Printing screws - is the output usable? (M3 or M4)

  • I just want to ask if anyone has successfully printed a screw (M3 or M4). Is the printed output usable as a screw? What printer is capable of printing screws? I am using an M3D printer - is there a configuration to successfully print a screw that is usable?

    Can anyone share a picture of the best 3D printed screw?

    It's better to print a cylinder and then tap it.

    @FarO: Disagree strongly, especially if you're printing the axis in the XY plane. The zigzag walls and how the shifted versions of them in each layer interlock are far stronger than a smooth cylinder printed in any orientation, even before you start cutting into it with a tap.

    @R..GitHubSTOPHELPINGICE good point, but interlocking requires parts of the thread to be smaller than the average one, areas which will have a weaker resistance. So it will lock better, but the surface which will then hold will be less than the optimal one. Also, screws don't rely on interlocking but on tension when the nut is tightened. Or am I making a mistake somewhere?

    @FarO: I don't understand what you're saying. Interlock was probably a poor word choice on my part but I'm not sure what the right word is. The point is that you have continuous uncut extrusions and almost nowhere the tension is along their length and nowhere it's pulling layers apart. Instead the tightened nut presses everything together more.

    On the other hand, if you print a cylinder with axis in the XY plane then tap it, all of the outermost extrusions will be cut repeatedly at spacing matching the pitch, only attached by their bonding to the next wall inward and some small surface with the (also cut) walls above/below, and the tension from the nut tightened on them will be encouraging them to compress along and break off from the next wall inward. Simple inline ascii art: `/\/\/\/` vs `-=-=-=-=`

    @R..GitHubSTOPHELPINGICE I see what you mean. My point was that if you tap, you are sure that you will use all the possible area for the thread (area measurd on the section perpendicular to the axis), while if you print it in its final shape, either you use all the available area (but then it's like tapping) or you have spots where the print does not fully cover the available area, and you have less material. This reasoning applies both to XY and to XZ prints. It's just a way to maximise the amount of plastic which will hold.

    @FarO: I see. I think that's best handled (see My Tech Fun's video linked in my answer) by printing the threads with slightly negative clearance then using a tap aligned with the printed thread, so as to remove well under a whole extrusion wall at all points, achieving both the maximum contact surface area and ideal extrusion/layer structure.

  • darth pixel

    darth pixel Correct answer

    6 years ago

    well... it's hard to imagine printing M3 or even M4
    I haven't try but I haven't because I'm pretty sure it's not possible (on my printer of course)

    but some time ago I've tried M8 which is of course way from your needs
    it was printed on 0.1mm layer height

    it went ok into the nut without any problems but the strength is not very high I suppose

    I know the quality is poor but even such bad photo shows issues

    enter image description here
    enter image description here

    I'd say it's not just your printer; no FDM printer is capable of doing stuff as fine as M3 or M4.

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

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