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Cheap Piezo Z-Probe Sensor and Marlin

Posted by disneytoy 
Cheap Piezo Z-Probe Sensor and Marlin
December 01, 2017 09:37AM
While I am waiting for a new Proximity sensor for my Prusa Clone to arrive. I saw on Aliexpress they have a Piezo20 Z-Probe Sensor. A small piezo that is hand fitted to your nozzle which senses the impact "touch" on the bed.

Question, Running latest Marlin, how would I implement this? I can wire it to the z endstop. But since this must be run with the nozzle cold, and after calibration, removed to print.

I don't know enough G-code to use it.

I don't have it in yet, but it was only a couple dollars so worth a try.






Re: Cheap Piezo Z-Probe Sensor and Marlin
December 01, 2017 11:20AM
That doesn't look like any piezo sensor I've ever seen, the transparent plastic and multiple layers look much more like an FSR to me. The easiest way to check would be to measure the resistance from one terminal to the other, a piezo will read very high resistance, probably 10Meg or more, a Force Sensitive Resistor will be more like 10k.

If it is a piezo element you can't just plug it straight into your controller. Piezos can generate very high voltages, enough to damage the controller, and you need to mitigate that.

If you're going to have something you have to manually attach and remove from your nozzle you may as well just use a microswitch or tactile switch, it's plenty accurate and even cheaper.

Idris


I am developing controller boards for piezo Z-probing and endstops
Re: Cheap Piezo Z-Probe Sensor and Marlin
December 01, 2017 11:26AM
Obviously not a piezo sensor as described in this forum, just a pressure switch and not suitable to use as is as a real effective Z home switch or probe. Cumbersome. Not much detail from the chinglish description but if made properly eventually with FSR could be useful.

Edited 1 time(s). Last edit at 12/01/2017 01:55PM by MKSA.

"You failed to maintain your weapon, son" (Harry Brown )
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