Stepper motor not working as expected

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Kunal Gupta: Guys plss help me .... I am having issues in using stepper motor

I have tried both 28bjy with uln2003 and l293d .. giving it output supply of 5V . Motor is vibrating but its shaft is not moving. And even if shaft runs then it is different from what is expected by the logic of code

Similarly tried NEMA 17 stepper motor 4.5 KG using drv8825 driver and L293D driver ... Giving 12 v external supply.

And same results as 28bjy .... motor vibrating but its shaft is mot moving as expected or absolutely not moving

I have read and understood all the concept of driving stepper motor by full step method and hafl step method ....and using at first direct examples from net .. but still not figuring out what is the problem

Kunal Gupta

github.com/gkunalupta

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My crystal ball says the problem is on line 72!     wink

 

 

(Possum Lodge oath) Quando omni flunkus, moritati.

"I thought growing old would take longer"

 

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My crystal ball says line 43.

 

A different Jim

 

Until Black Lives Matter, we do not have "All Lives Matter"!

 

 

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Slow your step rate way down. Stepper motors need step rate ramped up/down to accelerate/decelerate. If you 'spin' the magnetic field  faster than the rotor can keep up, the shaft will just vibrate as you described.

Stick with a smart driver like the drv8825. It is much more efficient than the other drivers you mention. Start with modest current and only increase as needed. Higher currents need better heatsink/cooling.

Use the highest voltage available (within the limits of the driver), voltage determines the maximum speed to can reach.

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4.5 KG

 

That's a big (10 pound) motor...can these little chips drive the coils?  How many amps do you need?  These are typically good for 1, 2, 3 amps, that kind of range.  If you need a 5, 8, 10 amp drive you need to keep looking.

Acceleration can take much higher motor current than when fully moving & underway (you can try to spin the motor with a rope to give it a hand starting up).

 

Voltage sag due to power supply capacitance, capacity,  weak ground, thin wires, etc can be an issue.

 

Did you try this with a smaller motor first?  Something that draws 250ma or 1 amp??

 

Grounding & supply lines are critical ...show your schematic & a photo of your wiring.

I have read and understood all the concept of driving stepper motor

Excellent!!  These days it is not quite as critical  (but still very important), since these smart chips (DRV88...)  do all the stepping for you ...you just say take a step and it generates all the needed stuff (at least simplistically speaking).  In  the old days, you were on your own.  

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

Last Edited: Sun. Oct 25, 2020 - 12:57 AM
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avrcandies wrote:

4.5 KG

 

That's a big (10 pound) motor...

 

A NEMA 17 motor is less than 2" square.  If it weighs 4.5kg - yikes!  I wonder if the OP meant something else.

 

https://reprap.org/wiki/File:Mot...

 

S.

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I wonder if the OP meant something else.

Maybe (improperly) 4.5 KG of force to be delivered?? Even then, you don't want force (units of N), it should be torque (Nm).  time to ride the mystery bus.

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

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Add a mass to the shaft. Sometimes these motors require some mass or load on the shaft to be stable.

 

Jim

 

Until Black Lives Matter, we do not have "All Lives Matter"!

 

 

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Got to be something fundamental. The microstepping drivers cost peanuts these days and are simple to use. Maybe the motor is not the right type? bipolar vs unipolar??

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It's most likely a torque rating of 4.5 kg*cm. That's about right for a nema 17 in the 1.5 to 2.0 amp range.

 

OP, show us your code. show us your schematic. show us your wiring. 

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a torque rating of 4.5 kg*cm

Note strictly speaking kg*cm is not torque, since you need force*distance.  Kg is mass, not force, but kg*g  is force (F= mass * accel) [g=accel=9.8]

....so sometimes it's allowed to slide...like saying you "weigh" 80 kg.

 

interesting....Kilogram-force is a (non SI) force unit: is defined as the force exerted on one kilogram of mass by a ~9.806 m/s2 gravitational field 

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

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Kunalgupta wrote:
I have read and understood all the concept of driving stepper motor by full step method and hafl step method ....and using at first direct examples from net .. but still not figuring out what is the problem

Have you read the app note AVR446, and looked at the code provided there and compared it to your own code?

https://www.microchip.com//wwwAp...

 

Jim

 

(Possum Lodge oath) Quando omni flunkus, moritati.

"I thought growing old would take longer"

 

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I imagine the motor is just incorrectly wired. You can identify the pairs of wires by putting a meter across them and measuring the resistance. Or just try each combination until it works.

 

It's worth pointing out that you should never disconnect the motor whilst the board is powered, otherwise you risk frying the driver IC.

 

Also, the DRV8825 and A4988 driver boards have a small pot to adjust the current. This needs to be done properly but the process is well documented.

 

The original design is by Pololu, from which all the cheaper clones are derived. Read this: https://www.pololu.com/product/2133