First layer woes  

Re: First layer woes

I like the -1.300 look ...

Bed contamination comes from many sources. Including finger and hand oils on the filament before it gets into the printer. I've had to unwind the full first layer to get to clean filament. Whether the bagger had just put on hand lotion or the inside to the vacuum sealed plastic bag had a special coating... no clue, but the filament just wouldn't stick.

Honestly the patch of white looks like a dirty bed. But it may also be dirty filament. One sign of dirty filament is when manually extruding 50mm or so, it will leave the 0.4mm nozzle orifice and immediately expand to 0.5mm or even foam up larger as it drops away.

Also - the plastic looks almost like you are running too hot. It shouldn't flow like that. Is that PLA at 215c / 60c?

Re: First layer woes

I've been using the filament for several meters. While I think i've just been "pinching" the filament in and out during loads I'll keep that in mind for the future.

Does the heat need to be backed down for doing detailed (0.05) work? Or the speed? Beyond what Slic3r does automatically?

Re: First layer woes

Does the heat need to be backed down for doing detailed (0.05) work? Or the speed? Beyond what Slic3r does automatically?

Yes. 210-205 is a bit more appropriate than 215 for detailed work, however, 215 is good for a first layer. If you see significant stringing reduce the temperature. Small stringing is invertible with some prints.

I agree that it looks like you have a dirty bed. Use a little elbow grease and some high strength rubbing alcohol to get it back in shape.

Pro tip: Don't use rubbing alcohol if you're printing with PETG. It can stick "too well" if you do. Windex is better for PETG. If printing flexible materials DO NOT print onto the standard PEI sheet without glue or masking tape. It won't come unstuck as it chemically welds itself to the PEI. Some random bed facts!

Re: First layer woes

So, I scrubbed the sheet with Dawn Original and a paper towel and dried it with more paper towel. I scrubbed it with 99% rubbing alcohol. And had the same issue. Double scrub and switched to Prusa Silver filament and same issue.

Did a quick 7.5x7.5 calibration square from the Life-Z on the theory that the whole thing is basically a first layer and, absolutely no issues.

I resliced at 0.15 and the first layer went better. Resliced again at 2.0 and it went better still to the point where I'm letting it run.

So, new questions.

How do I clean the nozzle? I'm pretty sure there gets to be build up but I'm wary about using my brass toothbrush on the brass nozzle. Any tips on cleaning the underside.

Re: First layer woes

Prusa's Slic3r PE settings for 0.05 printing work out of the box with most PLA filaments; no changes needed.

Use a paper towel dampened with a bit of alcohol on a warm touchable nozzle (not hot, alcohol has a low flash point). Use a dry paper towel on a hot nozzle (but use caution here because burns happen before you feel them). A wire brush must be used with caution, the wires to the heater are bare and a brush can cause shorts that damage the controller. A wire brush can also scratch the nozzle and cause burrs that make printing harder to do.

That white filament is being printed at too high a temperature. Reduce both layer 1 and other layer temp in 5c steps until actual distinct extrusions appear, rather than a melted flat. If I saw that on my printbed at 215c, I'd drop layer 1 to 190c and try again.

As for filament contamination, I experienced a bad spool from Prusa. I had to remove a lot more than a few meters to get down to clean plastic.

Alcohol doesn't clean the body oils off the bed; soap and water do. Do a streak test if you are curious.

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, use a fresh paper towel to scrub the bed. Wipe up all the alcohol.

Streak test: when contamination is suspected and after a wash
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: First layer woes

I resliced at 0.15 and the first layer went better. Resliced again at 2.0 and it went better still to the point where I'm letting it run.

Just to double check, you're not setting the first layer height to be equal to the normal layer height when you do this, are you?

Thinner first layers will be much more sensitive to the live Z setting and any bed height variations that aren't caught by the mesh leveling. I'd suggest not going any lower than the 0.2 mm default regardless of the height of the other layers, and I personally use 0.3.

Re: First layer woes

[...] How do I clean the nozzle? I'm pretty sure there gets to be build up but I'm wary about using my brass toothbrush on the brass nozzle. Any tips on cleaning the underside.

I had the same concerns with coated nozzles. Then I realized a small strip of cardboard can be used on a warm nozzle for effective cleaning. I keep a few 25mm strips nearby for nozzle touch-up, and mount a silicone sock to keep the heater block clean.

Re: First layer woes

Just to double check, you're not setting the first layer height to be equal to the normal layer height when you do this, are you?

Good question as I was tinkering with g-code to heat the bed on other projects but, no. I left this one at the default settings. The object had text written along the bottom and I think that was part of the problem. The figure printed out at the 0.2 Quality but the bottom was messed up; lots of loose fill. I think a contaminated bed plus trying to print something that maybe should have had a smaller diameter nozzle added up.

I had the same concerns with coated nozzles. Then I realized a small strip of cardboard can be used on a warm nozzle for effective cleaning. I keep a few 25mm strips nearby for nozzle touch-up, and mount a silicone sock to keep the heater block clean.

Thanks Bobstro, between the tips above and the cardboard I"ll put the brass brush away for emergencies. Is removing the nozzle and rinsing it in something a thing? The tech chat had me heat up the nozzle to 260 to clear a load/unload issue. Is that a general maintenaince thing or another emergency only?

Anyway, thank you for all your help and suggestions. The did say one reason to get a Prusa is the community 🙂

Re: First layer woes

Unless you plan to chemically etch the nozzle free of all plastics, soaking in acetone or MEK or other extreme solvent, I don't see a benefit to doing so. Some folk try burning out the plastic, but that also weakens the brass.

Cold pulls work very well to remove old plastic from withing the nozzle; and the out side of the nozzle can be cleaned using mechanical methods. I use a brass brush on a Dremel - but I avoid spending any time around the tip. You can melt a pile of plastic, heat the nozzle to stick the blob to it. Turn off the heater then pull the blob free as the nozzle cools past 90c ... an external cold pull. Usually removes any stubborn fragments from the outside and less damaging than a brass brush.

All that said, brass nozzles are cheap enough replacing one that isn't performing is a fair option.

Re: First layer woes

[...] Is removing the nozzle and rinsing it in something a thing? As Tim notes, that's not something typically done, and it sounds messy.

The tech chat had me heat up the nozzle to 260 to clear a load/unload issue. Is that a general maintenaince thing or another emergency only?In general, you want to clear the nozzle when switching from any high-temp material (e.g. PETG) to a low-temp material (e.g. PLA). Heating the nozzle up higher than the high-temp material print temperature ensures any left-over filament will soften and hopefully get pushed out.

Doing a cold pull occasionally is also recommended. You basically heat up above your highest print temp, insert some suitable cleaning filament (I like eSun cleaning filament, others swear by white ASA or nylon) and push it through until the extruder flows cleanly, then let the nozzle cool off completely with the cleaning filament still inserted. Once cool, open the extruder door, set the temp to normal print temp and at roughly 90C, begin pull upwards on the filament. It should pop out with the shape of the inside of the hotend, pulling along any accumulated crud that didn't extrude.

[...] The did say one reason to get a Prusa is the community 🙂
Oh definitely. I spend a lot of time on the various Reddit 3D printing groups, and the experience using other printers is vastly different. The best part is not having to print a half dozen replacement parts and flashing firmware to get decent prints without burning down the house!

Re: First layer woes

The best part is not having to print a half dozen replacement parts and flashing firmware to get decent prints without burning down the house!

Concur, fires are a less than ideal outcome.