The following little script imports an STL file generated generated by a
coworker in another program, and drills a hole in it. The rx and tz
functions are shorthands for rotation and translation on a specific axis;
they are well tested and work fine.

module boat2() {
difference() {
scale(10) rx(90) translate([-6.45, -3.43, -2.3])
import("boat2.stl");
tz(1.5) cylinder(d=pfdiam, h=pfheight+1, $fn=120);
}
}

Pressing F5 shows a correctly drilled hole. But pressing F6 gets the
assertion failure shown below, and effectively negates the difference
operation, so that no hole is drilled. What to do?

g http://forum.openscad.org/file/n17214/OpenSCADScreenSnapz005.png

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Hi

Try to fix it first using https://modelrepair.azurewebsites.net/, netfabb or
meshlab.

jpmendes

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This sounds like an instance of https://github.com/openscad/openscad/issues/1184

Could you share your STL, or otherwise check the STL in an external program to check if it displays any intersecting behavior?

-Marius