New Mini 2, various adhesion problems (PLA)

On my TAZ 6, I use 70% alcohol and its fine. I (carefully) use Scotch Brite pads on a hot nozzle if the auto-leveling sequence has problems. I have a brass brush but I have insulated the thermistor and heater wires with hi-temp silicone to avoid blowing the fuse (or worse).

I use a skirt on most of my prints and I have increased the number of lines and the minimum length. It is not uncommon for the first line to be incomplete but if the last line isn’t perfect, then something isn’t right and I abort the print and adjust settings until it is. I also don’t run the part cooling fan on the first layer but it is usually going 100% by layer 3 for PLA. I also use maybe 5 degrees more nozzle temp on the first layer.

Careful examination of the lines in the skirt can tell you if the Z-offset is correct. You can find pictures and explanations on the internet that would be better than my attempt, so I’ll let you look that up.

By default, I think Cura uses a thicker first layer height than the rest of the print.

Yessir, brand new, not used, ordered new straight from LulzBot’s site. Manufacture date on the QC paperwork was about 3 weeks ago.

So let’s say hypothetically (cough, cough) somebody, not knowing any better, used the included metal tweezers to yank filament off the nozzle and “may have” made contact with the nozzle itself. Is that micro-fuse you mention probably dead, or is it a resettable variety? Is it replaceable? How much did that cost me? Isn’t auto-leveling where it touches the washers? That still seems to work (it taps them, then does it again very slowly).

Yes at the initial extrusion the filament is very thin and tends to curl and stick to the nozzle (often, not always).

I’ll do some searching for examples of how to examine the skirt lines relative to Z-offset. Although I haven’t gotten a good-enough print (without using glue) lately to even have anything to examine yet. Good to know about 70% alcohol though.

Initial layer height is 0.425 and both flow values are 100% (all defaults). I only changed the couple of settings I mentioned. Skirt is on (that’s what I referred to as the priming perimeter line, didn’t know the right term). All defaults (skirt line count 1, distance 3mm, minimum length 250mm). I guess it stacks extra layers if it doesn’t reach the minimum length?

It sounds like you did not blow the fuse and the auto leveling is still working. In my experience the blown fuse knocked out the LCD display (TAZ 6), the mini 1 doesn’t have a display but you have a mini 2 so you do have a display. I don’t know what we’re to happen on the mini 2 if you were to blow the fuse. It’s just a hassle to do and the mini fuses aren’t easy to come by at your local store. Cost of new fuses are approx $10 or so for 3. Search Amazon or e-bay. Seems everything on Lulzbot site is always out of stock.

Yes auto leveling is where it touches the washers, the electrical path continues up through the nozzle.

I don’t think the skirt would stack, instead I think it will lay down another perimeter line until it pushes out 250mm of filament.

Run tests manually. Move the nozzle up, heat up the filament, extrude it in the air. How’s the flow? Does it flow freely? Or does it seem like there’s a clog impeding the flow? Printing in the air it will probably curl up on the nozzle, pull it off, let the weight of the filament pull it down.

Where’d you get this filament? Is it quality? 2.85 mm width?
Did you print with a different filament with a higher melting temperature prior?
It may be worth trying to do a purge. Remove the PLA filament, heat up your extruder to 260c. Some filament may come out. Insert the PLA manually, push it down and push through the residual filament. Read up on doing a cold pull to clean your nozzle. Can even try cleaning filament as that has a large working range and is designed to clean your nozzle between filament types.

When I changed the filament I did extrude in the air, and it does curl and stick, but eventually flows freely. This is how I purged the old filament color after changing to another. All I’ve used are the sample filaments shipped with the printer (mentioned in OP), both are same brand/type/size, just different colors

Interesting, hadn’t heard of cleaning filament. I’d noticed the “cold pull” button in Cura and have been meaning to look it up.

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@JoeBowler300 is correct, the skirt just keeps going around until 250mm is laid down. I use line count 3 and 500mm min length (probably don’t need to increase the min length).

I highly recommend the eSun cleaning filament. A cold pull (lowering the temperature below the melting point and then pulling the filament out) should give a nice imprint of the inside of the nozzle. On my TAZ 6 Single Extruder, I can shine a flashlight through the filament path when I’m done.

You can cold pull PLA at around 110C. The eSun cleaning filament down to about 90C. I can’t remember if I approached the best temperature from above or below. Too high and the filament stretches out and can break before pulling the inside of the nozzle. Too low and it just won’t pull.

With PLA the PEI sheet on the bed should work very well. I clean mine with 70% isopropyl alcohol regularly and hit it with a 3200 grit Micro-Mesh pad (or 2 of each) occasionally.

I would make sure that the nozzle is tight. Mine wasn’t when I got it and was unwinding (lowering) itself till I figured out what was going on. Tighten it when hot. Make sure that your printer is selected properly in Cura. Make sure the bed is clean. I wet sand it using alcohol and 1600 grit wet or dry paper once in a while is adhesion is an issue.

Finally circling back to this after a couple weeks of obsessing over another hobby, thanks for all the advice. I set skirt length to 500mm which is probably overkill.

Cold pull didn’t seem to do anything, it looked clean. I did order cleaning filament but haven’t tried it yet. Considering I only printed two things before changing filament, and haven’t had any successful prints yet with this other filament, I’d be surprised if it was very dirty in there (again, all filament so far are samples shipped with the printer from Lulzbot, same type/brand as the successful prints).

Calipers say my washers are 1.53 or 1.54mm thick depending on which one I check. Is my Z offset supposed to compensate for that difference? So in theory I should be using a Z offset somewhere in that range?

I get adhesion with Z offset -1.45 (which was suggested earlier) but I felt like it was squishing too much (the layers look flattened versus the rounded lines shown in the OHAI z-calibration pictures), whereas -1.40 wouldn’t adhere at all. So I’m not sure if it’s right to say I’m getting adhesion if it’s just sticking because the nozzle is squishing it. I backed off to -1.43 with the same results, it looked squished to me.

What causes roughness seen in the picture below? Those bits sometimes stick to the nozzle when it lays down the next line and it just gets worse the longer I let it run.

I also meant to ask, does anyone have a good STL for doing quick tests?

I noticed the OHAI build instructions mention something called “PLA_HS_QuickCircle.gcode” … is that maybe what is shown in the Z-offset calibration pictures? Anybody know where to get that?

Well I had a few files to upload for you to do some quick print tests but this site won’t allow .stl file uploads (ironic cause this is a 3D printing site :man_shrugging:). This site will only allow uploads of pictures. When I change the file extension to a supported picture format and attempt to upload it I get this error:
image

Therefore I cannot help you with my files. If you don’t have the ability to create your own .stl files you’ll need to download something from the Internet. I suggest going to Thingiverse to find something to print. Maybe search “Test Prints” or something of the likes. Or you might be able to find something by simply browsing the site.

Don’t download .gcode files cause those files are created based on hardware and it’s pretty unlikely that the file will match your hardware. Especially with Lulzbot printers having the ability to swap out printheads.

Cheers!

I believe this site accepts .zip files.

We have a TAZ 6. Based on your original pictures I had a similar result when using PLA and RAFT for build plate adhesion. The raft portion would start to stick and eventually look like the third pic you have posted. My issue ‘seemed’ to be high humidity in the ambient air. Stored filament with desiccant and waited a couple of days for the thunderstorms to pass and has successful print.

On a different note with your comment about using ABS. For me the village plastics ABS profile in Cura is working great for me. The print temps are higher than what is stated on the reel of filament I have (220) however when I use that setting it jams up.

Nope, won’t allow that either.
image

Sorry about that, I must have confused this forum with another… It does seem strange that .stl and .gcode files aren’t allowed in a forum on 3D printers. Probably need to figure out how to contact the moderators and get that changed. Otherwise, we are stuck uploading those types of files to file sharing sites and posting links here.

Thanks, I found some good test models to download. Thanks for the tip about gcode files, I hadn’t thought about them being machine specific. I sent a message to one of the admins asking if they’d consider allowing some of the common 3D file formats as attachments. Admin profiles are linked on the forum’s about page from that menu at the top right.

I suppose PLA or maybe all filament is hygroscopic then? How long does it take to have an effect? (Though I suppose that would depend on ambient humidity.) I’ll have to do some GoogleSleuthing.

This sample filament failed straight out of the sealed bag from Lulzbot, but I suppose it could be a bad batch? Come to think of it, on OHAI there are pictures with huge reels of filament in the background – the green stuff they do the test print with, so they apparently don’t store it sealed up, and the little samples they send aren’t pre-packaged either.

But if humidity is an explanation, I might be in a bind given that I live in Florida. Big bad storms are a near-daily occurrence. However, my thermostats always show a steady 40% humidity throughout the house. I’d have thought that’s pretty dry. What would a good target be for printing? I wonder if a room-sized dehumidifier would help?

I live in Colorado Springs and its pretty dry here (less than 20% much of the time) but I occasionally have problems with a “wet” filament. There are a variety of filament dryers (dehydrators) on the market. I have one from PrintDry and it has the capability to feed filament from inside the dryer.

I’ve got some rubber-sealed airtight storage containers on order that I’m going to try with good-quality dessicant first. I figure I can do one of those filament-wiper things as a sort of feed port. If that doesn’t help or is a problem for some reason, I can always try a dryer.

Still waiting on my storage containers but I read an interesting comment somewhere suggesting that something about the dyes in many white filaments make them harder to print – the point being they’re a poor choice for calibration. Since this is just the factory sample, maybe I’ll switch to the red sample once my dry boxes are ready.

Just wondering if anybody has ever heard of such a thing.

I have heard of the issue with “white” multiple times and experienced it myself. But sometimes filaments can change from spool to spool even in the same color. Still… I do seem to notice that white filaments have a bit of a reputation.

An air-tight storage container with desiccant will help avoid a spool absorbing moisture, but once the moisture is in, a desiccant bag wont pull it back out. It has to be heated to dry the spool.

I tried a few filament dryers but … they don’t get nearly as hot as they claim and made almost no difference. I ended up buying a toaster oven. I looked into reviews to make sure the oven could handle low enough temps (I’m not really cooking food) and it turns out Breville makes the most accurate oven (they maintain the oven temp with 2° … some ovens swing 20-25°) and I they let me set the temp low enough for drying filament without melting it.

For what it’s worth, I find that any filament that’s kind of “extreme” in color tends to need tweaking in terms of temperature at least. White is certainly one of those colored ones that needs special care, but metallic filaments and wood-filled are also touchy – PLA is not all the same by any means.

I found it helpful when starting out with my original Mini to have a roll of “Natural” eSun PLA-plus. That behaved very well, in general, with the provided stock profiles in Cura for PLA – I tweaked it to get it perfect, and that formed the basis for my eSun PLA-plus profiles.

White has always needed higher temperatures to print, and for the eSun PLA-plus, the white tended to be a bit more stringy than the other colors.

I use a food dehydrator modified for filament. Any roll gets a 24 hour dry before it gets used, and every few months I go through my stock of filament and re-dry every roll, re-seal it (vacuum sealer), with a freshly-dried silica packet. Filament is expensive, a few hours a month to keep it dry and usable is not too hard.