Wondering on best board for my guitar pickup winder

Projects General Guidance
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I am slowly working towards building a guitar winder, but wondering about the best choice of motherboards. I have a Mega, (and I still might have an Uno around here somewhere)
I will be running two Nema 17 stepper motors, both the same speed, but one will need to reverse direction several times. There is no requirement for this to be battery operated. I will only be using it indoors, with power nearby.

I know the Mega has more inputs but is slower processing speed. It will probably be okay for this project though. I'm not going to be doing production winding, there is not massive computations going on (just counting), I'm just experimenting. If I can automate it totally, I can leave it unattended, and the speed doesn't matter.

I would like to encase this in a small cabinet in the end though, after I work out the LCD and input keyboard, so, I will have one eye towards board size, heat dissipation, etc, but, if need be, I can just build a large enough box around it. Doesn't need to be portable.

Stepper motor specs, which I originally lapsed on:

  • [Parameters]: Body Length: 40mm/1.58inch; Step Angle: 1.8 degree; Phase: 2; Rated Voltage: 3.3V; Rated Current: 1.5A; Phase Resistance: 2.2Ω; Phase Inductance: 4.5mH; Holding Togque: 42N.cm (59.47oz.in); Detent Togque: 1.8N.cm (2.55oz.in); Weight: 280g.
  • [Dimensions]: Nema 17 Bipolar Stepper Motor: 42x42x40mm / 1.66x1.66x1.58inch, Shaft Diameter: Φ 5mm ( D Shaft Φ 4.5mm ), Shaft Length: 24mm, 2 phase, 4 leads.

Any suggestions?

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  • Sounds like an UNO would suffice.

  • Don’t overlook using a geared motor for this.

  • Suggest you look at using a modern stepper driver chip.

  • Always show us a good schematic of your proposed circuit.
    Show us good images of your ‘actual’ wiring.
    Give links to components.
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Thanks. I know I said speed doesn't matter, but, the unipolar pictured in your image won't run over 15rpm. I was thinking 100-200rpm maybe. But I did just get that unipolar to run (when I finally lowered the speed to 15). Otherwise it just sat there and got hot, not turning.

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  • You know that is a link to a YouTube video :thinking:
    It is a good starting out video.

  • BTW, there are many stepper libraries available for Arduino projects.
    One very good one is the AccelStepper library.

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Sorry, I just flashed on the image and it brought up what I just found out with trying to use the unipolar. I have that video saved off in my useful links, but haven't watched it within the last week. I have a couple of different stepper controller boards I just got to experiment with:

TB6600,

L293D (seems it said it would handle stepper too)

# CNC Shield V3.0 Expansion Board Kit with Board for Arduino, 4PCS DRV8825 Stepper Motor Driver and Heatsink

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  • Put this in a picture frame and hang it on your workroom wall. :smiling_face_with_sunglasses:
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Meaning, it won't do the job?
image

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Slower than what?
The Uno R3, classic Nano and Mega all run at the same clock speed of 16MHz.
I once ran 48 stepper motors at max speed with a single classic Nano.

A 3.3volt/1.5Amp stepper motor requires a current controlling driver, like the DRV8825
And a 12volt (minimum) supply.

An Uno R3 with a CNC shield could be the most practical way to control two stepper motors.

No.
A L293D motor shield is totally unsuitable for 3.3volt/1.5A stepper motors.

Normal behaviour.
BYJ28-48 stepper motors with ULN drivers use the most power when standing still.
Leo..

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  • That driver is based on old BJT technology.
    Its ON voltage is quite high therfore low efficiency.

  • Modern MOSFET based controllers are far superior and have better features.

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I guess I need to start doing calcs and reading the details, instead of just reading the headlines
image

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An L293D would want to put 12/(3.3volt/1.5A)= 5.5Amp into each coil on a 12volt supply, which will release the magic smoke.

3.3volt/1.5A stepper motors need current control, not just a H-bridge.
Uno R3 CNC shield. for up to four drivers.
Leo..

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Ok, it looks like I'm going to have to study myself out of my "I don't want to have to think, I want this all to be plug and play". What are some introductory sources for calculating handling capacities? I know V*A=W. I know ohms is resistance. I guess I'm needing to figure out how I put this knowledge into play when gauging component parameters. Any pointers? I'm decent at math (except trig has been too long ago for me to do some things).

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Forget about calculating.
Stepper drivers work like switching buck converters.
The keep a constant current through the coils, independent of motor speed.
Voltage falls automagically into place.
DRV8825 drivers have a pot, to set the desired coil current before you connect the motor.
Leo..

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There are CNC shields for the Uno (it also fits a Mega, but a Mega is really overkill here). You have a choice of motor drivers that fit these boards.

I made my first winder with this shield, on an Uno. There was enough pins left over to add a potentiometer (connected to an analog input, for speed adjustment) and the SDA/SCL lines open for a display.

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