@Phaedrux Okay thanks i'll check it soon

@BjornH currently I'm using Heater3 pin from expansion port. In the past i tried heater 5 and got the same results In My previous printer i isolated Bltouch wires from any other cable and that made a job but i dont want to make two separate cable harnesses

Forgot about something else. When i'm making mesh bed leveling around 400 points (500x500mm bed) this problem never occur..

Hi,
So i have strange problem with my BLTouch (Smart V3.1). 90% of the time my bltouch is working correctly. But sometimes on homing from Home all button on web interface or homing before print from start g-code bltouch pin just slide inside body and entire bed is crashing into my nozzle. I tweaked some settings. Tried various speeds. Made another set of wires. Nothing helped. I'm using Duet 2 wifi on newest stable firmware 3.2.2 i believe. Printer is a coreXY based on RatRig V-core V2.

On checking z height and setting true 0 for nozzle i got readings around +/-0.08mm i think its pretty ok for this type of sensor?

; homeall.g
; called to home all axes
;
; generated by RepRapFirmware Configuration Tool v2.1.8 on Wed Apr 01 2020 22:00:59 GMT+0200 (czas środkowoeuropejski letni)
G91                     ; relative positioning
G1 H2 Z2.5 F200         ; lift Z relative to current position
G1 H1 X-495 Y-495 F3000 ; move quickly to X or Y endstop and stop there (first pass)
G1 H1 X-495             ; home X axis
G1 H1 Y-495             ; home Y axis
G1 X5 Y5 F600          ; go back a few mm
G1 H1 X-495 F360        ; move slowly to X axis endstop once more (second pass)
G1 H1 Y-495             ; then move slowly to Y axis endstop
G90                     ; absolute positioning
G1 X230 Y238 F3000     ; go to first bed probe point and home Z
M558 A1 F600			; Set single probing at faster feed rate 
G30                     ; home Z by probing the bed
M558 A3 F100 ; Set multi probing at slower feed rate
G30 ; Probe again to get a more accurate position

; Z-Probe
M950 S0 C"exp.heater3"                             ; create servo pin 0 for BLTouch
M558 P9 C"zprobe.in" H5	R0.2 F100 T4000 A5 B1 		;set Z probe type to bltouch and the dive height + speeds
G31 P25 X-3 Y-48.5 Z1.8	                      	 ; set Z probe trigger value, offset and trigger height
M557 X25:440 Y25:440 S20                            ; define mesh grid
M307 H3 A-1 C-1 D-1								   ; Unbind the Heater Pin

So guys i just dissasembled entire axis for gantry and assembled again. Tensioned belts a little bit less and got this.

I think problem is solved? Idk what caused this thing

@Phaedrux cube have perfect 20.00mm X and Y dimensions are 20.4mm

@Phaedrux entire gantry is running smoothly everywhere in range. I'll check the bearings thanks. And i got another problem. I left the printer for 2 days. Nothing changed and printed a new cube for a test.... I got an ugly uneven layered cube... It looks like stretched belts or something? 1587016723028726541296325768824.jpg

@mrehorstdmd Heat-break almost stuck in Titan aero and volcano block is very tight impossible to unscrew without tools. Entire gantry is very stiff but heavy bcs of titan aero

@dliving I'm using reprap firmware probably 3.0

@mrehorstdmd printed 150mm vase and some artefacts appeard around the top but the bed is completly flat with glass and everything is directly laying at the entire z axis frame. Frame is on 4 sets of wheels with 3 z lead screws. I think its impossible to shift entire bed frame to one side. Rails and wheels are completly clean