Wiring issue

Mostly Printed CNC - MPCNC Troubleshooting
1

I’m having some troubles with my MPCNC wiring. When I detach my stepper motors from RAMPS and try to move axis by hand I get lots of vibration and drag from the motors as the coils would be connected (even without any powers on). I followed MPCNC wiring tutorial and connected my motors in parallel.

Here’s the type of motors I have: http://www.ebay.co.uk/itm/5PCS-59Ncm-Nema-17-Stepper-Motor-2A-4-wire-1m-Cable-for-DIY-3D-Printer-CNC-Robot-/121658128135?hash=item1c5363b707

Now I’ve connected black wire (A) leading from RAMPS to the black wires of the both stepper motors. Same goes with the green wires ©. Now the red wire (B) I’ve attached to the red wire of the first stepper motor and to the blue wire (D) of the second stepper motor. With blue wire I’ve inverted connection.

When I move my axis I start to get drag and vibration as if magnets of the motors are activated. Problem disappears when I detach either first or the second motor. Problem start if I connect parallel even only the other coil (black and green wires or red and blue). What I’m doing wrong here?

2

Unfortunately the color codes of steppers aren’t a standard, so they could be wired differently internally. You’ll need to play around with the wires to figure out the correct pairs.

3

Thanks for the tip Barry. I’m aware that there’s no stardardized colors but from the link above you can see that black and green wires form a coil. The other coil pair is red and blue wires. I also tested that these match description.

4

You should not be moving it fast enough by hand to get that kind of feedback even if it is disconnected.

You can wire them in series or parallel.

What happens when it is plugged in and you try to move it?

parallel for those would be black (a) and green© on both motors to the first two pins on the ramps port, and then red(b) from one and blue(d) from the other to the third pin, then the two that are left to the fourth pin.

series is in this order ramps pin1-stepper1 a, stepper1 c-stepper 2 a, stepper 2 c to ramps pin2. understand what is happening here you can follow the current from the ramps board through both coils back to the ramps board. Then ramps pin 3-stepper 1 b, stepper1 d-stepper 2d, stepper 2 b-ramps pin4.

5

Thanks for the clarification. Well I was wondering how this should work since stepper motors should work as a generator if pulled by hand. If coils of two stepper motors are connected (or even one) this should form a closed circuit. So when I pull one of the axis by hand it should generate electricity which activates magnets and thus it starts to resist movement at the same time.

Before I began to play with wires I got stuttering moves (just like one descibed before) when I tested movements from RAMPS. It is entirely possible that I had attached some wires wrong. Seems like I have to return on this one again tomorrow.

6

Problem is fixed now. Seems like there was some improper connections made up. After rewiring motors the problem disappeared. Just got my first moves with MPCNC. Tomorrow I’ll be running a full test.

7

Awesome, it sucks to try and track down a bug but hopefully it didn’t discourage you too much and you learned a little something along the way.