A spade bit is provided of the type particularly adapted to be employed with a hand-type power tool such as an electrical drill or drill press for purposes of cutting through a non-metal material such as wood. The spade bit has basically three main portions, namely, a shank, a blade and a point. In accord with the preferred form thereof, the spade bit is formed as an integral member. The shank of the spade bit has a generally cylindrical configuration with the free end thereof being of polygonal shape to provide a plurality of surfaces which can be cooperatively grasped by the jaws of a chuck into which the shank of the spade bit is desired to be inserted for purposes of cooperatively associating the spade bit with a power tool. The other end of the shank terminates in the portion of the spade bit referred to as the blade. The blade has a generally rectangular configuration which is formed by a pair of substantially planar surfaces and has a thickness which is substantially less than the diameter of the shank. The blade at the leading end thereof terminates in a pair of beveled surfaces with one of the beveled surfaces being inclined in one direction and the other of the beveled surfaces being inclined in the opposite direction. The latter surfaces of the blade comprise the cutting surfaces thereof. Projecting outwardly from the leading end of the blade intermediate the pair of beveled surfaces provided thereat, there is formed a generally diamond-shaped point. The point is ground to reduce the negative rake and thereby improve the cutting ability thereof. In addition, the point is provided with a relatively large point angle to make the point because of its increased cutting efficiency perform more of the cutting function and with less of the cutting function being performed by the cutting surfaces of the blade.
The present invention concerns in brief a drill (1) for making of preferably through installation bores, through which bores flexible shafts, cables and the like can be lead in. The drill (1) comprises a bore crown (2) and a shank (3). The bore crown (2) has main cutting edges (6, 7) for forward drilling, side cutting edges (8) for radial drilling, and end cutting edges (9) for rearward drilling. The shank (3) preferably has a significantly smaller thickness than the area being drilled by the main cutting edges (6, 7).
4286904 - Wood bit - Owned by Parker Manufacturing Company (Worcester, MA)
Bit for drilling wood or the like consisting of a spade from which extends a centrally-located point, the point being provided with a groove defined by two plane surfaces extending at an obtuse angle.
The cutting rate of a spade bit is greatly improved by the provision of radial flutes on the lateral shoulders of the bit, extending transversely to the bit axis. Further improvements are obtained if the shoulder flutes are stopped by spurs positioned at the outer ends of the shoulders.
An improved drill bit for wood boring or boring in other relatively soft material, having a generally cylindrical shaft (20), with a flattened blade portion at one end (24). The blade portion (24) is broad and flat with essentially parallel side surfaces (41,42) and having negatively beveled edges along the length of such side surfaces, such side surfaces giving way to a modified end edge. The modified end edge includes a center spur that is of rectangular cross section, with a length of one half to several times the thickness of the blade, and said spur (34) is centered on the end edge and is made with a concave tip (35). The edges of the center spur are parallel from vertex (36) to base. Outer spurs of rectangular cross section (29 and 30) with a negative bevel away from the leading edge are located on the lateral extremities of the end edge. Radially extending cutting surfaces (45 and 46) with a negative bevel away from the leading edge (37 and 38) extend at right angles from the base of the center spur to the inside edge of the outer spurs.
A spade drill bit device including an elongated shaft formed for rotation about a longitudinal axis thereof, and a flattened blade portion at one end of said shaft. The blade portion has generally planar and parallel opposing faces, and defines opposing side edges, and an end cutting edge therebetween. The cutting edge includes a pair of opposing side spurs each having spur tip portions positioned at the lateral extremities of the cutting edge and terminates at the corresponding side edge. A cutting edge triangular-shaped center tip is included axially aligned with the longitudinal axis, and having a distal end extending beyond the side spurs. The center tip is defined by downward edge portions extending away from the distal end. The cutting edge further includes respective converging edge portions extending between and connecting each side spur to the center tip. Each converging edge portion intersects a respective downward edge portion at a corresponding curved nadir portion positioned closer to the center tip than the respective spur portion.
