Problem with precision PIezo

alil2096

Good morning everyone,

I have a problem with my precision piezo (original). I've a duet with these settings:
Board: Duet WiFi 1.02 or later
Firmware: RepRapFirmware for Duet 2 WiFi/Ethernet 2.05.1 (2020-02-09b1)
Duet WiFi Server Version: 1.23

When I send G29, the force needed for activate the piezo is very very high.

But the most stranger things is that, if I try to put P8 (or another one number except for P1) in M558 line, the value showed in Z-Probe field in DWC is 0 or 1000 (it depends if I put I0 or I1 in M558 line), and if I try lo lunch G30 command, nothing is heppening when I touch the piezo.

My probe config are:

; Z-Probe
M558 P1 I1 H2 T7000 R0.3 F360			; digital mode, NO/NC, delay, speed, not used as axis endstop
G31 X0 Y0 Z-0.45 P530				; X Y Z offsets. P=debounce interval (The debounce interval in ms smoothes the signal)
M557 X15:375 Y20:320 S30			; define mesh grid

Some additionals info:

my piezo is used only for probing, for homing I've two physical endstop;
the wirings are good (not connector, but the wires are solder on pins, all is isolated correctly);
in my DWC, in Z-probe field, are showed the value "523", and it change if I try to push the piezo;

Thanks in advance

Andrea

Phaedrux

P8 is digital mode, so 0 or 1000 makes sense.

P1 is analog mode, so you'd get a range of values.

It sounds like your piezo has lost sensitivity. Is it possible that there is some damage to the mount or printer structure that is allowing more flex than before?

I'm not sure what the lifespan of piezo sensors are, but perhaps it's become fatigued or a connection has become marginal?

alil2096

@phaedrux thanks for your reply

I'don't belive, because I've re built a new carriage, and I've check all connetions..

But with P8, if I send G30 command and touch the nozzle, nothing happening.

Phaedrux

If you give it a sharp tap with a piece of metal does anything register?

Can you try changing to G31 P25 if you intend to use P8 mode?

alil2096

@phaedrux

absolutly nothing
what do you mean? I don't know G31 command

alil2096

@phaedrux Ok, I've tried and nothing happening..

alil2096

I've tried to connect a NPN sensor (LJ12A3-4-Z/BX), with the signal line on Z_PROBE_IN (and using an external power supply) the behavior is the same:

My code:

; Z-Probe
M558 P5 I1 H2 T7000 R0.3 F360			; digital mode, NO/NC, delay, speed, not used as axis endstop
G31 X0 Y0 Z-0.45 P25				; X Y Z offsets. P=debounce interval (The debounce interval in ms smoothes the signal)
M557 X15:375 Y20:320 S30			; define mesh grid

and when I send G30 command the probe works well (the led is correctly activated when a metallic surface is near the sensor) but the bed doesn't stop.

I'm going crazy with these configurations

But by completely changing the type of sensor, it makes me think that the problem is on the board.

Edit:
my last test was to connect the sensor directly to the scehda, to avoid interference on the cables, but nothing, it doesn't work. The stop sign is completely ignored.