Boolean Intersect Problem

i modeled a cylinder diameter 42mm and 15mm height, then i modelled a Helix with the same height and diameter and a pitch of 1mm. Then i made a closed polyline object looking like a cut triangle. I oriented that triangle perpendicular to the helix and made a sweep1 to extrude the cut triangle allong the helix to get a M42x1 thread.
So far so good, but now when i model a cylinder over my sweep1 object and try to do a boolean intersect or a boolean union if i orient the triangle facing outwards, non of the boolean operations works. I already set the tolerance down to 0,1mm but that doesn´t help.
Any idea what i might do wrong ?

Hi Manuel,
Did you close the ends of the surface you created with Sweep1 (command “Cap”)? Otherwise, it will not be a closed polysurface, and the boolean does not work. ( I did an exercise very similar to yours recently, that’s how I found out… :grinning:)

I’m guessing that the vertical edge of your triangle is right on the OD of the cylinder. A helix is an approximated curve and with tolerances of 0,1 mm, the swept surface is probably not exactly on the surface of the cylinder at all places. You can use the intersect command on both objects to troubleshoot a boolean operation.

It’s best to make sure that the triangle extends well through the wall of the cylinder on both sides.
Note, 0,1 tolerance is pretty tolerant. I would go to 0,001 for a model like this.

Thanks maxz and wim both tips lead me to a working boolean operation. I didt cap my sweep object that was my first fault, then i set the tolerance back to 0,001 and finally increased the Render Mesh Quality, so i could examine the model better, and there i found that my sweep object was cutting itself just a tiny bit, so i changed my profile curve and now it worked. :smile: thanks, great to get help so fast here !