Taper drill

Claim 2

A tapered drill for drilling hard materials having improved features of safety, drilling ease, and utility comprising a tapered cutting body of progressively increasing diameter extending from a cutting end of small diameter substantially to a rearward section of largest diameter, said tapered body being capable of cutting a straight hole in a workpiece of a diameter corresponding to said largest diameter of said rearward section, an intermediate shank portion extending rearwardly from said section and having a progressively decreasing diameter, said intermediate shank portion by virtue of the decreasing diameter thereof providing jam-free operation of the drill as the hole is completed, the tapering of said cutting body providing jam-free operation if the drill is accidentally leaned to one side during drilling, and a rear shank portion extending rearwardly of said intermediate shank portion for engagement by a chuck of a drilling tool.

Claim 3

Drill of claim 1 wherein said tapered cutting body has at least one cutting edge, each said edge being disposed in a right to left spiral, thereby to avoid pulling of the drill into said hole during drilling using right-hand rotation of the drill, a reduced portion between said intermediate shank portion and said rear shank portion, and a collar at said reduced portion for engaging said workpiece to prevent further passage of the drill therethrough.

Claim 4

A tapered drill having improved features of safety, drilling ease, and utility comprising a tapered cutting body of progressively increasing diameter extending from a cutting end of small diameter substantially to a rearward section of large diameter, said tapered body having at least one cutting edge with each said edge being disposed in a right-to-left spiral, thereby to avoid pulling of the drill into a workpiece during drilling, said tapered body being capable of cutting a straight hole in said workpiece of a diameter corresponding to the largest diameter of said body, each said cutting edge having primary and secondary clearances with respect to the walls of a hole being drilled in said workpiece, an intermediate shank portion extending rearwardly from said section and having a progressively decreasing diameter, said intermediate shank portion aiding to provide jam-free operation of the drill, a collar adjacent the back end of said intermediate shank portion for engaging the workpiece and preventing further passage of the drill therethrough, and a rear shank portion extending rearwardly of said collar for engagement by a chuck or other driving means.

Claim 5

A tapered drill having improved features of safety, drilling ease, and utility comprising a tapered cutting body of progressively increasing diameter extending from a cutting end of small diameter substantially to a rearward section of large diameter, said tapered body having at least one cutting edge with each said edge being disposed in a right-to-left spiral, thereby to avoid pulling of the drill into a workpiece during drilling, said tapered body being capable of cutting a straight hole in said workpiece of a diameter corresponding to the largest diameter of said body, each said cutting edge having primary and secondary clearances with respect to the walls of a hole being drilled in said workpiece, an intermediate shank portion extending rearwardly from said section and having a progressively decreasing diameter, said intermediate shank portion aiding to provide jam-free operation of the drill, a collar adjacent the back end of said intermediate shank portion for engaging the workpiece and preventing further passage of the drill therethrough, and a rear shank portion extending rearwardly of said collar for engagement by a chuck or other driving means.

Claim 6

Drill of claim 3 wherein said section of large diameter comprises a circumferentially extending edge.

Claim 7

Drill of claim 3 wherein said section of large diameter comprises a circumferentially extending rounded portion.

Claim 8

Drill of claim 3 wherein said section of large diameter comprises a cylinDrical portion of short length.

Claim 9

Drill of claim 3 wherein said small diameter cutting end is blunt.

Claim 10

Drill of claim 3 wherein said small diameter cutting end is pointed and able to start its own hole.