Best posts made by Acid

@Nxt-1

Well drawn explanation of the piezo sensitivity!

Sorry for necroing this thread, but your drawing inspired me to design a program that can generate a point cloud for probing, that avoids the points near the towers and prefers the points near the underbed piezo's.

Sadly it's made in Grasshopper so I can't share it as a script or executable, but maybe this could be inspiring to someone.

I just finished my DIY Delta printer today and I noticed that the probing wasn't that great across the bed so I wanted to see if I could fix that somehow. Assuming my bed is flat enough, I came up with this, where the colored circles are the piezo locations:

Example with lines drawn:

Outermost points culled and I tweaked the amount of points a little bit (and the point data is rounded to whole numbers):

And this is the output point list that can now manually turned into a list for the reiterative probing sequence for example (with the point data rounded to two decimals):

This data can be changed on the fly, so I can see what the probing pattern will look like live without having to first run a script, it's live:
https://youtu.be/0ofXqwViaMc

I hope this could serve as an inspiration to someone and if you have ideas of a good type of point distribution I'd love to hear your ideas.

I have yet to try out this set of points but it's kinda late now so I'll do that tomorrow when I'm sharp and present again.

Just a small update on this reply, which I might turn into a post later on if anyone thinks it deserves its own post:

The results are in, initially it had quite a big deviation, but the second probing sequence was an immediate hit:
Calibrated 8 factors using 18 points, (mean, deviation) before (-0.009, 0.034) after (0.000, 0.022) Auto calibration successful, deviation 0.022mm

I also incorporated a point sorting algorithm. Before the point list was random, causing long travel times during probing, but now it's just moving from one point to the next closest point making this a painless probing sequence.

@infiniteloop said in [Delta] Precision Piezo issues:

@Acid

I actually am using it in analog mode. I think I've run out of options…

The ADC converters I know of in MCUs are relatively slow, for example, the sampling frequency of an Arduino ADC at 10 bit resolution is specified with 9.6 Hz. That means: you get about 10 measures per second. Sure, the Duets are much more responsive, but they too need a finite time for a sample. If you evaluate the data points with a script, the runtime of the script comes on top. All this accounts for a rather limited resolution over time.

I use a probe with a light sensor in analog mode on a Duet 2. In oder to get some kind of precision readings, I had to reduce the probing speed to 200 (F parameter of M558). Note that I use the generic setup with M558, just one sensor, no (interpreted) script involved. So I strongly recommend to try a probing speed way below your F500.

Now there are two things I can think of trying, the first one will be to isolate all the sensor wires as it looks like there is interference that is sending false readings, however I have no idea how to make isolated wires in the first place anyway.

You can either cannibalise shielded USB cables (not all of them are shielded), or use audio input cables - those for microphones and other sources with low signal strength are always shielded.

Thanks for your tips. I have seemed to solve the problem by switching to Digital Output on the PrecisionPiezo PCB and then tuning the VR2 setting on the PCB. It's not perfect, but it's close enough.

After this I finally activated my DIY oscilloscope that I built years ago and measured the Analog signal and it only fluctuates a few mV when triggered, so the issue is probably with the Analog signal coming from the PrecisionPiezo PCB.

With the fixed setup I now achieve this autocalibration measurement first try:
Calibrated 8 factors using 18 points, (mean, deviation) before (-0.120, 0.029) after (0.000, 0.022) Auto calibration successful, deviation 0.022mm

Normally it had to probe at least 5 or 6 times before it would even start, and I had to raise the tolerances. I can't imagine all that pounding of the hotend onto the bed has been good to my machine so I hope that nothing got damaged. Due to issues I had to remake the diagonal rods three!!! times and I was getting really demotivated But somehow I pulled through and managed to finish the build.

Is there some place where we can share out DIY machines in some kind of showcase subforum?

Hi, I've been looking into the option to display a message on my LCD panel (using an 12864 LCD).

Right now I'm using M291 but no matter the option used, it still also displays an overlay on my DWC. This gets in the way when I am running a job, but at the same time, am monitoring some things in the DWC via my browser.

I know it's a simple case of waiting or clicking to make the message disappear in DWC, but I wish there was an option to let the message display on LCD only.

Right now the moment when this bugs me the most is when I do an auto-calibration on my Delta printer and I want to briefly display the deviation on the LCD via this message:
M291 P{move.calibration.final.deviation} ^ "mm" S1

It shows up beautifully on the LCD, but it also overlays the entire DWC screen.

After this I tried all options of M118 and I tried M117, but these messages didn't show up on the LCD screen at all.

This question was first discussed on a discord I'm in, but nobody knew about a way around this. Hence this feature request.

In all honestly it probably doesn't happen often that someone would want to use this feature this way, and it might not even be possible due to firmware/DWC archicture, but I thought it was interesting enough to share and ask.