An efficient twist drill fir layered drilling comprises a drill bit body, wherein the drill bit body comprises a shank portion and an operation portion; the shank portion is connected with the operation portion; the operation portion has a cutting portion at a front end thereof; a plurality of flutes distributed in parallel and at intervals are symmetrically arranged along a flank surface of the cutting portion; the flutes divide main cutting blades into a plurality of first cutting blades and second cutting blades; and connecting lines of the first cutting blades and the second cutting blades form a step-like structure. During drilling, a drill bit of the twist drill requires a decreased drilling force, produces less cutting heat, is positioned easily and has improved processing efficiency so that a processed circular hole has high precision and few burrs at an edge where the drill bit exits.

The combination tool (2), in particular a drilling/chamfering tool, comprises a drill (6) extending in the longitudinal direction (4) with a clamping sleeve (8), which is designed to receive the drill (6) and fasten the drill (6) at a variable length and which has a holding seat (38) for a cutting insert (12). The drill (6) comprises a cutting region (22) provided with grooves (14), wherein the grooves (14) extend helically and are formed between two grooves (14) drill backs (18). At least one of the drill backs (18) is partially flattened to form an adjustment surface (16) for the cutting insert (12), wherein the adjustment surface (16) extends helically. As a result, a length adjustment over a large length range is made possible independently of the twist angle ().

A debris ejector for a drilling tool is disclosed. The ejector may be provided as part of a tool assembly where the ejector is coupled with bit. In an example, a tool includes a cup and a drill bit passing through an internal void of the cup. The cutting end of the bit extends out the open end of the cup at a fixed distance, while an attachment end of the bit extends out the back of the cup. The tool further includes an ejector within the cup. The ejector spins with the bit and independently of the cup. In one example, the ejector includes ramped or angled wings that eject material within the cup. In another example, the ejector includes tapered wings with straight and/or angled walls that push material out of the cup through one or more holes of the cup.

A method includes inserting a machining tool through a hole of at least one workpiece that includes a first surface and a second surface opposite the first surface and extends from the first surface to the second surface. The hole forms an inner wall. The machining tool includes a shaft and a cutting tip proximate to one end of the shaft. The cutting tip includes a cutting portion. The method includes positioning the cutting portion of the cutting tip to abut an edge of the hole. The edge is located at a junction of the second surface of the one of the at least one workpiece and the inner wall. The method includes forming a surface modification at the edge with the cutting tip. The method includes removing the machining tool from the hole. The method includes installing a fastener within the hole. The fastener engages the surface modification.

A method includes inserting a machining tool through a hole of at least one workpiece that includes a first surface and a second surface opposite the first surface and extends from the first surface to the second surface. The hole forms an inner wall. The machining tool includes a shaft and a cutting tip proximate to one end of the shaft. The cutting tip includes a cutting portion. The method includes positioning the cutting portion of the cutting tip to abut an edge of the hole. The edge is located at a junction of the second surface of the one of the at least one workpiece and the inner wall. The method includes forming a surface modification at the edge with the cutting tip. The method includes removing the machining tool from the hole. The method includes installing a fastener within the hole. The fastener engages the surface modification.