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No retroactive changes with M851 Z

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If using babystep to adjust the Z probe offset, the axis will move and the mesh will be updated at the same time, causing a doubling of the Z offset over the rest of the print.

To correct for this, the current Z position would need to be modified in the opposite direction, canceling out the additional Z offset added to the mesh. This would be confusing to users, and moreover it would not be accurate without also taking the current Z fade level and current Z height into account.

It might make sense to change the mesh in the case where no babystepping is taking place, but this could be considered an undesirable side-effect of changing the `zprobe_zoffset`.

One way to remedy this would be to return to storing the mesh with `zprobe_zoffset` included, then subtracting `zprobe_zoffset` from the returned Z value. Thus, a babystep moving the Z axis up 1mm would subtract 1 from `zprobe_zoffset` while adding 1 to all mesh Z values.

Without including the `zprobe_zoffset` in the `z_values` there is no safe way to alter the mesh in conjunction with babystepping, although it's fine without it.
This commit is contained in:
Scott Lahteine
2017-11-16 16:53:55 -06:00
parent 7dacc999b9
commit 3bba7d60f3
6 changed files with 8 additions and 63 deletions
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36
Marlin/src/module/probe.cpp
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@ -640,42 +640,6 @@ float probe_pt(const float &rx, const float &ry, const bool stow, const uint8_t
return measured_z;
}
void refresh_zprobe_zoffset(const bool no_babystep/*=false*/) {
static float last_zoffset = NAN;
if (!isnan(last_zoffset)) {
#if ENABLED(AUTO_BED_LEVELING_BILINEAR) || ENABLED(BABYSTEP_ZPROBE_OFFSET) || ENABLED(DELTA)
const float diff = zprobe_zoffset - last_zoffset;
#endif
#if ENABLED(AUTO_BED_LEVELING_BILINEAR)
// Correct bilinear grid for new probe offset
if (diff) {
for (uint8_t x = 0; x < GRID_MAX_POINTS_X; x++)
for (uint8_t y = 0; y < GRID_MAX_POINTS_Y; y++)
z_values[x][y] -= diff;
}
#if ENABLED(ABL_BILINEAR_SUBDIVISION)
bed_level_virt_interpolate();
#endif
#endif
#if ENABLED(BABYSTEP_ZPROBE_OFFSET)
if (!no_babystep && planner.leveling_active)
thermalManager.babystep_axis(Z_AXIS, -LROUND(diff * planner.axis_steps_per_mm[Z_AXIS]));
#else
UNUSED(no_babystep);
#endif
#if ENABLED(DELTA) // correct the delta_height
delta_height -= diff;
#endif
}
last_zoffset = zprobe_zoffset;
}
#if HAS_Z_SERVO_ENDSTOP
void servo_probe_init() {