Drill bit fitting and removal

Drill bit fitting and removal

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Drill bits have to be inserted into the drilling machine spindle, This is done by two methods,

Drill chuck
Taper sleeve drill

Drill chuck

Drill Chucks are used to hold drills & cutting tools to a spindle for high speed drilling.

Most drill chucks require a key which is used to turn the gear teeth and open/close the jaws (there are also keyless chucks which, as the name implies, do not require keys

Drill chucks have been provided with a taper shank (Morse taper) that will fit into the spindle of the drilling machine,

Taper sleeve drill bit

Drill Chucks have are suitable for small drill bits up to +-12 mm, Large drill bits have to fit directly into the spindle that is provided with a Morse taper.

Taper shanks are cone-shaped. One advantage of such an arrangement is that it centre the drill very accurately. For shanks of the size and with the degree of taper in the Morse series, friction alone is enough to turn the tool and to hold the shank in the socket.

At the end of the shank is a flat protrusion called the “tang” or “tongue”. To release the shank from the socket, a wedge (a key with a taper of 1.75 in 12) is tapped through a keyway at the bottom of the socket. It pushes on the bottom of the tang and frees the tool. The wedge key is also known as a drift.