Different tools are used for performing different operations. They are fitted into the drill spindle by different methods. They are
- By directly fitting in the spindle
- By a sleeve
- By a socket
- By a chuck
- Tapping attachment
Almost all drilling machines have their spindle bored out to a standard taper(1:20) to receive the taper shank of the tool. While fitting the tool, the shank of the drill (or any other tool) is forced into the tapered hole and the tool is gripped by friction. The tool may be rotated with the spindle by friction between the tapered surface and the spindle. But to ensure a positive drive, the tang of the tool fits into a slot at the end of the taper hole. The tool may be removed by pressing a tapered wedge known as drift into the slotted hole of the spindle.
The drill spindle is suitable for holding only one size of tool shank. If the shank of the tool is smaller than the taper in the spindle hole, a taper sleeve is used. The outside taper of the sleeve conforms to the spindle taper and the inside taper holds the shanks of the smaller size tools. The sleeve has a flattened end or tang which fits into the slot of the spindle. The tang of the tool fits into a slot provided at the end of the taper hole of the sleeve. Different sizes of tool shanks may be held by using different sizes of sleeve. In order to remove the drill from the spindle, the drill along with the sleeve is removed with the help of a drift. The drill is then removed from the sleeve by the same method.
Drill sockets are much longer in size than the drill sleeves. A socket consists of a solid shank attached to the end of a cylindrical body. The taper shank of the socket conforms to the taper of the drill spindle and fits into it. The body of the socket has a tapered hole larger than the drill spindle taper into which the taper shank of any tool may be fitted. The tang of the socket fits into slot of the spindle and the tang of the tool fits slot of the socket.
This type of chuck is particularly adapted for holding tools having straight shanks. The drill chuck has a taper shank which fits into the taper hole of the spindle. The jaws fitted in the body of the chuck holds the straight shank drills.
The tapping attachment is used to hold the tool known as ‘tap’. It serves as a flexible connection between the spindle and the tap. The taper shank of the attachment is fitted into the drill spindle. The tap is fitted at the bottom of the attachment. The tap is fed into the specific hole by the spindle, rotating it in clockwise direction. After the threads are cut, the spindle is released from the hole. The bottom of the attachment rotates in anti-clockwise direction causing no damage to the tapped hole. Tapping attachments are used during production work.