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    Precision Piezo z probes guide for duet users reference

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    • DjDemonDundefined
      DjDemonD
      last edited by

      @krzaku:

      Can the 3-piezo under-heatbed setup be directly attached to the silicone heater? And wont the heat damage the piezo speakers? The temperature is quite high, up to 140 degrees.

      No that won't work. The way I do it is make bed mounts which contain the Piezos and attach your bed to the mounts. I've tried using mounts which just support the bed at the sides, and mounts with screws to attach the bed to which are also adjustable. The Piezos can take a little temperature rise but not more than 60 degrees C approximately.

      Here's something to you started https://www.thingiverse.com/thing:2461746

      Simon. Precision Piezo Z-Probe Technology
      www.precisionpiezo.co.uk
      PT1000 cartridge sensors NOW IN, just attach to your Duet board directly!

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      • krzakuundefined
        krzaku
        last edited by

        I think there's something wrong with the link you posted.

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        • DjDemonDundefined
          DjDemonD
          last edited by

          Nope opens thingiverse to my design for a possible underbed piezo mount.

          Simon. Precision Piezo Z-Probe Technology
          www.precisionpiezo.co.uk
          PT1000 cartridge sensors NOW IN, just attach to your Duet board directly!

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          • krzakuundefined
            krzaku
            last edited by

            Shows a 404 error for me.

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            • whosrdaddyundefined
              whosrdaddy
              last edited by

              @krzaku:

              Shows a 404 error for me.

              +1, link doesn't work

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              • DjDemonDundefined
                DjDemonD
                last edited by

                That's weird when I click it it loads the page I linked to maybe because it's cached on my phone.

                Try this https://www.thingiverse.com/DjDemonD/designs

                It's about the 4th or 5th one down.

                Simon. Precision Piezo Z-Probe Technology
                www.precisionpiezo.co.uk
                PT1000 cartridge sensors NOW IN, just attach to your Duet board directly!

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                • SuperJETTundefined
                  SuperJETT
                  last edited by

                  I've had no luck getting mine to act as a z endstop and may be confused what I need to do.

                  On my corexy I have a mechanical z switch and have the piezo on my Titan Aero bracket (my own design, flexes/lights the led easily).

                  What do I need to do, do away with the switch and just use the piezo for endstop and mesh bed leveling or some combination?

                  Custom CoreXY at home with Duet Wifi, Hemera

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                  • whosrdaddyundefined
                    whosrdaddy
                    last edited by

                    Yes no switch need, use the probe for homing.

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                    • DjDemonDundefined
                      DjDemonD
                      last edited by

                      So home x, then home y, move to bed centre and send G30.

                      That should do it.

                      The only time this is not going to just work is if the motion required to bring nozzle and bed into contact is triggering the probe. If so lower acceleration and jerk for Z, and make sure you are using the R parameter in M558, such as M558 R0.4 to allow the frame/axis to settle before probing.

                      Also make sure M558 has X0 Y0 Z1 in it which means probe is used for homing Z. Although probably not necessary, as you can instead change your homez.g and probably your homeall.g file, to have the move to bed centre and G30 commands instead of the G1 S1 xxxx commands you would have been using before.

                      Simon. Precision Piezo Z-Probe Technology
                      www.precisionpiezo.co.uk
                      PT1000 cartridge sensors NOW IN, just attach to your Duet board directly!

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                      • SuperJETTundefined
                        SuperJETT
                        last edited by

                        Ah, now I finally figured it out after some confidence from your post. I had it all configured but when I was issuing G30 earlier after already doing it once, I'd get Error: Z probe was not triggered during probing move which means I needed to override the Z position.

                        Custom CoreXY at home with Duet Wifi, Hemera

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                        • SuperJETTundefined
                          SuperJETT
                          last edited by

                          A bit of interest.
                          https://www.facebook.com/groups/makerbot/permalink/1442086032575563/

                          Thanks DJ for helping me out so quickly.

                          Now I just have to implement it into my printing.

                          Custom CoreXY at home with Duet Wifi, Hemera

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                          • Lakkoundefined
                            Lakko
                            last edited by

                            Hi,
                            I have a D-BOT coreXY (30x30x30cm), i've purchased the precise piezo last week and it is on its way.
                            While i'm waiting for it i want to prepare the firmware.
                            So in Z probe section of config.g i've put the digital code:

                            M558 P5 I0 R0.4 F300 X0 Y0 Z1        ; Digital Z probe, also used for homing the Z axis
                            G31 X0 Y0 Z-0.1 P100				 ; Set the probe height
                            
                            

                            i would like to use the piezo also for the z home in z min so i put "Z1 in M558".

                            These are my homez.g and homeall.g:

                            ;**********************************
                            ;homeall.g
                            ;homing using a x-MIN, Y-MAX and z-MIN endstops
                            ;**********************************
                            
                            G91                       ; relative mode
                            G1 Z4 F400 	          ; lowers bed 4mm to avoid dragging nozzle over the bed
                            G1 S1 X-340 Y340 F2000    ; move 340/340mm in -X (x endstop is MIN) and +Y(y endstop is MAX)
                            G1 S1 X-340               ; course home X
                            G1 S1 Y340                ; course home Y
                            G1 X4 Y-4 F500             ; move away from the endstops
                            G1 S1 X-10                ; fine home X
                            G1 S1 Y10                ; fine home Y
                            
                            G1 Z4 F200                ; lowers bed 4mm to avoid dragging nozzle over the bed
                            G90                       ; back to absolute mode
                            G1 X150 Y150 F4000        ; put head over the centre of the bed, or wherever you want to probe
                            G30                       ; probe
                            G91                       ; relative mode
                            G1 Z4 F50                 ; move slowly 4mm in the +Z direction
                            G90                       ; back to absolute mode
                            G30                       ; probe
                            
                            
                            ;**********************************
                            ; homez.g
                            ;homing using a z-MIN endstop
                            ;**********************************
                            
                            G91                       ; relative mode
                            G1 Z4 F200                ; lowers bed 4mm to avoid dragging nozzle over the bed
                            G90                       ; back to absolute mode
                            G1 X150 Y150 F4000        ; put head over the centre of the bed, or wherever you want to probe
                            G30                       ; probe
                            G91                       ; relative mode
                            G1 Z4 F50                 ; move slowly 4mm in the +Z direction
                            G90                       ; back to absolute mode
                            G30                       ; probe
                            
                            

                            and in my starting code i put this to perform the bed leveling/compensation:

                            M561                      ; Cancel any existing bed compensation by sending 
                            M557 X10:290 Y10:290 S40  ; Define the probing grid
                            G29                       ; Probe the bed and save height map to SD
                            ;M190 S[70]               ; i don't have a bed heater 
                            M109 S130          ; set 130 extruder temp
                            G28                       ; home axes
                            
                            

                            Is this correct or i have to change something?
                            Any advice and suggestions will be greatly appreciated

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                            • DjDemonDundefined
                              DjDemonD
                              last edited by

                              Looks okay to me, but then I'm not so good at just eyeballing it and spotting errors, just use low motor current at first so any crashes just stall the z motor, not do any damage. And tune the piezo carefully, so that a gentle tap up triggers it, and you see the trigger on DWC screen in Z-probe box goes red and says 1000.

                              The do G30 with nozzle way above the bed, tap up with your finger or a tool, to make sure the firmware registers triggered and reacts to it before trying it on your bed.

                              Then hit home all and go from there. But I'd say you are well prepared.

                              Simon. Precision Piezo Z-Probe Technology
                              www.precisionpiezo.co.uk
                              PT1000 cartridge sensors NOW IN, just attach to your Duet board directly!

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                              • deckingmanundefined
                                deckingman
                                last edited by

                                I don't have a Piezo probe so can't comment on your homez.g but your homeall.g file has errors related to homing Y.

                                I note that the Y end stop is at Y max so the course homing part is fine but after this:
                                G1 S1 Y340 ; course home Y
                                you have this:
                                G1 X4 Y4 F500 ; move away from the endstops
                                G1 S1 X-10 ; fine home X
                                G1 S1 Y-10 ; fine home Y

                                In the first line above you want to move Y away from the end stop but it's already at max (Y=340 from the previous course home) so to move it away from the end stop, you need to move it negative i.e G1 X4 Y-4 F500 (Y minus 4)
                                Then you have G1 S1 X-10 which is fine but G1 S1 Y-10 is wrong as it'll be moving away from the end stop so it needs to be G1 S1 Y10 (no minus sign).

                                What will happen if you don't correct this is that course homing will work fine, then fine homing of X will work but after that, Y will move slowly away from the end stop (towards you) and keep going for ever (or at least until something nasty happens).

                                HTH

                                Ian
                                https://somei3deas.wordpress.com/
                                https://www.youtube.com/@deckingman

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                                • Lakkoundefined
                                  Lakko
                                  last edited by

                                  Ok, thank you! I have edited the homeall.g code.
                                  When the piezo arrive i will edit all the code so it can maybe help someone else and use it for a starter point.

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                                  • vbtalentundefined
                                    vbtalent
                                    last edited by

                                    I'm wanting to replace my Z axis home switch on my CoreXY, Z home's at the top.

                                    M558 P0 X0 Y0 Z0 H5 F120 T6000
                                    
                                    

                                    I think I need the following in my config.g,

                                    M558 (P1/P5) I1 R0.4 F300 X0 Y0 Z0
                                    G31 X0 Y0 Z-0.1 P600
                                    
                                    

                                    I'm using the v2 PCB in a NC configuration. I'm also unclear what the difference is between the analog/digital and what it is used for? Does the board still need to be tuned in a digital usage or is that irrelevant?

                                    I also am a little confused on the homing sequence. I think I need to home X/Y then move to the center of the bed and run a G30, is this correct?

                                    Appreciate some help.. thanks.

                                    ampapa,

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                                    • DjDemonDundefined
                                      DjDemonD
                                      last edited by

                                      You need to tune the PCB first whatever method you use this sets up the pcb to trigger when the nozzle is tapped. This sets up the sensor itself. If it's the v2 kit it triggers active low I1 if it's the Piezo20 unit it triggers active high I0 in M558.

                                      Next step is setup how your printer will use this information.

                                      Analogue mode (not present on most other lesser 3d printer controllers) allows you to set a threshold, if you are over it the firmware considers the z probe triggered, so you can use M558 P1…... As you have shown. Set the threshold for 500 and see how you go, you can raise it or lower it to change sensitivity. You can see the current value in the Z-probe box on DWC or paneldue.

                                      You can also make it more or less sensitive on the piezo pcb read the instructions see www.precisionpiezo.co.uk on how to do it as this is not duet/RRF specific but applies to any setup.

                                      Digital mode P5 is how most other 3d printer controllers run endstops and sensors either on or off. In this mode a change from 0v to more than 1.65v on the z probe signal wire (or 3.3v to less than 1.65v if using active low mode) will be considered a trigger (its probably more complicated than that but that's the gist of it). So use this mode if you prefer (I do). If using P5 then there is no adjustable threshold, as the threshold is fixed, as described above. But you can debounce the signal by filtering it slightly and that's what the G31 Pxxx refers to when P5 mode is chosen in M558. 100ms seems to be the right value.

                                      There is also a P8 mode on 1.20 firmware which removes filtering and is digital like P5, so that you get more precision, once you have got your system working smoothly using P1 or P5 try it instead, but you'll only notice the improvement when doing sensor testing and using high microstepping.

                                      Simon. Precision Piezo Z-Probe Technology
                                      www.precisionpiezo.co.uk
                                      PT1000 cartridge sensors NOW IN, just attach to your Duet board directly!

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                                      • vbtalentundefined
                                        vbtalent
                                        last edited by

                                        Thanks for the quick feedback DjDemon.

                                        I ran a first test with the unit and it seems to be working correctly.

                                        https://youtu.be/rqbH40s8HNE

                                        In my homing files (homez/homeall) what would that look like now, something like the following?

                                        ORIGINAL homez.g

                                        G91                ; Relative positioning
                                        G1 Z-350 S1 F300   ; Move Z down until the switch triggers
                                        G1 Z2.5 F300
                                        G1 Z-5 S1 F150     ; Move Z down until the switch triggers
                                        G1 Z2.5 F150
                                        G90                ; Back to absolute positioning
                                        G92 Z2.5           ; Tell the firmware where we ar
                                        
                                        

                                        NEW homez.g

                                        G91                       ; relative mode
                                        G1 Z4 F200                ; lowers bed 4mm to avoid dragging nozzle over the bed
                                        G90                       ; back to absolute mode
                                        G1 X150 Y150 F4000        ; put head over the centre of the bed, or wherever you want to probe
                                        G30                       ; probe
                                        G91                       ; relative mode
                                        G1 Z4 F50                 ; move slowly 4mm in the +Z direction
                                        G90                       ; back to absolute mode
                                        G30                       ; probe
                                        G1 Z2.5 F150
                                        G90                ; Back to absolute positioning
                                        
                                        

                                        EDIT

                                        Just wanted to close the loop on this and post my working Z homing file.

                                        G91                     ; relative mode
                                        G1 Z4 F400              ; lowers bed 4mm to avoid dragging nozzle over the bed
                                        G90                     ; back to absolute mode
                                        G1 X40 Y265 F4000       ; put head over the center of the bed, or wherever you want to probe
                                        G30                     ; probe
                                        G91                     ; relative mode
                                        G1 Z4 F150              ; move slowly 4mm in the +Z direction
                                        G90                     ; back to absolute mode
                                        G30                     ; probe
                                        G1 Z2.5 F150		;Move Z to 2.5 above the bed
                                        G90  			;back to absolute
                                        G1 X0 F4000 		;move to X0
                                        
                                        
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                                        • DjDemonDundefined
                                          DjDemonD
                                          last edited by

                                          Yes that should work.

                                          Simon. Precision Piezo Z-Probe Technology
                                          www.precisionpiezo.co.uk
                                          PT1000 cartridge sensors NOW IN, just attach to your Duet board directly!

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                                          • vbtalentundefined
                                            vbtalent
                                            last edited by

                                            One additional follow up question on setting the Z axis positioning.

                                            [c]G31 X0 Y0 Z-0.1 P600[/c]

                                            If the piezo is effectively able to find Z=0 then why the need for an offset in the config.g file? Is this to force the probe to go below the bed surface?

                                            When the probe touches the bed surface shouldn't that effectively be the Z=0, no offset is needed from that point forward?

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