Stepper Motor Question

Hi there,

I'm about to order one of the following stepper motors:

 [u][b]Model      A     V   N/cm[/b][/u]

 57BYG    2.8     ?    120

Nema17    1.7   2.8     36
Nema17    1.2     4     31
Nema17    0.4    12     20

Nema14    1.0   2.7     14
Nema14    0.5    10     10

I'm looking for an easy setup with a low price driver and no cooling.

For example: The DRV8824 driver can deliver up to 0.75 A per coil without a heat sink which should be enough for the Nema17 with 0.4 A and the Nema14 with 0.5 A. Are there other things to keep in mind? Or similar drivers for the more powerful steppers?

And how to handle the power supply for the stepper?

Thanks in advance!

The stepper motors with higher currents and lower coil resistances work better at higher speeds. If you don't need higher speeds then I would go for the cheapest motor and driver combination that has enough torque.

The most common drivers used with Arduinos are the A4988 and DRV8825 - the latter has slightly more current capability. The A4988 would be fine with the 1.2 amp motor but the DRV8825 might be marginal with 1.7 amps. For the 2.8 amp motor I would suggest a driver that can manage 4 or 5 amps.

...R
Stepper Motor Basics
Simple Stepper Code

My vote is 1.2A and DRV8825, but you will need good airflow around the heatsink on the DRV8825.

And torque is a product of force and radial distance, not a ratio. Nm is the SI unit of torque, N/cm is
a measure of spring constant / stiffness!

Thanks guys, that helped a lot.

But I can't get the 57BYG out of my head. If I read the specs correctly it should be able to spin much faster than the other ones for a similar price. Would the TB6560 Driver be sufficient for the stepper?

I don't see why the 57BYG would much (or any) faster than the 1.2 amp motor - assuming that the 1.2 amp motor has enough torque for your project. I have been assuming that all of the motors on your list have enough torque.

You have not told us how many steps per second you require.

I suspect that the TB6560 driver would be struggling - but I don't have any direct experience. I believe there are drivers that use TB66xx chips that can provide more current. If it was my project that is what I would choose.

...R

Ok, I just thought that the 2.8 A would be faster than the 1.2 A stepper when the load is the same.

I dont have a hard requirement for the steps per second -- the faster the better. I need the stepper to do ~40 fast revolutions and stop at a certain step (a 25th of a revolution). The load is relatively low, but I cannot give you a certain number right now.

Then I may go with the 1.2 A stepper and a DRV8825 driver. I've found two types, the first one seems to be a regular one, the other one has a heat sink installed and is cheaper.

NEMA17:
Ok, I just thought that the 2.8 A would be faster than the 1.2 A stepper when the load is the same.

The torque of a stepper motor declines as speed increases so, yes, a higher torque motor should be able to work at a faster speed for a given load. However if the 1.2 amp motor can make your project work as fast as required the bigger motor won't be any advantage. The better motor manufacturers produce graphs showing how th torque varies with speed. If speed is critical to your project it would be sensible to study the graphs.

However in your Original Post you did not mention any requirement for high step speeds.

I dont have a hard requirement for the steps per second -- the faster the better

Without numbers that is meaningless.

40 fast revolutions and stop at a certain step (a 25th of a revolution)

If the motor is running at high speed you will need to decelerate over a number of steps if you are not to overshoot your target. And you will need to accelerate at startup to avoid missing steps.

...R

I can work with that. Thanks so far for your help!

Robin2:
If the motor is running at high speed you will need to decelerate over a number of steps if you are not to overshoot your target. And you will need to accelerate at startup to avoid missing steps.

...R

You always need to do this for steppers this size unless going very slow. AccelStepper library is the
first port of call I suggest.

MarkT:
You always need to do this for steppers this size unless going very slow. AccelStepper library is the
first port of call I suggest.

I read about that, thanks. How long would it the NEMA 17 1.2A approximately take to get 40 revolutions without load and with proper acceleration and deceleration?

NEMA17:
How long would it the NEMA 17 1.2A approximately take to get 40 revolutions without load and with proper acceleration and deceleration?

This is similar to "how long is a piece of string"

Tell us what your performance requirement is.

Would it be sufficient if the motor could do about 1000 steps per second?

...R

I dont know how long the process of accelerating and decelerating takes. The stepper should be able to do up to 5k PPS @ ~13 N.cm.

1.000 steps per second would be 5 revolutions per second @ 200 steps. That would be sufficient, yes.

NEMA17:
1.000 steps per second would be 5 revolutions per second @ 200 steps. That would be sufficient, yes.

That should certainly be achievable - see the benefit of numbers

The acceleration should all happen within about a half revolution - but you will need to experiment with your actual machine.

...R

That would be great. Thanks again for your effort!

No point tuning an unloaded motor, tune it under the actual load, as the max speed and acceleration
depend on many factors including the load and the load resonances.