Centroid Community CNC Support Forum

After a long absence, during which I had emergency surgery, then recuperated, and took a long planned (and delayed) safari to Kenya, I am back at the conversion. Have basically finished the enclosure and the electronics. Here is the current state of the control using a Rittal box:


And a few more shots:
Have wired up and configured the KP-3 using Marty's youtube video, and will move to rebuilding the base next.

Glad to be back, and thank you all for all your help thus far, will surely be back with many more questions.

I have added a Teknic z-axis brake that takes 24VDC. How do I wire it in? I tried using Axis3BrakeRelease as an output, but did not behave as expected (lock when e-stop activated, release otherwise). Any suggestion on what output to use or how to wire it?

Second, the diagram in the manual suggests using a Flyback diode. I know nothing of electronics, so can anyone advise specs or provide a link to what diode to buy?


Thank you.

DesertRider wrote: ↑Wed Feb 16, 2022 9:19 pm I have added a Teknic z-axis brake that takes 24VDC. How do I wire it in? I tried using Axis3BrakeRelease as an output, but did not behave as expected (lock when e-stop activated, release otherwise). Any suggestion on what output to use or how to wire it?

Second, the diagram in the manual suggests using a Flyback diode. I know nothing of electronics, so can anyone advise specs or provide a link to what diode to buy?

FLyback diode.png



Thank you.

Axis brakes are LOCKED when not energized. They unlock when the axis is called to move, whether jog, homing, MDI, when voltage is applied and stay that way unless there is a fault or an estop condition.

Agree, but how do you wire it in to the Acorn? In the most trivial approach, one can draw two wires from the 24V terminal block, so when the system is turned on the brake unlocks, and when the whole system is turned off, the brake activates and prevents the z-axis from creeping down. I had already done that and the brake works as expected and as you describe in the message above. That solves the problem of keeping the head from dropping and damaging the table, after the system is turned off, which is nice.

However, I want to add a second functionality, and that is where the brake will justify its value proposition (over a wood block). Specifically to lock the z-axis when either the hardware e-stop (on the control box) or the RESET button on the Acorn VCP is pushed. Why? Because pressing the VCP reset button during milling, but after probing the work coordinates allows the head to creep down, and thus the system loses the z position. So it'd be important to cut power to the brake (ie. allow it to lock) when the VCP Reset is pushed. I hope this makes sense.

So I think best practices would be to power the brake from an Acorn output, and that what I am asking. @cnckeith, @Centroid_Tech2, any suggestions? As mentioned, I tried using "Axis3BrakeRelease" as an output, but did not behave as expected. Any way to program this in the PLC?

A partial solution is to wire the brake through the hardware e-stop. I will try this today and report back. But that still leaves the VCP reset button question unsolved.

Finally, any suggestions or links to the diode?

You need a separate power supply, wire the positive side to the common terminal of the Acorn output relay you chose and assigned to axisbrakerelease, then from the normally open contact to the positive side of the brake. Then the negative side of the brake to the negative side of the brake power supply. Do not use the Acorn power supply for this.

A fault, VCP reset, or Estop press will open the brake circuit. Anything else would require custom work to the PLC
Marty

martyscncgarage wrote: ↑Thu Feb 17, 2022 11:28 am A fault, VCP reset, or Estop press will open the brake circuit. Anything else would require custom work to the PLC

Axisbrakerelease does NOT change the state of the output relay when the VCP reset is pushed. This is the crux of the matter. Any thoughts @cnckeith, @centroidsupport?

DesertRider wrote: ↑Thu Feb 17, 2022 2:35 pm

martyscncgarage wrote: ↑Thu Feb 17, 2022 11:28 am A fault, VCP reset, or Estop press will open the brake circuit. Anything else would require custom work to the PLC

Axisbrakerelease does NOT change the state of the output relay when the VCP reset is pushed. This is the crux of the matter. Any thoughts @cnckeith, @centroidsupport?

It certainly does on my test rig on the bench. I just tested it.
Please post a fresh report and I will load it on my bench test rig.
PLEASE post a screen shot of your diagnostics page as well (Alt i)

Marty

E-stop buttons are 99% of the time NC switches. I have my axis brake wired through one of the contactors on my E-Stop, so when the E-stop is pressed, it engages the brake. Also when the power is turned off to the mill, it engages the brake.
I didnt do anything with acorn I/O for the brake

As mentioned above, power to brakes release it. They are spring loaded.

martyscncgarage wrote: ↑Thu Feb 17, 2022 2:49 pm
Please post a fresh report and I will load it on my bench test rig.
PLEASE post a screen shot of your diagnostics page as well (Alt i)

Here are the attachments. Thank you for looking into this. The output is OUTPUT2.