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design of an o-ring groove in Openscad?

trying to work out how to design an o-ring groove in openscad.. Wondering if anyone has built something in this space? I can see that I need to do a difference to a rotate_extrude of a square to cut the groove.. but not sure on the equation.

Thanks

Solution

  • I liked this image of a groove I found here. The groove is L x G in dimensions.

    enter image description here

    First of all I've written down a cross-section and I've labeled the important dimensions:

    enter image description here

    On the left, the groove sits in the interior side of the cylinder cross-section. On the right, the groove sits on the exterior of the cylinder cross-section.

    Now we're able to use rotate_extrude in order to generate the solid with the require groove on it.

    I'll add the code for the interior_groove here:

    module interior_groove(alpha=360) {
    L0=2;
    L=2;
    L1=0.7;
    G=2;
    G1=6;
    G2=2;

    rotate_extrude(angle=alpha, $fn=80)
    // mirror([-1,0,0]) translate([-(L0+L+L1+L0),0,0])
    polygon(points=[
    [L0,0],
    [L0,G1],
    [L0+L,G1],
    [L0+L,G+G1],
    [L0,G+G1],
    [L0,G+G1+G2],
    [L0+L+L1,G+G1+G2],
    [L0+L+L1,0]
    ]); 
}

    This is the result of the code when we draw two types of grooves, one on the interior (left) and one on the exterior (right):

    enter image description here

    All the code used for this can be found here.