Piezo20 probe and piezo kit now available
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That's fair enough. I would only use large dive height (combined with a slightly increased starting homed height (H parameter in config.g M665) if I were regularly swapping beds in and out of varying thicknesses, and allowing auto-calibration to adjust for it on a per-print basis.
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I updated my piezo mount: http://www.thingiverse.com/thing:2268205
The changes might be helpful to others. Basically I've learned that you can make the spacer above the hotend that presses on the piezo, and the ring that goes around the hotend both "full width" with just enough of a gap they slide nicely. I'm still using a nylon washer for my center spacer, but uploaded an STL for a spacer the same size. Making both of those wider added even more stability to my nozzle, but didn't lower the sensitivity at all.
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In the end I've modified Idris's effector to work with Hayden's mag arms at 64mm spacing. He also made some 15mm piezos for me
Pict and details here https://www.thingiverse.com/thing:2361081/#files
I coud only make it work in analog mode on my Duet. VR1 is at 11 and VR2 at 4 o'clock
I'm probing on PEI at 210c hotend (Tested and is fine at 220 for 3 seconds) and 65c bed temp.
Z offset is -0.15 and trigger value 500
Deviation aroud 0.023
This mesh is done on the aluminium plate.
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Looks great.
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Here's another possible configuration:
1. Drill and tap the top end of an E3D heatsink with 3 small holes, probably M2.5 or possible M3. I hate groove mounts.
2. Take a piezo element with the active element about 20mm diameter. Perhaps this one http://www.digikey.co.uk/product-detail/en/murata-electronics-north-america/7BB-27-4L0/490-7714-ND/4358154. Drill a central hole for the Bowden tube and collet, and 3 smaller holes around it.
3. Attach the disk to the top of heatsink using 3 nylon screws, with a piece of insulation between the piezo and the heatsink. The purpose of the insulation is so that if the heater cartridge develops a short and makes the heatsink live, we don't get a short between the heater and the piezo.
4. Clamp the brass surround of the piezo disc between the effector (which has a hole in it for the top of the heatsink to pass through) and a printed ring.
For the electronics, I would take one of my IR sensors, remove the optical components, and feed the piezo into the analog input. Then program it to produce a nice clean pulse when it detects a shock. Piezos produce a good voltage from a very small mechanical shock if the load resistance is very high.
I'd have a go at this myself, but I don't have a drill press for drilling the top of the E3D heatsink.
David, or anyone else who may know how to answer this, you'd be helping me out of a bind I've found myself in. Once upon a time I had gotten two of DJ's new piezo sensor systems for probing accurately, but since I accidentally fried the spare i had and had to employ the second one, leaving me one more kit, though minus the circuit board with the potentiometer for tuning.
My question is regarding the quoted text. Has anyone actually succeeded in converting an IR sensor board by dc42 into a feasible board to utilize with piezo discs? It certainly would be very helpful and much appreciated if you could explain to me how to go about converting dc's board (which, as s luck would have it, I've got four out five lying around currently so it'd be great to repurpose one to enable be to compete the second Piezo kit that's missing that very component.
Thank you in advance for assisting me on this one.
Cheers!
Jonathan.
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Just to say we have stock currently of Piezo20 ready to use modules, and piezo z-probe kits (hotend or underbed use) at https://www.precisionpiezo.co.uk/shop .
We are also selling printed part kits for both the Piezo20 Module so you can build your own (much cheaper than ready made) and the titan/titan aero piezo bracket enabling use of piezo sensing for these popular extruders (and in theory others that can be attached via this bracket).
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Hi Simon,
i did some tests with the Seedstudio Grove piezzo vibration sensor with your mount.
While it does work, it is not near sensitive enough for probing use.
I am going to buy your board and see how it goes
I see in your shop that I can order the board with one drilled piezzo.
Is it possible to order the board with 2 drilled piezzos? One 20mm and one 27mm (I have a feeling the 20mm is not sensitive enough, but I could be wrong…) -
Yes sure leave a note on your order, or email me the order number and remind me and I'll drill 2 for you.
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Yes sure leave a note on your order, or email me the order number and remind me and I'll drill 2 for you.
Last question, if I buy the full kit, is it already calibrated or is that something I will need to do?
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The kit is not assembled or tuned in any way, you attach the piezo, insert it in a suitable assembly, then attach endstop wires to your controller then tune the board (usually just one pot to set), its not tricky. How well it works will depend on whether the assembly mechanically works, i.e. is as firm as it can be whilst still compressing or flexing the piezo on nozzle contact, and on whether you can set it up in your firmware (easy on duet) and manage mechanical noise from your printer (use the R parameter in M558 to pause after moving to a probe point before diving to probe).
The Piezo20 module is ready assembled and tested and should work out of the box as long as the delivery service haven't bashed it about too much and moved the potentiometers, if they have you re-tune it in the same way as the kit board. Full instructions are on our site).
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Ok, I went ahead and bought the full kit (ref Kryotech) I will see how it goes
/Kris
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Thank you. You'll be pleasantly surprised once you start probing, its very accurate/versatile.
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Hi there,
I got the full kit yesterday, and I'm configuring it with DjDemonD groovemount for Piezo20. So far, I'm quite surprised about how this works, and it wasn't too hard to configure, however, there is something that bugs me, and I'm not sure if I'm doing something wrong, my mechanics doesn't allow to do it better or is just that I didn't tweak it fine yet.
I've recorded this: https://youtu.be/QJUzIwRm_js
You can see there that the led triggers when I push the nozzle, then I executed Z Homing, the nozzle touches the bed, and although is hard to see it in the video, the entire carriage moves slightly up a bit, then the nozzle goes down 5mm and waits. After that I requested in the web that Z goes 0, and (around second 38 in the video) the nozzle hits the bed and moves up (so it doesn't stop exactly at the bed), then I move the bed 1mm and the pressure over the hotend is released (that's the point where 0 should be). Summarizing, I'm getting 1mm Z offset consistently.I've tried with different Z speeds and accelerations, and it's always like this, in fact, I've configured an offset of 1mm in my Slicer and prints really well, but I cannot stop thinking I'm doing something wrong.
This is my config:
; PiezoSensor
G31 X0 Y0 Z0 P100
M558 P5 F200 H3 R2 X0 Y0 Z0
M557 X5:300 Y5:300 S50 ; Define mesh gridM566 X900 Y900 Z12 E120 ; Set maximum instantaneous speed changes (mm/min)
M203 X6000 Y6000 Z200 E1200 ; Set maximum speeds (mm/min)
M201 X900 Y900 Z150 E250 ; Set accelerations (mm/s^2)Regards
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This might be a really simple one reverse the polarity of your piezo then retune (wont be far off). I think its backwards. When you tap up it looks like it lights up when you release rather than the instant it is tapped. It will still trigger but in that clumsy way as shown in your video.
In M558 probably take your probing speed up a notch try F300 R you can probably get away with as little as 0.2. Youll be confident to do this when its triggered nicely.
The rest is fine.
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Thanks DjDemonD, will try it now.
Funny thing, I thought yesterday that the polarity was reversed and I swapped it xD.
Regards
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Did it make any difference?
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No, is exactly the same… I've swapped it to be active all the time (led is ON until touch), then it touches, led goes out and the offset is still 1mm.
Something I'm not sure about is that, when I do Z homing, once the nozzle touches the bed, the web interface shows 0'70 and then the bed moves to 5mm as configured:
; Lift Z relatively to current position
G91
G1 Z5 F6000; Back to absolute positioning
G90; Go to first bed probe point and home the Z axis
G1 X5 Y150 F6000
G30; Uncomment the following lines to lift Z after probing
G1 Z5 F100Apart from that, I've executed a series of G30 S-1 (with a G1 Z5 to move the bed before each G30), and the results are more or less the same:
22:57:46Stopped at height 0.685 mm
22:57:43Stopped at height 0.686 mm
22:57:41Stopped at height 0.686 mm
22:57:38Stopped at height 0.685 mm
22:57:35Stopped at height 0.683 mm
22:57:33Stopped at height 0.683 mm
22:57:30Stopped at height 0.683 mmIf I adjust the VR1 the stop height changes (0.6 is the lowest I got, 0.8 was the highest), but I'm not sure what means that offset... I guess is the real distance the bed forces the nozzle up.
Any advice?
Regards
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If you can measure vr1 pot resistance between a piezo pin and the pot itself, 0.4Mohm is a good setting, but 0.6Mohm or 0.8Mohm increases the sensitivity, the pots can be a little jumpy so make sure the reading is fairly stable.
Determine the polarity for certain by pushing up on the hotend, if the LED changes on push up its right, if its on release its reversed.
When you turn vr2 make sure its just a fraction past the point where the LED comes on and no further, this increases sensitivity even more.
Make sure you have switch I1 in your M558 if you are using the board in NC mode (i..e led goes out when triggered).
If your hotend is very wobbly this might be a problem as it doesn't give the piezo a firm tap on contact more of a gentle squash which generates a much less sharp rise in voltage and is harder to detect.
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I see something in your video which might be a problem or not, I can see some nuts between the top and bottom part of the module. These might be an issue. The idea is that the top part which has the printed groovemount, these holes need to not bind to the screws, the lower part of the module prints with holes which are 2.8mm so your can tap m3 screws into them.
The disc needs to be able to be squeezed between the two parts of the module. Its only 0.2mm but unless the module can easily compress you might not be getting a full signal.
If you take it off and change the assembly, reassemble it and before you mount it wire it up and make sure the led changes on the slightest tap on the bed holding it in your hand.
Make sure it looks like this assembled
And ensure the solder pads on the disc sit in the recess in the flange on top of the lower part. -
At some point I am going to do an assembly video for youtube.
