Tap, 5/16"-24, Spiral Point 

Spiral point plug style tap, ground from solid high speed steel (HSS) with ground thread.

Three flute fine thread, with an H3 thread allowance (plus 0.0010 to plus 0.0015).

Spiral point style plug taps have the same general tap dimensions as straight flute taps however they have the first few threads cut at an angle which enhances the removal of chips from the cutting surface. This design makes spiral point taps ideal for production tapping of through holes.

The flutes on a spiral point tap are more shallow than those of a conventional tap resulting in more surface area for cutting, making them stronger thereby allowing for higher cutting speeds and less power required for the tap to travel.