Home Shop Machining/Machining Operations/Threading

Single Point Threading

Single Point Threading on a Lathe

The basic idea is to tie the rotation of the work in the spindle with the travel of the carriage along the ways such that the cutter makes groves at a defined rate. Engine lathes do this by linking the spindle to the leadscrew with a set of gears. This gearing can change, either by a selectors or by actually changing the gears out. See The Annotated Lathe for where all these parts are.

Alternative Technique

Sometimes, the threading dial either can't be used (cutting metric threads on a standard lathe) or the lathe simply doesn't have one. It is still possible to cut threads by always leaving the carriage connected to the spindle through the gears. Moving the carriage back to the start for the next cut involves backing the tool out and then reversing the motor of the lathe and letting everything move back to the start of the cut under power.

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