OK - complete noob here. New to steppers and practical electronics a bit rusty.
I’m building a cnc machine using nema 17s. I’m building the engineering hardware first and \i want to test each axis as I make it with a stepper. I’m not ready to develop the electronics side of the project yet.
So, all I want to do is simply and cheaply turn a nema 17 at full speed (200 steps) in either direction with as little extra hardware as possible.
I read somewhere if you keep STEP high it will operate the stepper continuously like a DC motor. Is that true?
No, that is not true. On the A4988, each transition from low to high on the STEP input advances the stepper motor one step. So, keeping STEP high will result in the stepper motor remaining stationary. The coils will still be energized, however, so the output shaft will try to hold its position.
For a simple way to test your stepper motors, you might be interested in our Tic stepper motor controllers, which are general-purpose modules for controlling stepper motors through a variety of control interfaces, like USB for direct connection to a computer.
Now THIS looks interesting…
May I ask a couple of extra questions?
Of the 6 you show, only 1 says terminal blocks and headers are ready soldered - are two of your descriptions wrong (I dont want to do any soldering if possible!)
Does your software allow for continuous rotation and will it run on windows 10?
I can’t quite see the practical difference between the 3 types. All can be USB controlled, but there are slight differences in input voltage and maximum current - is that all?
Please could you advise me on the best for my purpose? I will pc control via usb, don’t want to solder, will be using nema 17s (I added the spec below), and I’ll probably power it with a 5V mobile phone charger.
Motor type: Bipolar Stepper
Motor Length: 40mm
Phase Resistance: 1.5Ohm
Phase Inductance: 2.8mH
Detent Torque: 2.2N.cm
Rotor Inertia: 54g.cm2
Holding Torque: 40N.cm
Motor Weight: 280g
Unfortunately, those descriptions were wrong! We have made some corrections, so it should now be obvious which Tic products come with soldered headers and terminal blocks. (For each of our 3 types of Tics, there should be two versions: one that comes with male headers and terminal blocks included, but not soldered and another version that has those things already soldered.)
Yes, given that your stepper motor is appropriate for the Tic, you should be able to run it continuously. The Tic software works with Windows 10. More on that can be found inside the Tic’s user’s guide, which you can find under the “Resources” tab of any Tic product page, like this one.
In addition to the differences in input voltage and maximum current, another key difference between the drivers is that the Tic T500 can only achieve 1/8 microstepping, while the others can make smaller steps with 1/32 microstepping. The stepper motor drivers on the Tics perform slightly differently, so which Tic is most appropriate for your system depends mostly on the specifications for the stepper motor you want to control and how you want to control it. Can you share a link to a datasheet or product page for the stepper motor you plan to control? (I saw the specs you wrote out, but am looking for a couple other things like the rated coil current and rated voltage.)
Thanks Jon. Heres the link. I took a risk and ordered a POLOLU-3134 Tic T500
It should be possible to control that stepper motor from the Tic T500. However, note that the Tic T500 can only handle about 1.5A continuously if you do not have additional cooling, so you will have to set your current limit to lower than the 1.7A rated coil current of your stepper motor. If you want to control your stepper motor with the current limit set at the rated coil current of 1.7A, you will need to do something like add a heatsink and external forced airflow to help keep the driver cool.
Thanks for that. I might pop it in a box with holes and a little cpu fan but in practice itll only be run for a few seconds to test the mechanics of my axes.
Thanks for your help Jonathan. It arrived yesterday and got it up and running first time today. No fuss, no soldering - just added an old 19v HP printer power supply and made some ends with a crimper.
Already put my endorsement on the DIY CNC facebook group.
Now I have to start planning what to get to run my 4 axis home made lathe.