ACCUSHARP Gun drills are straight fluted drills which allow cutting fluid (either compressed air or a suitable liquid) to be injected through the drill’s hollow body to the cutting face. ACCUSHARP drills used for deep drilling—a depth-to-diameter ratio of 300:1 or more is possible.
Gun barrels are the obvious example; hence the name. Other uses include mold making, die making, and the manufacture of combustion engine parts such as crankcase, cylinder head, and woodwind musical instruments, such as uilleann pipes, as gun drills can drill long straight holes in metal, wood, and some plastics.
The coolant provides lubrication and cooling to the cutting edges and removes the swarf or chips from the hole. Modern gun drills use carbide tips to prolong life and reduce total cost when compared with steel tips. Speed of drilling depends on the material being drilled, rotational speed, and the drill diameter.