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    Piezo20 probe and piezo kit now available

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    • Zesty_Lykleundefined
      Zesty_Lykle
      last edited by

      I like the idea of no moving parts, just a little flex in the system. That might be a good way to reach the compromise between flex and no wobble. Of course, the problem here is that the wobble and the flex go in the same direction, sort of. It would be nice if one was vertical and the other horizontal.

      I will have a look at a different effector design that will locate the hot end with a little up flexibility. If we tune it right, we might use the force of the extruder to keep the hot end down against the stops. Can't wait for the Peizo, so I can have a look at the actual forces happening on a hot end.

      Lykle
      Design, make and enjoy life

      Co Creator of the Zesty Nimble

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      • Sakeyundefined
        Sakey
        last edited by

        Had the same problem with the thin wires pulling off the Piezo. Not solved that problem yet…. As my mount for the hotend allows laterally movement so I used a spacer between the flat part of my e3d and Pieso. This allows space for the wires too. Only problem at the moment is sensitivity but Im pretty sure I can fix this with a design different design for the clamp. Was going to print this but got a clog in my hotend.... so need to strip that down first when I get a chance. Bah!

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        • DjDemonDundefined
          DjDemonD
          last edited by

          Lykle in most ways the nozzle wobble is lateral and comes from the clamp resting against the piezo which is compliant - and the 2 screw fixing system is the line about which it pivots, the triggering force is vertical and is the whole hot end plus clamp pushing up into the piezo. This is why I am keen to test the design with the four rods to slide the clamp up and down on. Or as you said use a version with 4 screws (like the mk I but smaller). Its no problem for the nozzle to move upwards by 0.15mm, its equivalent to having a sprung bed (but only very slightly sprung), its the lateral movement which can cause issues with squashed down first layers which are uneven when the nozzle passes over them on the second layer and curling edges of overhangs etc…

          Sakey - If I might be so bold to suggest a strategy start with my mk5 design and try it then tell me where you changed it, if this is feasible. It seems silly to design from the ground up when my version works albeit needs refining to reduce lateral nozzle movement without eliminating vertical (upwards) nozzle movement.

          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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          • Sakeyundefined
            Sakey
            last edited by

            Not taking anything away from DJ's work, was just trying to mount it into onto a Rostock with a machined mount to hold the hotend already (it seems to lets it slide up and down and then is clamped via 3 points at the top already which is seemed a good platform to start with for a piezo. I wanted to use this with as little modification as possible. My temp spacer is just a nut with a cut out in . Ill post a picture and stl when I re-assemble and get it working somewhat reliably.

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            • DjDemonDundefined
              DjDemonD
              last edited by

              That makes sense, it will be nice if these can be fitted between two existing parts without much change but my experience so far shows they need to be able to flex on probing contact, by an amount (around 0.15mm if my z resulting offset is anything to go by) to trigger clearly above the noise they generate.

              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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              • Zesty_Lykleundefined
                Zesty_Lykle
                last edited by

                Hmm, if the hot end can slide up and down in the clamp, you might be able to avoid sideways wobble.
                Only trouble I see here is tolerances. You have to get it exactly right so that there is no sideways play but just enough space to slide up and down. That will be very hard to achieve with printed parts. So it will have to be post processed.

                But I like the idea of a sliding hot end, A little like the Auto lift hot ends but then for calibration.

                Lykle
                Design, make and enjoy life

                Co Creator of the Zesty Nimble

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                • DjDemonDundefined
                  DjDemonD
                  last edited by

                  Well unfortunately the rods Doug sent to me have not appeared, so lost in the post might be the issue, but I have now got some 4mm steel rods (wood screws shanks cut down with a dremel). I am printing a version now with holes for these rods. I intend to bond/heatpress the rods into the top piece, and then hand file the clamp piece so the rods fit and slide. This might be difficult due to the fact that the clamp will have to be tightened around the hot end exactly the right amount or these holes won't line up.

                  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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                  • DjDemonDundefined
                    DjDemonD
                    last edited by

                    Okay so this latest version with rods to support the assembly is working extremely well. Almost no nozzle-wobble and calibration deviation at 0.02mm. It seems to be the optimum between sensitivity and nozzle wobble.

                    If you intend to make something like this, and are not planning to design your own (or if you are making your own, consider downloading this one and perhaps copy the salient features to your design - to save you time) this is the version to make. I am now calling this the beta version.

                    I have yet to test it with acetal or PTFE rods instead of steel but 4mm smooth steel rods work.

                    It's now on Thingiverse - http://www.thingiverse.com/thing:2069480

                    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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                    • Dougal1957undefined
                      Dougal1957
                      last edited by

                      DJ I'll put some more in the post tomorrow mate

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                      • Zesty_Lykleundefined
                        Zesty_Lykle
                        last edited by

                        Glad to see it is working so well.
                        It was a pleasure working on this, even tho it was just a small part.

                        Lykle
                        Design, make and enjoy life

                        Co Creator of the Zesty Nimble

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                        • DjDemonDundefined
                          DjDemonD
                          last edited by

                          That's way too kind Doug, the post is a constant source of irritation.

                          This version does seem quite solid. I've done one to fit Lykle's (congrats on getting the nimble on sale ordered mine already) effector and the other generic one to bolt onto underside of an effector or carriage.

                          I might make one up for the corexy (and a new x carriage to fit it to) be nice to try it on a ramps setup for the benefit of the majority who haven't got a duetwifi.

                          Also along the same lines thinking if I can make it fit a clone hotend bowden with the much larger push fit bowden couplers, might be tricky can't cut a 12mm hole in the Piezo…

                          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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                          • dvmourikundefined
                            dvmourik
                            last edited by

                            I am really impressed by your works guys!!! great to see such projects.

                            Bigger and bigger… sky is the limit.

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                            • DjDemonDundefined
                              DjDemonD
                              last edited by

                              Thanks on behalf of all who are contributing, it's been a very encouraging collaboration. 3d printing needs a z probe that's cheap, accurate and reproducible, that minimises the effects of tilt because it has no offsets.

                              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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                              • Dougal1957undefined
                                Dougal1957
                                last edited by

                                Dj

                                Another package on it's way you should get it tomorrow sent it first class handed in at the PO desk

                                Doug

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                                • DjDemonDundefined
                                  DjDemonD
                                  last edited by

                                  Awesome, much obliged. I've printed another one with the rod supported version on the kossel Xl and came out looking awesome and a mount for my corexy so hopefully I can use those rods and test the setup on ramps with marlin. I'm aware it's all been very DuetWifi so far. Rods have turned up so thank you very much.

                                  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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                                  • DjDemonDundefined
                                    DjDemonD
                                    last edited by

                                    Okay so made another one this time with 4mm wide 15mm long acetal rods (thanks Doug). Works fine nozzle is quite firm, sensor triggers normally.

                                    Have attached it to my corexy (ramps/mega/Marlin RCbugfix 31-01-07 on). The usual messing around with Marlin and uploading firmware. However it will home nicely and entering a z offset of 0.2mm means the nozzle is nicely positioned just above the bed at z=0 on the lcd. It will do grid levelling if auto_bed_levelling_bilinear is enabled.

                                    I have added instructions for configuration of Marlin on ramps/mega or compatible in the thingiverse listing http://www.thingiverse.com/thing:2069480

                                    Interestingly Marlin allows the M48 probe repeatability test the result is:
                                    Recv: Mean: -2.492500 Min: -2.510 Max: -2.475 Range: 0.035
                                    Recv: Standard Deviation: 0.009014

                                    So hitting a standard deviation of 10 probes at just below 0.01mm repeatability.

                                    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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                                    • DjDemonDundefined
                                      DjDemonD
                                      last edited by

                                      Been chatting with Moriquendi about making it safer in terms of a wire break. Currently you'll just get a head crash.

                                      Current thinking is that putting two Piezo transducers back to back into the unit (might need slight adjustments to the top part), would enable redundancy as well as potentially stiffening the system. The second Piezo has to be wired in parallel but with black and red reversed so they don't cancel one another out. If one Piezo is disconnected the other will still function. However you won't know it's failed potentially unless it begins triggering differently,which it might not given the way the comparator works in the signal board.

                                      Any thoughts?

                                      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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                                      • Toddimusundefined
                                        Toddimus
                                        last edited by

                                        First of all, VERY COOL idea. I presently have FSRs on my bed. I'm following this thread with lots of interest.

                                        One thought on redundancy, using your idea of back to back transducers… Maybe set it up such that both sensors are handled separately with signal conditioning, then the outputs are logically "AND"ed together. Then, if both don't trigger as expected (maybe after an RC time constant??), the ANDed output stays triggered (or is somehow latched triggered), which will signal an issue to the Duet's firmware.

                                        Or similarly, have a second output from the signal conditioning board that would change states if the outputs don't behave as expected (i.e. last time, only one triggered). This signal could be monitored by the Duet firmware to identify a fault condition.

                                        In either of these cases, you would probably have to match the gain and offset of the signal conditioning/comparator for each sensor such that they trigger at the same time. Or get really slick about it and let a tiny PIC automatically configure gain/offset for each side and also have it drive the triggered output with a buffered signal. 🙂

                                        Hope that all makes sense. I don't know if what I suggest is feasible, but I thought I'd throw it out there.

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                                        • dc42undefined
                                          dc42 administrators
                                          last edited by

                                          One option my be to test the Z probe before doing the first probing move. I would expect a short downwards movement that is reversed rapidly to trigger the probe.

                                          Duet WiFi hardware designer and firmware engineer
                                          Please do not ask me for Duet support via PM or email, use the forum
                                          http://www.escher3d.com, https://miscsolutions.wordpress.com

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                                          • DjDemonDundefined
                                            DjDemonD
                                            last edited by

                                            Toddimus - these are great ideas, some of it slightly over my head (not an electronics native), but I'll leave Moriquendi to comment as he made the boards. Suffice it to say some of our discussions earlier were about a new version of the board he is considering, which can support up to 3 piezo's as they are being used as under-bed sensors in one system, but which could also support a twin piezo in this design and perform some safety checking. Auto setup etc.. would be a great feature at this early stage, but if it ever becomes a product then I'd test a wide range of available transducers and pre-set each unit to function with very minimal adjustment by the end user.

                                            David - I advise in the thingiverse listing to manually press up on the hotend at the start of a printing session and observe the led changing, and (on duet) to check the analogue sensor value is normal when the sensor is open, mine reads 216 and rises above 600-700 when given a firm upward press. I probe with 1/3 motor current so head crashes if they happen as I'm tweaking it all the time, are fairly undramatic. But yes a macro or something to test the probe automatically would be a nice addition.

                                            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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