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  1. #1

    Warping/shrinking PLA problem

    Hi

    I am very new to 3d printing (about a week now), but this one is a little odd and I wonder if someone can point me in the right direction...

    I have a Wanhao i3 Plus. I am trying to print a few parts to firm up my z axis on the printer. I am using Cura, setup for the i3 with all the default settings other that a shell of 1.2mm and layer height of 0.2mm.
    I am printing with 1.75mm black PLA from 3D4Use.

    In the photo, I am holding the part in the same orientation it was printed. The warping seems to be happening quite late into the print, well after the layers that are warping.
    I lef tthe print running over night , with all 3 parts that I printed coming out with the same issue, this one being the worst.

    I am printing with the bed cold and no raft.

    Could this be a filament issue?

    Many thanks

    Mr S




  2. #2
    Staff Engineer printbus's Avatar
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    Congratulations on your first post. Welcome to 3DPrintBoard.

    Your print doesn't have adequate adhesion to the print bed, and the print starts to lift from the bed as the printed part cools and shrinks. PLA isn't as bad as other filaments like ABS, but it can still happen.

    Are you using the aluminum bed and adhesive tape sheet from Wanhou? I'm not an expert with the Wanhou adhesive sheets. For others to help, you might elaborate on how you are preparing the print bed. Are you cleaning the adhesive sheet at all? I use blue painters tape which might be equivalent to your adhesive sheets, and swabbing it with isopropyl alcohol seems to clean off wax from manufacturing, finger oils from installing the tape, etc. I just know my prints stick far better if I prep the tape that way.

    If you didn't, try using a brim of a few millimeters around the first layer of the part. This is an option in the slicer. Like the brim of a hat, it will increase the surface area of the first layer and help with adhesion. After the print completes, you can peel the brim away from the rest of the part. You might also show a picture of the bottom of the print. It could be that issues with that first layer are part of the reason the print is lifting from the bed.

  3. #3
    Super Moderator curious aardvark's Avatar
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    you don't need a brim or a raft with pla - but you do need to heat the print bed to 60C
    Also calibrate a little tighter, you need to get a bit of squeeze on the first layer - if necessary it can quickly be filed off, you also need to print the first layer at round 10-20% of the actual print speed.

    We all go through this.

    You might also want to invest if some cheap gluesticks. Pla loves stiking to pva :-)

    And better quality pla will also help. The really cheap stuff does work, but you will need to implement the above procedures, the good stuff will just sit on a hot printbed with minimal stick and never warp.

    What you lose is higher cost you gain back in fewer failed prints.

  4. #4
    Thanks for the advice guys

    I was using aluminium bed with Wanhao tape, but hadn't wiped it, so gave it a good wipe with alcohol. Will try the brim or mouse ears if this happens again.

    Yes, my PLA is pretty cheap at £18 a kg. I have used some even cheaper with better results at just £12 per kg (from eBay), but guess I got lucky.

    The first layer does print slower, but not that slow, will try this as well.

    I didn't think I needed to heat the bed for PLA, but did this time (to 50), and following advice from both of you, the print came out perfect... well, best so far

    Many thanks for your help

    Would you recommend using glass on my bed? my thought is that I wouldn't have to keep levelling my bed if I remove my print from the glass, away from the printer. Instead of scraping it off on the printer, possible knocking out my levelling.



    Mr S
    Last edited by Scibbles; 09-17-2016 at 11:37 AM.

  5. #5
    Staff Engineer printbus's Avatar
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    Glad CA and I could help. If others had chimed in or if you do research on bed adhesion, you'll find there are countless other "suggestions" out there. Like CA said, this is just one of those areas each person needs to work through.

    There's rarely a single, best answer to issues like these. CA likes to use heat with no brim. The one time I inadvertently used heat with PLA and swabbed painters tape, I broke my bed glass trying to remove the print. I'll almost always use a brim, especially on a tall part with low first layer area. These differences don't make either of us wrong - it just demonstrates that different things work better for different people, and sometimes even on different prints.

  6. #6
    Engineer ralphzoontjens's Avatar
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    Bed adhesion is an important factor and hairspray on blue tape, plus a tight calibration, a small brim and low first layer height helps greatly.
    Besides bed adhesion you also want to make sure these critical areas in your part are already cooled enough before the next layer is put on.
    Make them hollow, minimize the infill and place them in a position where the fan will hit them optimally. Another strategy is printing multiple parts at once during the same print run so the layers have more cooling time.

  7. #7
    and not on topic per sae, but i dont think you want to use PLA for functional parts.. PLA is brittle as heck you want PETG or ABS

  8. #8
    my temperature are set like that for PLA

    S3D 4.1.1 -> edit process -> temperature -> bed -> layer 1 : 70C, layer 3: 60C
    S3D 4.1.1 -> edit process -> temperature -> extruder -> layer 1 : 195C, layer 3: 205C

  9. #9
    Engineer Roberts_Clif's Avatar
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    I am a firm believer in the Blue Tape, I do not use blue tape because I use Vinyl Transfer Tape which is so close to blue tape I call it Blue Tape.

    Largest Print

    Filament Spool.jpg

    Print Speed 8.5mm^3/ per sec " As shown it you hover over Print Speed in Cura 15.04.6
    I print PLA with a bed temperature of between 40-56C an filament temperature of 190-202C
    Open Air, Model cooling fan speed minimum 42% after first layer.
    Print Time 4 hours.

    Print Speed 8.5mm^3/ per sec " As shown it you hover over Print Speed in Cura 15.04.6
    I print ABS with a bed temperature of between 94-98C an filament temperature of 228C
    Enclosure temperature 100F
    Enclosure Outside Vent Fan 70%
    Inside Printer Enclosure, Model cooling fan speed minimum 42% after first layer.
    Print Time 6 hours.
    Print new 3D Printer ABS Parts On Chinese Bed Surface
    MPCNC
    3D Printing Large Part
    https://youtu.be/KOUEevmqa48
    Last edited by Roberts_Clif; 05-06-2019 at 09:21 AM.

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