I think the Pololu stepper motor swith 38cm lead screw will do the job I want, but I need some advice on the additional devices I need to buy to control and power them.
I want to mount 4 pairs of screw drives to work in tandem, each pair to move a set distance and later move back.
For the prototype that I am currently building, simple manual switiching would do to prove the design in principle, but untimately the final product would have a computer controler.
I also need to know what is the maximum force each screw can exert.
Hi Jim, welcome to our forum!
There are a few components required for getting steppers to turn:
- Controller of some kind: This will generate pulses on the step pin to tell the stepper driver to advance one step, and drive the direction pin high or low to tell it which direction to move in for that step. Microcontrollers are good at this provided you find the right code to put on them, and a favourite of mine is the Pi Pico:
Raspberry Pi Pico (with Soldered Headers) | Core Electronics Australia
Pololu also make boards that are already pre-programmed to control steppers in their Tic series:
https://core-electronics.com.au/catalogsearch/result/?q=tic
As an added bonus these also include stepper drivers on-board too! - Stepper driver: This will handle energising the coils of the stepper driver in the right order, and with the right amount of current (too much and you’ll cook the motor). The motor you’ve picked has a current limit of 1.7A, so whichever driver you pick, make sure it’s capable of that, and capable of limiting to that. A suitable model might be the 8825 in your case:
DRV8825 Stepper Motor Driver Carrier, High Current | POLOLU-2133 | Core Electronics Australia
Have a read through that product page for usage tips. - Power Supply: Make sure it can deliver enough watts to the stepper driver, and if you run into insufficient speed issues with the motors, try a higher voltage (see product page above for more info)
- Stepper Motor: Looks like you’ve got this one covered, it connects to the driver through 4 phase wires that need to be in the right order, otherwise the motor will skip instead of turn.
As for the code you will run on a microcontroller if you go down that route, you’ll have to do some research on what is available already, but in general you probably want a limit switch to “home” your steppers, and to think about whether the 4 motors need to move independently.
As for the moving torque, it’s usually less than the “hold torque” quoted on stepper motor pages, and you will probably be limited by the axial force maximum quoted on the motor datasheet of 10N or ~1kg.
Let me know if this spurs any followup questions 
This is an example of a manual controller. You still need the driver.
There are several varieties of this controller.
You could use it in analog mode (a potentiometer) or Step/Direction mode (two momentary switches).
For prototyping, if exact precision is not required, this would work:
https://www.ebay.com.au/itm/175074906656?chn=ps
The cheapest solution is a simple MCU, with additional work required to create some software to drive it. This effort is minimal as any MCU will have examples of how to drive steppers. This option is not only cheapest but is probably closest to the final design. For example:
1 Like
Thank you for your very helpful replies.
The protoype curently requires a force of 3Kg per driver but it only has simple sliding mecganisms, so I expect I could reduce the friction to 1Kg either by adding roller bearings or leverage. But a more powerful motor would be a better option. Can Core supply a more powerful motor drive?
Hi Jim,
GoBILDA have much larger motors/screws, though they carry quite a bit more cost:
Could you share some more details about the project? Maybe a diagram? We might have some more suggestions in that case as to where to go next.
Thank you. You have given me lots of options to explore & refine my design. I’ll get back to you soon.
