There’s a lot of confusion surrounding centre drills and spot drills. The names are often used interchangeably and fail to explain how the centre drill and the spot drill work respectively.
Allow us to explain...
The centre drill
Centre drills are used to make a centre hole to be able to support the workpiece on a lathe. The small diameter ensures that the tip of the centre is always clear.
The most commonly used centre drill has a 60° angle, but centre drills based on a collar, radius, 90° and 60/120° are also available.
The spot drill
Spot drills are used for accurately positioning the material before drilling into it. The spot drill can also be used for precise positioning and countersinking in one operation.
90° spot drills are used for accurate positioning when using HSS drills. 120° spot drills are used for self-centring drills with a top angle of 118° or less. 142° spot drills are used for self-centring drills with a top angle of 140° or less.
Watch the video of a 90° spot drill in action here.
Three differences between centre drills and spot drills
The differences between a centre drill and a spot drill are summarised below.
