Results of printed parts

New Home Forum Mostly Printed CNC – MPCNC Troubleshooting – MPCNC Results of printed parts

This topic contains 5 replies, has 4 voices, and was last updated by Profile photo of MJ MJ 1 year, 5 months ago.

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  • #5672
    Profile photo of Tad Ghostal
    Tad Ghostal
    Participant

    I am thinking of trying out this system but wasn’t sure how accurate the printed parts need to be to get a properly working machine. I can get within 0.1mm in the outside dimension but have holes up to 0.5 mm too small. Since it seems to the problem everyone has, have you all had an issues with the printed parts not fitting well enough? I don’t want to print all the parts and find out they don’t fit the hardware. I don’t mind a little sanding if it comes down to it.

    #5678
    Profile photo of 3dTI
    3dTI
    Participant

    You can scale your parts slightly to achieve better fit, or file sand slightly.

    I’d recommend printing one corner block to start. Get your conduit to fit into that before printing a complete set of parts. I printed my parts scaled slightly to achieve a good fit, and also hand finished them when needed.

    What material are you printing in? PLA is recommended for dimension accuracy and rigidity.

    #5688
    Profile photo of Ryan
    Ryan
    Keymaster

    0.5mm too small should be fine if you are concerned with the bolt hole you can pre-drill them with the right sized bit. I drill the printed parts I send out because some are oval when printed on the horizontal.

    #5696
    Profile photo of Tad Ghostal
    Tad Ghostal
    Participant

    Thanks, that’s good to know.

    Also, as an engineer I am very impressed with all of your work.

    #5714
    Profile photo of Ryan
    Ryan
    Keymaster

    Nice of you to say, thank you!

    #6587
    Profile photo of MJ
    MJ
    Participant

    We also had problems with fit. All of the holes were too small. It is easy enough to drill out the bolt holes, but those for the conduit are a different story and we don’t have a good way to ream them. Looking into the problem, we found there were two main issues.

    First, the filament we used (Makerbot PLA) seemed to have dimensional issues. In other words, it laid down thicker on perimeters and insets. We found better results with 3D Solutech and Hatchbox. Both appear to offer more consistent results at a 0.26 layer height. As an added bonus, they don’t peel away from the build plate during the print as much as the Makerbot either.

    Second, our extrusion speeds were much too fast. The factory settings seem higher than reasonable (90 mm/s for example). This hurt dimensional accuracy as well. Ryan helped us clear it up a bit with some recommendations. For a 0.4mm nozzle, we settled on > Infill: 40 mm/s, Insets: 20 mm/s, Outlines: 20mm/s. Your printer may be different, but this is what worked best for us. It may also be worth mentioning that we bumped our active cooling fan speed up to 65% (from the 50% factory speed).

    We had trouble with some of the parts pealing away from the plate as well. Adhesion is critical to accuracy! We used the following procedure to prepare our build surface.

    • Clean the glass build plate with 70% alcohol and let it dry completely
    • Lay down strips of blue painters tape (we used 1.5″ wide) on a diagonal (45 degrees to the build plate instead of parallel or perpendicular)
    • Use a flat edge to smooth it out and remove bubbles (we did this after every print)
    • Wipe the blue tape with 70% alcohol to remove any fingerprints, oil, debris, etc. (again, we did this after every print)
    • Do not touch the build surface tape after you have cleaned it! The oil from your hands may interfere with adhesion.
    • Level your build plate (we did this after every third print)

    We hope this helps some of you.

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