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I have been working on a robot project for a while. Now I am tired of finding parts that just does the job, so it is time to do create parts.

A 3D printer will do the trick for many parts, but 3D printers share a lot with a CNC mill in terms of control and parts. So my question is this:

I am building a Reprap style printer, but I will use more heavy duty parts and motors, hoping to make a aluminum capable 3 axis mill later. I found some bipolar NEMA 23 stepper motors at 1.9 Nm and 3 Amps per coil. According to the reprap.org website, they recommend NEMA 17 and low voltage. Seems to me that they use voltage to limit the current.

Can I build a reprap, and use current limiting stepper drivers with an Arduino and some software I find online, and get away with these large stepper motors? Or am I in for a lot of trouble?

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I'm using a NEMA23 on my Y axis on my greatly frankensteined MendelMax. The bed was elongated to 350mm along with other upgrades, so I needed the bigger motor. It's running nice and cool at 26 volts on standard Pololu DRV8825 stepper motor controllers.

Note however that CNC platforms and 3D printer platforms have only three things in common: X, Y, and Z axes.

Otherwise, 3D printers tend to want to be very fast (150+ mm/s), very light, low torque, with modest precision (0.1mm is ok).

CNC mills tend to have a lot more torque, can be much slower (5mm sec would be ok), and would want higher precision (0.01mm).

While many reprap based 3D printer designs use belts for the X+Y axes for their speed (and screws for the Z axis for holding power); most CNC designs tend to use leadscrews on all three (or four) axes.

If you want a machine that can do both, it's best to start out with a CNC design and use leadscrews. Then you can make a very slow but very precise 3D printer.

That's much better than a wimpy belt-based CNC machine that won't have enough torque to even mill out plastic.

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  • $\begingroup$ Could I get away with more heavy duty belts? Or is the gearing from leadscrews required, torque-wise? $\endgroup$ – frodeborli Jul 9 '14 at 23:44
  • $\begingroup$ Edit: You need the torque, holding strength, lack of backlash and stretch of a leadscrew. $\endgroup$ – RoboKaren Jul 10 '14 at 2:29

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