A drill bit for drilling holes in metal sheets or panels in which the drill is of generally conical form having a series of cylindrical drill portions increasing progressively in diameter from the point end of the drill whereby a single drill may be employed to drill holes of various diameters within a given range. The drill has a single flute of generally right-angle form in cross section with the apex of the right angle extending generally along the axis of the bit. Each cylindrical portion has a beveled end connecting it with the next smaller cylindrical portion and this beveled end extends helically at a relatively small angle to provide the usual axial clearance and to limit the rate of feed of the drill into the work.
A power drill bit having a stepped construction, referred to as a cone drill, and a quick change capability provided by a shank having a non-circular cross-section and a circumferential groove for quick connect-disconnect in a power tool or drill. The preferred embodiment includes a hexagonal shank which is at least one-half of the axial length of the drill bit in order to provide a better engagement to the power chuck.
A self-drilling and reaming screw for clampingly securing a plurality of superimposed panels and providing a clearance hole in at least the upper panel. A plurality of axially spaced wings of differing and increasing radial dimension from the cutting edge of the drill point to the threaded shank portion are provided and located between the upper and lower extremities of the flutes on the drill point.
An extensible drill assembly comprising a plurality of separate drill members having different drill diameters which are arranged to permit assembly of two or more of the drill members into a continuous drill combination having a stepwise increasing diameter from the outermost drill member.
Drill bit for drilling holes of different diameters which has a series of cylindrical outer surfaces of increasing diameter from the outer to the inner end of the drill bit. A beveled conical surface interconnects each adjacent pair of cylindrical surfaces. At least two flutes are machined at two circumferentially spaced locations to provide two cutting edges on each diameter of the drill. At each cutting edge the cylindrical surfaces are relieved radially and the conical surface is relieved axially over an acute circumferential angle. The major peripheral portions of the cylindrical and conical surfaces for each diameter are respectively concentric to the axis of the drill and of zero pitch angle.
A blade type rotary cutter for cutting tapered holes in metal workpieces. The cutter blade is elongated and generally flat, being tapered in the "width" direction for applying the taper to the hole, and being tapered in the "thickness" direction so that the cutting edge along the length of the blade will lead the cutting edges proximate the point and thereby minimize point drift. All cutting edges of the blade are provided with a substantial negative rake for chip control, and the chips are blown out of the hole by jet streams of cutting fluid directed along the longitudinal cutting edges of the blade.
