Feedback on my Masso G3 controller build PART 2

MX4660 driver wiring:

Power comes from the 48 VDC PSU through two pairs of POS+/NEG- wires into the two POS+/NEG- inputs

Stepper motor step/direction wiring follows that of the DB9 enclosure connectors: red=A+/green=A-/yellow=B+/blue=B-

I have ferrites on the step/direction wires from each motor

The DB9 black ground wires from the motors are connected to a set of five joined ground terminal blocks, which are connected back to the mains VAC ground terminal blocks

I temporarily have the MX4660 Estop+ and Estop- pins shorted with a wire loop until I decide how to connect them to the overall safety circuit

I have a DB25 cable connecting the MX4660 to a screw terminal breakout board for ease of wire connection. I also added a ferrite to this cable

I connected pi #25 on the breakout board to one of the shared common terminal blocks

MX4660 driver/stepper motor related suggestions/guidelines I tried to follow:

  1. Do not exceed the voltage rating of the driver. I chose a 48VDC to stay below max rating of 60 VDC

  2. Provide enough amperage for the motors. I chose 12 Amps which is over 2/3s of peak (12A / 4.2A X 4)

  3. Provide common ground termination point for motors

  4. Provide electrical ’noise’ protection using ferrites on motor/component signal wires

MX4660 driver/stepper motor related questions:

  1. I already asked a question regarding how to wire the MX4660 estop with the Masso, and have it part of my safety circuit – thank you for those who responded. I have yet to decide what to do.

  2. I have connected a wire from Pin #15 on the MX4660 which provides a 5V ‘Fault’ signal that can warn if any of the 4 driver modules are in protection mode (e.g.; over current/voltage). What is the best way to connect this to the Masso.

  3. Could Pin #25 on the breakout board instead be connected to one of the Masso GND(G) inputs? The manual has it as I have done - to the Masso power supply (-) common.

Masso G3 wiring:

Power comes in from the dedicated 24VDC PSU. The POS+ wire connects through a 1 Amp fast blow fuse terminal block to one of the PWR+ inputs of the Masso.

The NEG- wire connects from one of the shared common terminals to one of the GND (G) inputs on the Masso

The Masso S+ step signal outputs for the X, Y, Z, and B axes are connected to pins 2, 4, 6, and 8 respectively on the BB9 breakout board

The Masso D+ direction signal outputs for the X, Y, Z, and B axes are connected to pins 3, 5, 7, and 9 respectively on the BB9 breakout board

*Pin #25 from the breakout board is already connected to a shared common terminal block

I have connected an Estop button using one available NC switch. The POS+ wire from the Masso PSU terminal block connects to one terminal of the NC Estop switch. There is then one wire that connects the other terminal of the Estop NC switch to the Masso ESTOP input Pin #2.

MX4660 driver/stepper motor related suggestions/guidelines I tried to follow:

  1. Try to keep step/direction wiring short between the Masso and the MX4660 driver

  2. Use the ‘B’ axis on the Masso for a CNC that uses a pair of Y axis motors

Masso G3 wiring related questions:

  1. Is using one large ferrite core around all 8 step/direction wires, as effective as using four smaller ones around each pair of step/direction wires?

  2. I have read numerous posts about this but just to confirm – Masso GND (G) Pins are actually common (NEG-) connections?


Wow, looking great Tom! I haven’t visited this part of the forum in some time so I just now stumbled across this. Nice work!

Thank you. I have learned a great deal from this and other forums (Masso, CNCzone,…). My controller is still just a temporary mock up as I will still be adding a few components to support a spindle, but also to see how to best use the space inside the enclosure. I received my 1F a few weeks ago, and am slowly setting it up. So far I have 3D printed mounts for my proximity sensors (used for homing), and have set them up and tested them in the Masso software. I also upgraded the stepper motors, and just received new Oldham couplings that I will install (my motors have 3/8" shafts, and for now have been running using 3D couplings I designed in Fusion 360 - they work surprisingly well with the other half of the original 10mm spider coupling). I ordered drag chains, and my next job is to design and print support brackets to attach them. I plan to soon provide updated photos in case anyone is interested in my build. I am excited to be able to soon test the accuracy, precision, and repeatability of my new CNC build.


Dang, look at you go!! That’s awesome! Looking forward to pics when you get everything pulled together.

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This is looking really good!

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Hi, how did this turn out (or any updates?)

Hi @TMToronto qq: can you view the masso status over the network? I often key an eye on simple runs from my PC which is a distance from the cnc.

This is possible using Masso Link software.
Here is a link to the description.
Jump to the 5 minute mark if you want to skip the software installation instructions.

:smile: Hello Mr @TMToronto . I’m missing your kind offer of a link

Apologies, I was up at 3:00AM calling Germany, and perhaps was not as awake as I had thought.


That’ll do nicely. Not the same experience as with the buildbotics web app but does the key elements for me; load files from PC, mill status.

I hope your call with Germany was fruitful.

Thank you, it was - I am helping my Mum sort out pension and tax details.
My situation will most likely not make much use of the Link software, but it is nice to have it available.