A countersunk magnetic disc is a magnetic disc with a countersunk hole in the centre of one of its magnetic faces, either the north or south pole.
A countersunk hole has a flat top on one magnetic face which tapers towards the other, in the shape of a cone. This allows the magnet to be attached to a surface with a countersunk screw. The surface is kept flat as the countersunk hole allows the screw to sit flush with the magnet.
Flush means that the top of the screw and the magnet are perfectly level and even with the surface, rather than protruding above it like other types of screws would do, in a ring magnetic disc, for example.
The screws used with a countersunk magnetic disc need to be the same diameter as the countersunk hole. For example, you will need a screw that is 4.8mm (0.19″) in diameter to fit inside a 4.8mm (0.19″) diameter countersunk hole in a countersunk magnetic disc.
Countersunk magnetic discs, with the aide of a screw, are ideal for holding wooden kitchen cabinet doors closed.
Sizes of countersunk magnetic discs
Countersunk magnetic discs are always measured as their diameter x depth x countersunk hole diameter.
The diameter refers to the distance between the two widest points of the countersunk magnetic disc. The diameter ranges from 10mm (0.39″) to 50mm (1.97″).
The depth of a basic magnetic disc is the distance between the two magnetic faces and can range from 2mm (0.079″) to 30mm (1.18″).
The diameter of the countersunk hole ranges from 3mm (0.12″) to 6.2mm (0.24″) and measures the diameter of the narrowest section of the countersunk hole.
The magnetic pull ranges from 0.9kg (1.98lb) to 81kg (178.57lb).