I found an issue. I understand that such scale is too small and the difference is almost 0, but sometimes it causes a problem. just be careful with sweeps and screws.

Hi glmr, it's not possible to represent a 100% exact helix with a NURBS curve, it has to be approximated. But it's also normal for many operations to be approximated in a similar way - things like intersections between non-analytic surfaces and sweep surfaces themselves.

But the amount of error should be very small, if what you show is causing a problem for you can you please post the .3dm model file you used to make the screenshot so I can take a look at it?

- Michael

the amount is small, but I had a problem when I made a sweep of triangle with helix rail and tried to make a boolean operation with a cylinder with a same diameter as my helix. I'll try to create a file

Hi glmr, the sweep itself goes through a refinement process. For the boolean it's best to have it push a little bit through the cylinder you are using instead of trying to make it skim right along the same surface area. It's harder for booleans to get a clean intersection on surfaces that just barely graze each other.

- Michael