Stepper motor + driver - Is a 12V 2A power supply enough?

Other Hardware Motors, Mechanics, Power and CNC
1

PLAN / USE CASE:

I’m planning to build a 360° turntable with a Nema17 step motor, that is controlled by an arduino uno r3, A4988 step motor driver and is supplied with a 12V 2A external wall adapter. (arduino is powered separately via usb or onboard dc power socket)

I’m not planning to run the stepper motor at “high” speeds, since I want to film and photograph objects that are rotating fairly slowly (around 6 to 10rpm). When taking photographs, the stepper motor will be stopped every time I want to take a photo.

Not sure if this is the correct context for this kind of problem. If not, feel free to direct me!

USED PARTS & DATASHEETS:

Disclaimer - I did not build anything yet, because the parts have yet to arrive.

POTENTIAL SETUP: I oriented myself on this source

QUESTIONS: (I am assuming that I did a lot of things wrong, because I’m really new to this!)

  1. Power supply:
  • Will the power supply be sufficient enough to run the A4988 and the Nema17?
  • if not, what would you recommend and how did you calculate it?
  1. Step motor:
  • Is it correct, that the step motor has a holding torque of around 3,67kg-cm?
  • Are the rated voltage and rated current really “only” 2,4V and 1,3A? And should I power it with a 12V power supply?
  • Do I need anything else, if I want to run the motor at low speeds or does it support that, in combination with the driver, from the start?
  1. Step motor driver:
  • Do you have experience with this particular step driver?
  • Are there other drivers, that would be better suited for my goal?

Are there any other things that I really should pay attention too, if shopping for other parts or while building the circuit? - don’t want to fry everything with the first try :smiley:

EDIT:
In another forum I got the question, why I want to build the "system" from scratch and why I couldn't just copy what someone else has already done. - like these guys [LINK]

My answer: I want to learn the dos and don'ts of the hard-/ software I use. I want to be able to calculate the necessary factors myself so I can make changes to the setup when I want, without running into a new information/ knowledge gap every time.

Thank you very much for your help on this, really means a lot!

Jobbel

2

My reading of your datasheet is that the stepper motor current is 1.5 amps and the A4988 may struggle to provide that - even with a heat sink - however it is marginal and worth trying if you already have the driver. If you need the full motor current (for max torque) a DRV8825 driver may be a better choice.

However if the load is small and the required speed is low and if the A4988 cuts out at 1.5 amps you may find that you have sufficient torque with the driver current set to a lower value.

The motor voltage is essentially irrelevant. But you must adjust the current limit on the stepper driver to match the motor (or to a lower value) to protect the motor.

The 12v 2amp power supply should be fine.

I think your torque calculation is about right - but I often get those things mixed up.

...R
Stepper Motor Basics
Simple Stepper Code

3

I'm sorry for the super late reply! - but appreciate your answer and the VERY informative links you posted! :slight_smile:

Especially the "stepper motor basics" helped me a lot.

As you pointed out the A4988 is struggling to provide the 1.5 amps. - The maximum I can get out of the driver is around 1.2 amps.

Also with the setup I'm using the driver is heating up quite fast, even with a heatsink on. (average 85°C to 125°C)
Except for the temperature issue the driver & stepper motor are working just fine.

But I will probably buy a new / better driver in the next couple of days ^^

Kind regards,
Jobbel