Very stuck on first layer calibration
I finished building my Prusa MK3S printer yesterday. Was very anal/OCD on building and took my time, as it is my first printer. I bought it from VoxelFactory. My firmware is 3.5.3
Last night I got my layer calibration working and started printing benchy. The layers were slightly rough but not bad. Halfway through the print, the bottom detached and I figured I would recalibrate the first layer.
Now I am on the first layer calibration step. And here is where I am stuck (I cleaned the metal plate with 99% isopropyl. That leaves lots of streaks :/). I try to print. At -1.300, the print is too low and the result is plastic that is too flat. However, if I try to raise it any higher, I cannot for the life of me get my PLA to stick to the bed.
I mean, roughly -1.200 would be good for me I think, but I am really struggling to get there. When I try to raise to those levels (or any level past -1.300), the pla layer seams to curl up immediately after getting laid down by the nozzle. And then of course it bunches up and gets into a complete mess.
I have tried the calibration many times, with many bed cleans. I am at a bit of a loss of what to do. I would really really appreciate any help you guys have.
Thank you
RE: Very stuck on first layer calibration
If you have streaks on the bed, your bed is dirty.
IPA and Acetone are not good at removing general dirt and grease, especially if the bed is hot...
What I do, is to remove the build plate, take it to the kitchen sink, use dish wash detergent, like dawn or fairy liquid, (sometimes called dish soap) and some hot water, scrub the build plate using a new sponge 
and rinse clean with fresh hot water, keeping fingers off the build plate surface, then I dry with a clean paper towel. NOT a cloth!
(Cloths often get treated with Conditioner. which acts as a release agent, messing up your nice clean surface...)
After cleaning the PEI buildplate, I don't need anything else to help with adhesion for PLA.
regards 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: Very stuck on first layer calibration
adjusting live Z is difficult with the first layer calibration tool, most people find Jeff Jordan's 'Life Adjust Z My way' is a better approach
Link to 'Life Adjust Z My Way'
Version 6.1 files are in a zip folder at the bottom of the first post on the thread!
regards 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: Very stuck on first layer calibration
As Joan stated, contamination on the bed is a hard learned lesson we all struggle with.
Here's my guidelines - and I have now adopted Soap and Water as my last step because alcohol just removes the oil from your fingers and coats the bed with it. If you have doubts, try a streak test.
Hot Water wash: often, as needed
Handle the bed only by the edges.
Wash the bed in hot water, use a fresh paper towel as a wash cloth, with a few drops of plain dish soap (Dawn, unscented, no anti-bacterial, etc.). Rinse well in hot water - if you have very soft water, rinse a bit longer.
Dry the bed with a fresh paper towel.
Handle the bed only by the edges.
Place bed on printer.
Alcohol rinse: every few prints
Once in a while, an alcohol rinse is helpful to remove PLA residue. It does not remove finger oils.
Pour a 5 cm puddle of 91%+ alcohol in the middle of the bed, with clean hands use a fresh paper towel to scrub the bed. Wipe up all the alcohol.
Streak test: when contamination is suspected
With a fresh piece of paper towel, and very clean fingers, dampen the towel with 91%+ alcohol, and wipe the bed side to side moving back to front, like you're painting it with alcohol. The alcohol should be thin enough on the towel it quickly evaporates. If you see any streaks, the bed is dirty and needs a wash.
Acetone wash: infrequent
Pour a 2 cm puddle of acetone on the bed, scrub it around with a fresh paper towel. It will evaporate fast as you clean. This step removes PEI oxides that form over time and with heat, and improves PLA adhesion to a like new state.
RE: Very stuck on first layer calibration
I finished my Prusa maybe 6 weeks ago. So I am definitely new to it. My experience so far has been:
The "Life adjust my way" technique is key - the results are very different from the default calibration (I don't know why Prusa doesn't build this in). You may be surprised at what this tells you about where your extruder is currently positioned. I had thought for sure I was good - turned out I was still way too high up.
Alcohol never works for me for bed cleaning. I use tim-m30's washing approach for almost every print. Acetone will work if I am feeling lazy, or is good to do occasionally as he mentions just to clean up residues.
For some prints, especially those that begin with very small and fiddly pieces, I need to manually live adjust z down even further for the first layer, then move it back to the usual setting after the printer moves on to the second layer.
RE: Very stuck on first layer calibration
I use IPA happily for most of my printing and it does remove at least my own fingerprints rather well, as long as I use a new towel (using lab-grade lint-free non-paper towels) every time. But then, I don't usually get the bed covered in fingerprints much.
I do wash the bed in hot water from time to time, though, using a strong degreaser spray rather than dish soap. Dish soaps tend to have all kinds of skin care stuff in them that's oily.
And I've come to learn that wet-sanding the smooth PEI with a 600-1000 grit sandpaper also does miracles for adhesion. A few drops of detergent/degreaser in the water while wet sanding makes for a smoother experience - the dust binds to the detergent and is removed from the sanded surface faster.
Nitrile gloves are definitely recommended when degreasing by any of the methods. Good for both protecting hands and for protecting the clean bed from the hands. 🙂
RE: Very stuck on first layer calibration
Wet sanding ... that's so funny. There are a few people that insist they don't need to use soap and water then resort to sanding to get PLA to stick. +1 to that list.
Alcohol is a solvent, not a surfactant. It can't remove finger prints.
RE: Very stuck on first layer calibration
A surfactant is a molecule with polar and non-polar ends. It binds to non-polar fats and oils by the non-polar (hydrophobic) end and enables them to be dissolved in polar solvents, like water, thanks to a ion forming at the polar end.
Isopropyl alcohol is a solvent that's only mildly polar and will dissolve organic fats (triglycerides and ceramides) well.
What matters in the end is the final concentration of the fats in the solvent that then leaves them on the surface.
With water and detergent/surfactant that is helped by a stronger affinity of the fats to the surfactant and the surfactant to water than of the fat to PEI. Still, as always in chemistry, there will be a balance between concentrations, so some fat will be staying on the surface.
The same with the solvent. The balance will be between fat on PEI, fat in solution and fat attached to the towel fibers. The capacity for fat removal is much smaller with a solvent, but if there is not too much of it on the PEI, the solvent can do a good job still, moving most of the fat to adsorb on the fiber. Fiber quality (porosity, amount of surface) matters here.
So in a way I do insist that IPA does remove fingerprints from PEI, despite being "just a solvent", but I also do agree that a detergent/surfactant/degreaser is a much stronger method to get rid of them.
And in case we add silicone oil to the mix, often found in hand soaps and hand creams (and McDonald fries ;), then IPA is a lost cause, since they don't dissolve silicone well at all. Acetone fares a little better, but not by much. This may be a reason why people differ in their opinion about the efficacy of IPA removing fingerprints.
The wet sanding is not about removing fingerpints, it's about increasing the surface contact area per square centimeter of the PEI sheet. 🙂
RE: Very stuck on first layer calibration
I challenge you to use the gallons of solvent required to obtain the same low enough concentration that a simple hot water wash and rinse at 5 gpm leaves.
Add that I have never had to sand my PEI sheet to get good adhesion, adds to my statement. Proper cleaning is enough.
RE: Very stuck on first layer calibration
I never had any issues getting good adhesion with PLA on PEI, whatever the cleaning method used. PLA/PHA was a little trickier, but getting the temperatures right fixed that. But I was tearing my remaining hair off getting Nylon to stick to anything. Now I know that it's either a thick layer of PVA on PEI or a sanded Phenolic sheet that Nylon will stick to. The commercial ones even ship with a piece of sand paper to prime them. A hot water + detergent washed Phenolic was no good for Nylon.
The main reason why I sanded my PEI sheet was light, but visible surface damage caused by PETG sticking way too well and me not knowing about the need for window cleaner yet. But after sanding I observed better adhesion of PVA (again, never had trouble with PLA) when fighting with Nylon. The Nylon (PA12) would tear the PVA off the smooth PEI surface while warping but rather tear itself off the PVA when on a sanded PEI surface. In any case creating bubbles in the acrylic glue underneath. Eventually I gave up, decided this needs a heated chamber and switched to PA6/6.6 which can be printed without a chamber.
I can't outright say "challenge accepted" as I can't promise I'll find the time to actually do the experiment, but I'll try. One side of my PEI sheet is sanded, the other is not, so I can compare that, too.
What model would you suggest for an adhesion test? The PRUSA demo plaque? What protocol? Smudge all over, test, clean with cloth dampened in IPA, test, wash in IPA, test, wash with hot water and detergent, test?
RE: Very stuck on first layer calibration
Ok, this turned out to be rather boring.
I loaded cheap Gembird PLA Natural into the printer and proceeded to smudge the PEI sheet thoroughly. I then started a print of the Prusa plaque demo model from the SD card that came with the printer. It's gcode, so I didn't tune any settings. The printer started, and proceeded to create a nice blob on the nozzle. I stopped the print and used my standard tools - lintfree wipes, 99.9% isopropyl alcohol and nitrile gloves to clean the surface of the PEI sheet. I limited myself to one wipe and only wetting the wipe with IPA, no pouring IPA on the heat bed. Done after about 10 seconds, I nervously started the print again. 1st layer looked fine, at least to my eyes, so I let the print finish. The printed part held on well and popped off after bending the sheet. And that's it.
I didn't do any of the further steps, because there wasn't much room for improvement.
IPA works well enough.
RE: Very stuck on first layer calibration
I'm intrigued by the OP saying "At -1.300, the print is too low and the result is plastic that is too flat."
In reality, if the print head is somewhat too low on the first layer, you get "plowing" where there is nowhere for the plastic to go except off to the sides of the small "flat" on the bottom of the nozzle, so the result is a rough surface. The ideal height is where the first layer feels perfectly smooth to the touch. If using the built-in Z adjust, that means the 10mm X 10mm square at the end of the adjusting pattern should feel smooth. If it has traces with gaps between the traces, you are too high; if it has no gaps and adheres well but is rough, you are too low.
RE: Very stuck on first layer calibration
The ideal height is where the first layer feels perfectly smooth to the touch. If using the built-in Z adjust, that means the 10mm X 10mm square at the end of the adjusting pattern should feel smooth. If it has traces with gaps between the traces, you are too high; if it has no gaps and adheres well but is rough, you are too low.
👍 Yes, that's what I also found to be a very good and quick indicator of correct Z offset. That and a caliper. 😉
RE: Very stuck on first layer calibration
To Datadex: here'a photo of a first layer test that is useful. A large circle or square that allows time to adjust z-offset while printing. The result should be a patch that is a solidly welded sheet of plastic. As stated above, it should be smooth, flat without gaps. This example is barely thin enough, and there are a few gaps.
Jeff's "Life Z" procedure provides more detail for achieving this and is a good resource to check out.
RE: Very stuck on first layer calibration
What really surprised me when I did the "life adjust my way" procedure is that when I did my first run peeled the patch off the plate, the individual stripes all separated from one another when the square was flexed. This made it crystal clear the extruder was too high. But this was not at all visible when using the native calibration. Until then, I thought everything was hunky-dory.
RE: Very stuck on first layer calibration
adjusting live Z is difficult with the first layer calibration tool, most people find Jeff Jordan's 'Life Adjust Z My way' is a better approach
Link to 'Life Adjust Z My Way'
Version 6.1 files are in a zip folder at the bottom of the first post on the thread!
regards Joan
Thank you so much! Prints are going much better. After a proper cleaning with dish soap and using life adjust z my way really really helped
RE: Very stuck on first layer calibration
As Joan stated, contamination on the bed is a hard learned lesson we all struggle with.
Here's my guidelines - and I have now adopted Soap and Water as my last step because alcohol just removes the oil from your fingers and coats the bed with it. If you have doubts, try a streak test.
Hot Water wash: often, as needed
Handle the bed only by the edges.
Wash the bed in hot water, use a fresh paper towel as a wash cloth, with a few drops of plain dish soap (Dawn, unscented, no anti-bacterial, etc.). Rinse well in hot water - if you have very soft water, rinse a bit longer.
Dry the bed with a fresh paper towel.
Handle the bed only by the edges.
Place bed on printer.Alcohol rinse: every few prints
Once in a while, an alcohol rinse is helpful to remove PLA residue. It does not remove finger oils.
Pour a 5 cm puddle of 91%+ alcohol in the middle of the bed, with clean hands use a fresh paper towel to scrub the bed. Wipe up all the alcohol.Streak test: when contamination is suspected
With a fresh piece of paper towel, and very clean fingers, dampen the towel with 91%+ alcohol, and wipe the bed side to side moving back to front, like you're painting it with alcohol. The alcohol should be thin enough on the towel it quickly evaporates. If you see any streaks, the bed is dirty and needs a wash.Acetone wash: infrequent
Pour a 2 cm puddle of acetone on the bed, scrub it around with a fresh paper towel. It will evaporate fast as you clean. This step removes PEI oxides that form over time and with heat, and improves PLA adhesion to a like new state.
thanks for the handy guide! I am saving this for sure
RE: Very stuck on first layer calibration
To Datadex: here'a photo of a first layer test that is useful. A large circle or square that allows time to adjust z-offset while printing. The result should be a patch that is a solidly welded sheet of plastic. As stated above, it should be smooth, flat without gaps. This example is barely thin enough, and there are a few gaps.
Jeff's "Life Z" procedure provides more detail for achieving this and is a good resource to check out.
thanks for the photo. I will use it as a comparison when I do further calibrations