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Piezo20 probe and piezo kit now available

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  • undefined
    Dougal1957
    last edited by 19 Jan 2017, 08:27

    @Zesty_Lykle:

    The design will be on Thingiverse. I was kinda waiting for DjDemonD to print it first to see if it would work, before publishing it, but I will do it as a work in progress. So be aware it is untested as yet.

    edit: Here is the thing: http://www.thingiverse.com/thing:2047422

    The Nimble, is ready to go, we are chomping at the bits to go. Wait is for the legal stuff. We now have a registered company so it is a matter of days rather than weeks before we can open the web shop. Need to get the bank account and register it with Paypal, that sort of stuff.
    It is amazingly difficult to find a bank that will accept 2 business partners that live on separate continents. They all insisted Brian to come into the office and sign in person. A 27 hour one way trip. Not going to happen. But we have it sorted now. (sorry, going off topic here) Rant over, I will post the designs now on Thingiverse.

    Good news?

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    • undefined
      DjDemonD
      last edited by 19 Jan 2017, 08:53

      Sorry didn't get chance to print it but I suspect others may have done already by now. Looks great.

      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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      • undefined
        Moriquendi
        last edited by 19 Jan 2017, 13:26

        I'm glad everybodies boards have arrived, if you have feedback I'd like to hear it. I know that the trimmers are too small, it's hard to visualise how tiny something is by the footprint in the PCB software.

        I'm currently debating getting some V1.1 boards made with:
        Individual connectors for three Piezo elements
        Onboard series resistors for each element
        6mm trimmer pots (standard size)
        Footprint to replace VR2 with fixed resistors (VR2 seems to be a fairly fixed value)

        I also have a board design for replacing endstops with piezo elements, three separate channels with three outputs.
        Thoughts welcome.

        Moriquendi

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        • undefined
          Rommie
          last edited by 19 Jan 2017, 14:39

          well sent my donation to Moriquendi last night and bought my piezo today so just need to print the parts and then get it all together and fitted I guess, have you got any config changes that is required DJ and wiring diagram to the duetwifi board if you could, thanks in advance

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          • undefined
            DjDemonD
            last edited by 19 Jan 2017, 21:34

            I intend to edit this as it develops. This now refers to the Mk III version (http://www.thingiverse.com/thing:2069480)
            Edited 29-01-17
            Edited 22-01-17
            Edited 21-01-17
            Edited 20-01-17

            So when assembling ensure the top circular part is attached to the lower clamp parts fairly firmly, doesn't matter if it bends a bit, get the torque around equal on each side. Then firmly attach it to the effector. Make sure the clamp is sliding on the rods. There will be almost no nozzle wobble if the clamp slides on the rods but doesn;t rock laterally.

            Okay so I have these two gcodes, about 10 lines up from the bottom in my config.g

            M558 P1 F500 I1 X0 Y0 Z0 ;analogue piezo sensor output falls on contact, probing speed 500 mm/min
            G31 X0 Y0 Z0 P600 ;sensor is nozzle, offsets for probe (nozzle) and trigger value.

            M558 sets an analogue sensor using the z-probe connector with an inverted output i.e. drops as it contacts the surface. It does not home any of the axes. I have selected probing speed 500 mm/min which gives the bed a firm tap, this increases the gap between signal and noise from the piezo sensor.

            The G31 offsets are 0,0,0 although depending on how compliant the assembly is it might need a tiny offset for z. So Z could read 0.05 to 0.015. You are likely to need a slight positive offset to counteract the fact that the assembly squashes down slightly into the bed to trigger (like with FSR's). You can add this offset in your slicer if you prefer. I think David is implementing babystepping soon which will be great. P600 is the trigger value from 0 to 1000. I chose this value by connecting it up, setting the signal board (see below) then moving around a bit and seeing what value is displayed under z-probe on the web interface during travel moves and sudden jerks etc… I chose a value above this, to prevent false triggers.

            Wiring. On Moriquendi's board the piezo has a two pin connector. I believe + and - need to go the right way around, the piezos come with red and black wires. It seems initially as though the series resistor is not required - but watch this space.

            The other side has +, -, sig which go to the Duetwifi z-probe port. You need a 3 pin connector at Moriquendi's board and a 4 pin connector on the duetwifi.

            On the duetwifi the z probe connector has 4 pins looking from the front of the board (the side with the LED's and USB port), the closest pin is signal, the next is -, the 3rd is unused and the 4th is +.

            On the signal board there are two trim pots. Adjust them cautiously if the power is on, as you might with a step stick, I momentarily made contact with something with my screwdriver bit and it triggered a reboot on the duetwifi - no damage done but take care! As I have mine configured (which is slightly different to Moriquendi's instructions) I turn VR2 until the led just comes on, then around a quarter turn more. Then try a few upward presses on the hot end, if it flashes off/on convincingly you are probably there, if not try VR1 in a variety of positions and try a few more head moves and nozzle pushes. You're looking to minimise triggers under normal movement but get a solid off/on on the LED when you push up on the hotend. If you see a few slight flickers during head movement that's okay, as long as when you press up on the hotend you get a much more obvious off-on on the LED. Don't be tempted to set it up so that only a really hard push gives a change in the LED this won't be sensitive enough. Mark the trim pots when you have a good position, they are very sensitive.

            Alternatively you can set VR2 so the LED just turns off, which is Moriquendi's method, then adjust the sensitivity on VR1, it seems to reverse the logic so that the signal rises as the piezo is bent/triggered. If you prefer this mode then change I1 to I0 in M558. I have not found this mode to work as well but let me know if you do.

            I have these lines in bed.g before probing, please modify to suit your machine, basically its low motor current, low jerk and low acceleration.

            ;slow down movement to improve accuracy, improve probing and lmit damage in case of head crash
            M906 X500 Y500 Z500 E800 I60 ; Set low motor currents (mA) and increase idle current to 60%
            M201 X250 Y250 Z250 E1000 ; Accelerations (mm/s^2)
            M203 X15000 Y15000 Z15000 E3600 ; Maximum speeds (mm/min)
            M566 X100 Y100 Z100 E1200 ; Maximum instant speed changes mm/minute

            and these after

            ;restore speed settings to normal printing speeds
            M906 X1100 Y1100 Z1100 E800 I60 ; Set normal motor currents (mA) and increase idle current to 60%
            M201 X3000 Y3000 Z3000 E1000 ; Accelerations (mm/s^2)
            M203 X15000 Y15000 Z15000 E3600 ; Maximum speeds (mm/min)
            M566 X1200 Y1200 Z1200 E1200 ; Maximum instant speed changes mm/minute

            So that the machine accelerates/decelerates and jerks much less for probing, improving accuracy and eliminating false triggers.

            Make sure you delete your config_override.g file and set the approximate height in m665 in config.g by jogging down and measuring the distance travelled. This assembly lowers your nozzle by around 15mm (Lykle's effector does not so ignore this bit) if you don't do this (or forget to delete config_override.g) you will crash your nozzle on the first run.

            Calibrate with the bed hot, but with the nozzle, depending on the toughness of your printing surface, either stone cold - in which case you will need a z offset when printing as the hotend will expand when heated. Do the paper grip test after calibration to determine how much z offset. Or with the nozzle at your full first layer temp - I don't use this as a head crash onto printbite with nozzle at 250 deg C melts a hole in it, perhaps brief contact doesn't but I don't want any more holes, so I use 160 deg C (below ooze temp for ABS) and have a +0.2mm z-offset which I set in slic3r. I set the nozzle to come up to 160 in start gcode before autocalibration at start of each print, then to first layer temp after probing. It's better to have the nozzle hot (at least above glass transition temp) in case there's a bit of filament on the end from the last print, which will just squash down to nothing.

            A video of how I have it setup, and it working is now on youtube, apologies for the low production value.
            https://www.youtube.com/watch?v=F3vi6BOi6sA

            All feedback and any grammatical/spelling errors let me know I will try to incorporate this into the thingiverse listing along with some idiots-guide assembly pics, and make a wiki page here/wherever needed.

            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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            • undefined
              Moriquendi
              last edited by 19 Jan 2017, 22:18

              The other two pins next to the piezo input are designed for a remote LED, I found it useful so I included it. The three pins at the other end of the board are meant to be the connection to the controller, V+, Signal and GND. On my Smoothieboard endstop headers are these three pins so thats what was convenient for me. However the only difference is that the LED output has a 1k series resistor on board. The resistor in series with the piezo element doesn't appear to be critical.

              Moriquendi

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              • undefined
                Sakey
                last edited by 21 Jan 2017, 17:49

                Set mine up today ( thanks Moriquendi for the board) but having a problem with it outputting a signal to the duet I think. The led triggers fine by the looks of it when I tap the Nozzle ( on board and the external ) but i'm not getting a trigger. Is this something to do with the way i set up the Potentiometers or Duet?

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                • undefined
                  Moriquendi
                  last edited by 21 Jan 2017, 19:09

                  If the LED is flashing you should have a signal going to the duet. Check what kind of signal the Duet is expecting, active low or active high. I'm afraid I have no experience with the Duet so I can't help you with that but I'm sure someone else on here can.

                  One other thing to mention is that a trigger event is very brief, on the order of miliseconds, you won't be able to check the output of the board with a g-code to report z-probe state. Have you tried asking for a z-probe and then tapping the sensor to see if the Duet registers the trigger?

                  Moriquendi

                  PS. I've just had a look at the Duet documentation and I think people may be configuring it incorrectly for this type of z-probe. The output of the piezo sensor board is digital, not analogue. It appears from DjDemonDs config above that he has configured the Duet to expect an analog signal. Does this make a difference? I don't know but it's worth a shot.

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                  • undefined
                    DjDemonD
                    last edited by 21 Jan 2017, 21:30

                    Have been probing away and changing things for the last few hours now.

                    Setting it as digital M558 P5 for me anyway is not working. If I leave it set to analogue M558 P1 I1, inverted output and set the piezo board by turning VR2 until the LED is just on with sensitivity fairly high (VR1), but use a trigger value of 600 it works. Its also worth setting a probing speed of 500mm/min M558 F500 so that the nozzle gives the bed a fairly sharp tap rather than descends very slowly which sometimes doesn't trigger.

                    My probe settings currently are

                    M558 P1 I1 F500 X0 Y0 Z0 ;analogue piezo sensor output falls on contact, probing speed, not used to home axes
                    G31 X0 Y0 Z0 P600 ;sensor is nozzle and trigger value.

                    You can monitor the "analogue" output on web interface. Setup as I have mine the value shows approx 215 when head is stationary, during normal travel moves it goes up to 400-500, on a sharp tap with the bed it goes above 600 often to 1000 (max - essentially digital ON). At this setting on the piezo board I can get reliable and sensitive triggers.

                    Of course having faster probing speed is risky its harder to pull the power in case of a head crash there is less time to do so, suggest setting your stepper motor current to as low as you can go whilst still moving, so that these are less severe if they happen. However faster probing speed will show false triggers requiring slightly less sensitivity (VR1), so its useful in that respect.

                    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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                    • undefined
                      DjDemonD
                      last edited by 21 Jan 2017, 21:39

                      My bed.g if it helps:

                      [[language]]
                      ; Auto calibration routine for delta printers
                      M906 X500 Y500 Z500 E800 I60 ; Set low motor currents (mA) and increase idle current to 60%
                      M561 ; clear any bed transform, otherwise homing may be at the wrong height
                      G28 ; home the printer
                      G28 ;home again in case of endstop problem
                      ;slow down movement to delineate bed touch from travel moves
                      M201 X250 Y250 Z250 E1000 ; Accelerations (mm/s^2)
                      M203 X15000 Y15000 Z15000 E3600 ; Maximum speeds (mm/min)
                      M566 X100 Y100 Z100 E1200 ; Maximum instant speed changes mm/minute
                      G30 P0 X0.00 Y120.00 Z-99999 H0
                      G30 P1 X75.20 Y89.63 Z-99999 H0
                      G30 P2 X109.80 Y19.36 Z-99999 H0
                      G30 P3 X95.08 Y-54.89 Z-99999 H0
                      G30 P4 X38.37 Y-105.43 Z-99999 H0
                      G30 P5 X-40.44 Y-111.11 Z-99999 H0
                      G30 P6 X-103.92 Y-60.00 Z-99999 H0
                      G30 P7 X-118.18 Y20.84 Z-99999 H0
                      G30 P8 X-77.13 Y91.93 Z-99999 H0
                      G30 P9 X0.00 Y60.00 Z-99999 H0
                      G30 P10 X46.66 Y26.94 Z-99999 H0
                      G30 P11 X43.81 Y-25.29 Z-99999 H0
                      G30 P12 X0.00 Y-54.74 Z-99999 H0
                      G30 P13 X-51.96 Y-30.00 Z-99999 H0
                      G30 P14 X-51.96 Y30.00 Z-99999 H0
                      G30 P15 X0 Y0 Z-99999 S6
                      ;restore speed settings to normal printing speeds
                      M201 X3000 Y3000 Z3000 E1000 ; Accelerations (mm/s^2)
                      M203 X15000 Y15000 Z15000 E3600 ; Maximum speeds (mm/min)
                      M566 X1200 Y1200 Z1200 E1200 ; Maximum instant speed changes mm/minute
                      G29 S1 ;load grid levelling mesh
                      M376 H10 ;taper off compensation after 10mm
                      M906 X1100 Y1100 Z1100 E800 I60 ; Set normal motor currents (mA) and increase idle current to 60%
                      G1 X0 Y0 Z75 F3000 ; get the head out of the way of the bed
                      M500 ;save calibration to config_override.g

                      Remove the G29 if you aren't using grid levelling, and the M500 unless you want auto-save of results to config_override.g and obviously replace the G30 points with your preferred probing locations and number of factors.

                      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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                      • undefined
                        Sakey
                        last edited by 22 Jan 2017, 00:13

                        Its weird. Both P1 and P5 do more a less the same thing for me but get slightly less crashed heads with P5. When I send the command to probe and it tap the nozzle it will register the tap .

                        It's like seems to be a delay between the trigger of the sensor and duet reading the probe point before it pushes though the bed. I don't think its a sensitivity problem because sometimes it will trigger from just the movement of the effector.

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                        • undefined
                          DjDemonD
                          last edited by 22 Jan 2017, 08:35

                          Sounds like you've got everything there, its just a case of finding the sweet spot where it triggers well. I might do a few videos later showing how I have it setup. You might have the clamp/piezo assembly tightened too much, try loosening it off a tiny bit. There is a zone where you find the optimum between a tight assembly/less sensitivity/firm nozzle, and a loose assembly/high sensitivity/wobbly nozzle. I say this as there is no delay as I have it setup the lightest touch of the nozzle gives an above threshold trigger.

                          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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                          • undefined
                            Boyan Silyavski
                            last edited by 22 Jan 2017, 16:55

                            A question. Why all this trouble and not use a simple conductive touch plate with an known thickness? Same like most DIY CNCs use? Hot end could be wired constantly , led could be implemented for visual check if working, prior to test. Costs absolutely nothing. Plate could be moved sequentially manually to predefined places on heat bed. Is this possible with the Duet board?

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                            • undefined
                              Moriquendi
                              last edited by 22 Jan 2017, 17:52

                              Because the end of a hot end nozzle is not a good contact, it's frequently coated in a layer of gunky/charred plastic.

                              Moriquendi

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                              • undefined
                                T3P3Tony administrators
                                last edited by 22 Jan 2017, 18:17

                                Boytan

                                It would be possible as it could be setup as a switch, and the firmware will accept any sort of trigger as an endstop. (The signal needs to be within the 3.3V range however that is manageable).

                                One issue is as Moriquendi described - inconsistant conductivity due to plastic buildup on the nozzle. The other issue is that many(most) bed surfaces are non conductive to you have to have the manual intervention of applying a conductive sheet to the bed.

                                www.duet3d.com

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                                • undefined
                                  DjDemonD
                                  last edited by 22 Jan 2017, 18:32

                                  Yes I'd love to use a electrified nozzle and at one point I used to print onto aluminium and considered it. Plastic on the nozzle isn't really an issue if you probe hot. But now I print onto printbite which is super convenient and permanent and about as conductive as ceramic. I'd say most people are using glass or polymer surfaces of some sort.

                                  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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                                  • undefined
                                    DjDemonD
                                    last edited by 22 Jan 2017, 22:20

                                    Updated the tuning guide (long post) above and included a video of how I have it setup which might make it easier to see what I'm on about. https://www.youtube.com/watch?v=F3vi6BOi6sA

                                    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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                                    • undefined
                                      T3P3Tony administrators
                                      last edited by 22 Jan 2017, 23:05

                                      Awesome! I linked your post and the video from the Tutorials page:
                                      https://duet3d.com/wiki/Tutorials#Experimental_Features

                                      Although at the rate this is progressing it wont be experimental for much longer.

                                      www.duet3d.com

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                                      • undefined
                                        DjDemonD
                                        last edited by 23 Jan 2017, 21:50

                                        Next iteration is to make the nozzle wobble disappear almost completely, I had in mind attaching the upper part of the piezo sensor module to the lower with small smooth rods (or delrin rods?) which would slide into the lower clamp part, and if metal, could be greased. This would result in a very firm nozzle constrained laterally but free to move upwards by a small amount to flex the piezo disc.

                                        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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                                        • undefined
                                          Dougal1957
                                          last edited by 24 Jan 2017, 07:41

                                          DJ

                                          PTFE rod is quite cheap and would probably be a better choice than Delrin or steel (Has self Lubricating properties IIRC).

                                          a 500mm length of say 10mm Diam is about £2.50 from one of my local suppliers it is available in 4,5,6,8,10 mm diam plus a lot bigger as well.
                                          https://www.directplastics.co.uk/ptfe-rod

                                          Look forward to seeing your design for it lol

                                          Doug

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