Sources and scope for this page: Industry convention — no single governing standard (conventional usage, definitions vary between sources), covering the definition of spiral point vs spiral flute tap. No independent source check is recorded for this page: the content rests on the sources listed and on the working shown on the page. How sources, methods and updates are recorded.
Definition
A spiral point (gun) tap has a left-hand helix that pushes chips forward through the hole — correct for through holes, and stronger because the flutes are shallower.
A spiral flute tap has a right-hand helix that pulls chips back out of the hole — necessary for blind holes, where pushed chips would pack at the bottom and break the tap. It is weaker and more expensive.
Common misuse
Using a spiral point tap in a blind hole. The chips have nowhere to go, pack at the bottom, and the tap breaks.