Hi Im super new to using arduino and would need some advice on a project im working on!
Im planning on using a motor that needs to be turning really, really slow. Its going to be connected to a spool which is winding a thread that in turn is connected to a weaving - undoing/unraveling the weaving. A slow winding machine basically. I've played around with the arduino and a dc motor that came with it, but figured i needed somthing like a stepper motor so it can go slow enough and still have some torque. Or is there another motor that can be used that would better suit the project?
Also how would you even go about calculating tourqe? The spool will be filled up with more and more yarn continuously but it will not be heavy, a couple hundred grams, like a ball of warn, at most. And there will be a slight resistance when the tread is pulled out from the weaving... I tried looking up how to calculate this but am left really confused haha.
Im also wondering about the power. Im thinking of using a nema17 which is 12V and 0.7A, what happens if I use some sort of powersupply that has a higher amp than the motor. Ive been looking at some videos where they have regulated the amp on the motordriver manually with a small screw. But my plan was to use this tutorial: https://docs.arduino.cc/learn/electronics/stepper-motors
but can i regulate the amp on the SN754410ne H-Bridge?
A stepper sounds to me like a great solution for this kind of job, as they're so easy to speed control even at low speeds. You may even look at steppers with a gearbox, slowing them down even more (and increasing torque as well of course).
For a stepper motor, use a stepper driver like the DRV8833. Very easy to control from an Arduino (just a pulse to have it make a step), and it can regulate the current as well.
The SN754410 chip is a very old design, it's from the 1980s. It is not designed to work with steppers (you will need some kind of external current control), and it is BJT transistor based (meaning huge losses compared to modern MOSFET based designs) so you will need a heatsink for it as well. I'd call this kind of chips obsolete.
For a 0.7A stepper I'd be looking at a 1.5A or bigger power supply, to have a comfortable margin. You just need one that has enough current available. If you happen to have a 5A one on the shelf, use it, the motor will only get what it's given by the stepper controller.
Steppers tend to run hot, if yours has more than enough torque you may lower the current it gets. It will keep the motor a bit cooler.
Maybe you think of the DRV8825? The DRV8833 is only a H-bridge and needs more than simply a pulse to turn the stepper.
I would prefer a stepper with lower voltage and higher amp ( about 1.5A for a NEMA 17). You can use e.g. a DRV8825 then and set the current as needed. PSU voltage for this driver must be considerable higher than the rated voltage of the stepper. As already mentioned, you can set the current as low as possible to still get the required torque. And you can use microstepping to get a smoother run of the stepper.
That's a dual H-bridge. Not dedicated stepper driver.
Depends on the current you put through... NEMA17 is a front plate size indication, it doesn't say anything more about the stepper itself. Of course as a rule of thumb bigger front plates mean bigger stepper motors mean more torque/power, but it's still not a power indication.
The TB6612 is not a dedicated stepper driver, but only a dual H-bridge. It is typically designed for DC motors. If used with a stepper it needs more pins to control ( not only step/dir ) and it doesn't support microstepping nor is it able to control the coil current.
But it works. Unless it takes quite a bit of force to remove the yarn from the weave he doesn't need much current. Have the light weight drum running on quality hearings.
I didn't say it doesn't work. But a dedicated stepper driver like the DRV8825 ( or many others ) give you much more flexibility and easier controlling ( with only step and dir input ). So I don't see why to use the TB6612 if there are much better alternatives.
Thanks for the answers! Ended up getting the DRV8825. The guy selling it insisted I also needed a breakout board for it to work. Which what I understand isnt the case? Couldnt say no and bought it but when I came home it says that the limit on it is 9V haha. So I guess I cant use it with my 12 V motor?
What did you buy in the end? The DRV8825 can handle up to 45V at Vmot. And I don't think a breakout board will change this ...
The DRV8825 is usually sold with a driver carrier like this:
The usable Voltage doesn't depend on that board, but on the driver board you put in. The printing on the board obviously refers to the A4988. And this stepper driver needs at least 9V as Vmot. (Min voltage for the DRV8825 is 8.2V, so not much less)
