Abstract: A device and method of tapping an engine component to orient a spark plug includes measuring a tap pitch, measuring a first distance between a tap end surface and a full tap tooth center at a first rotational location, calculating a phantom first tap tooth based on the pitch and first distance, determining a tap rotational offset from the first location to a location where the end surface intersects the phantom first tooth, calculating a tap rotational starting orientation that is the first location minus the tap rotational offset minus a spark plug offset, rotating a tool head to the rotational starting orientation, positioning the tap so the end surface is a pitch incremental distance away from the engine component, synchronizing a rotating speed of the tool head and a feed rate to the tap thread pitch, and operating the tool to cut or form threads in the engine component.

Abstract: A device and method of tapping an engine component to orient a spark plug includes measuring a tap pitch, measuring a first distance between a tap end surface and a full tap tooth center at a first rotational location, calculating a phantom first tap tooth based on the pitch and first distance, determining a tap rotational offset from the first location to a location where the end surface intersects the phantom first tooth, calculating a tap rotational starting orientation that is the first location minus the tap rotational offset minus a spark plug offset, rotating a tool head to the rotational starting orientation, positioning the tap so the end surface is a pitch incremental distance away from the engine component, synchronizing a rotating speed of the tool head and a feed rate to the tap thread pitch, and operating the tool to cut or form threads in the engine component.