Enveloping worm threads with less than one revolution have on one side
concave surface and on another side convex surface. This makes generation of concave
and convex enveloping worm surfaces simultaneously and makes modification of surfaces
by individual machining of each surface. Proposed method uses cutting edges that
have rotation radius according with radius of curvature of machining surface. Another
variation simultaneously cuts several threads, where enveloping worm blank has
rotation around its own axis of rotation and relative motion to helical cutter
around tooling axis. This reduces production cost and makes manufacturing easily.
