x and y vibrate when moving to the z safe homing point

X and Y vibrate and move erratically when moving to the Z safe homing point

X,Y, and Z all move smoothly when moved individually.
X and Y both HOME smoothly
The problem occurs when X and Y move from their home positions to the SAFE_Z_HOMING_POINT
ABL is in Bi-linear mode and works pretty much as expected.

SKR 1.4 Turbo
TMC2209 Stepper Drivers Diag. pins removed. Mechanical Endstops for X and Y min
BLTouch ABL Endstop fro Z Min

Steps to Reproduce
Initiate "Home All" from BT TFT 24

Expected behavior:
X Homes to the Mech Endstop in the min. position
Y Homes to the Mech Endstop in the min. position
Z moves diagonally to the Z_SAFE_HOMING_POINT (roughly the center of the bed)
BLTouch deploys
Z homes to the build plate until BLTouch triggers

Actual behavior:
X Homes to the Mech Endstop in the min. position
Y Homes to the Mech Endstop in the min. position
--> X and Y vibrate and move erratically towards the Z_SAFE_HOMING_POINT but never fully make it.
--> The Main Screen on the LCD Displays the proper X and Y position
BLTouch deploys
Z homes to the build plate until BLTouch triggers

Additional Information
Lowering XY _HOMING_FEEDRATE (20*60) and raising HOME_BUMP_DIVISOR (5,5,2) help.
If I physically push the X and Y carriages they will move to the Z_SAFE_HOMING_POINT
Junction deviation is set to 0.013 by default. (I dont understand this one yet).

Please let me know what additional information might be helpful?

mlm: attachmnet MarlinConfigFiles.zip

OK, Found it.

Short answer:
make XY_PROBE_RATE the same as HOMING_FEEDRATE_XY
In My case:
#define XY_PROBE_SPEED (20*60)
#define HOMING_FEEDRATE_XY (20*60)

Slow but stable.


Long answer:

#17857
acwest opened this issue on May 3 · 5 comments
Comments
@acwest
acwest commented on May 3 •
Bug Description
When homing with G28 Marlin (at least in Bugfix-2.0.x, I didn't check any other versions) is using the wrong speed to move to the safe homing position. Currently the code is using XY_PROBE_SPEED, which is the speed to use when moving between points while doing ABL, which may or may not be configured by the user. This speed is often set quite high (the default is certainly quite high on my system), which tends to cause quite a lot of noise at the beginning of every print.
This should probably be HOMING_FEEDRATE_XY, as this is part of every G28, not ABL at all.

My Configurations
configuration.zip

Steps to Reproduce
G28 (with safe homing enabled)
Expected behavior: homes using the homing feedrate

Actual behavior: homes using the ABL probing feedrate

Additional Information
The code in Marlin/src/gcode/calibrate/G28.cpp uses do_blocking_move_to for both quick_home_xy() and home_z_safely(), while it should probably be using do_homing_move()
The other possibility is that do_blocking_move_to() should use homing_feedrate() for xy, it already uses it for z, but it seems unlikely (although the fact that it uses it for Z might be a bug)

@thinkyhead
Member
thinkyhead commented on May 5
When not defined HOMING_FEEDRATE_XY is assigned to it automatically. It is the preferred setting to use because it is intended to differentiate the speed that could harm the probe from the speed of approach to endstops.

@thinkyhead thinkyhead closed this on May 5