MPCNC Primo - power?

I bought the MPCNC Primo kit, with series wiring from V1. I’m confused as to how I’m supposed to wire up both motors & logic. I saw posts/documentation about bridging them, but I wasn’t given any short wires with my kit. I also don’t know what wires I’m supposed to be using to connect the provided power supply to the motors/logic area. The power brick has the green adapter on it for +/-, but not sure if I need to source my own wires (was under the impression only thing I needed to source was conduit for the rails).

Any assistance is appreciated :slight_smile:

Hey there. Check out this post I made Houston Build. Let me know if you still have questions after reading that. Item 3 and 4 are on wiring and power. There is also advice from others on things I did wrong with the power in there.

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Wow - that definitely helps. I will probably buy some thicker wire for the power though - but this makes more sense to me! Thank you!

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There’s no point in using wire that’s bigger than the one running from the power supply for the bridging.

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Yeah, I was just commenting on the pictures that banjodelta sent - the wires he used looked extremely thin, for low voltage things. What gauge wire do you think is ideal?

I cut the end off the power supply and wired it directly

I’m not using that board or power supply, so my comments are from my general past experience.

There are multiple recommendations on these message boards that the barrel connector/screw terminal adapter can cause reliability problems. If this were my setup, I would cut the barrel connector off the end of the power supply wire, then cut a couple of inches off the power supply wire and use that to make the bridge.


Thanks - I’ll do that. Any suggestions for gauge thickness?

No I think I used 22 gage and the wire from the power supply

Like Tom said there are multiple recommendations on these boards regarding the barrel connector, but after I switched out my jumpers I’ve been using the barrel connector since December and its been working fine. Just throwing it out there.

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Tom’s suggestion of using a section of power supply wire is a good one, but wired right, you can use much smaller wire for bridging if you want. Bring the power directly to the motor connections and then bridge to the control board terminals. The control board draws very little power compared to the stepper motors and doesn’t require heavy gauge wire.

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If you have main power into the steppers then bridge from there to the board power you shouldn’t need anything bigger 24awg to jumper between stepper and board power.

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Thanks everyone - this is all very helpful.

I ran into the same issue with the missing wires and wrote it up in my build thread. I bridged the gap with leftover wire from another project much thicker than required… and some helpful forum readers wrote on later what size was closer to appropriate which was not documented in the build instructions. The thicker wires are safe but don’t bend all that tightly.

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