Getting my first stepper

I’m working on a project right now that’s going to require – among other things – a stepper motor. As such I’m on the market for a motor shield and a stepper, two things I’ve not bought before. Here’s what I’ve been looking at:

Shield-wise:

I’ve been looking at Arduino’s Motor Shield R3, mainly because it will still allow me to access the other pins on the board. I’ll be controlling 4 micro servos (from a dedicated power supply) too, so I need to keep four other pins available:

http://arduino.cc/en/Main/ArduinoMotorShieldR3

Stepper-wise:

I’ve been looking at Sparkfun’s ROB-09238 (albeit from a UK seller) for a balance of power and price, which I should also be able to power using a 12V DC supply I picked up for driving a solenoid a while back. Right?

https://www.sparkfun.com/products/9238

Will these two play nice? Is there anything specific I should know about power requirements etc.? I've got plenty of experience using servos now, so I'm cool with those, but steppers are new to me!

What will you use for the stepper power supply? What will you use for the servo power supply?

Hi,

Sorry, I wasn't clear in my previous post: I've already got a 5v power supply I've used for servos in the past, and I've got a 12v wall-wart that I've used for solenoids (both with wires trimmed and connectors added for protoboards/breadboards).

I just wanted to confirm - or not - that I'm barking up the right tree with this shield and motor?

What performance are you wanting from the motor? That one has 33ohm windings so it won't be very fast - also it would be easier to drive if it was unipolar.

I'd check the motor can do what you want before committing to it.

An A4988 driver is superior to the L298-based motor shield.

1) Interface designed specifically for steppers -- only needs two pins to control it (step and direction) 2) Current limiting is automatic 3) More efficient (mosfet-based vs. the L298's transistor-based design) 4) max 35V input allows your stepper to reach higher peak speeds

Putting that another way, using L298-based drivers is a huge hassle compared to drivers designed specifically for stepper motors.

The A4988 board is compatible with any bipolar stepper but can only supply max 1A current (continuous or without a heatsink/additional cooling). You can use a motor that allows more than 1A current but you won't get the maximum torque from the motor.

Thanks for the tips!

That A4988 driver looks to make things much simpler, takes up fewer pins, and is cheaper! I've found some good examples online, including some that utilise the AccelStepper library.

Speed isn't an issue, but I'll need to weigh up the carriage I want it to move. At this stage, I'll probably pick one up just to get some experience using a stepper, then work out what's right for my project as it progresses.

Many thanks for your advice and input, this is giving me plenty to read about and learn!

A4988 driver probably needs 18 to 24V minimum to convincingly drive that motor - there needs to be some overhead in the voltage for the chopper buck-conversion to work. Chopper drivers are normally used with low impedance motors to get better performance.

Just to follow up on this:

Stepper and driver arrived today and they're working just fine. The stepper's running pretty quickly, although I'm yet to try pulling any weight with it.

It was getting pretty hot to begin with, but I tuned the pot right down on the Pololu board and it cooled off, seemingly without losing any performance.

Thanks again for all the help and advice, I'll keep it on hand and study up more as I go along!