BLTouch (cheapo) don't trigger.



  • Having some issues hooking up my BLTouch knockoff. Or well the wiring is all good and as far as i can see the config is golden to.
    When i turn on the printer the probe does it's self test thing where it deploys and retract's with blinking a couple times before it stays in it's retracted state with the blue LED on.
    If i run the deploy or retract scrips they also work..

    The problem however comes when i actually try go get a reading from the bugger, it simply don't send a signal (or the duet don't pick it up).
    If i do a do a G30 and the bed starts rising (CoreXY machine) the probe dorps and LED goes off as it should, and if i touch the pin it retracts and stay there and LED turns on. But no reaction from the board.
    I've double checked and ohmed the cables all the way from the PCB side on the probe and down to the connector on the duet side and it's all good (even sanity checked that the resistor was up to spec and it read 248,4Ω).
    After that i disassembled the probe and adjusted the Z-screw on it so it's flush +/- 0.1mm with the top cap and tried again. Still no difference.

    If i measure the voltage over the "GND" and "Z-probe in" with power on it reads 3,2mV ish.

    My config.g setup: (i have it connected to pin31/heater7 btw, it's not a typo).

    M574 X1 Y1 S0 ; Set active low endstops
    M574 Z1 S2 ; Define Z to use Probe, home to min

    M307 H7 A-1 C-1 D-1 ; Disable the 7th Heater to free up PWM channel for BLTouch on the expansion header (pin31)
    M558 P9 H5 F500 T4000 X0 Y0 Z1 ; Set Z probe type/mode 9. H=Dive Height. F=Speed the bed moves
    G31 P25 X58 Y5.5 Z0.0 ; Set Z probe trigger value, offset and trigger height
    M557 X15:309 Y15:309 S20 ; Define mesh grid

    deployprobe.g:
    M280 P7 S10 I1

    retractprobe.g:
    M280 P7 S90 I1

    I totally see that cheaping out on the probe might been a dumb decision, but since it ain't exactly rocket sience going on inside it thought i would get away with it.

    Hope some of you see something wrong and can slap me in the right direction here, cheers!



  • Double check the crimps on the white wire.



  • the bltouch trigger signal is very short duration. most of the time you will not see a change in value.

    however there are numerous reports of quality problems with the bltouch clones.
    i had a clone myself and got fed up with the problems it was causing.

    so i build this
    https://www.thingiverse.com/thing:3303618



  • @phaedrux said in BLTouch (cheapo) don't trigger.:

    Double check the crimps on the white wire.

    Like i said I've ohmed the whole cable run from end to end and all is good, not a bad crimp this time.

    @veti said in BLTouch (cheapo) don't trigger.:

    the bltouch trigger signal is very short duration. most of the time you will not see a change in value.

    however there are numerous reports of quality problems with the bltouch clones.
    i had a clone myself and got fed up with the problems it was causing.

    so i build this
    https://www.thingiverse.com/thing:3303618

    Yeah think i read somewhere it's only 10ms or something, but even though i can't see the signal the board should when i send G30 and then tuch the tip (no pun intended).

    Unfortunately so, i can't even understand how it's possible to f**k up such a simple trigger type unless the hall sensor is borked, but then again if the hall sensor is dead the led shouldn't turn on/off whem the pin is manipulated either.

    Cute thing you've designed there, but if it comes to having to order more crap from Asia to get a z-probe it's going to be a original BLTouch 😂 I would def. give your thing a go if i had the optical sensor and servo laying around though!



  • it has other advantages. it is not prone to interference or magnets like the bltouch.



  • @veti
    True, but it adds quite a bit of weight and takes up more print head realestate 😕 and i guess it needs a somewhat more sturdy mount to (not that it's the biggest issue in the world to fix ofc).



  • I've been playing around with the "P" parameter in G31 changing anywhere from 25-600 (not one at a time ofc.) and no difference sadly.



  • @exerqtor

    when the bltouch triggers the signal goes to 1000. so any value above 0 would trigger it.



  • @veti said in BLTouch (cheapo) don't trigger.:

    @exerqtor

    when the bltouch triggers the signal goes to 1000. so any value above 0 would trigger it.

    Yeah that's what i found out after the post to, the only way i can get anything other than 0 is if i put I1 in the M588 lol.

    Any way to check the actuall in on the board? To simulate a trigger signal so to say.


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