Piezo20 probe and piezo kit now available

Jackal

I am interested to give this a go, when will the drop in z-probe be back in stock?

DjDemonD

Okercho - make sure you know your Z-offset, after doing G30, do a paper test and see where the nozzle really is, and have entered it in G31 in config.g it will be a small negative number i.e. -0.1, -0.15, -0.2.

My solution to the grid level problem, is home Z (G30) at bed centre, then run G29. You are getting a flat bed just the system thinks its all too low.

If you have the module assembled and its giving sensitive triggers please do not adjust it any more the rest is all in the firmware now. You wont get a different grid levelling result adjusting the sensor. Once its working its zero maintenance.

higher vr1 resistance is more sensitive

Jackal - I've got some piezo20 PCB's if you wanted to print a module and add some screws as in the videos, go to precisionpiezo.co.uk and send me a message.

dc42

Okercho, the Z height that is set when the probe stops in a G30 command is the trigger height defined in the Z parameter of the G31 command in config.g or config-override.g.

okercho

I've found the issue!!

I thought that the order in config file was not that important, and I don't know where I got this, but if I have my probe config like this:

G31 X0 Y0 Z0 P100
M558 P5 I1 F200 H3 R2 X0 Y0 Z0
M557 X5:300 Y5:300 S50 ; Define mesh grid
When the homeall is executed, Z reports 0.70mm height

However, if I have this (M558 and G31 swapped):
M558 P5 I1 F200 H3 R2 X0 Y0 Z0
G31 X0 Y0 Z0 P100
M557 X5:300 Y5:300 S50 ; Define mesh grid

Z reports 0.00 height and now the bed levelling is the expected one:

I guess that G31 asume some offset by default (0.70 was what I got) if M558 is not configured before with the type of probe… Anyway, now I can finally start doing printing test :D.

Thanks a lot DjDemonD and DC42!

Regards

DjDemonD

Yes the M558 sets up the type of probe and probing behaviour, the G31 defines the probe offsets and (oddly since it would make more sense for it to be in M558) the threshold (or debounce) P value.

Glad you've got it working.

okercho

After a few prints, a bit of feedback.

So far, I'm really really happy about how the sensor works (I'm checking the website periodically for stock, as I will probably get another one and a friend is willing to get one probably :P). The groove mount is really strong, I'm not having wobbling issues so far, and the way the sensor works is just… awesome, although I'm still trying to find the "sweet point" in the config to ensure repeatability (more about this below).

A few thoughts:

Good Things

The sensor is really sensitive, I'm testing a new surface in PC (check Whitewolf post for more info), and the PC sheet is not flat, but the sensor detected it (before I even noticed... I saw it in the image after the mesh leveling, and when I checked the surface it was as the sensor said)
A really good thing I like the most, is that DjDemonD says the sensor is the nozzle, but that's not "true", the sensor is the entire hotend, so for example, I had a bulldog clip for the PC sheet, and I put it by mistake in a place where the nozzle was doing the probing for the mesh... with an inductive or the optical sensor, this may be an issue if the sensor is in the other side (for example, sensor in the right place, and the clip in the left), as the heatblock/nozzle will crash with the clip much before the sensor detects the surface, potentially creating a mess... In this case, I just noticed a glitch in the mesh image, and thought that the sensibility was still too high, so I lowered it and repeated... and then I observed that the heatblock touches the clip before the nozzle reaches the surface, and assumed the bed was there, reported it in the mesh, and nothing else... accident avoided!
*No matter what surface you're using, you're ok, I started with Buildtak (the one I had problems with the IR sensor), and I've spent a lot of time leveling it, now I'm using the unleveled PC sheet, and I just had to do... nothing (well, to be honest, I've changed the point where I check the Z to the flattest point of the sheet, to try to have a realistic point for the bed position)

Bad Things

Sometimes is a bit too sensitive/Is a bit hard to find the point, I'm still trying to find the point, and I've added 2-3 seconds delays in the mesh leveling to try to avoid the sensor triggering when it shouldn't, although for the Z homing I'm still getting this issue when the head is traveling from a far point to the Z homing point.
My first layer is sometimes a bit more squished, others a bit less, my suspect is that my nozzle is not always same clean at it should, the temperature may be affecting a bit, and that I should remove a bit of sensibility. I'm ensuring the nozzle is really clean before each print, and I'm trying to do the mesh leveling before each print at the same temp (BTW, anyone using S3D? I'm using a crappy script executed after the slicing process that looks for the M104 for the hotend, and adds with SED the code for setting the temperature of the leveling process to 120 degrees, as I couldn't find any other way to do it automatically in S3D)
You will loose a bit of Z height, but honestly, I think is well "paid" compared with the benefits the sensor is giving.

Cheers!

DjDemonD

Wonderful feedback thank you.
If you dont mind I might it on the reprap forum which is our main support thread for others to view/learn from.

Loving all the positives.

To address the bad bits
-Try reducing the sensitivity a little bit, using VR2 just turn it a tiny bit past the point where the triggered LED goes out. Try a few different probing speeds. Some get better performance at 240mm/min others as high as 420-480mm/min. You shouldn't be troubled by triggering during moves, unless something in the firmware isnt set up right as the firmware isnt looking for a Z-trigger during moves it should ignore it completely, only looking for it when probing (an extra LED comes on on the duet when a probing dive takes place, I believe this is the MOD signal which is the fourth, unused in most cases, pin in the z-probe connector.

My recommended nozzle clean is to heat bed to 1st layer temp, then nozzle to 130 deg C, this enables you to remove any residual plastic with side cutters. There should be no ooze at this temp. Any that remains should be compressible enough to not affect your second reading as it gets squashed out of the way on the first reading. You can setup the firmware to probe twice on a probing point (search for it on the forum here) and then use second reading?
-Check your bed is firmly attached and nothing is "wobbly" I'm sure its not but were only talking 0.1-0.2mm.

Will have some more in stock soon. Looking into way of getting PCB's in bigger numbers now, seems there is enough demand.

okercho

Thanks for the answer, I'm following the reprap thread too, so I can post it there too if you want to.

I'm doing the test with the nozzle at 120, although I think I will need to increase it, for PETG I think is too low. I will look for the 2 readings stuff, and play a bit more with the sensibility, I'm not worried about that, I've reduced the false triggering almost to zero.

Cheers!

WZ9V

Has anyone switched from under bed FSR setup to under bed piezo?
If so was it a major improvement over the FSR setup?

DjDemonD

I'm a little biased but if you consider going from 50-100g of force to trigger with FSR's (I used to have them), to 10-15g with piezo, then it must be an improvement.

However when it comes to the best approach for a delta I would say fix the bed rigidly, use the hotend based piezo probe. The results speak for themselves, I get 0.007 deviation when auto-calibrating, and that's probing 64 points, to ensure it wasn't just a lucky result.

Whitewolf

any update on when the drop ins will be available?

WZ9V

OK, Thanks. The under bed approach would be much easier but I have started to see some progress on Rostock Max V3 integration at the effector.

@DjDemonD:

I'm a little biased but if you consider going from 50-100g of force to trigger with FSR's (I used to have them), to 10-15g with piezo, then it must be an improvement.

However when it comes to the best approach for a delta I would say fix the bed rigidly, use the hotend based piezo probe. The results speak for themselves, I get 0.007 deviation when auto-calibrating, and that's probing 64 points, to ensure it wasn't just a lucky result.

DjDemonD

@Whitewolf:

any update on when the drop ins will be available?

Should have some PCB's this week and then I can list some on the site. I will post here but the main channel for announcing new stock is the thread on reprap under general.

whosrdaddy

Finally got time to install the piezo probe on my selfmade I3 clone.
I must say I am impressed, it works really well.
Have on issue though, when I run mesh bed leveling the heightmap is like this:

someone has an idea what could be wrong?

these are my current parameters in config.g (running on 1.19b10):

M558 P5 I0 X0 Y0 Z1 H2 F150 T1500 R0.8 ;digital piezo sensor, output rises on contact, probing speed, used to home Z axis
G31 X0 Y0 Z-0.14 P150 ;sensor is nozzle and debounce value.
M557 X1:210 Y1:300 S40 ; Set probe grid

heightmap.csv contents:

RepRapFirmware height map file v1 generated at 2017-06-20 12:03, mean error 0.138, deviation 0.315
xmin,xmax,ymin,ymax,radius,xspacing,yspacing,xnum,ynum
1.00,210.00,1.00,300.00,-1.00,40.00,40.00,6,8
0.110, 0.127, 0.165, 0.165, 0.147, 0.150
0.030, 0.075, 0.105, 0.085, 0.072, 0.028
-0.035, 0.002, 0.020, -0.017, -0.052, -0.070
-0.045, 0.005, 0.040, 0.000, -0.032, -0.075
-0.015, 0.008, 0.020, 0.000, -0.052, -0.097
0.040, 0.080, 0.123, 0.082, 0.062, 0.082
0.115, 0.203, 0.198, 0.168, 0.160, 0.080
0.265, 0.360, 0.428, 0.467, 0.467, 0.358

Jackal

DWC hasn't been updated to support 1.19 beta 10 mesh leveling grid display

whosrdaddy

@Jackal:

DWC hasn't been updated to support 1.19 beta 10 mesh leveling grid display

That's weird, where did you get that info from?
It was showing a correct map when I was using the inductive probe?

DjDemonD

Go to bed centre and issue G30 (no parameters) this resets Z level, then do G29.

Also make sure you erase/change the G31 z offset in config_override.g as it overrides the value you set in config.g - this has got me multiple times!

whosrdaddy

@DjDemonD:

Go to bed centre and issue G30 (no parameters) this resets Z level, then do G29.

Also make sure you erase/change the G31 z offset in config_override.g as it overrides the value you set in config.g - this has got me multiple times!

this is basically what I am doing, I home Z before doing G29 (and I have no config_override.g).

My homez.g file:

G91
G1 Z5 F100
G90
G1 X100 Y150 F9000
G30

small resume: probing/mesh bed leveling works and my heightmap looks ok when I look at the numbers, but the graphic is not ok in DWC.

Jackal

@whosrdaddy:

@Jackal:

DWC hasn't been updated to support 1.19 beta 10 mesh leveling grid display

That's weird, where did you get that info from?
It was showing a correct map when I was using the inductive probe?

I had the same problem with the height map and here's David's response
https://www.duet3d.com/forum/thread.php?pid=19176#p19176

whosrdaddy

Thanks, missed that bit