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Piezoelectric disks for Z contact detect and bed levelling

Posted by leadinglights 
Re: Piezoelectric disks for Z contact detect and bed levelling
October 18, 2017 06:30AM
Definitely make one then, all our designs are freely available and they work. We've about 80 Piezo20 modules out there now no issues so far. You get 10 microns accuracy with 7 microns standard deviation (you can improve on this slightly making it out of pla with 100 infill but it's a hotend clamp so not sure if it's worth it) and that's repeatble from one probing to the next, unlike microswitches which never redeploy in exactly the same place each time.


[www.precisionpiezo.co.uk] Accurate, repeatable, versatile z-probe plus piezo discs, endstop cables, pt100, 50w heaters.
[www.facebook.com] we want to see your first layer photos... give us a like/share
[www.thingiverse.com] DemonDeltaMicro - Micro Delta Printer & Things I've made/remixed.
Re: Piezoelectric disks for Z contact detect and bed levelling
October 18, 2017 06:31AM
I see your point except that the $3 Chinese module doesn't do what this does, you've got to decide whether the price difference is worth it to you. On which point, it's not an endstop, it would be more accurate to compare it to something like a BLTouch or IR sensor, except this is more accurate and tolerant of any print surface.

Idris


I am developing controller boards for piezo Z-probing and endstops
Re: Piezoelectric disks for Z contact detect and bed levelling
October 18, 2017 07:58AM
Is there any reason the piezo leads can't be really long? The idea here would be to keep the sensor board close to the controller board and just run the piezo wires through the same harness as the hot-end power and thermistor wires. (assuming a delta setup)

tnx.

g.
Re: Piezoelectric disks for Z contact detect and bed levelling
October 18, 2017 08:09AM
There is a limit to how long the piezo leads can be as longer wires, especially if they're routed near switching power wires (like the hot end), will pick up interference and cause false triggering. I don't know how long the wires can be before you have problems but it probably depends on how electrically noisy your printer is, I've run piezo wires from the effector to the top of a kossel mini without problems. One forum user has experimented with using shielded cable for the piezo I think with some success but our normal advice is to put the board close to the piezo and run the three wires back to the controller.

Idris


I am developing controller boards for piezo Z-probing and endstops
Re: Piezoelectric disks for Z contact detect and bed levelling
October 18, 2017 08:46AM
I wasn't aware the piezo wires would be sensitive to induced current, but it makes sense.

tnx.

g.
Re: Piezoelectric disks for Z contact detect and bed levelling
October 18, 2017 09:18AM
Electrically, I had 80cm leads at one point with 1 hotend heater and 2 fans wired in the same loom. No issues. Added a second extruder and started getting flickering on the piezo pcb from induced current. So it's marginal in mist cases, but try to locate your piezo pcb as close as is practical to the piezo disc/s.

The system is so sensitive mechanically it can trigger as you walk past the printer if you set it that high.


[www.precisionpiezo.co.uk] Accurate, repeatable, versatile z-probe plus piezo discs, endstop cables, pt100, 50w heaters.
[www.facebook.com] we want to see your first layer photos... give us a like/share
[www.thingiverse.com] DemonDeltaMicro - Micro Delta Printer & Things I've made/remixed.
Re: Piezoelectric disks for Z contact detect and bed levelling
October 20, 2017 02:05PM
Regarding the chinese clones, I've first bought the $13 chinese piezo kit (ali)since precision-piezo.uk didn't have the boards in stock, it's useless!
Go for the real deal, you can get the "normal" board with 3 piezo inputs, the price and shipping is more than affordable. I got 2 of them and mounted on both my printers and what can I say besides that I'm delighted.
The piezo discs you can get from ali/ebay, I went for the larger 30mm ones since they have a little more ceramic to be drilled, don't go over 30mm however since you won't get more ceramic, just larger metal disc.
You can print your own holder from thingyverse or use my design for a laser cut one out of 3mm acrylic, I get 3 micron resolution/deviation. You can get the files in the other thread.
Thanks again guys for the wonderful things you make!
Re: Piezoelectric disks for Z contact detect and bed levelling
October 20, 2017 02:18PM
Kind words sir. Thank you.

Edited 1 time(s). Last edit at 10/20/2017 02:18PM by DjDemonD.

[www.precisionpiezo.co.uk] Accurate, repeatable, versatile z-probe plus piezo discs, endstop cables, pt100, 50w heaters.
[www.facebook.com] we want to see your first layer photos... give us a like/share
[www.thingiverse.com] DemonDeltaMicro - Micro Delta Printer & Things I've made/remixed.
Re: Piezoelectric disks for Z contact detect and bed levelling
October 20, 2017 02:26PM
We're never out of stock for more than a couple of days anymore. If they're showing as out of stock it's worth dropping myself or Simon (DjDemonD) a message to find out how long they'll be, chances are there's already a batch of boards in the post ready to get put into kits.

Always good to get positive feedback, so far it seems that everyone who's tried it has been satisfied.

Idris


I am developing controller boards for piezo Z-probing and endstops
Re: Piezoelectric disks for Z contact detect and bed levelling
October 21, 2017 02:21AM
Having tried both Moriquendis' sensor board and This cheap Chinese sensor board I would have to say that they both work. The Chinese board is certainly less sophisticated and may well not work as well in some printers that are electrically noisier than some, but I have no problem with mine on either a delta or a self design cube. As far as the moral question goes the Chinese board is advertised for use with Arduino, not 3D printers, so I don't think you can claim it is a 'rip off' clone or a copy - it just happens to offer the same function as Moriquendis' boards...which I must say do work well.
Re: Piezoelectric disks for Z contact detect and bed levelling
October 21, 2017 02:31AM
That board is no clone or copy there are a lot of piezo amplifier boards for arduino. There is however a direct replica of our product which even uses our name and links to our documents directly. That's a little bit cheeky but we have to be doing something right for this to happen.

I've used plenty of cloned things in the past so it would be hypocritical to get too annoyed, but it has encouraged me to buy the genuine item when I needed another or the clone died.


[www.precisionpiezo.co.uk] Accurate, repeatable, versatile z-probe plus piezo discs, endstop cables, pt100, 50w heaters.
[www.facebook.com] we want to see your first layer photos... give us a like/share
[www.thingiverse.com] DemonDeltaMicro - Micro Delta Printer & Things I've made/remixed.
Re: Piezoelectric disks for Z contact detect and bed levelling
October 21, 2017 03:06AM
Those boards certainly aren't clones and if they work for you great, there are plenty of ways to interface to a piezo.

What I object to is people who literally clone a product without contributing to the development of the concept or providing support. In this case they've not even written, or hosted, their own instructions or documentation. This is what kills open source innovation in my opinion.

Idris


I am developing controller boards for piezo Z-probing and endstops
Re: Piezoelectric disks for Z contact detect and bed levelling
October 23, 2017 07:29AM
I have the final results of the tests at 80°C showing the stability of discs in compression (un-drilled) and in flexing (drilled disc) disc after a week of soaking. The rig was not really satisfactory for the drilled discs as there is more bounce than a small child on a trampoline - see the scope plot with the wild ringing at the point of contact.



Even this stability was only got by reducing the the pressure change from 450 grams to 250 grams. The output voltage for the drilled discs has been multiplied by 1.8 to correct for this.



I think these plots show that even under this considerable mistreatment the piezos should give an adequate life.

Mike
Re: Piezoelectric disks for Z contact detect and bed levelling
December 04, 2017 12:50PM
Back at the beginning of this thread I speculated that it may be possible to use a piezo disc without any amplifier as I had seen them used in maze runners directly connected to an Arduino. The Github entry below shows just this being done but input to the analogue side

[github.com]
There doesn't seem to be any further information on implementation.

I am not recommending that that is the way to go: I think that reliability dictates the use of a high impedance input with both high frequency and low frequency filtering and some additional protection such as you get from Moriquendi's amplifier; but this approach can be used to get a minimum system.

Mike
Re: Piezoelectric disks for Z contact detect and bed levelling
December 04, 2017 01:01PM
I know many people have implemented piezos into their printers and wont be impressed.. But i thought I'd just thank moriquendi and Simon for all their hard work. I got the 1.2v board when it was still quite new.. And tried multiple ways to adapt the hotend version to my effector... Which was massive pain in the butt. So i just went for the underbed version which turned out great.

Thanks for everything

P. S. G31 on my delta
[photos.app.goo.gl]

Edited 1 time(s). Last edit at 12/04/2017 01:02PM by RandomFactoid.
Re: Piezoelectric disks for Z contact detect and bed levelling
December 04, 2017 01:04PM
No worries glad it's working so well.


[www.precisionpiezo.co.uk] Accurate, repeatable, versatile z-probe plus piezo discs, endstop cables, pt100, 50w heaters.
[www.facebook.com] we want to see your first layer photos... give us a like/share
[www.thingiverse.com] DemonDeltaMicro - Micro Delta Printer & Things I've made/remixed.
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