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Precision Piezo Z-probe Now available.

Posted by DjDemonD 
Re: Precision Piezo Z-probe Now available.
July 05, 2020 05:26PM
I Have a question about using this kit with CR10/Ender3 printers.
I have a CR10S with a E3D Titan Aero. So far I have only found one mount that supports the Titan Aero, and Piezo ABL. The problem is you lose about 10mm of bed space over the position of the head. Sadly the Titan Aero is hard to use on the CR10 and not lose some space just from the size of everything.
Have you (or anyone on this thread) had any luck with this combination?
I have an Ender3 Pro that I would like to upgrade at some point, I'm still using a BLTouch with the default hot end, but want to go DD with it at some point, Titan, or hack job to modify the default hot end into a DD, I'm still trying to make my mind up.
From what I can tell the only implementations for Piezo on the hot end is to drill the center and mount inline with the bowden tube.
Does anyone have alternative mounts to use complete disks without needing to drill?

Thanks, I've had a few hiccups here and there, it seems that the system is extremely sensitive, and took me some time to dial in, I still have to re calibrate and spend some time turning the trim pots to get it dialed back in every time I remove the hotend and reattach it (had to replace belts once, and had to take it apart for jams a few times)
I definitely get that the other method with the drilled hole makes for an assembly that is independent from the hot end thus no need to reconfigure each time, I just cannot use that method with the hot end I have. I've somewhat fixed this by making my own piezo (soldering my own 22awg wires to the disk directly) and zip tying the holy crap out of it. But any ideas for other mounts would be most appreciated! (I'm starting to play with Fusion 360 so I may try my hand at modeling one of my own) but I'd rather not recreate the wheel if there were a mount that already exists.

Cheers! and thanks for making this PCB I definitely like this ABL above any other I have tried!.

Side question, if the trim pots do eventually die on me, can you tell me the ratings, so I can try to replace them should this become a problem?
Thanks again!
Re: Precision Piezo Z-probe Now available.
July 15, 2020 09:14AM
Quote
Moriquendi
The Orion is as small as it can be, ...

Never say never smiling smiley
Attachments:
open | download - pcb.PNG (66 KB)
Re: Precision Piezo Z-probe Now available.
July 15, 2020 11:12AM
Thinking about it... i was wondering why these 2 extra empty holes? And then... would the diagonal arrangement possibly translate in tilting off side where there is less resistance?
Anyhow... 3 might be the magic number. I'd call her trinity.
Attachments:
open | download - pcb2.PNG (158 KB)
Re: Precision Piezo Z-probe Now available.
July 16, 2020 10:49AM
If it were simply a matter of fitting the parts as close together as possible then yes, it could be made smaller, but there are other factors at play here.


{Precision Piezo} Accurate, repeatable, versatile z-probe plus piezo discs, endstop cables, pt100, 50w heaters.
Re: Precision Piezo Z-probe Now available.
July 16, 2020 11:46AM
Quote
Moriquendi
If it were simply a matter of fitting the parts as close together as possible then yes, it could be made smaller, but there are other factors at play here.

Which you obviously don't want to share...
Re: Precision Piezo Z-probe Now available.
July 18, 2020 05:00PM
So maybe I'm just thinking way too complicated here, but I'm sketching a Delta mount for my heated bed:




The 'depressor' is held up on two little black pieces of rubber that go around each screw. This is supposed to 'preload' the piezo discs to a certain extent.

On the bottom there is a hole so the piezo disc rests only around it's edge:


Am I making it too complicated? The depressor is a floating part that sits flush against the heated bed underside. The tapered point is 5mm wide in diameter and compressed with a preload onto the piezo disc. I will add a layer of cork to insulate the bottom of the heated bed to try and minimize the piezo heating up.

Edited 1 time(s). Last edit at 07/18/2020 05:01PM by Ohmarinus.


http://www.marinusdebeer.nl/
Re: Precision Piezo Z-probe Now available.
July 18, 2020 07:03PM
I don't see any issues with that design, should work well.

Idris


{Precision Piezo} Accurate, repeatable, versatile z-probe plus piezo discs, endstop cables, pt100, 50w heaters.
Re: Precision Piezo Z-probe Now available.
July 19, 2020 06:31AM
Printed one example, and it looks like it could actually work. I don't even think that the rubber is needed between the left and right bolts. If I 'bend' the compression arm by using a spacer between the bed and the arm at the bolt points, this will cause the sides of the compression bar to curve down and logically the center of the bar will be the highest point, logically causing it to be the only point the bed then rests on. The bolts will only keep the bed in place and apply a bit of downforce.

Finished module; the top bar is pushing on the piezo disc with a 5mm round point:


Top view, notice the hole for the wires:


Here you see the bottom of the disc and how it is supported around it's rim:


I wonder if anyone has ever made something similar.

When I print the other three parts, I will show it mounted to the heated bed.

Meanwhile, concerning the electronics... Does anyone have an idea how to best connect the wires? And is it critical all piezo's have the same total wire length? I have bad experiences with crimping such thin wires and the wires are only 40mm long so they need to be extended because in this setup the three discs cannot be connected to the PCB with such short wires.

Furthermore, is a 5mm surface point enough to depress the piezo? Do I have to visually deform the piezo under stress to generate a signal, or is simply pushing on it already enough? I can re-design the pressure bar to have a smaller point, resulting in a lower surface area of contact, and a higher pressure in the center of the piezo.


Edit;
One more example showing how the bed is mainly touching the piezo:
(in this configuration the bolts are not tied down completely so the bed is really only resting purely on the piezo)


Edited 3 time(s). Last edit at 07/19/2020 06:47AM by Ohmarinus.


http://www.marinusdebeer.nl/
Re: Precision Piezo Z-probe Now available.
July 19, 2020 10:32AM
5mm should be fine. If the contact point is too small then there is a risk of damaging the PZT ceramic while if it is too large much of the bending would be in theo uoter part where there is no piezoelectric material.

Your design should work well but try not to let the perimeter of the bed snag on the body part of your supports - as long as there is a little clearance around the edge then a quick tap with your knuckles or the blunt end of a screwdriver will stop it snagging.

Mike
Re: Precision Piezo Z-probe Now available.
July 19, 2020 12:19PM
Quote
leadinglights
5mm should be fine. If the contact point is too small then there is a risk of damaging the PZT ceramic while if it is too large much of the bending would be in theo uoter part where there is no piezoelectric material.

Your design should work well but try not to let the perimeter of the bed snag on the body part of your supports - as long as there is a little clearance around the edge then a quick tap with your knuckles or the blunt end of a screwdriver will stop it snagging.

Mike

Thanks for the feedback! The edges won't snag, I'll keep an eye on it. Printing the second module now and the third in an hour or so. Today is the day! I'll update if it worked.


http://www.marinusdebeer.nl/
Re: Precision Piezo Z-probe Now available.
July 20, 2020 03:30AM
Something confused me a bit, the guide: Guide still talks about the 2.75 version. Some pinouts are different and I noticed a 'D' and an 'A' on the v2.85

But the guide doesn't explain the difference, I have searched for both digital and analog in the guide but to no avail. From what I understand is that with the Analog connection you can set the sensitivity, and with the Digital, you cannot? Which mode is best for me? I'm using the v2.85 on an SKR 1.3 as the z-min endstop (on a Delta).

Also, I have read the wires to the piezo's should be as short as possible. But at the same time, I need to be able to tune the sensitivity. I'm about to add around 5~10cm of wire to the piezo's. Does that matter much, and is it okay if the wire length is different for each piezo? I can imagine the wire length might influence the signal timing a little bit? I'm no expert on this, but won't it cause a small shift in reading and therefor the signal can be seen as noise?

Going to go ahead, but would like to know the theory so that I can at least change the wiring if it turns out to not be working and I don't know why.

PS first results are in:
[www.youtube.com]

Edited 3 time(s). Last edit at 07/20/2020 10:36AM by Ohmarinus.


http://www.marinusdebeer.nl/
Re: Precision Piezo Z-probe Now available.
July 20, 2020 02:22PM
You can solder extension wires to the piezo disks cables, try to keep the total length short but you shouldn't have issues with lengths up to 300mm. I strongly suggest you secure the wires close to the piezo disk and ensure that there is no stress on the solder joints of the disk itself, they are quite delicate. The lengths do not need to be the same.

You do not need to see any deflection of the disk, movement of the disk will probably be well under 0.1mm.

The guide has not been updated since the release of the v2.85 board, for your application use the D pins and everything will behave identically to the v2.75 described in the guide.

The A pins output an analog signal that can be used with a Duet to set the trigger threshold through the web interface, as far as I know this cannot be done with any other controller.

Idris


{Precision Piezo} Accurate, repeatable, versatile z-probe plus piezo discs, endstop cables, pt100, 50w heaters.
Re: Precision Piezo Z-probe Now available.
July 21, 2020 01:45PM
Okay, so far the system runs fine (by the way, I'm using the analog signal without having it even tuned and it runs perfectly!), I have made a correct mesh, but all of a sudden after stopping one print and starting it again, the heated bed is suddenly not even anymore according to the machine. I do not understand what's happening since I've been printing fine for about a whole day without this issue. The system is fixed and everything is in place. The hotend is straight, didn't move and the bed is also still exactly in the same place. I checked the flatness with a ruler and the heated bed doesn't seem to bend after some time of being hot.

Is there a way so I can do a bed-level check before each and every print instead of relying on:
G29 L0
G29 A

at the beginning of every print?

Because somehow the printer seems to vary in first layer height. This is giving me too much of a headache. On my MendelMax 1.8 printer I use an inductive sensor and before each print it measures 9 points on the bed and it always has perfect prints. Is there a way to get my Delta run the same type of calibration before each print with the piezo setup? I don't want to use mesh bed leveling anymore because due to some unknown reason the printer seems to lose it's calibration even though everything is fixed. Must be heat creep or something.

Update;
It seems the machine is more bipolar than its motors.. Now all of a sudden it wants to lay down perfect layers.
[youtu.be]

Do I have a machine with a mental disorder? Btw Digital output is extremely sensitive and not usable. It already triggers when the motors think of moving.

Edited 3 time(s). Last edit at 07/21/2020 03:47PM by Ohmarinus.


http://www.marinusdebeer.nl/
Re: Precision Piezo Z-probe Now available.
July 22, 2020 10:51AM
The digital output probably needs tuning using VR2.

Unfortunately I don't have much current experience of Marlin so I can't help you with that.

Idris


{Precision Piezo} Accurate, repeatable, versatile z-probe plus piezo discs, endstop cables, pt100, 50w heaters.
Re: Precision Piezo Z-probe Now available.
July 23, 2020 06:02AM
Quote
Moriquendi
The digital output probably needs tuning using VR2.

Unfortunately I don't have much current experience of Marlin so I can't help you with that.

Idris

Thanks, I'll try the digital way the next time I open the machine.
For now I discovered that with this startup script it works perfectly:

G28 ;Home
G29 A ; Activate the UBL System.
G29 L0 ; Load the mesh stored in slot 0 (from G29 S0)
G29 J ; No size specified on the J option tells G29 to probe the specified 3 points and tilt the mesh according to what it finds.


http://www.marinusdebeer.nl/
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