What are countersinks used for?
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).
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 second is if you want to hide a screw head, the countersink hole will allow the head of the screw to sink below the material it is inserted into and can then be filled over and painted. To drill a countersink, place the countersink bit in your drill and push down lightly on the pilot hole.
- The point angle of a twist drill is the angle made by the cutting lip and the axis of the drill. For general purpose drilling a point angle of 59° (118° included angle) is recommended. The point angle may vary somewhat, one way or the other, but the variation should be uniform in both cutting lips.
- A hole saw (also styled holesaw), also known as a hole cutter, is a saw blade of annular (ring) shape, whose annular kerf creates a hole in the workpiece without having to cut up the core material. It is used in a drill. Hole saws typically have a pilot drill bit at their center to keep the saw teeth from walking.
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.
- 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.
- 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.
- Method 2 Using a Drill Press
- Affix the material firmly to a flat surface with clamps or a vise.
- Use a center drill bit in the press to mark your hole accurately.
- Drill with a bit 0.016” narrower in diameter than the hole desired.
- Clear the hole.
- Affix your reamer into the drill chuck.
- Ream the hole.
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.
- Starting on April 25th, airline passengers can carry pocketknives with small blades. We're not talking tactical knives. Even most Swiss Army Knives are still banned. But the new rules allow small knives with blades of 2.36 inches or shorter to come into the cabin and travel in your pocket or a carryon bag.
- Medication in liquid form is allowed in carry-on bags in excess of 3.4 ounces in reasonable quantities for the flight. TSA does not require passengers to have medications in prescription bottles, but states have individual laws regarding the labeling of prescription medication with which passengers need to comply.
- A. Makeup is subject to the same liquid and gel rules as all other substances — so if you're bringing liquid mascara, lip gels (such as Blistex) or other liquid- or gel-like items, they will need to be placed in your quart-size plastic bag in 3.4-ounce or smaller containers.
Updated: 3rd December 2019