Marlin (3D PRINTING) with dc motor

Hi,

Hi have an extruder for 3d printing with nema 17 stepper motor. I need more power and for that the ideia is use a DC motor with gearbox.

What is the best way to user ramps 1.4 and stepper driver to control a DC MOTOR ? it's possible to user step and dir to control a DC motor easly ?

thanks.

You would need to add an encoder to the DC motor. Then modify the Marlin firmware to read the encoder. Or insert an extra component that takes the step+direction signal and counts the divisions on the encoder. You need an H-bridge driver for the DC current.

You would also need more gearbox as a DC motor doesn't perform well at 10RPM whereas a stepper is perfect for that speed.

Why not just get a bigger more powerful stepper? There are many different power ratings available in the NEMA17 case size and going up one case size will be smaller than the DC motor and gearbox.

RAMPS has all the stepper drivers on the big PCB. I haven't looked but I expect that it will be easy enough to hijack the step+direction and take that off-board to a new driver for your bigger stepper motor.

jot4p:
it's possible to user step and dir to control a DC motor easly ?

No, not unless its a full blown servomotor with accurate position control.

You don't need more power, you need more torque, ie a larger gear ratio from the existing size of
motor.

Thanks.

My machine is used to print clay, my extruder is a peristaltic pump controled with ramps stepper motor driver and 2 cogs ( stepper TO pump ).

I need to use a big motor for the clay pump (12-24 volts dc )

Its easy to use for small tests but i need to scale for a large version :slight_smile:

So space isn't a problem? Then get a bigger stepper with a bigger driver.

Maybe run the dc motor full bore and use a stepper motor to turn a valve to control flow rate. figuring out the steps per mm might be a little tricky....