Zprobe Weird Problem

Controllers Smoothie
1

Hi all,

I have an issue with my zprobe that I can’t explain.

After every successful print, the next print it will try and probe the bed but instead it will push the head in to the bed and then move to each point without lifting it up. When I cancel it, then try it again it does it properly.

I have an inductive sensor and an aluminium heat bed, so there is no issues there. I am using a relay on the sensor as I couldn’t get it to work properly using a voltage divider.

Here is my start gcode using cura 15.04:

;Basic settings: Layer height: {layer_height} Walls: {wall_thickness} Fill: {fill_density}
;Print time: {print_time}
;Filament used: {filament_amount}m {filament_weight}g
;Filament cost: {filament_cost}
M104 S{print_temperature} ;Start heating nozzle without waiting
M190 S{print_bed_temperature} ;Uncomment to add your own bed temperature line
M109 S{print_temperature} ;Uncomment to add your own temperature line
G21            ;metric values
G90            ;absolute positioning
M82            ;set extruder to absolute mode
M107        ;start with the fan off
G32            ;perform zprobe

I can’t work it out.

Imported from wikidot

2

Are you on a delta or a cartesian ? Which levelling system are you using in config ?

Can you try homing before the G32 ?

Thanks.

3

I am on a Cartesian using Z-Grid Levelling.
I had to remove the G28 as it would home Z and the grid levelling would complain about the probe already being activated so it wouldn’t probe.

Here is my Zprobe Config

zprobe.enable                                           true                    # set to true to enable a zprobe
zprobe.probe_pin                                        1.28^!                  # pin probe is attached to if NC remove the !
zprobe.slow_feedrate                                    5                       # mm/sec probe feed rate
#zprobe.debounce_count                                  100                     # set if noisy
zprobe.fast_feedrate                                    100                     # move feedrate mm/sec
zprobe.probe_height                                     3                       # how much above bed to start probe

leveling-strategy.ZGrid-leveling.enable                 true

leveling-strategy.ZGrid-leveling.wait_for_probe         false

leveling-strategy.ZGrid-leveling.home_first             true

leveling-strategy.ZGrid-leveling.bed_x                  158.5

leveling-strategy.ZGrid-leveling.bed_y                  200

leveling-strategy.ZGrid-leveling.rows                   4                       # X divisions (Default 5)

leveling-strategy.ZGrid-leveling.cols                   4                       # Y divisions (Default 5)

leveling-strategy.ZGrid-leveling.probe_offsets          0,0,0

leveling-strategy.ZGrid-leveling.slow_feedrate          100
4

Not sure what your isssue is, but on Smoothie Zprobes are not designed to be run every print or from a gcode file.

Zprobes are specifically setup to be run manually ONCE then you save the results and do not need to probe again unless you change the bed.

Also inductive probes are not very accurate and not really suitable for probing a bed as they return different results at different parts of the bed and detect not the surface of the bed but the uneven and uneven density of the metal underneath the bed.

5

I run it before every print because the print bed warps ever so slightly differently at different bed temperatures… I am using a 3mm thick aluminium sheet as my heated bed so there should be no uneven density and there is nothing on top of the bed for the sensor to ‘see’ through.

I think I will change my start gcode so that it doesn’t probe each time, and I can just manually do the probing when I think it needs it.

Thanks for the idea wolfman! :slight_smile:

6

Unfortunately this hasn’t solved the problem as everytime I try to do a G32 it will drag the nozzle over the print bed.

7

You have to home before doing G32 otherwise it has no idea where it is. it needs an initial reference which Home provides.