Controlling steppers

#1

Hello,

I need a quick and easy way to control six stepper motors - probably NEMA 18s - from a Python program on a Raspberry Pi.

Is there a quick, neat and cheap solution for this?

Any pointers gratefully received!

#2

pimoroni have these but you would need to stack 3 of them so it falls under the pick 2 rule when it comes to cheap.

#3

I meant to ask: control for position or speed?

#4

Position. It’s for a Rubik’s cube solving robot.

#5

Ah.

I’m not sure that Adafruit board is what you want then. Hardware PWM will correctly drive the stepper at various speeds, but at the price of not being able to count the pulses.

As you’re going slow, I’d suggest using an Arduino with the accelstepper library. That gets you guaranteed pulse timings, and lots of options for the driver electronics. If you still need the Pi for e.g. logic in python, then interface the two (or use an Arduino Yun).

This Pi + Arduino code is over the top for what you want, but I could rip out the complications: https://github.com/tobyspark/TekonOneThree-Controller

#6

Or: you attach an encoder, and wire that absolute position information into the Pi and your code.

#7

I have a cheapo chinese 3d printer which you can have to salvage parts from, the mainboard, 3 steppers etc. won’t give you 6axis obviously but maybe its a helpful step (lol) in the right direction.

I think it has 4 nema 17’s.

In addition to the 3d printer:
I just found what looks like a knock off arduino and ramps board with 4 stepper drivers for it, in one of my boxes at home.

I guess for X,Y,Z, and the extruder.

#9

That’s a very kind offer, and I’d like to accept it!

I’ll need to come into the space this week to drop off my Secret Santa gift - I can’t make the party on Saturday. Are you in this week at all?

#10

Sure thing. :smiley:

Im considering coming in today at some point, but I’m fairly local to the space and can drop the stuff off on a more convenient day for you?

#11

Let me know what you find @RichM. I’m interested to know how those boards work.

#12

The adafruit ones?

#13

Looks like I’ll be over on Tuesday morning. Does that fit on with your plans?

#14

Which? Any of them. Used in anger is often different from looking at a website =]

#15

I’m thinking I will head in around midday. if thats ok?

#16

PMd you

#17

On my way in. Might be a few minutes past 12

Correction - hit traffic, WILL be a few minutes after 12!