Sherline 3021 – 3-piece Center Drill
Center drills are used with the lathe to drill a hole in the end
of stock for mounting between centers in the lathe. They are
designed to drill a small diameter pilot hole followed by a 60?
countersink that provides a bearing surface for the 60? point of
the lathe center. Center drills are also used extensively with the
milling machine to accurately start holes. The hole locations can
be dialed in using the milling machine?s calibrated handwheels,
then the hole is started using the center drill. The large diameter
shank on the center drill holds the drill point right on center.
Once the hole is started, the center drill is replaced with a drill
of the desired diameter and the hole is finished. It is imperative
that a cutting lubricant is used, and the center drill is backed
off several times to prevent the smaller tip from twisting off.
This center drill set includes a #1, #2 and #3 double-ended
high-speed steel drill. The #1 drill (P/N 30240) has a 1/8″ shank,
the #2 drill (P/N 30260) has a 3/16″ shank, and the #3 drill (P/N
30270) has a 1/4″ shank. The tip diameter of the #1 is .047″, the
#2 is .078″ and the #3 is .109″. Other smaller sizes are available