Getting mixed results from calibration
I recently got my hands on an I3 MK3S kit and assembled it with some help. The day we finished my roommate and I took about 2-3 hours to calibrate it as we had some problems with the nozzle to bed height. We got a good result which resembled what it should look like according to the manual and we printed the PRUSA and Marvin model which comes with the software you download. They came out fine and there was no issues at all. Fast forward to this morning, we wanted to experiment with the Marvin model and how different print settings looks like and the print had some issues. It almost finished the first layer and then the filament started attaching to the nozzle. We thought this was kinda strange but we had selected the finest option for printing (0.05) and we thought maybe there had to be some extra adjustment to print that fine. We then started the original Marvin print with 0.20 and it also failed (Same problem). We ran calibrations again and with the same settings for nozzle to bed height we used last time it didn't get the same result (Not the same good looking plate at the end and the filament was too squished). After trying different solutions (Altering the height of the PINDA sensor, making sure all screws on the bed was OK) I'm still unable to get good results.
Here's where I get confused by the nozzle to bed calibrations. According to the manual, a flat line too low. Mine was flat, so I moved the nozzle up by a very small amount. With this alteration, the PLA filament doesn't attach to the bed. Doing some research, this is a sign that the nozzle is too high. I ran it again and this time I had flat filament in some parts, the filament didn't attach to the bed on some parts and the plate in the end was looking like the example of a good height. So according to everything I read, the nozzle is too high, too low and at a good height at the same time.
Is there anyone who's had a similar issue and might have something that I can try, or anyone that might have an idea based on the description of my problem? Thanks in advance.
RE: Getting mixed results from calibration
You have 3 places on the right of the decimal in millimeters to adjust the Z calibration. How can you go from squished flat to not adhering at all within 1 adjustment?
How much did you change? Change it back 50%.
I had difficulties with looking at the line. Since gray on black was not very visible. I ran the first layer a few times and inspected the cross section of every try with my microscope (x10 for smd soldering). Perhaps a macro photograph also works for this.
Original Prusa i3 MK3S
RE: Getting mixed results from calibration
Your PEI surface has probably become contaminated, which will make an accurate Live-Z calibration nearly impossible. Here's and old family recipe for copypasta that should get you going...
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A dirty PEI print surface. Even if you don't think this is the cause, it's always a good idea to make sure your PEI surface is clean before trying any other fixes. Take it to the kitchen sink and give it a good dunk with Dawn (original formula, no vinegar or hand softener variants) dishwashing soap or your local equivalent (e.g. Fairy in UK). Use a clean paper towel to clean it off, and another to dry it. Avoid using any sponge or cloth that has been in contact with grease. Above all else, avoid touching the PEI print surface. Once it's good and clean, you should be able to use 91%+ isopropyl alcohol between prints, 100% acetone when that fails, and another dunk when acetone fails. Worst-case, use a 3M 7445 ScotchBrite pad or equivalent to give it a very light buff, but only infrequently.
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If you have not already done so, try using Jeff Jordan's "Life Adjust" procedure for calibrating your Live-Z setting. It is much easier to use and understand than the on-board routine.
and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan
RE: Getting mixed results from calibration
How much did you change? Change it back 50%.
I just made another couple of tests. I kept going lower each test until it the filament stuck to the board and then did the entire test. The result, compared to the ones from the manual tells me it's too low (I base this mostly of how flat the filament is and how the nozzle has disturbed the surface of the small plate at the end). This was at -1.430. I then did a test where I upped it from -1.430 and the filament started to attach to the nozzle very soon after (-1.350).
@bobstro:
I think you're right. The issue is probably the print surface. Yesterday evening we googled how to clean the print plate and my roommate used something for cleaning windows. For some reason we use this a lot for cleaning up dust on any surface, and not just windows, but I should have been more careful. I will try to get some of the recommended products you told me about tomorrow and post result from Jeffs Z test. I read about it before but I thought the in-built one would be easier.
Is it easy to "destroy" i.e render the print surface un-usable/fixable if the above mentioned product has been used on the surface?
RE: Getting mixed results from calibration
Is it easy to "destroy" i.e render the print surface un-usable/fixable if the above mentioned product has been used on the surface?
No, not at all. The Prusa PEI surfaces are made with some sort of devil magick that renders them nigh-on indestructible to anything but physical forces. The biggest thread is over-adhesion with PETG or other sticky filaments leading up to ripping the PEI surface, or somehow driving the bed into the surface. In general, any sort of mess you make on the sheet can be cleaned with a good applications of dish soap and water, together with only using plain paper towels for drying. Try to keep any grease or lotions well away, and don't use sponges or cloths that might have accumulated grease.
and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan
RE: Getting mixed results from calibration
You'll notice PEI degradation where the intro line is placed first. Damage is hard, only easy by using knifes to remove prints or overadhesion of PETG on a too clean surface.
Original Prusa i3 MK3S