Abstract: A grounding member made of a spring steel includes a hexagonal top with a through hole, contact pieces extending from straight sides of the hexagonal top, and a grounding strip brazed to one of the contact pieces. The grounding member attaches to a spark plug with a spark plug insulator passing through the through-hole. The contact pieces pressure contact a peripheral surface of a hexagonal nut of the spark plug. A grounding wire is connected to a negative electrode of a battery. Electric charges generated in a spark gap are returned to the battery negative electrode from an external electrode of the spark plug via a spark plug housing, the grounding member, and the grounding wire. If the spark plug is loosely fitted in an engine cylinder head, or even if some engine body components are aged, electric charges flow without problems, preventing reduction of discharging performance.

Abstract: A grounding member made of a spring steel includes a hexagonal top with a through hole, contact pieces extending from straight sides of the hexagonal top, and a grounding strip brazed to one of the contact pieces. The grounding member attaches to a spark plug with a spark plug insulator passing through the through-hole. The contact pieces pressure contact a peripheral surface of a hexagonal nut of the spark plug. A grounding wire is connected to a negative electrode of a battery. Electric charges generated in a spark gap are returned to the battery negative electrode from an external electrode of the spark plug via a spark plug housing, the grounding member, and the grounding wire. If the spark plug is loosely fitted in an engine cylinder head, or even if some engine body components are aged, electric charges flow without problems, preventing reduction of discharging performance.

Abstract: An end mill for finishing the face or side of hard work comprising a shank, a plurality of helix cutting edges on the periphery of the end mill, and a cutting edge section perpendicular to the axis of the end mill having a polygonal shape with three or more angles, the cutting edge being the edge formed at each vertex of the polygonal shape along the axis of the end mill and being circumscribed by an imaginary cylinder, and the end mill being characterized in that the helix direction of the cutting edge is identical to the rotational direction of the end mill. The end mill of the present invention is able to cut the face or side of the hard work at a feed rate several times higher than that of conventional end mills. Moreover, the end mill of the present invention assures superior surface roughness of finished work.

Abstract: A cermet solid end mill having a helix angle of 45 to 50 degrees and being composed essentially of NbC-TiC-TiN-based composition and being far superior to conventional end mills in cutting characteristics, i.e., cutting length, tool life and durability.

Abstract: An end mill has a plural number of helical blades formed on the main body of a machine tool. Each of the blades is provided with a plural number of notches spaced along its length and shifted relative to the corresponding notches in the preceding blade. When the notch is shifted to the tool end of the tool, the notch is inclined toward the shank end. On the other hand, when the notches are shifted toward the shank end of the tool, the notches are inclined in the opposite direction, i.e. toward the tool end. Therefore, the wear by rubbing on the side of the blade is diminished, the cutting resistance is decreased and the cutting performance is increased.