ClipArt ETC
A convenient screw cutting using a lathe to create threads on the metal rod.

Screw Cutting Device using Lathe

A convenient screw cutting using a lathe to create threads on the metal rod.

The shaping machine used to cut triple threads on a screw viewed from a lengthwise axial section.

Cutting Triple Worms Screw

The shaping machine used to cut triple threads on a screw viewed from a lengthwise axial section.