# Do You Know The "Secrets" Of The Stepper Motors?

Hello guys! How are you?

If you know something about arduino and stepper motors, then read this: my name is João and I'm trying to build an selective laser melting machine.

To do that, I am going to use 6 stepper motors to move the axis, and I was thinking about using arduino to control then.

I have zero knowledge on arduinos but I need to learn it as fast as possible.

Do you have any tips on how to control then and also what is the best thing to study regarding this topic?

Thanks,

Joao.

Hi,

I am learning about stepper motors as well. To run a stepper motor from the Arduino you add a "shield". shields will control 1 and maybe 2 stepper motors but I don't remember seeing one that can handle 6, so you may end up using more than one Arduino.

Why do you need six steppers? I can see X,Y and Z axis plus an axis to index lasers but that only makes four, what are the two other axes for?

When the stepper motor is stopped it still draws power but it will hold its position without the need for a brake.

Check what size of step your stepper motor makes. It may step by 1.8 degrees, though micro-stepping may be possible. So, if you want to move by less than 1.8 degrees you may need gearing.

Because the you can count the steps the motor takes you don't need to use encoders to work out your position. That is providing you use the motor within it limits and you do not cause it to jump by applying too much force.

It is worth remembering that mechanical devices have inertia. You cannot move them to full speed instantly or stop them instantly. If your laser system has a lot of mass then you will need to accelerate the stepper motor up to full speed and then decelerate it back down.

That is about all I know. I am not sure how big a motor the shields can handle i.e. how much power the motor can draw.

These links should help get you started

...R

I have a stepper motor that I know nothing about, voltage/current wise. It is probably from an old printer or scanner, and it will probably take 12V, but I used 5V to test. It has six wires in two bunches of three.

By measuring the resistance, I figured out the center tabs.

Yesterday I built this on breadboard and got it to rotate by playing that sequence.

I believe I'm making 8 half steps.
When I go through the sequence 12 times, the motor makes one complete rotation.

If you are not set on what to use, get the A4988 as Robin2 says.

they use 2 pins and because of the commands, they are easier to use.

if you know nothing of motors, the best simplest I can offer is to get the LOWEST voltage possible and pay more for lower voltage.

power is based on how many times more voltage you supply.

say you have a 12v motor and drive it at 12 volts.
with the exact same motor rated for 5 volts, but supplied with 12 volts will deliver over twice the power.
same motor rated at 1.2 volts and powered by 12 volts and you might get close to 10 times more power.
(very sloppy enginnering, but trying to make a point)

also, you cannot deliver more than 24 volts to almost every driver under 2 amps and under \$50. they use chips that are rated for 35 volts INCLUDING spikes. and you WILL get spikes by the nature of the motor.

so, your 12v motor is never going to deliver as much power as your 5v motor.

Jobi-Wan:
I have a stepper motor that I know nothing about,

@Jobi-Wan, are you hijacking this Thread with your own question or are you trying to help @Josdc?

...R

Robin2:
@Jobi-Wan, [...] If you want help with your own question [...]

I do not need help with my motor. I was just playing with it for the sake of it; to see if I could control it.

Since this worked out for me, I figured it could be helpful for Josdc as well, to show how it was wired up and what high/low pattern I used. I know there are different kinds of motors around, so what worked for me might not work for Josdc.
(I am by no means an expert and had to figure out the coil layout by trial and error. Tonight I'm going to try 2 H-bridges.)

Jobi-Wan:
Since this worked out for me, I figured it could be helpful for Josdc as well, to show how it was wired up and what high/low pattern I used.