Precision Piezo z probes guide for duet users reference

DjDemonD

So R is a pause before probing. Use around 0.4 seconds, some points on the bed might false trigger if your bowden cable goes tight.

xepherys

I have an Orion on a new build (not in service yet). I'm using this in config.g:

;Precision Piezo Orion
M558 P8 I1 H5 R0.5 F150
G31 X0 Y0 Z-0.05 P600

Last night I finally got the Orion wired and was able to home Z with it several times... all was well. This afternoon I came back to it, and it crashed the bed (not bad, I have the speed fairly slow and was able to kill it quickly). I discovered that the blue LED (trigger) is constantly lit. What can cause this?

Thanks!

DjDemonD

I would check the calibration potentiometer. Adjust it as per the documentation. It is a good idea to make this adjustment, at the temperatures you would normally use when probing the bed. So if thats with heaters off, calibrate with heaters off and vice versa. Piezos do change sensitivity when heated or cooled, its a very sensitive instrument.

ajcraig99

I am having trouble getting my new peizo to trigger using G30, it works when I run homez.g but when I run G30 it just crashes into the bed.

Is the issue with my M558 line?

; homez.g
; called to home the Z axis
;
; generated by RepRapFirmware Configuration Tool on Sat Jul 21 2018 13:51:16 GMT+1200 (New Zealand Standard 
Time)
G91               ; relative positioning
G1 Z5 F6000 S2    ; lift Z relative to current position
G1 S1 Z-295 F1800 ; move Z down until the switch triggers
G92 Z2.5          ; set Z position to trigger height

; Uncomment the following lines to lift Z after probing
;G91              ; relative positioning
;G1 Z5 F100 S2    ; lift Z relative to current position
;G90              ; absolute positioning

From config.g

; Z-Probe
;M558 P0 H5 F420 T6000             ; Set Z probe type to switch and the dive height + speeds

G31 X0 Y0 Z-0.1 P600               ; Set Z probe trigger value, offset and trigger height
M557 X15:305 Y15:285 S20          ; Define mesh grid
M558 P8 H5 I1 R0.4 F1800 X0 Y0 Z0

dc42

See item #1 in the FAQ page on the Duet3d wiki.

Agniusm

I have a concept i would like to test including piezo. I have bought a set for my extruder assembly but had difficulties mounting it and i scrapped that idea and using prusas induction probe ever since. Resolution is very good and i am happy with it. That being said i have thought of a concept that i would like to validate with you clever people.
i have large cartesian printer based on CR10S4 frame. As i have piezo "in stock" i would like to try and use it as tool offset. Mainly the idea came from thinking about e3d tool changer.
I want to mount piezo disc on the frame beside the bed. i will know piezo Z offset from the bed which will be constant. If i can have duet and piezo cooperate so the Gcode would move my nozzle off the bed where piezo disc is located and touch it to record Z offset then go about the routine of mesh mapping with induction probe.
This would eliminate the need to fiddle with Z offset all together, when you change the nozzle, clean a clog or do maintenance.
Any outside pointers on this?
alt text

Moriquendi

I don't see any reason why this wouldn't work, others are working on a similar idea using the new M585 command.

Idris

Agniusm

@moriquendi said in Precision Piezo z probes guide for duet users reference:

I don't see any reason why this wouldn't work, others are working on a similar idea using the new M585 command.

Idris

Can you point me to those workings?

Moriquendi

@agniusm I can't I'm afraid, he's not published it yet so it's not on a forum. No doubt when it's ready I'll be able to link to it.

Idris

tjb1

Maybe I missed something in my M558 setup but I can't seem to get analog to work on the Orion? Does the Orion have an analog signal? I've watched DWC while moving/probing and its either at 0 (red light) or 1000 (blue light), I don't see any numbers in between.

Moriquendi

@tjb1 The Orions output is strictly digital, you will only ever see 0 or 1000 unless there is noise on the signal wire.

Idris

cabal2000

@ajcraig99 Sir. Did you get it working?

Lakko

What I have to do if I want to reset a piezo 20 to factory value?
I have doubt that it is broken.
Other questions, if I use P1 in M558 so I can change sensitivity on the fly, the P in the g31 is useless?

Moriquendi

Which version of the Piezo20 do you have, there is a version number on the back, underneath the piezo connections pins.

You cannot change the sensitivity using P1, the output of the module is digital, it's either on or off. The only way to adjust the sensitivity is with the potentiometer/s on the board.

Idris

Lakko

@moriquendi said in Precision Piezo z probes guide for duet users reference:

Which version of the Piezo20 do you have, there is a version number on the back, underneath the piezo connections pins.

I have the piezo20 v0.6

@moriquendi said in Precision Piezo z probes guide for duet users reference:

You cannot change the sensitivity using P1, the output of the module is digital, it's either on or off. The only way to adjust the sensitivity is with the potentiometer/s on the board.

Idris

Sorry Idris i badly explained myself, i meant that if i use P1 instead of P5 or P8 for example:

M558 P1 I0 R0.4 F330
G31 X0 Y0 Z-0.1 P100

Than i can use VR1 on piezo PCB to adjust the sensitivity on the fly but the threshold P100 in the G31 is useless or it is still used?

Moriquendi

To reset the v0.6 to factory settings, turn VR1 and VR2 so that the flat part of the adjuster is closets to the bottom of the PCB.

You CAN use P1 but it has no advantage over P5 or P8 and may have some disadvantages. The output of the PCB is either 0v (roughly) or 3.3v (again roughly, later boards are better at this, they go closer to 0v but for this explanation assume 0v). The duet reads these values as either 1000 or 0. Because the output is digital, the value is either 1000 or 0 but nothing else inbetween. So the threshold makes no difference except that noise or interference on the signal wire might cause a false trigger.

David might be able to give more detail about how the firmware processes P1 and P5/8 differently.

TLDR: use P8

Idris

Lakko

@moriquendi said in Precision Piezo z probes guide for duet users reference:

To reset the v0.6 to factory settings, turn VR1 and VR2 so that the flat part of the adjuster is closets to the bottom of the PCB.

Last question, clockwise or counterclockwise?

@moriquendi said in Precision Piezo z probes guide for duet users reference:

David might be able to give more detail about how the firmware processes P1 and P5/8 differently.

it isn't necessary, it was just a curiosity.

Thank you for your help Idris

Moriquendi

Either way, there are no physical stops.

Idris

papilio

@moriquendi ...

Hi Idris!

I'm afraid that I seem to be having quite a lot of trouble with the new V2.75 board which I just received from you. I'm using an under-bed setup and had gotten it to work well, and fairly easily, with the V2.02 board -- but I wore out the pots on that one. Now I'm getting an insane level of false triggering which I seem unable to tune out. Might you by chance still have any V2.02 (or equiv) lying around?

I am wondering whether my trouble may merely be caused by the long (slightly over recommended) cables from the piezos, perhaps since in the current state of the build they're still just draped across other electronics under the bed -- but again, the same was true with the earlier board and no problems were evident. Might shielded cables resolve my issue? Having trouble locating stranded ones on Amazon.

I'm still stunned every time I look at your piezo endstop board, knowing that you soldered the entire thing by hand.

Michael

Moriquendi

Hi Michael

The v2.75 version of the universal PCB has two solder jumpers on the back, closing the two jumpers will allow you to use the full tuning range of the board.

As supplies the v2.75 board has the tuning window reduced, this makes it easier to tune because you need more rotation of the pot for the same change in tuning. For most people this is a good deal because most people don't need the full tuning range but for those who do it's just a matter of putting a blob of solder on each of the jumpers.

If you're looking for flexible, shielded cable you might try a headphone lead, they're often shielded.

I don't exactly solder them all by hand, I assemble them by hand and reflow them in an oven, I've got a video of the process here

Idris