Can PINDA be blocked from reading calibration points?
Sorry for the long history, but I think it's important to know how I got here. I had an issue with a PETG print sticking to the bed so hard that when it finally came off, it pulled PEI off the bed with it. I tried printing around it for awhile, but suddenly the first layer just stopped sticking and the print head looked like it was way too far away from the bed surface. I ran the XYZ calibration and first layer a dozen times, but when I'd go to actually print something, the nozzle would again get too far away from the bed. I finally decided to replace the PEI so I wasn't trying to use just a small portion of the bed. Unfortunately, I shied away from ordering from Prusa because it makes little sense to me to pay more in shipping that the item I want to purchase. So I bought an off brand PEI sheet from Amazon that turned out to be more like plexiglass than the PEI film I removed from the bed. I got a successful XYZ calibration and went to set the live Z layer height per the instructions in the "opening" forum post (!!! Before you ask) which I have done dozens of times. Even though I used my credit card to set the PINDA height, the live z adjust went beyond 1mm. I was only able to get it to a reasonable amount by sitting it a 3x5 card height off the bed. I know that's way too close, but only then would the live adjust procedure yield a value between .4mm and 1mm. Of course when I did the first layer calibration, the PINDA was dragging on the first layer and deflecting the nozzle as it did. I was going to go through the whole process again when it started dragging the nozzle on the paper while doing the XYZ calibration even with the PINDA that low. Working with Prusa support, we decided that the PINDA was malfunctioning and Prusa send out a new one. After putting the new PINDA in, I went through the whole self-test process and then started the XYZ calibration. This time it drug the paper on the first of four calibration points. Rather than shut it down, I watched to see if it was going to drop the nozzle any lower with my finger on the power switch. It never dug into the bed at all, but it also quit after the first point saying it couldn't find the calibration point.
So I'm wondering it's possible for the thick PEI sheet to inhibit the ability of the PINDA to find the calibration point? I'm at a loss as to what to do next.
Re: Can PINDA be blocked from reading calibration points?
yes. the PINDA looks for metal. so I would think if the PEI sheet is thick, it might not like it.
cant think of a workaround for you, but there are smarter people on the forum then me 😀
you trashed both sides of you PEI?
I have a Prusa,therefore I research.
Re: Can PINDA be blocked from reading calibration points?
Not sure what you mean by both sides. The PEI that peeled off was just a film...one side was glued to the bed. The places that were damaged by the PETG print separated from the bed and stuck to the part. What I got to replace it was 1mm thick. 1mm doesn't seem like much, but it's probably 4x thicker than the film.
Re: Can PINDA be blocked from reading calibration points?
Not addressing the other points, but if you are using the Prusa PEI sheet, turn it over. Both sides are printable. I believe thats what toaf was referring to.
Re: Can PINDA be blocked from reading calibration points?
Hi Stephen,
is this a mk2 printer?
the Mk3 has a removable build plate, which should be taken off for XYZ calibration
you have posted in the Mk3 section of the forum...
Chris (Toaf) was asking about both sides of the PEI, because the removable build plate has PEI on both sides...
Pinda probes are confusing...
I understand that you started off with the Pinda spaced One Credit card higher than the Nozzle... this means that the Pinda is probably too low... and that ties in nicely with your experience of the nozzle being too high when you complete XYZ calibration...
You advise that you then used 3 to 5 credit cards... and this is where I get confused... My credit card is 0.8mm thick, but the text part is 1.25mm thick... if I stacked three of them I would expect the thickness to be about 3.3 to 3.9mm thick... five cards would be even thicker... (Allowing for embossed text) that seems too high with standard PEI and even worse with Thick PEI... remember this 'Physical' spacing works from the top of the PEI, not the metal below where the PINDA inductive sensor registers
raising the PINDA higher results in the nozzle being closer to the build plate.... so you were going in the right direction but you may have gone too far.
then I believe you changed the PEI for a thicker PEI sheet... that could exacerbate the issue.
The PINDA Senses the metal in the heatbed, under the PEI, not the top of the PEI...
SO.... I think you probably need to lower the Pinda, and try again...
Lowering the Pinda, should allow the XYZ calibration to complete, and then you can try adjusting Live Z for your new PEI surface.
If you simply can't get the nozzle low enough for a good first layer, than raise the PINDA a touch and try again...
My Mk2 was set up with a new bed and the Live Z value was around -.700mm
I chose to put a spare steel build plate on top of the heatbed... and the Live Z went way out of calibration... probably because the PINDA responds to steel build plate different to copper tracks on the original heat bed... so without moving the PINDA to nozzle relationship, I have had to revise my Live Z to about -1.2mm Works fine, no problems... I don't do ABS, so curling is less of a common occurrence for me.
Live Z over -1.00mm is not a terrible issue... but it does mean that the Pinda is closer to the nozzle height than ideal... (this may become a problem if you get a model curling or lifting.... )
because your PEI is thicker than the original PEI, you need to have your Pinda, that bit closer to the nozzle height... BUT You should be able to sort it out...
(Do you use 'Life Adjust Z, My Way' by Jeff Jordan, this process may help you sort your Live Z adjustments! https://shop.prusa3d.com/forum/assembly-and-first-prints-troubleshooting-f62/life-adjust-z-my-way-t2981.html#p106130
Best wishes Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
Re: Can PINDA be blocked from reading calibration points?
Wow...i could have sworn I clicked on the MK2/S Mulit Material forum before I started. My apologies...
I'm totally confused about the positioning of the PINDA probe. I've followed the instructions https://shop.prusa3d.com/forum/assembly-and-first-prints-troubleshooting-f78/-before-you-ask-troubleshooting-video-updated--t472.html#p39190 to set the z height. It contains the following:
NOTE: If your Live Adjust Z value is >1mm something is wrong. It should be approx the distance from the PINDA probe to the nozzle. Anything between 0.4mm and 1.0 should be fine. (Less than 0.4 means the PINDA probe might catch on some print that curles up a bit, greater than 1.0 means either you did something wrong, or are just barely in the PINDA’s detection range.)
My interpretation is that the live z adjust is measuring the difference between the height of the nozzle and the height of the PINDA. If the PINDA is too high, your live Z adjust will be > 1mm. So getting values of > 1mm when I used the credit card height meant that I should lower the PINDA. I did that by using 3x5 index cards (not 3 credit cards) to set the height, thus moving the PINDA lower (toward the bed). For what it's worth, my credit card doesn't have raised numbers.
Again, I apologize for posting in the wrong forum. I'll repost in the right one. thanks for responding
Re: Can PINDA be blocked from reading calibration points?
If your Pinda is too high, the nozzle will hit the PEI.
which I believe is the issue you are having...
and I believe I moved the topic for you!
Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
Re: Can PINDA be blocked from reading calibration points?
Unfortunately, I think you misinterpreted what I meant by 3x5 cards. I'm talking about index cards which are .1mm thick, not multiple credit cards. By the time I was finished, my Pinda was just over .1mm higher than my nozzle. And the problem that I see is not that nozzle is crashing into the bed, but that the PINDA can't read the calibration point. Before I realized you could move my post to the correct forum, I reposted the question myself. That post is at https://shop.prusa3d.com/forum/viewtopic.php?f=59&t=24496&p=107169#p107169 . It contains this youtube video that shows it failing to find the calibration point
Re: Can PINDA be blocked from reading calibration points?
lower the pinda. the pinda will detect the metal sooner. the only thing I can see is you might have to lower it so much that the pinda is lower then your nozzle. but lets hope it doesn't have to go that low.
it would be cool if you can make it work, but if the bed thing is a 1 mm it might be difficult.
I have a Prusa,therefore I research.