3D printer - Piezo Z probing

[tekkydave]

I would double check the wiring.

Edited June 17, 2019 by tekkydave

[Gina]

Yes, that's what I thought.  I'll check the cable.

[tekkydave]

I've had 3 different products from PP and the wiring has been different on each one

 

[Gina]

Continuity from Sig pin on Piezo to Duet connector on end of cable is good.  Not the cable.

[tekkydave]

4 minutes ago, Gina said:

Continuity from Sig pin on Piezo to Duet connector on end of cable is good.  Not the cable.

But is it connected to the correct pin at the Duet end?

[Gina]

Yes.  Left hand pin looking at front of board.

Edited June 17, 2019 by Gina

[tekkydave]

That's correct.

[Gina]

Any other suggestions?

[Gina]

The new piezo probe unit seems very good - big improvement on the separate disc and amplifier board.  Triggers with a light tap on the nozzle but doesn't trigger when moving the bed until the bed touches the nozzle.  Haven't needed to alter the sensitivity setting.

[Gina]

All I can think of is to connect a bench PSU between Gnd and Z-Probe signal line and increase the voltage for zero to +3v and watch the Z-Probe value.  May need to do this while Z homing and if so set the Z speed low to give me time.

[Gina]

Thought I would check the open circuit voltage on the Z probe input pin as with most logic systems the input sits at logic "1" when not connected.  This has proved correct here too.  O/C the pin shows +3.25v on my DMM.  The Z-Probe display shows 0.  Tried pulling the pin low with a 22K resistor and the voltage dropped to 0.55v.  At the same time the Z-Probe read 1000.  So the input is working.

[Gina]

Guess next thing is to dig out an oscilloscope and see what the piezo signal looks like.  I think I have gone as far as I can with the DMM.

[tekkydave]

Good plan. Will you need to pull the sig line up?

[tekkydave]

What version of Orion pcb do you have? According to their website the V2 pcb has an analog and digital output. You have to ensure you connect to the correct pins.

[Gina]

Aha!!  It's a V2.  I didn't find that when I scoured their site for info.  I wondered why there were two sets of pins to connect to.  It didn't twig that D was Digital and A was Analogue.  I'll try the other set of pins.  No wonder my oscilloscope trace didn't make sense - I have the Duet connected to the A pins and the oscilloscope to the D pins and only seeing noise.

[Gina]

That was it!!  WORKING!!!  YIPPEE!  Thank you very much Dave

[tekkydave]

Glad to help

I only noticed it cos PP sent me an ad for the V2 Orion about an hour ago on FB. Strange - as if they knew you had a problem

 

[Gina]

Tried running Mesh Grid Compensation cold and it was fine though could do with a bit of bed adjustment but when I tried it hot the Z homing was fine but the Mesh Grid Compensation didn't trigger.  May need the trigger threshold turned down a bit to allow for a bit of soft filament on the nozzle.

Edited June 17, 2019 by Gina
typos

[Gina]

OK, turned the trigger level down a bit and it's now triggering fine with hot bed and nozzle.  Not triggering with XY motion.

[Gina]

I'm thinking of yet another 3D printer build, for which I would like suggestions for a name (like you did before Dave).  The idea is to make an extremely accurate precision printer with the absolute best quality printing.  Better than could be achieved with the very long timing belts of Core-XY by using Cartesian drive.  This will have a solid box construction like the Concorde and trapezoidal screw drive for the Z axis with a 300mm x 300mm print bed.  It could have a name derived from the Concorde or a completely separate name (probably better as it will use some different concepts).  I have a few ideas but thought I would throw it open for suggestions.

Edited June 17, 2019 by Gina

[leadinglights]

Hi Gina,

You asked about the voltage output from a piezo disc a few posts ago. I think you may be interested in the first post of this thread.

https://reprap.org/forum/read.php?1,635075

Mike (aka leadinglighs on various 3D printer forums)