https://avatars.discourse-cdn.com/v4/letter/j/f1d935/32.png) [@jinantha](https://community.sparkfun.com/u/jinantha)\
**Post date:** [November 6, 2020, 7:13pm UTC](https://community.sparkfun.com/t/easy-driver-stepper-motor-not-spinning-smoothly/40839/2 "2020-11-06T19:13:02Z")

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one thing to add.

I checked the stepper motor coils with a multimeter on continuity mode.

the motor has 6 pins, Pin no’s from left to right

pin no. 1 and 4 and 5 has continuity. so I guess this is coil 1 with a center tapping.

and

pin no 2 and 3 and 6 has continuity. And this is coil 2 with a center tapping.

and just to be sure, I checked there resistance.

between

pin 1 and 4 = 6 ohms

pin 1 and 5 = 6 ohms

pin 4 and 5 = 0 ohms

and

pin 6 and 2 = 6 ohms

pin 6 and 3 = 6 ohms

pin 2 and 3 = 0 ohms

so i’m confused.

what sort of stepper motor is this?

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**Author:** ![TS-Chris](https://yyz1.discourse-cdn.com/sparkfun/user_avatar/community.sparkfun.com/ts-chris/32/6057_2.png) [@TS-Chris](https://community.sparkfun.com/u/TS-Chris)\
**Post date:** [November 6, 2020, 7:34pm UTC](https://community.sparkfun.com/t/easy-driver-stepper-motor-not-spinning-smoothly/40839/3 "2020-11-06T19:34:01Z")

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> what sort of stepper motor is this?

Not sure, the measurements you're getting don't make any sense. 

I’d expect to see 6 ohms between one end of the coil and a center taps, 6 ohms between the other end of the coil and the center tap and 12 ohms between both coil ends. You might need to get a hold of a data sheet for your motor to figure out how it’s wired and what it’s rated for, there may be diodes or something inside the motor that cause the odd resistance readings you’re seeing.

> the stepper does not spin smoothly, but rather is spins in a jerking motion back and forward.

That usually means you're not giving the motor enough current but you're going to want to figure out what's going on inside the motor first before attempting to feed it more current, you wouldn't want to blow up the Easy Driver.

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<div class="post-metadata">

**Author:** ![jinantha](https://avatars.discourse-cdn.com/v4/letter/j/f1d935/32.png) [@jinantha](https://community.sparkfun.com/u/jinantha)\
**Post date:** [November 7, 2020, 5:46am UTC](https://community.sparkfun.com/t/easy-driver-stepper-motor-not-spinning-smoothly/40839/4 "2020-11-07T05:46:31Z")

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Thanks Chris for your reply.

As you said I had to disassemble the motor to see whats inside.

See the picture [https://photos.app.goo.gl/RCYVc6rxdNdLzNLU7](https://photos.app.goo.gl/RCYVc6rxdNdLzNLU7)

It explains why the weird readings.

So basically;

Coil A is pin 1 and 4 or 5

Coil B is pin 6 and 2 or 3

pins 4 and 5, 2 and 3 are connected together inside. No clue why they did it like that :shock:

Some photos of the motors below,

working motor from 3D printer on the bottom :- [https://photos.app.goo.gl/reJoQcaWBQxxZbkEA](https://photos.app.goo.gl/reJoQcaWBQxxZbkEA)

Newly bought motor:- [https://photos.app.goo.gl/w6BEkcXorqaCBRfK7](https://photos.app.goo.gl/w6BEkcXorqaCBRfK7)

Resolution:

Swapped the wires to match the coils as per above findings, and now all works.

With my current vref settings (2v), motor does not jitter and spins smoothly.

hence the EasyDriver is very hot to touch, so I might reduce the vref a bit further, but will have to see if that makes an effect for needed torque.

Thanks a lot for you guidance Chris!