Method for configuring a machine for production of a thread and apparatus for producing a thread

A method of configuring a machine for production of a thread, having a pitch, on a workpiece, the machine comprising:

• a tool having a thread centered on a first axis and comprising one or more thread-producing peaks for producing the thread having the pitch;
• and
• a tool holder holding the tool,
• the method comprising:
• determining a first distance, in a first direction parallel to the first axis, from a reference position of the tool holder to a first thread-producing peak on the tool when said tool is held in the tool holder;
• and
• setting a first configuration of the machine wherein the reference position of the tool holder has a displacement parallel to the first axis from a reference position of the workpiece depending only upon:
• the determined first distance;
• a translation parallel to the first axis to account for an angular offset between the first thread-producing peak and a desired thread start position on the workpiece;
• and
• an integer multiple of the pitch.

A method of arranging the position of a spark plug at a predetermined angular position in a cylinder head of an internal combustion engine, comprising:

• providing spark plugs with predetermined angular positions of ground electrodes with respect to a thread employed to secure the spark plug in the cylinder head;
• and
• producing a bore in the cylinder head to receive said spark plugs, said bore having a thread with a predetermined desired thread start position and a pitch, wherein producing the bore is performed by a machine comprising a tool holder and a tool having a thread centered on a first axis and one or more thread-producing peaks for producing the thread;
• wherein the tool has a first end and a second end, wherein a portion adjacent the first end is configured to be held by the tool holder, and wherein a thread start position on the tool at the second end of the tool is angularly offset relative to the first thread-producing peak;
• wherein there is a first distance, in a first direction parallel to the first axis, from a reference position of the tool holder to a first thread-producing peak on the tool when said tool is held in the tool holder;
• and
• wherein there is a first configuration of the machine wherein the reference position of the tool holder has a displacement parallel to the first axis from a reference position of the cylinder depending only upon:
• the first distance;
• a translation parallel to the first axis to account for an angular offset between the first thread-producing peak and a desired thread start position on the cylinder;
• and
• an integer multiple of the pitch.

A method of manufacturing an engine comprising:

• producing a thread in a bore of an engine cylinder head;
• wherein producing the bore is performed by a machine comprising a tool holder and a tool having a thread centered on a first axis and one or more thread-producing peaks for producing the thread;
• wherein there is a first distance, in a first direction parallel to the first axis, from a reference position of the tool holder to a first thread-producing peak on the tool when said tool is held in the tool holder;
• and
• wherein there is a first configuration of the machine wherein the reference position of the tool holder has a displacement parallel to the first axis from a reference position of the cylinder depending only upon:
• the first distance;
• a translation parallel to the first axis to account for an angular offset between the first thread-producing peak and a desired thread start position on the cylinder;
• and
• an integer multiple of the pitch;
• and
• wherein the angular offset between the first thread-producing peak and the desired thread start position on the engine cylinder head is the sum of:
• a first angular offset between a target orientation of a spindle in the machine in the first configuration and the desired thread start position on the engine cylinder head;
• and
• a second angular offset between the first thread-producing peak and the target orientation of the spindle in the machine in the first configuration