Drill chucks are held on the machine spindle by means of

15.8 mm

Smaller than the machine spindle

Drill sleeve is used when the taper shank of the drill is smaller than the machine spindle.

8 Degree to 12 Degree

The lip clearance angle of twist drill for general purpose should be 8 Degree to 12 Degree.

Soluble oil

Soluble oil are made from mineral oils with emulsifying material added to make for mixing with water. Soluble oil is diluted with water to form an emulsion. The water cools whilst the oil lubricates. The extent of dilution depends upon the type of operation.