New Button Idea & Awful Stepper Motor Controller

by Octapoo

Tuesday, May 19, 2020 at 23:46:00 UTC

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I've been trying to think of how to make button boxes more easily.

The simplest idea I've had is to make putting the foil on the back of the buttons easier. Each button gets a piece of foil tape which I then have to carefully trim with a razor blade to make the foil fit the button. Not only does it take about 90 minutes to make a full set, but it's also very frustrating work as it's 90 minutes of trying to carefully keep a razor blade within a range of about 0.1 mm while rotating this little thing and so it requires a lot of focus.

It occurred to me that it could be a lot easier if the buttons were to spin on their own. Then it would just be a matter of holding the razor blade in the correct place for a second or two. Assuming I could trim each button in about 10 seconds, it would only take 5 minutes to do a full set.

So to facilitate spinning the button I decided to make it a hexagon. This makes the button slightly smaller since I can't make the points of the hexagon stick out, but rather then sides just have to come in. However, I don't think that's a big deal, as hitting the already-smaller-than-I-would-like buttons is rather far down on my list of problems when playing the button box. The biggest issue is simply button wear and so making the buttons easier to produce is more important I think.

So here's the old buttons in green, and the new model in purple:

I also made an adapter to go on a stepper motor shaft that the button can fit inside of:

...and here's where I hit a problem: I can't make the motor go.

I have these stupid fucking motor controller boards I got on eBay:

There's a link printed on them,, but that doesn't actually say much about how you're supposed to use them. It says a lot, but primarily not much that's of use to anyone other than "don't put them in backwards" which seems like necessary advice given that the boards offer nothing in the way of any indication as to which way they should be oriented. There's no pin one marking and all of the text is printed in random directions. The pins are labeled, but only on the bottom where you can't see the labels while it is inserted into anything.

Anyway, all I could learn for sure is that the chip dies if a motor isn't connected. So I connected one, and then connected voltages to the pins I think are supposed to receive them, and the first chip overheated and died and the second one killed my 5 volt regulator. So, no spin.

I hate shit like this. I have a dozen guesses as to what might be the problem, but with no clear documentation to suggest which might be true, I don't really have any interest in trying a bunch of random guesses of which possibly none are the actual problem.

Long ago, a friend told me about these things and warned me that they die if used without a motor connected. So the motor was the first thing I connected. However, the motor has a connector on it which attaches to a cable with another connector that I poked some wires in (they did fit quite well) and those wires went to the solderless breadboard which went to this board. That's a lot of room for a loose connection. The connector on the motor seemed particularly loose, which kind of makes me afraid for my 3D printer since its motors have the same connectors and cables.

So I took the motor apart and soldered the motor cable directly to its internal wiring to remove the connector there. I also thought about soldering the cable to the controller board, but decided to read every word of the data sheet first for more ideas about what I might be doing wrong.

The datasheet just says stuff like "thermal overload protected" and "short circuit protected" and "requires no special start-up sequence." It doesn't mention that the chip will die if run without a motor attached, something my friend and the whole internet says is true. So I have no faith that the datasheet is giving me the whole picture.

So rather than try again, I just ordered a DC motor with a gearbox that's supposed to spin at about 30 RPM. It's supposed to arrive Tuesday.

It's also possible these boards just suck. I did get them from eBay, so for all I know it's a counterfeit A4988 or these boards were rejects.


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