G28 move Z-axis up too fast

I am having issues with the G28 command moving the Z-axis up in 20mm increments (the raise before homing value). The first move is faster than my steppers can move so they stall on my Prusa i3, running Ramps 1.4 with 8825 drivers.

I have changed the homing values, below are the settings from my configuration_overall.h

#define HOMING_FEEDRATE {150*60, 150*60, 300, 0}
#define MANUAL_FEEDRATE {100*60, 100*60, 300, 60}
#define DEFAULT_AXIS_STEPS_PER_UNIT {80, 80, 800, 94.1, 625, 625, 625}
#define MICROSTEP_MODES {16, 16, 32, 16}
#define MOTOR_CURRENT {1, 1, 1, 1, 1, 1, 1}
#define DEFAULT_MAX_FEEDRATE {5000, 5000, 100, 200, 100, 100, 100}
#define DEFAULT_MAX_ACCELERATION {1000, 1000, 100, 5000, 3000, 3000, 3000}

Edited 1 time(s). Last edit at 10/18/2015 03:05PM by randyf1965.

You have too high values

My values are:
#define HOMING_FEEDRATE {50*60, 50*60, 10, 0}
#define MANUAL_FEEDRATE {100*60, 100*60, 20, 60}

---

Davide
Immagina e Crea
Progetto Flusso canalizzatore 4 vie
My Thingiverse

With feedrates set at 10 Z axis BARELY moves

I am running 8mm acme lead screw Tr8*8-4 from [openbuildspartstore.com]

Still having the same issues with the 1st G28 moving too fast and too far

I reflashed my controller and have a similar issue

Now it works the 1st time :


>>>G28
SENDING:G28
echo: gcode_G28 >>>
echo: setup_for_endstop_move > enable_endstops(true)
echo: Raise Z (before homing) by 5.00 > (home_all_axis || homeZ) > destination: (0.00, 0.00, 5.00)
echo: >>> homeaxis(0)
echo: setup_for_endstop_move > enable_endstops(false)
echo: setup_for_endstop_move > enable_endstops(true)
echo: > TRIGGER ENDSTOP > current_position: (0.00, 0.00, 0.00)
echo: set_axis_is_at_home 0 > (home_offset[axis]==0.00) > current_position: (0.00, 0.00, 0.00)
echo: > AFTER set_axis_is_at_home > current_position: (0.00, 0.00, 0.00)
echo: <<< homeaxis(0)
echo: > homeX: (0.00, 0.00, 0.00)
echo: >>> homeaxis(1)
echo: setup_for_endstop_move > enable_endstops(false)
echo: setup_for_endstop_move > enable_endstops(true)
echo: > TRIGGER ENDSTOP > current_position: (0.00, 0.00, 0.00)
echo: set_axis_is_at_home 1 > (home_offset[axis]==0.00) > current_position: (0.00, 0.00, 0.00)
echo: > AFTER set_axis_is_at_home > current_position: (0.00, 0.00, 0.00)
echo: <<< homeaxis(1)
echo: > homeY: (0.00, 0.00, 0.00)
echo: >>> homeaxis(2)
echo: deploy_z_probe > current_position: (0.00, 0.00, 0.00)
echo: setup_for_endstop_move > enable_endstops(false)
echo: setup_for_endstop_move > enable_endstops(true)
echo: > TRIGGER ENDSTOP > current_position: (0.00, 0.00, 0.00)
echo: set_axis_is_at_home 2 > (home_offset[axis]==0.00) > current_position: (0.00, 0.00, 8.41)
echo: > AFTER set_axis_is_at_home > current_position: (0.00, 0.00, 8.41)
echo: > SERVO_LEVELING > stow_z_probe
echo: stow_z_probe > current_position: (0.00, 0.00, 8.41)
echo: Raise Z (after) by 5.00
echo: > SERVO_ENDSTOPS > do_blocking_move_to_z 13.41
echo: do_blocking_move_to: (0.00, 0.00, 13.41)
echo: <<< homeaxis(2)
echo: > (home_all_axis || homeZ) > final: (0.00, 0.00, 13.41)
echo: setup_for_endstop_move > enable_endstops(false)

But the 2nd time it moves down instead of up unless I do a G92 Z0:

>>>G28
SENDING:G28
echo: gcode_G28 >>>
echo: setup_for_endstop_move > enable_endstops(true)
echo: Raise Z (before homing) by 5.00 > (home_all_axis || homeZ) > destination: (0.00, 0.00, 5.00)
echo: >>> homeaxis(0)
echo: setup_for_endstop_move > enable_endstops(false)
echo: setup_for_endstop_move > enable_endstops(true)
echo: > TRIGGER ENDSTOP > current_position: (0.00, 0.00, 13.41)
echo: set_axis_is_at_home 0 > (home_offset[axis]==0.00) > current_position: (0.00, 0.00, 13.41)
echo: > AFTER set_axis_is_at_home > current_position: (0.00, 0.00, 13.41)
echo: <<< homeaxis(0)
echo: > homeX: (0.00, 0.00, 13.41)
echo: >>> homeaxis(1)
echo: setup_for_endstop_move > enable_endstops(false)
Reset.
echo: setup_for_endstop_move > enable_endstops(true)
echo: > TRIGGER ENDSTOP > current_position: (0.00, 0.00, 13.41)
echo: set_axis_is_at_home 1 > (home_offset[axis]==0.00) > current_position: (0.00, 0.00, 13.41)
echo: > AFTER set_axis_is_at_home > current_position: (0.00, 0.00, 13.41)
echo: <<< homeaxis(1)
echo: > homeY: (0.00, 0.00, 13.41)
echo: >>> homeaxis(2)
echo: deploy_z_probe > current_position: (0.00, 0.00, 0.00)
start THIS IS WHERE I RESET since the extruder is trying to drive thru the hot bed