What Is a Thread Dial

The thread dial consists of a worm wheel meshing with the lead screw. It is connected by a short shaft to the indicating dial. The dial is calibrated with four numbered lines and four others midway between them. These lines are used when cutting threads on a manual lathe.

What is a thread dial used for?

A thread dial indicator tracks revolutions of the leadscrew when screw cutting. It is essential that the “drop in point” used to engage the half nuts is consistent from pass to pass. This is important to ensure the tool follows the same path across the workpiece otherwise double start threads may result.

What is the purpose of a groove adjacent to a shoulder?

Grooving or recessing operations, sometimes also called necking operations, are often done on workpiece shoulders to ensure the correct fit for mating parts. When a thread is required to run the full length of the part to a shoulder, a groove is usually machined to allow full travel of the nut.