What is a self countersinking screw?
GRK's R4 Self Countersinking screw has six self-contained cutting pockets which act like a router and transport the drill dust away from the edge of the screw hole. They also widen the countersink hole only around the head shape.
Fluted countersinks come in several sizes, able to cut conical holes intended to fit screws of varying head dimensions. A pilot hole is first drilled for the screw, followed by countersinking the hole to allow a flathead screw to seat flush with the work surface.
- The straight shank is the most usual style on modern drill bits, by number manufactured. The whole of the drill bit, shaft and shank, is usually of the same diameter. It is held usually in a three-jaw drill chuck. Such a drill bit is called a reduced-shank or blacksmith's drill.
- Spade Drill Bits. Also commonly known as paddle bits, these flat bits are commonly used by tradesmen such as electricians and plumbers for drilling holes in studs in walls (to run wiring or pipes through the walls), but they also have a place in the woodshop for drilling on fine woodworking projects.
- This bit's ancestor, the two-cone rotary rock drill bit, was invented by Howard Robard Hughes, Sr., an Iowa boy who drifted to southeast Texas in the wake of the Spindletop discovery and started a drilling company in 1902 in partnership with a man named Walter Sharp.
A common use is to allow the head of a countersunk bolt, screw or rivet, when placed in the hole, to sit flush with or below the surface of the surrounding material (by comparison, a counterbore makes a flat-bottomed hole that might be used with a socket-head capscrew).
- A counterbore hole is typically used when a fastener, such as a socket head cap screw, is required to sit flush with or below the level of a workpiece's surface. Whereas a counterbore is a flat-bottomed enlargement of a smaller coaxial hole, a countersink is a conical enlargement of such.
- Bottoming tap or plug tap. The tap illustrated in the top of the image has a continuous cutting edge with almost no taper — between 1 and 1.5 threads of taper is typical. This feature enables a bottoming tap to cut threads to the bottom of a blind hole. Plug taps are the most commonly used type of tap.
- COUNTERSINKING, COUNTERBORING, AND SPOTFACING are three machining operations used to enlarge the opening of a hole. In countersinking, a conical, reamerlike tool is used to cut a tapered enlargement at the opening of a hole for receiving the head of a fastener, for receiving a center, or for deburring.
A countersink is a cone shaped hole cut into the laminate. It is typically used to allow the tapered head of a screw to sit flush with the top of the laminate. By comparison, a counterbore makes a flat-bottomed hole and its sides are drilled straight down. This is usually used to fit a hex-headed cap or screw.
- Fluted countersinks come in several sizes, able to cut conical holes intended to fit screws of varying head dimensions. A pilot hole is first drilled for the screw, followed by countersinking the hole to allow a flathead screw to seat flush with the work surface.
- Forstner bits are guided by the wide outside rim of the bit, unlike most drill bits, which are guided by the tip. Because of that, they can be used along with a drill press to drill angled holes, holes that partially overlap, and holes on the edge of the material.
- In rotary broaching, the broach is rotated and pressed into the workpiece to cut an axisymmetric shape. A rotary broach is used in a lathe or screw machine. In both processes the cut is performed in one pass of the broach, which makes it very efficient.
Updated: 4th September 2018