Anycubic i3 Mega to CNC

[n3roGit]

https://raw.githubusercontent.com/n3roGit/Anycubic_i3_Mega_CNC/refs/heads/main/Klipper/printer.cfg

Hi everyone,

I'm in the process of converting my Anycubic i3 Mega into a CNC router and have already made several modifications:

✅ Modifications and current setup:

Z endstops have been moved to the top instead of the default bottom position.
The filament runout sensor (^!PD2) is now used as a Touch-Off probe.
The spindle is controlled via the heated bed output (PH5).
Running Klipper (naikymen’s CNC fork) on a Raspberry Pi Zero 2W with MainsailOS.
✅ Motion and Endstop Configuration:

Cartesian kinematics (kinematics: cartesian_abc)
Work area: X: 220 mm, Y: 209 mm, Z: 200 mm
Stepper motors set to 8 microsteps
Dual Z-axis motors (stepper_z + stepper_z1), each with separate endstop pins
Max Z speed: 5 mm/s, Max Z acceleration: 100 mm/s²
✅ Touch-Off Configuration:

[probe]
pin: ^!PD2
x_offset: 0  
y_offset: 0
z_offset: 0
samples: 3  
sample_retract_dist: 5.0  
speed: 5.0  
activate_gcode:
    M400
deactivate_gcode:
    M400

❌ Issue:
I can't get Touch-Off to work reliably because G38.2 is not supported.
I’ve tried using PROBE or QUERY_PROBE as alternatives, but the behavior is inconsistent.

Has anyone successfully set up Touch-Off in Klipper's CNC fork?
Is there a specific approach required to make probing work correctly?

Thanks for your help! 😊

[noobydp]

There's not much info here on the error you're receiving, but I'm going to assume you've hit the same problem I had trying to write a macro to handle probing...

Note I use multiprobe2, not probe, but I think the issue is the same using probe, but you might want to swap to use multiprobe so you can use the touch off probe in all the axis, as well as using the dedicated endstops for the min/max position.

The info below assumes that you already have the probe working as an endstop, if not... you probably need to ignore this message.

You cant use probe in a macro and try to set a variable or offset with the 'current' position, because the system variable printer.toolhead.position is not updated within the macro.
My solution was to run the probe sequence and use update_delayed_gcode feature in klipper to call a second macro that does all the calculations based on the new position.

I have a macro that performs axis probing here: https://github.com/noobydp/CNC-Macros/blob/main/kcncCustomOperations.cfg
Look at PROBE_AXIS and the related _PROBE_AXIS_DELAYED

Because I have multiple probes, it expects a probe name as defined by the probe_G38_multi config. You could modify this if you didnt want to use multiple probes.