Touch Sensor and Plasma Torch Height Control Configuration for UCCNC 



There are two ways of commanding the plasma cutting sequence.  You could command all the actions using gcode commands (M3/M5 to as torch on/off, G31 for probing, and G4 for piercing delays) or you could set all the operating parameters and just command the plasma using the M32/M52 macros.  These instructions will configure the system to use it both ways.  

M32 Macro performs the following actions:

  1. Probes or moves down the Z axis to the "Z Min. height" position that is set in the DRO for this value and the feed that is set in "Probing feed rate".
  2. Verifies that the Probing Enable is disengaged if the option is checked in the config "Check probe disable".
  3. Set the current position to be the new Z = Zero considering the Z Offset if a Floating Head is used.
  4. Moves the Z up at max velocity to the piercing position or DRO = HEIGHT.
  5. Turn on the Torch.
  6. Wait for pierce time or DRO = THC Delay.
  7. Moves the Z up at max velocity to the cut position or DRO = CUT HEIGHT.
  8. Activate THC.

M52 Macro performs the following actions:

  1. Turns the torch off.
  2. Deactivates the THC.
  3. Moves the Z axis at max speed to the position where it would be safe to move at max velocity to the next cutting position.  This is DRO =Z Top.

The screen holds the new DRO values and also has the code that will enable the probe while the system is probing.

Software Used: UCCNC Version 1.2115

Hardware Used:
THC-1 or THC-2, PTS-1



Start by making a backup of the existing installation:

Make a backup of the configuration and file installation, we recommend creating a backup of the current installation by right-clicking in the current installation folder and zipping it.



Download and install the new screen and macro files:

Download the compressed file containing the macros and screen that work with the macros:

You will need to install the screen found in the download folder and place the macro in the macros directory for the profile folder.


Make a backup of the original M32, M52, and M99998 macros by zipping them into the same folder, just so you may have access to the original macros if you need to revert the installation later: 




Set UCCNC to use the new screen that you just copied:



Apply Changes, Save Settings, and Restart UCCNC for all the changes to take effect. 

On the Main Screen, you need to set the piercing parameters: 


  1. Set Z_Top which is the safe position from which you can do a rapid motion to the new cutting position.
  2. Set how low you want the Z-axis to go while probing or touching the plate.
  3. Set the THC delay or Piercing Time.
  4. Set the height at which you want to start cutting or do the initial pierce.
  5. Set the OFF SET_Z.
  6. Set the Probing FR.
  7. Set the Check probe disabled.
  8. Set the THC MAX.
  9. Set the THC MIN.
  10. Cut height




Probe pin configuration.  This is the pin used to sense the probing action.  This pin will go high when the probe touches the plate. If using a floating head where the z axis will need to travel to the switch position, you need to set the Z offset.





STEP 8: Post for SheetCam:

  • 8.1 UVCCNC CNC4pc plasma no Z CNC4pc plasma no Z

This post-processor works with all the data on the screen and uses the M32 and M52 macros.


The function of these instructions is to show the operation of the postprocessor for sheet cam with Z for UCCNC.


Load the postprocessor to be used: Select the "UCCNC CNC4pc plasma with Z" postprocessor in Options/Machine.


Click on "Set a post-processor variable".


Enter the values of the variables to be used on probing: Steps 2 and 3 may need to be repeated for each variable.  these can be: offset (offset of the floating head switch), zminheight  (how low the Z axis goes while probing), and probingfr (Velocity at which probing will be executed).


Create Cut Feature:  After having entered all the variables, we proceed to do the cutting operation.

Scroll through each step.


Testing and Troubleshooting Considerations:

Test Probing with a PTS-1 or Floating head:

  1. Note that all the position values are considering that work Z zero is the plate position and we recommend setting this before executing the gcode.
  2. For the initial testing, make sure the plasma machine is off and you can observe the plasma relay activating and deactivating accordingly.
  3. Do the initial testing using the G31 Z-40 F20 command in the MDI screen, and you should be able to see the torch start probing.
  4. You can observe the probe enable LED on the screen LED and the Enable LED on the PTS-1 unit itself when it starts probing and the touch LEDs on the screen and PTS-1 unit.

Test that the Touch Relays Starts/Stops the Plasma

M3 should start the plasma and M5 should stop it.  Observe action on the screen LEDs, Output pins of the breakout board, relay and plasma cutter.


Test THC action:

  • Press the knob three times to enter test mode in the THC and observe the ARC OK signal activate.
  • Turn the knob up or down to move the axis and observe the Torch UP and Torch Down LEDs activate when moving in each direction.  The Z-Axis should also move to adjust the position.
  • To exit test mode, press the knob once.

Test the complete sequence which includes probing, piercing cutting with THC.

Configure the THC parameters according to the manual: 

Run this G code that does not use macros:

N0050 F20       (Set the Probing Speed 20mm/sec)
N0060 G31 Z-10  (Start probing axion on the Z-axis to a depth of up to 10mm)
N0070 G92 Z -3  (Set work zero for the z axis using an offset of the switch) 
N0080 G00 Z 2   (move the Z-Axis 2mm up. initial pierce )
N0090 M3        (Start the Torch)
N0100 G04 P2    (Set a Pause of 2 seconds to allow the pierce time.)
N0110 G00 Z 3   (move the Z-Axis 3mm up. Cut height)
N0120 G01 X5    (Cut a 5mm square.)
N0130 Y5
N0140 X0
N0150 Y0
N0160 M5        (Turn off the Plasma)
N0170 G0 Z5     (move the Z-Axis 5mm up. Z_top)

Feel free to adjust it to your units or other preferences.


Test using the macros


Keep in mind the macro will now execute the following actions when M32 (Start Cutting) and M52 (End Cutting):

  1. If using a PTS-1 (Plasma Touch Sensor), the first section is to Enable the Probing action.  You should see the ENABLE LED on the PTS-1 and also on the breakout board on the LED for the pin that you wired and configured for activating the probe.  In these instructions, we are using Pin 1 on Port 2. 
  2. The Z-axis lowers until the nozzle or sensor that you connected on the nozzle touches the plate and closes the circuit and activates the probe input.  You would momentarily see action for this on the TOUCH LED on the PTS-1 unit or the switch if using a Floating Head, on the LED for the input pin you assigned on the Breakout Board, and on the Probe LED on the UCCNC screen.
  3. As soon as probing is completed, the Probe ENABLE is disabled and the z-axis moves to the Pierce position or the Pierce Height that you configured.
  4. The plasma starts by activating the plasma relay and stays cutting for the duration of time that you configured or set as Pierce Time in Seconds.
  5. After pierce time the z axis moves to the cut position that I set in cut height
  6. The Plasma stays on and continues to execute g-code and THC if implemented until an M5 is reached or e-stop is pressed.


Configure the operation parameters in this screen:

G code with macro:

N0090 M32       (Probes, pierces, moves to cutting position, and start the torch)
N0100 G01 X5    (Cut a 5mm square.)
N0110 Y5
N0120 X0
N0130 Y0
N0150 M52       (Turn off the Plasma and move the z axis to Z_Top)


This instruction is the update for these old instructions.