What is a through hole pot magnet?

A through hole pot magnet is a pot magnet with a large hole through the centre, known as the boss. The boss allows the magnet to be attached to non-ferromagnetic items with a bolt. 

The boss is wide enough to accommodate the bolts without them touching the magnet. This allows the bolt to be attached to a non-ferromagnetic material very tightly, as clamping directly onto the magnet could break it, as it is very brittle.

The boss in a through hole pot magnet can be M4 to M20. This stands for a through hole which is 4mm (0.16”) to 20mm (0.79”) in diameter. However, this only refers to the size of the through hole rather than the size of the bolt which can be attached. This is because some through hole pot magnets provide a larger air gap between the magnet and the bolt to stop the two from touching.

The size of the bolts which can be attached to a through hole pot magnet depends upon the diameter of the hole in the top of the pot magnet's shell. This hole can fit M3 to M12 bolts - which stands for a bolt which is 3mm (0.12”) to 12mm (0.47”) in diameter.

The bolts used with a through hole pot magnet need to be the same diameter as the shell's through hole. For example, you will need a bolt that is 4mm (0.16") in diameter to fit inside a 4mm (0.16") diameter through hole in a through hole pot magnet.

Through hole pot magnets can be used as retrieval magnets, which are magnets used to pick up or retrieve ferromagnetic objects from hard-to-reach places, (e.g. underwater). This is useful for treasure hunters hoping to find money at the bottom of a river.

Through hole pot magnets can also be attached to the bottom of tow lights to enable users to attach the tow light to a car to warn other road users that the car has broken down.

How to use a through hole pot magnet

To use a through hole pot magnet, a bolt needs to be placed through the hole until the head touches the top of the steel shell, with the magnetic face pointing outwards away from the ferromagnetic surface.

The bolt is then attached to the ferromagnetic material with a nut to hold it securely in position. The through hole pot magnet will now be ready to use.