How to Wire a Stepper Motor Brake (Back to Wall Mounting)

I’ve got my X50 and QCW frame installed on my shop wall, and will be mounting the controller and wiring everything next. I’ve modified the frame to hang my 1F with the X rail horizontal.

The weight of the X rail assembly is tremendous, and gravity brings it quickly to the bottom of the frame. I’m changing the Y steppers to 1.9Nm motors with friction brakes, and need help wiring them to brake upon power off or Estop activation.

The brake on the stepper will be connected to a 15W 24V power supply that seems like it should be wired into the control box at the on/off switch. But I need the brakes to hold the stepper in position when I press the EStop button, too. I have the breakout board in my controller, and pin 23 is marked EStop. Can that be used somehow to interrupt the 24v power to the brake? And where would the flyback surge suppressor need to go? I’m clueless about electronics, and all my research hasn’t made it clear to me, so far. Thanks in advance for any help you can offer!

Hey Justin,

in a datasheet of a stepper driver that supports motors with brake, you can find the conditions in which you want the brake to be activated:

Brake is fixed at:

  • Alarm Signal active
  • Enable Signal inactive
  • Error in the power connection of the motor
  • Error in the power connection of the brake

This means, you would need a logic that checks these four points, that are the cases where the system itself still has power (not the “hard” power cutoff of entire system) but you need to have the brake activated (you want that when the stepper’s electromagnetic detent / holding current is gone for some reason to prevent movable parts move by themselves because of gravity then).

The question is how works Emergency Stop on your system.

On the Masso-G3-Touch-based Onefinity Elite Series, the Emergency Stop Button(s) are directly connected to the “Enable” pins of all motor drivers (see motor driver specs) (besides being connected to the “ESTOP” input of the Masso G3 Controller, which in turn activates its “ES” output that controls the two relays inside the Elite Power Supply Box which interrupt the power supply sockets for “Router” and “Vacuum”. Note: The DC power supply sockets for the stepper motors in the Elite Power Supply Box are not powered off when hitting Emergency Stop Button!)

See also Elite stepper motor and driver specs for “Enable” and “Alarm” pins.

That’s just a summary of the facts you need to know in order to find a solution.

On the Buildbotics-derived Onefinity Controller on the Onefinity X-35/X-50 Series, Onefinity does not make use of the hardware input for triggering the “Estopped” mode. The big red button on top of the Controller Box is not triggering “Estopped” mode (as confirmed here), which means, hitting the big red button on top of the box will not take care to stop the router or the spindle!

But the Controller’s “Estopped” mode *will* take care to stop the router (if it is connected over a relay to ‘tool-enable’ on pin 15 of the 25-pin I/O port) and the spindle (by sending the VFD “STOP” command via ModBus over the RS-485 serial communications port on pins 10 and 11).

For this reason, it is always a good idea to wire a big red mushroom-shaped button to the “estop” input on pin 23 of the 25-pin I/O port and make it accessible near the machine operator.

(to be continued, got to leave for one moment)

I’m glad to have your help, sir. Could I not set a relay to pin 15 of the breakout board ( is that the I/O you mention?), which would shut power to the 24V power supply of the brake, rather than shutting power to a router? I’ll be running a spindle, so pin 15 is available.
I hate that I’m a dunce at electronics, but I’d much rather be spending my evenings designing pieces to carve rather than trying to learn enough electronics to design simple systems safely. What class of electrician specializes in this field of electronics? Who would I reach out in my small city to hire to set up this safety brake system? Or could I hire you to line up the correct parts and provide the details for me to assemble and connect everything? This is way different from my woodworking talent!

Hey Justin,

sorry that today I could not find the time to continue the post above :frowning:

I would agree to this. I am an electronics person as well as a woodworking person, so I can achieve the electronics solutions that are needed for this purpose.

pin 15 is the ‘tool-enable’ pin, that is activated with the ‘tool-enable-mode’ setting on the TOOL page, which means, pin 15 is triggered through the g-code command “M3 (start spindle)” and “M5 (stop spinde)”, and also when ‘estopped’ mode is entered (but not when big red button on the Onefinity Controller box is hit! Connect a big red button to pin 23 and ground on the 25-pin I/O port to make a big red button use of activating the ‘estopped’ mode).

The ‘tool-enable’ functionality is out of use when the ‘tool-type’ on the TOOL page is set to one of the VFDs for driving a spindle, since then the buildbotics-derived Onefinity Controller supports Modbus over a RS-485 serial communications line (unlike Elite Series/Masso G3 who do not) and controls the VFD over the serial ModBus port. But unortunately pin 15 ‘tool-enable’ cannot be assigned to be used to something else.

However the possible solutions for wiring the motor brake are not that complicated.

But unfortunately I can’t write more at the moment, got to leave again!

Hey all,

OT: please see author’s post about current health issue.