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Patch for G29 final Z position

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Include all the necessary pieces to get the final Z position after
probing the bed, and add commentary about other possible changes.
This commit is contained in:
Scott Lahteine 2015-07-22 20:23:40 -07:00 committed by Richard Wackerbarth
parent d233976737
commit 5a7356b6fc
1 changed files with 20 additions and 3 deletions
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23
Marlin/Marlin_main.cpp
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@ -2744,11 +2744,28 @@ inline void gcode_G28() {
float x_tmp = current_position[X_AXIS] + X_PROBE_OFFSET_FROM_EXTRUDER,
y_tmp = current_position[Y_AXIS] + Y_PROBE_OFFSET_FROM_EXTRUDER,
z_tmp = current_position[Z_AXIS],
real_z = st_get_position_mm(Z_AXIS); //get the real Z (since the auto bed leveling is already correcting the plane)
real_z = st_get_position_mm(Z_AXIS); //get the real Z (since plan_get_position is now correcting the plane)
apply_rotation_xyz(plan_bed_level_matrix, x_tmp, y_tmp, z_tmp); // Apply the correction sending the probe offset
//line below controls z probe offset, zprobe_zoffset is the actual offset that can be modified via m851 or is read from EEPROM
current_position[Z_AXIS] = z_tmp - real_z - zprobe_zoffset; // The difference is added to current position and sent to planner.
// Get the current Z position and send it to the planner.
//
// >> (z_tmp - real_z) : The rotated current Z minus the uncorrected Z (since homing)
//
// >> zprobe_zoffset : Z distance from nozzle to probe (set by default, M851, EEPROM, or Menu)
//
// >> Z_RAISE_AFTER_PROBING : The distance the probe will have lifted after the last probe
//
// >> Should home_offset[Z_AXIS] be included?
//
// Discussion: home_offset[Z_AXIS] was applied in G28 to set the starting Z.
// If Z is not tweaked in G29 -and- the Z probe in G29 is not actually "homing" Z...
// then perhaps it should not be included here. The purpose of home_offset[] is to
// adjust for inaccurate endstops, not for reasonably accurate probes. If it were
// added here, it could be seen as a compensating factor for the Z probe.
//
current_position[Z_AXIS] = -zprobe_zoffset + Z_RAISE_AFTER_PROBING + (z_tmp - real_z);
// current_position[Z_AXIS] += home_offset[Z_AXIS]; // The probe determines Z=0, not "Z home"
sync_plan_position();
}
#endif // !DELTA