centre drill BrE technical
center drill AmE technical

One of the best solutions for this, is a machinists centre drill.

At its front two centre drills, one above the other, made "burn holes" about 5 inches in diameter to relieve explosion pressure.

Demonstration of centre lathe - facing off, centre drill, drill and centre bore hole.

One of the best solutions for this, is a machinists centre drill.

A center drill has a thick shaft and very short flutes.

First, a center drill should be used.

A center is inserted into a matching hole drilled by a center drill.

At its front two centre drills, one above the other, made "burn holes" about 5 inches in diameter to relieve explosion pressure.

Center drilling is typically performed using a drill with a special shape, known as a center drill.

While the above is a common use of center drill bits, it is a technically incorrect practice and should not be considered for production use.

New drill and center drill retract options.

Demonstration of centre lathe - facing off, centre drill, drill and centre bore hole.

A center drill bit frequently provides a reasonable starting point as it is short and therefore has a reduced tendency to wander when drilling is started.

Center drill bits are meant to create a conical hole for "between centers" manufacturing processes (typically lathe or cylindrical-grinder work).

Center drills are made specifically for drilling lathe centers, but are often incorrectly used as spotting drills.

However, the true purpose of a center drill bit is the latter task, while the former task is best done with a spotting drill bit (as explained in detail below).

For example, a centering lathe is a dual head machine where the work remains fixed and the heads move towards the workpiece and machine a center drill hole into each end.

Two Holes Should Be Centered Drill one horizontal pilot hole an eighth of an inch in diameter completely through the door's sides and a similar hole into the door's edge.

Most modern solid-carbide bits should not be used in conjunction with a spot drill bit or a center drill bit, as solid-carbide bits are specifically designed to start their own hole.

Nevertheless, because of the frequent lumping together of both the terminology and the tool use, suppliers may call center drill bits combined-drill-and-countersinks in order to make it unambiguously clear what product is being ordered.

The pilot drill may be a standard twist drill, another type of drill bit appropriate for the material, or, when the primary purpose is precisely locating a hole, may be made with a short, stiff center drill.

If it is deemed necessary to chamfer a hole with a spot or center drill bit when a solid-carbide drill bit is used, it is best practice to do so after the hole is drilled.

Some self-tapping screws are also self-drilling, which means that, in addition to the tap-like flute in the leading threads, there is also a preliminary drill-like fluted tip that looks much like the tip of a center drill.

The hole must be centered by hand so that the center drill point is directly over the centerpunched mark. Other larger drilling machines have slotted tables and bases so that the work and work holding devices can be bolted or clamped firmly.

Center drill bits, occasionally known as Slocombe drill bits, are used in metalworking to provide a starting hole for a larger-sized drill bit or to make a conical indentation in the end of a workpiece in which to mount a lathe center.

Center drills are available with two different included angles; 60 degrees is the standard for drilling centre holes (for example for subsequent centre support in the lathe), but 90 degrees is also common and used when locating holes prior to drilling with twist drills.