force_move: Provide defaults for SET_KINEMATIC_POSITION parameters

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

3 files changed, 18 insertions, 14 deletions

diff --git a/docs/FAQ.md b/docs/FAQ.md
index 8a67dcf2..b9c1cd23 100644
--- a/docs/FAQ.md
+++ b/docs/FAQ.md
@@ -157,9 +157,11 @@ the desired movement to the "custom g-code" section of your slicer.
 
 If the printer requires some additional movement as part of the homing
 process itself (or fundamentally does not have a homing process) then
-consider using a homing_override section in the config file - see
-[example-extras.cfg](../config/example-extras.cfg) for further
-details.
+consider using a homing_override section in the config file. If you
+need to move a stepper for diagnostic or debugging purposes then
+consider adding a force_move section to the config file. See
+[example-extras.cfg](../config/example-extras.cfg) for further details
+on these options.
 
 ### Why is the Z position_endstop set to 0.5 in the default configs?
 
diff --git a/docs/G-Codes.md b/docs/G-Codes.md
index c97e77df..8ca4440c 100644
--- a/docs/G-Codes.md
+++ b/docs/G-Codes.md
@@ -195,10 +195,12 @@ section is enabled:
   low-level kinematics in an incorrect state; issue a G28 afterwards
   to reset the kinematics. This command is intended for low-level
   diagnostics and debugging.
-- `SET_KINEMATIC_POSITION X=<value> Y=<value> Z=<value>`: Force the
-  low-level kinematic code to believe the toolhead is at the given
-  position. This is a diagnostic and debugging command; use
-  SET_GCODE_OFFSET and/or G92 for regular axis transformations.
-  Setting an incorrect or invalid position may lead to internal
-  software errors. This command may invalidate future boundary checks;
-  issue a G28 afterwards to reset the kinematics.
+- `SET_KINEMATIC_POSITION [X=<value>] [Y=<value>] [Z=<value>]`: Force
+  the low-level kinematic code to believe the toolhead is at the given
+  cartesian position. This is a diagnostic and debugging command; use
+  SET_GCODE_OFFSET and/or G92 for regular axis transformations. If an
+  axis is not specified then it will default to the position that the
+  head was last commanded to. Setting an incorrect or invalid position
+  may lead to internal software errors. This command may invalidate
+  future boundary checks; issue a G28 afterwards to reset the
+  kinematics.
diff --git a/klippy/extras/force_move.py b/klippy/extras/force_move.py
index d7d357b7..a6d7adc2 100644
--- a/klippy/extras/force_move.py
+++ b/klippy/extras/force_move.py
@@ -89,13 +89,13 @@ class ForceMove:
         self.restore_enable(stepper, True, was_ignore)
     cmd_SET_KINEMATIC_POSITION_help = "Force a low-level kinematic position"
     def cmd_SET_KINEMATIC_POSITION(self, params):
-        x = self.gcode.get_float('X', params)
-        y = self.gcode.get_float('Y', params)
-        z = self.gcode.get_float('Z', params)
-        logging.info("SET_KINEMATIC_POSITION pos=%.3f,%.3f,%.3f", x, y, z)
         toolhead = self.printer.lookup_object('toolhead')
         toolhead.get_last_move_time()
         curpos = toolhead.get_position()
+        x = self.gcode.get_float('X', params, curpos[0])
+        y = self.gcode.get_float('Y', params, curpos[1])
+        z = self.gcode.get_float('Z', params, curpos[2])
+        logging.info("SET_KINEMATIC_POSITION pos=%.3f,%.3f,%.3f", x, y, z)
         toolhead.set_position([x, y, z, curpos[3]], homing_axes=(0, 1, 2))
         self.gcode.reset_last_position()