Can't get print to stick, no matter what I try

  • I'm new to 3d printing, so I might be missing something obvious. If so, please let me know.

    I printed my model successfully yesterday, but today I'm trying to print the same model and the first layer refuses to adhere, which means at best several layers after that are messed up if it manages to recover, but usually it just means I have to cancel and start again.

    It will print one horizontal line (across the x axis), then when it tries to vertical line (across the y axis) the horizontal line doesn't adhere and gets dragged along with the print head and everything is screwed up.

    I've tried leveling the bed over and over again. (I use a sheet of paper and try to slip it between the bed and printhead. I adjust the bed so that I feel a bit of resistance as I push and pull the paper under the printhead.)

    I've tried increasing the preheat on the printhead and on the bed. I'm using black PLA 1.75mm that says it has a print temp of 205-225. I've tried printing at 205, 210, 215, 220, and 225. I've tried a bed temp of 50, 55, 60, 65, and 70.

    I've tried setting the print speed multiplier to 0.5 to give it time to adhere, but no changes.

    I'm trying to print something a wireframe cube that is at the extent of my printable size, so I don't know of a way to use a raft or a brim to help adhesion.

    This is what my model looks like:

    my wifeframe-ish partial cube model

    When I printed a good one yesterday, here is what the first two lines looked like:

    good first layer

    When I print today, even after multiple attempts to level the bed, this is what the first layer tends to look like:

    enter image description here

    I'm using a Monoprice 15365. I created my model in SketchUp, then exported as STL, which I imported into Cura 2.3.1. Then I used Cura to export a gcode file to an SD card. I put the SD card into my 3d printer and printed from there.

    Any advice is welcome. I don't know if the problems I'm having are because the bed is too low or too high or too hot or too cold or if the printhead is too hot or too cold... nothing I've tried seems to change the results.

    What are you printing on - white painter's tape / masking tape?

    Print a large skirt or brim around your object. Now you have time to adjust the bed level to the correct height.

    @vwegert It's whatever came with my 3d printer (as I said, I'm brand new). It appears to be one giant sheet of a material like masking tape.

    @Gunslinger The screws to adjust the height are on top of the bed, so I'd be really worried about the allen wrench getting in the way of the machine. :/ The model I'm trying to print is as big as my max print size, so I don't think I have any extra space for a brim or raft.

    I stopped using paper as a feeler gage to set the gap between the nozzle and bed and just bought a set of metal feeler gages for a few dollars. A small but noticeable improvement.

    I threw away the white cheap-o masking tape that came with my printer right at the start and bought a roll of blue tape. That helped a lot, but in my case, it clearly was some cut-off crap stuck into the packaging to make it look complete.

    I've been trying all of the suggestions below and not getting any improvements. I've been watching a bunch of YouTube videos and I've been inspecting the machine while it prints, etc.. and I'm starting to think my nozzle is clogged. I don't think enough material is coming out and THAT is why it is sticking. I'm getting these tiny, almost hairline, plastic lines, but when I watch videos of the same printer I see nice, thick lines being laid down.

  • Eureka! All of the other answers and suggestions on this post were all very helpful, and would likely be the right answers 90+% of the time, but they didn't give me any relief. I spent a bunch of time watching YouTube videos about 3D printing and I started to notice a difference in size of the lines of plastic being laid down on the build plate.

    In the videos, the lines of plastic looked bigger. Mine were very fine lines. That lead me down a series of different search terms until I found some other videos that talked about nozzle cleaning.

    I noticed that one of the symptoms they mentioned was that when the plastic would come out of the nozzle that it would curve around. That's a sign that it's partially blocked and causing it to bend and curve. After the people in the YouTube videos cleaned their nozzle, the plastic would then extrude and drop straight down.

    If my nozzle was partially blocked and only about half the right amount of plastic was coming out that would make sense since there wouldn't be enough surface area of the plastic to make a good connection to the build surface.

    I acquired some 0.4mm drill bits from Amazon and followed the instructions on this YouTube video.

    Sure enough, when using the 0.4mm drill bits, I could tell the nozzle was clogged. After clearing it out, the plastic started extruding in a straight line down, just like the video. I was stoked!

    I tried another print and it was NIGHT AND DAY. I was finally getting nice plump lines that stuck to the build plate. I still had an issue or two on certain parts of my build plate, but I think that's because in all of my tries I had damaged the masking tape. I put down new blue tape and started up my print and it's BEAUTIFUL.

    Thank you all very much for your help. Hopefully, this will be helpful to someone else as well.

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Content dated before 7/24/2021 11:53 AM