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Precision Piezo Z-probe Now available.

Posted by DjDemonD 
Re: Precision Piezo Z-probe Now available.
April 14, 2019 12:18AM
I can't home Z. It says G28 Z Forbidden on the LCD. M119 returns a triggered on the z, even if the blue light is not on.
Re: Precision Piezo Z-probe Now available.
April 14, 2019 04:55PM
I've been using the Orion successfully for about five months. Earlier today it started behaving erratically, it would only trigger after it had pushed on the bed a couple of mm's.
I tried adjusting the sensitivity, but eventually I got to a setting where it sometimes triggers without touching the bed and sometimes pushes the bed at least 2mm down on the springs. This tells me this is not a calibration issue, but rather something wrong with the hardware...
Re: Precision Piezo Z-probe Now available.
April 14, 2019 06:05PM
anything change?
piezos like to be moved rapidly.
does tapping on it during a Z home stop it?
what is your homing speed?
Re: Precision Piezo Z-probe Now available.
April 18, 2019 01:57PM
Quote
Moriquendi
@CodeBuster,

Sorry if I appeared to ignore your question, I didn't intend to. Have I talked with you about this issue on another platform? It can be hard matching up email addresses and forum names so forgive me if we've already covered some of this.

Unfortunately I have no experience with Repetier firmware so I'm afraid all I can do is run through verifying with you that the output of the Piezo board is as expected. Hopefully, other people with more experience of Repetier will be able to help you with the firmware setup.

With the pullup enabled, measure the voltage of the pin on the RAMBo, without the piezo PCB plugged in, should be 5v
Plug in the Piezo PCB, red LED on, measure the voltage of the SIG pin on the piezo PCB, should be 5v
Turn VR2 to illuminate the blue LED, measure the voltage of the SIG pin, should be 0v (or very close)
Turn VR2 back to illuminate the red LED, tap the piezo and check for blue LED flash.
If you can, measure the voltage of the SIG pin while tapping the piezo, you should see some reaction but it may not reach 0v as multimeters typically measure quite slowly and the output pulse is quite brief.

If all these things are responding as expected then you have a configuration/firmware issue, I wish I could help more with that but I've never used Repetier.#

Idris

The RAMBo has 5V on both VCC and SIG (with pullup enabled) without the PCB plugged in.
The voltage of the SIG pin on the Piezo20 when it is plugged in is 3.55V ; it does drop to 0V when triggered and observed by multimeter.

Is it bad that the Piezo20's SIG is 3.5V? This would induce a constantly undefined logic state in the inactive position, probably registered as triggered by Repetier. I know the fault isn't in my wire up to the effector, the wire holds 5V when it's only plugged into the RAMBo side. (I probed the RAMBo headers, and I probed with the wire in place to be sure.)

Edit: About how long does the PCB pull the SIG low for? .5 seconds? Variable based on pulse strength?

Edited 1 time(s). Last edit at 04/18/2019 06:39PM by CodeBuster.
Re: Precision Piezo Z-probe Now available.
April 21, 2019 05:21PM
Been messing with it for a week now. No matter what I try, I cannot get it to not be in a not triggered state. I'm about to give up on these things and go back to a good reliable sensor. Cannot even get the Z axis to move because it says G28 Z Forbidden. It is hooked to a MKS Base 1.4 board and has 4.95v input.
Re: Precision Piezo Z-probe Now available.
April 23, 2019 04:04AM
@Veaceonee,

Please can you PM me your order number, I'll send you a replacement PCB.

@CodeBuster,

Sorry, I'd assumed you were using a Universal PCB, the Piezo20 is based on an earlier version of the circuit and does read about 3.5v when not triggered, this should still be read as a logic high.

The output pulse on the Piezo20 will be about 200ms, it should not vary.

Idris


{Precision Piezo} Accurate, repeatable, versatile z-probe plus piezo discs, endstop cables, pt100, 50w heaters.
Re: Precision Piezo Z-probe Now available.
April 23, 2019 03:48PM
@Moriquendi

Thank you for verifying the Piezo20's circuit is working as expected. I am discussing this with Repetier on their forum to figure out why the G30 probe cycle isn't behaving correctly. Repetier Forums - Z probe with Piezo element errors

I see in the Arduino documents that what you say is true. On a 5v atmega2560 anything above 3V on a pin is registered as the pin being high.
Do you think it would be detrimental to use a level shifter in line with the Piezo20 to bring the 3.5V up to 5V anyways?
Re: Precision Piezo Z-probe Now available.
April 23, 2019 05:34PM
Quote
CodeBuster
I see in the Arduino documents that what you say is true. On a 5v atmega2560 anything above 3V on a pin is registered as the pin being high.

That isn't safe to rely on. The atmega2560 datasheet specifies that the minimum input voltage to guarantee being read as high is 0.7 * Vcc. Which at Vcc=5V is is 3.5V.

A few other 5V processosr use TTL-like signal levels. For example, the atmega32u4 requires only 0.2Vcc + 0.9V to guarantee being read as high, which at Vcc=5V is 1.9V.

Edited 1 time(s). Last edit at 04/23/2019 05:34PM by dc42.



Large delta printer [miscsolutions.wordpress.com], Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Re: Precision Piezo Z-probe Now available.
April 23, 2019 05:39PM
Then the Piezo20 PCB is definitely straddling the edge by a whole .05V over the minimum.. Do you think a level shifter would be an appropriate move, @dc42 ?
Re: Precision Piezo Z-probe Now available.
April 23, 2019 09:14PM
Here is the way mine is acting, And it is working perfectly as far as homing and probing is concerned.
My Vcc = 4.97 and the Vout = 3.69 at the piezo board.

When I scope it, I get varying pulse outputs even multiple outputs and they vary in pulse width VERY significantly, from a few ms to almost 500ms
If I hold pressure on the piezo I can get it to trigger almost constantly, like it is reading my blood flow.

I do not believe putting a level shifter on it is going to buy you a thing.
I am betting you have too much pressure on the piezo and breathing on it will make it trigger, so it looks like it is constantly triggering to the rambo.
If you have a scope, that would verify everything.

Since yours is different than mine I can't tell you how to back off on that clamping but I think that is your problem.
I can't believe I never had an issue with that as I did not take much care in adjusting the pressure.

Edited 1 time(s). Last edit at 04/23/2019 09:16PM by ruggb.
Re: Precision Piezo Z-probe Now available.
April 23, 2019 09:53PM
I read that increased static clamping force actually decreases the intensity of the voltage spike and increasing the force required to make a piezoelectric pulse sufficient for triggering the sensor PCB. I assure you, I have tried breathing on it. A light tap , but not too light, is what is required to trigger my Piezo20. As it should be, this was one of its lauded features; a nozzle Z-probe that needed almost no offset and didn't require a lot of force to trigger as with underbed-mount force sensitive resistors. The effector assembly is definitely compliant enough that I can make it move and compress, and if I do it slowly enough, not even trigger the PCB since the voltage spike isn't big enough for the PCB to care.

Do you have the Piezo20 v1.2 PCB or the Universal Piezo v2.xx PCB? The universal has way more headers.
Re: Precision Piezo Z-probe Now available.
April 23, 2019 10:26PM
It looks like a V2. I got it from AliExpress - China knockoff. It has 2 pots and one green LED which hangs off the output that drives the Ramps and Arduino. It flashes off when triggered. The Piezos I bought separately and I designed and printed the carriage holder. The store bought ones would not mount on my home built CoreXY printer.

If your piezo to PCB wires are short and your PCB functions as you state and your Vcc at the PCB is 5v ±0.1V and the output goes to <0.7V when triggered then it is either a mechanical problem or a firmware issue.

Also, fans are noisy. They should not affect the output signal, but if the input wires are near fan wires, that is bad. I had very erratic temp control because my thermistor wires ran with the fan supply lines.
Re: Precision Piezo Z-probe Now available.
April 24, 2019 06:29AM
Question,

Has anyone or is there any plans to make the Piezo sensor work for the E3d Chimera set-up?
Re: Precision Piezo Z-probe Now available.
April 24, 2019 08:53AM
@p40whk Like this? Thingiverse

Although 3.5v is theoretically marginal it hasn't caused issues in the past and it's unlikely that a level shifter would help. Later versions don't have this issue.

Idris


{Precision Piezo} Accurate, repeatable, versatile z-probe plus piezo discs, endstop cables, pt100, 50w heaters.
Re: Precision Piezo Z-probe Now available.
April 24, 2019 09:57AM
@codebuster
I understand you are using Repetier firmware, is that correct? I looked at it and see that, to me, it is rather confusing as to how to set the various endstop #defines.
The Piezo is negative logic - goes to 0V when triggered. Your mechanical Z endstop should be the same logic. If so, at this point, I would change over to the mechanical Z endstop and verify that it works properly as setup. Then disconnect the mech stop and connect your Piezo to the same input as the mechanical endstop. It should work the same with the same settings. The only difference in the two is that the mech stop will stay at 0V until it moves. The piezo will not. That does not affect my setup (Marlin) and should not affect Repetier either, but........

The only other diff is that if your mech stops are just switched (2 wires), there is no pullup and pullups will need to be enabled. Otherwise, pullups should not be enabled for either since they are already pulled up, but I didn't see a diff except for slightly more current use which could make the 0 level a little higher.
Re: Precision Piezo Z-probe Now available.
April 24, 2019 09:59AM
Quote
Moriquendi
@p40whk Like this? Thingiverse

Although 3.5v is theoretically marginal it hasn't caused issues in the past and it's unlikely that a level shifter would help. Later versions don't have this issue.

Idris

I actually found this after posting my question. However, what I don't understand with this setup is that the bowden tube holes look to be at a 45 degree angle (corner to corner from the square). I might be mistaken but it's difficult for me to visualize without seeing the hotend attached to it. If it is at that angle, then that would put the corner pointed towards the X-Carriage mount rather than the flat being against it.
Re: Precision Piezo Z-probe Now available.
April 24, 2019 10:51AM
You're correct, this mount uses a fortunate accident of the Orion design where there are two holes that happen to align with the filament paths in the Chimera. The only issue is that those two holes are not in the ideal position so either the PCB has to be mounted at 45 degrees or the Chimera does. If you mount the PCB at an angle you lose more print volume while mounting the Chimera at an angle it still fits under the PCB, no lost volume.

Idris


{Precision Piezo} Accurate, repeatable, versatile z-probe plus piezo discs, endstop cables, pt100, 50w heaters.
Re: Precision Piezo Z-probe Now available.
April 24, 2019 03:07PM
@ruggb

It is slightly confusing, which is why I posted both a table of the behavior of v1.0.2 of Repetier Firmware and crosslinked the posts on either forum.
The developer has replied and clarified for me that Z_PROBE_ON_HIGH tells the firmware that the probe's trigger state is high voltage (i.e. 5V), which obviously is incorrect since Piezo logic is designed active low. Since I've made him aware of the issue, he is checking into the probing routines and editing the firmware dev branch.
from forum.repetier.com:
Quote
Repetier
I have rechecked Printer::runZProbe and saw 3 places where a delay might be needed for safe signals. Will update the dev version later today along with an other addition I'm testing.

Edited 1 time(s). Last edit at 04/24/2019 09:22PM by CodeBuster.
Re: Precision Piezo Z-probe Now available.
April 25, 2019 10:47AM
Z_PROBE_ON_HIGH is set to 1 in the f/w I just downloaded.
Yours should be set to 0

It is a config option so it is only incorrect if you did not change it.
Re: Precision Piezo Z-probe Now available.
May 02, 2019 02:03PM
I am switching from Marlin to RRF and trying to reuse the Universal Board.

I thought I understood my setup until I read this- [forum.duet3d.com]

I was using the PP as both Z-Probe and Z-ENDSTOP in Marlin. I had them both defined as simple inverted switches and used the delay of 200us for probing.

This is what I ended up with from the RRF online configurator using the Smart Effector of Peizo option-

M574 Z1 S2
M558 P5 R0.4 H5 F720 T6000
G31 P500 X0 Y0 Z0.15

It does not seem right.

Should I be using one of the other options like Switch or Un or Modulated IR Probes?
Re: Precision Piezo Z-probe Now available.
May 03, 2019 07:07AM
The Orion behaves like a normally open mechanical switch.

Your settings are almost correct, you need to make these changes:

M558 P8 I1 R0.4 H5 F720 T6000

You might also like to reduce the probe height and speed

M558 P8 I1 R0.4 H2 F400 T6000

Idris


{Precision Piezo} Accurate, repeatable, versatile z-probe plus piezo discs, endstop cables, pt100, 50w heaters.
Re: Precision Piezo Z-probe Now available.
May 07, 2019 07:50PM
New changes added in Repetier 1.0.4 are very good.

With these settings, the probe works great. Getting .03/.04mm deviation:

Z_PROBE_ON_HIGH=false
ENDSTOP_Z_MIN_PULLUP=true
ENDSTOP_Z_MIN_INVERTING=true
ENDSTOP_Z_MIN=true
Z_PROBE_REPETITIONS=2
Z_PROBE_SPEED=4
Z_PROBE_WAIT_BEFORE_TEST=330
Z_PROBE_DELAY=330
Z_PROBE_HEIGHT=-0.01

Edited 2 time(s). Last edit at 05/07/2019 07:58PM by CodeBuster.
Re: Precision Piezo Z-probe Now available.
May 10, 2019 11:11PM
Your store page indicates that you are working on an orion hotend mount for a Chimera hot end - what is the status on that. I am setting up a CR10-S5 for dual extrusion and the Chimera hot end and would like to try out this sensor method.
Re: Precision Piezo Z-probe Now available.
May 11, 2019 05:31AM
The mount is available here, there isn't much demand for it so I don't offer it as a kit.

Idris


{Precision Piezo} Accurate, repeatable, versatile z-probe plus piezo discs, endstop cables, pt100, 50w heaters.
Re: Precision Piezo Z-probe Now available.
May 11, 2019 11:36AM
Thank you for the link to the mount. Is there a picture anywhere to see how the whole thing fits together. I am having trouble understanding how the mount attaches to the Chimera and how the whole thing fits together and works.
Re: Precision Piezo Z-probe Now available.
May 11, 2019 01:17PM
let me see if I figured this one out

Precision_Piezo_Orion_Cyclops_Chimera_stl.zip

The clamp mounts to the Chimera with 3 flat head screws
insert Piezo
screw both assy together with 4 flat head screws
mount the whole assy to the carriage with 4 screws thru carriage tapping into screw top
Re: Precision Piezo Z-probe Now available.
May 11, 2019 01:29PM
That's correct, Orion PCB gets sandwitched between the two plastic parts. You'll need brass threaded inserts for the assembly screw holes and the mounting screw holes.

Idris


{Precision Piezo} Accurate, repeatable, versatile z-probe plus piezo discs, endstop cables, pt100, 50w heaters.
Re: Precision Piezo Z-probe Now available.
May 11, 2019 03:21PM
I am obviously mentally challenged because I am still having problems figuring it out. I understand that the PCB goes between the two plastic parts. The only way this might work is if the plastic parts are not mounted 'straight' on the top of the Chimera but if the whole thing is angled 45 degrees along the vertical axis (if that description makes sense) and if the two holes in the mounting bracket then happen to line up with the holes for the filament. If this is correct then the bowden tube fittings are removed from the top of the Chimera and screwed into the top of the Orion assembly.
Is that how it goes ? With the two plastic pieces screwed together with the four flat head screws, what part of the assembly flexes against the piezo .... there seems to be no room for any flexing, not like the old mount where there was room for one part to slide relative to the second part.
Sorry for being dense .... sad smiley
Re: Precision Piezo Z-probe Now available.
May 11, 2019 03:47PM
You're not being dense, it's not straight forward.

You're correct, the heatsink does mount at 45 degrees to the other parts. The bowden tubes go through all three pieces and into the heatsink. I don't know about clones but the original Chimera heatsinks use embedded collets, nothing to unscrew.

The bottom of the mount flexes, if you look at the stl layer by layer you'll see that parts of it are cut away, this allows for movement in the Z-axis but not in X or Y. The centre of the bottom mount pushes against the centre of the Orion which is supported around the assembly screws, this is what causes the triggering.

Idris


{Precision Piezo} Accurate, repeatable, versatile z-probe plus piezo discs, endstop cables, pt100, 50w heaters.
Re: Precision Piezo Z-probe Now available.
May 11, 2019 04:17PM
Thank you for the explanation ! I have placed an order for two Orion boards to play with.
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