Piezo20 probe and piezo kit now available
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Just ordered thank you!!
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Many thanks.
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DWC hasn't been updated to support 1.19 beta 10 mesh leveling grid display
Chrishamm released 1.17+2 that fixes this problem…
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DWC hasn't been updated to support 1.19 beta 10 mesh leveling grid display
Chrishamm released 1.17+2 that fixes this problem…
…but you need RRF 1.19beta10**+2** to work with it, if you haven't already installed it.
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After some testing, I've found in my setup something I don't fully understand, let see if I can explain myself and if we can find if I´m doing something wrong.
I found that sometimes my first layer is closed to the bed than others (the first layer is always perfect, but sometimes is more squished than others), however, when I run a mesh leveling, the results seems to be fairly consistent, so I thought it was because I'm testing the PC sheet as printing surface and testing different heights for the first layer.
I found today the thread about the testing resolution and I've executed the gcode Russ provided, and I found something interesting, I edited it to use the same point I use for Z homing (is not 0,0 due to the bulldog clips), homed the printer and executed it twice, and this is what I've got:
First Execution
Bed probe heights: 0.089 0.075 0.079 0.076 0.076 0.076 0.076 0.075 0.076 0.076 0.079 0.078 0.080 0.078 0.076 0.078 0.079 0.081 0.080 0.078 0.080 0.082 0.081 0.080 0.085 0.080 0.080 0.078 0.079 0.078 0.080 0.080 0.080 0.080 0.079 0.076, mean 0.079, deviation from mean 0.003Second Execution
Bed probe heights: 0.078 0.076 0.078 0.079 0.076 0.076 0.076 0.076 0.080 0.086 0.082 0.078 0.078 0.076 0.078 0.079 0.076 0.079 0.080 0.081 0.078 0.076 0.079 0.075 0.078 0.079 0.078 0.078 0.079 0.078 0.076 0.078 0.080 0.079 0.079 0.078, mean 0.078, deviation from mean 0.002Is quite interesting, the printer didn't move the head after the homing, just homed and executed the testing in the same place, and the repeatability is really good (better in the second try), so, why I'm getting 0.07 of difference with the Z homing height? is like the system "heat up" after a few tests and improve… XD
Then I thought, "Ok, let's do a Z homing again (no a home all) and execute the gcode test again!" and what I got is even more interesting:
Bed probe heights: 0.001 -0.004 -0.006 -0.005 -0.002 -0.001 -0.002 -0.002 -0.001 -0.005 -0.008 -0.002 -0.006 -0.001 -0.004 -0.006 -0.005 -0.006 -0.005 -0.009 -0.006 -0.005 -0.004 -0.004 -0.002 -0.005 -0.005 -0.008 -0.005 -0.004 -0.002 -0.006 -0.008 -0.004 -0.001 -0.001, mean -0.004, deviation from mean 0.002I got what I was expecting at the first time!, high repeatability and barely difference with the Z homing... so I've executed a second time, and I got this, which is more or less the same:
Bed probe heights: -0.006 -0.004 -0.006 -0.004 -0.005 -0.005 -0.005 -0.005 -0.008 -0.008 -0.006 -0.004 -0.008 -0.008 -0.005 -0.001 -0.001 -0.002 -0.005 -0.009 -0.005 -0.006 -0.008 -0.005 -0.008 -0.005 -0.006 -0.008 -0.008 -0.006 -0.004 -0.002 -0.005 -0.005 -0.009 -0.006, mean -0.006, deviation from mean 0.002I'm using this as the config for the mesh, is slow, but I'm getting good results and the probe is not triggered accidentally:
M558 P5 I1 F200 H3 R3 T1000 X0 Y0 Z0However, for the Homeall I'm doing this:
; Go to first bed probe point and home Z
G1 X10 Y15 F6000
G30Maybe I should change the F6000 to a more slow motion to the point, or can I add any kind of pause/delay between the G1 and the G30?
What do you guys think?
Cheers!
Edit: I found that G4 SXXX should add a pause for XXXX seconds... I can use this, but I would like to know your opinion on this.
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Great results that's the best set yet for a Precision Piezo product. Please post them to Russ' thread, I might even give him a nudge to update his spreadsheet.
As for the repeatability after the move, yes I would consider moving there slower. We're talking tiny amounts here really 70 microns difference, which is just over a (default) babystep but try moving slower to bed centre and see what happens. It won't take much of a shift in something to change the height of your effector/carriage by 70 microns after a rapid move.
As for the pause you are already using R3 in M558 so the system pauses for 3 seconds before probing with your config. Try 0.4 its enough. I wouldn't add a second pause it serves no purpose. I'd also check everything is tight (it must be fairly tight to get that 2 microns repeatability result but check anyway).
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I will post it there too.
The problem is not the 70 microns, the problem is that the number is a bit random, is not always 70 microns after the homeall.
For example, I've changed my homeall to move to the point slowly, then wait for 5 seconds, then G30, and then execute the gcode for the testing, and this are the results:
Bed probe heights: 0.021 0.023 0.023 0.023 0.025 0.025 0.024 0.024 0.025 0.021 0.024 0.024 0.023 0.024 0.026 0.026 0.031 0.031 0.025 0.024 0.024 0.027 0.026 0.025 0.025 0.025 0.025 0.026 0.029 0.026 0.026 0.025 0.024 0.025 0.025 0.025, mean 0.025, deviation from mean 0.002As you can see, the repeatability is awesome, but now instead of 70 microns, is 20 microns… so if you setup your offset based in the 70 (or viceversa) now you get that sometimes is squished, sometimes is ok, sometimes is too far from the bed...
Cheers
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Thanks for posting the results. I think the sensor is now as good as the high end microswitches. Its a shame my latest effort with underbed mounts is on a marlin equipped printer as there isn't an easy way to run this test, and marlin only reports to 1 decimal place, as its the most sensitive piezo setup I've seen so far. See if the elusive 1 micron deviation is achievable. Almost worth buying a duet board just to do this test on it.
20 microns is probably not noticeable in a first layer. The heater block and heatbreak (below the heatsink) on a v6 can expand 20 microns when heated from 25 to 130 degrees. So that puts it in perspective. But this is constant if you always probe at the same temperature. I mention it in the Precision Piezo documentation going from 130 degrees recommended probing temperature to 250 degrees printing temperature you'll be 20 microns lower at the nozzle.
Try Russ' other test which moves the head around, then probes the same point, check the gcode first as it sometimes moves to extreme positions depending on your printer. If the sensor is reliable to 2 microns, then you are effectively testing the mechanical accuracy of your printer with the moving test. Try a few different speeds for the moves.
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Will test it tomorrow… What still bugs me is why that first Z is not constant... I changed the homeall to move to the point slowly, wait 5 seconds, do G30, and then do G28 Z (yeah, I know, I'm testing twice Z, one with the homeall and the other with homez), and I got this results:
Bed probe heights: 0.002 0.004 0.006 0.006 0.010 0.008 0.008 0.008 0.006 0.008 0.006 0.010 0.010 0.010 0.011 0.006 0.004 0.009 0.008 0.008 0.008 0.008 0.009 0.009 0.005 0.006 0.009 0.009 0.008 0.008 0.010 0.006 0.008 0.009 0.009 0.006, mean 0.007, deviation from mean 0.002
(here I do a G29 to mesh the bed: 56 points probed, mean error -0.054, deviation 0.057 and all again)Second time:
Bed probe heights: 0.013 0.013 0.009 0.013 0.013 0.016 0.014 0.013 0.011 0.013 0.010 0.011 0.011 0.010 0.010 0.013 0.013 0.013 0.013 0.011 0.013 0.010 0.011 0.011 0.014 0.010 0.009 0.013 0.011 0.011 0.013 0.008 0.014 0.011 0.013 0.014, mean 0.012, deviation from mean 0.002
(here I do again a G29 to mesh the bed: 56 points probed, mean error -0.051, deviation 0.056 and repeat all again)Third time:
Bed probe heights: 0.014 0.011 0.011 0.011 0.010 0.009 0.009 0.009 0.010 0.011 0.010 0.011 0.011 0.011 0.009 0.013 0.009 0.011 0.011 0.009 0.010 0.010 0.011 0.010 0.010 0.011 0.010 0.008 0.010 0.010 0.009 0.009 0.009 0.010 0.011 0.013, mean 0.010, deviation from mean 0.001
(here for the last time I do again a G29 to mesh the bed: 56 points probed, mean error -0.052, deviation 0.058)Always the same deviation (which is awesome), not always the same mean during the gcode execution, which is something I don't understand... So my issue is not with the mean, is with the repeatability of the process itself... I don't care if the prints needs 5 minutes to start because I'm doing 7 mesh and 15 homing if the print is always the same :D.
Please do not misunderstand me, I just don't understand why, seen the awesome precision and repeatability the sensor has, the homing is not always the same... although with my rubbish test it seems I'm getting at least similar values around 0.01 xD
Cheers
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Id say something mechanically not tight on the printer/hotend/sensor even. Maybe a youtube video might help.
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Just got my drop in unit today, just a quick inquiry before i screw something up. Should i losen the rear before tightening the front screws or should i just tighten the front?
I dont want to damage the disc so i figured i would ask, but it isnt level.
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So i just opened it up to check out the disc, while reassembling i noticed that it does not fit inside the middle plate which is what is casuing the mount to be tilted. Is this by design or should i print a new center plate?
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The disc is designed to sit on a flange just inside the outer circular recess. It is not supposed to be inside the deeper recess. The idea is the lower part bends the disc in the centre. Do up the screws gradually and ensure they are all done up the same amount with a little preload on the disc.
Then re-tune the module as per instructions, any change in preload level will affect the precision of it.
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If it's one that I made the disc fitted when I made and tested it. But sure you can print a new one if you want. Might be worth watching my YouTube video series on assembling it. It looks simple but won't work if done wrong.
How to Guides: https://www.youtube.com/playlist?list=PL9g_2J-RjkRCy5Sr5gIVwMYGhI9DrJewq
Sorry for being a while getting back to you I don't check here so often our official support thread is at reprap forum:
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Hi!
As cheap piezo discs are mostly made to build buzzers, why not using them this way?
The idea is to use 2 piezos: one on the head, and one somewhere on the heatbed. One of them is used to generate a vibration, and the other one to detect this vibration, which will be transmitted when the hotend is in contact with the bed.
It should be possible to find a resonant frequency to optimize transmission (far from motor vibrations and other noise…).
In fact, any kind of transducer can be used on the bed, to generate the frequency, to have more power than a simple piezo, so it can be easily detect by the head.
A friend in our hackerspace wrote, a few months ago, an Arduino routine to detect a single frequency, which can help to analyse the signal: https://gist.github.com/edgar-bonet/0b03735d70366bc05fc6
Just an idea. Let me know if it has already been discussed.
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Thanks, it has been discussed more so on reprap in the general piezo thread http://forums.reprap.org/read.php?1,635075. I've never tried it, but whilst its an alternative approach is it potentially a solution looking for a problem, as the current method works so well adding a second piezo, and possibly adjusting/changing the PCB to search for the frequency outputted by it, would only be worthwhile if we were going to gain some sensitivity or better discrimination between a trigger and a false trigger (with current firmware settings this isn't particularly a big problem). I'm down to 4g of force to trigger on my microdelta with underbed piezos.
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Well, I was trying to find a solution which doesn't need specific mount for the hotend nor the bed…
I will read the reprap thread. Thanks.
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The gold standard (unless you want to calibrate/level manually) is electrical contact, but we don't have conductive printing surfaces, on the whole, so it isn't practical. You can get conductive PEI at eye-watering prices.
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If it's one that I made the disc fitted when I made and tested it. But sure you can print a new one if you want. Might be worth watching my YouTube video series on assembling it. It looks simple but won't work if done wrong.
How to Guides: https://www.youtube.com/playlist?list=PL9g_2J-RjkRCy5Sr5gIVwMYGhI9DrJewq
Sorry for being a while getting back to you I don't check here so often our official support thread is at reprap forum:
It was how it arrived look at the photo, bought one of your drop in units. I only dissasembled to see why it was so lop sided (have not even installed the thing because i dont want a hotend that sits at an angle. the disc does not fit in the outer recess, i will print another and follow the video. or i might just wait and install the bed sensors that you are shipping to me
just giving you a heads up for QA
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That's just very odd, is it installed already? I'm tempted to send you another one and pay you the shipping to return it by regular airmail. I'd like to see what happened.
If it's installed and working then leave it if you're happy to.
