delta: Add print_radius option to customize valid XY radius

Add ability to override the default XY move checking radius.

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

config/example-delta.cfg

@@ -107,6 +107,13 @@ delta_radius: 174.75
 #   axis towers. This parameter may also be calculated as:
 #    delta_radius = smooth_rod_offset - effector_offset - carriage_offset
 #   This parameter must be provided.
+#print_radius:
+#   The radius (in mm) of valid toolhead XY coordinates. One may use
+#   this setting to customize the range checking of toolhead moves. If
+#   a large value is specified here then it may be possible to command
+#   the toolhead into a collision with a tower. The default is to use
+#   delta_radius for print_radius (which would normally prevent a
+#   tower collision).
 
 # The delta_calibrate section enables a DELTA_CALIBRATE extended
 # g-code command that can calibrate the tower endstop positions and

klippy/kinematics/delta.py

@@ -36,6 +36,7 @@ class DeltaKinematics:
             rail.set_max_jerk(max_halt_velocity, max_halt_accel)
         # Read radius and arm lengths
         self.radius = radius = config.getfloat('delta_radius', above=0.)
+        print_radius = config.getfloat('print_radius', radius, above=0.)
         arm_length_a = stepper_configs[0].getfloat('arm_length', above=radius)
         self.arm_lengths = arm_lengths = [
             sconfig.getfloat('arm_length', arm_length_a, above=radius)
@@ -80,7 +81,7 @@ class DeltaKinematics:
                     + half_min_step_dist)
         self.slow_xy2 = (ratio_to_dist(SLOW_RATIO) - radius)**2
         self.very_slow_xy2 = (ratio_to_dist(2. * SLOW_RATIO) - radius)**2
-        self.max_xy2 = min(radius, min_arm_length - radius,
+        self.max_xy2 = min(print_radius, min_arm_length - radius,
                            ratio_to_dist(4. * SLOW_RATIO) - radius)**2
         logging.info("Delta max build radius %.2fmm (moves slowed past %.2fmm"
                      " and %.2fmm)" % (