Centroid Community CNC Support Forum

Hello all,

Need some advice on how to handle Z axis sliding after shutting down CNC12 application or upon Power Up.

I am using Teknic SDSK servos on all my axis. Double drive Y axis with master and slave setup, X and Z single drives, with Z axis utilizing 24V brake assembly. The control of Z axis brake is tight to HLFB output of Z axis Servo motor (according to Teknic’s manual page 59) to assist holding position while there is no movement on Z axis. Everything seems to be working fine, but I found that during shutdown process of CNC12 software and after launching CNC12 application, when status of all my servos is OFF(solid amber led), the Z axis brake gets energized, thus releasing Z axis, which slides down as a consequence and looses its position. If I physically disengage the brake power from HLFB pin from SDSK servo motor before CNC12 application and click MDI soft button, then all servos get into idle status (flickering green) at which point I can connect the brake circuitry to HLFB pin and maintain Z axis position without loosing it, but at this point servo motor is capable of holding the position on its own.
In ClearPath -MSP V2.0 application I am utilizing HLFB (High Level Feed Back) All Systems Go option. There are additional options under HLFB setting that are available, but didn’t seem to help me to accomplish the Z brake engaging/disengaging properly. When I set HLFB mode to Servo On mode the brake is not energizing to release the grip when there is a movement command to Z axis from control board.

Options available are:

Servo On
In Range-Position
Measured Torque
All Systems Go (ASG)-Position
ASG-Position, w/Measured Torque
ASG-Position-Latched
ASG-Position-Latched, w/Measured Torque

I would appreciate if anyone who experienced such problem can shed some light onto how to overcome this issue. Currently I installed the latching switch to disengage the brake circuitry on startup and shutdown of CNC12 app to work around it.

P.S. At the present time HLFB circuit mode that I use causes a relay flickering in ramping motion if I choose slow DOC (depth of cut) or shallow angle.

Have you tried the built in z brake function by setting an output?

Hi Gary,
I don't quite understand what you mean. Can you clarify it for me?

Look in the output configuration lists. One is for spindle brake

Thanks Gary,

I jumped over mentioned output about zillion times and never thought it would be applicable in my case. Learned it otherwise now.
Thanks again!

On the second thought Gary,

Doesn't this mean that my Z axis brake would be locked while attempting to Home the machine?

You'll have to look it up, I may be confusing the actions of two different modes. Spindle brake is not the one you want

On the same thought Gary,
I think Axis1,2,3,4BrakeRelease sounds intriguing to try.

Thanks

Arthur wrote: ↑Fri Jul 09, 2021 10:36 pm On the same thought Gary,
I think Axis1,2,3,4BrakeRelease sounds intriguing to try.

Thanks

You want Axis 3 (usually Z) brake release

martyscncgarage wrote: ↑Mon Jul 12, 2021 5:42 pm

Arthur wrote: ↑Fri Jul 09, 2021 10:36 pm On the same thought Gary,
I think Axis1,2,3,4BrakeRelease sounds intriguing to try.

Thanks

You want Axis 3 (usually Z) brake release

Hi Marty,

I rewired Z-brake circuit to OUT 8, and configured it as Axis 3 Brake. It does work, but when I exit CNC12, Z axis still slides a bit rather that staying fixed in the position it was at.

Thanks