You’ve probably seen them before: ring-shaped magnets that look like washers with wedges cut out of the middle. These are countersunk magnets. Also called countersink magnets, the design is intentional—the wedge and hole exist so the countersunk magnet can be anchored in place by a single screw. Their strange design makes them extremely useful in the right situations. 

Two Variations of Countersunk/Countersink Magnets

Countersunk magnets come in two basic variations: all-magnet countersinks, which are solid pieces of magnet, and POT magnets, which house magnets inside steel casings.

The all-magnet countersinks have two advantages:

  1. They’re generally a little bit cheaper since you’re not paying for the housing.
  2. Their magnetic field is generally a little stronger because there’s no barrier (i.e., the housing) around them.

 

The big drawback to all-magnet countersinks is that they’re brittle. In many cases, these countersinks are made of solid neodymium. During installation, over-torquing a screw can cause the neodymium to crack, breaking the countersunk.

The POT magnets are a bit stronger. Thanks to the metal housing, you don’t need to worry as much about handling, especially during installation. This protective cover also allows for the use of ferrite magnets instead of neodymium, though it’s a less common choice.

In exchange for this durability, you’ll sacrifice a small amount of magnetic strength since there’s a barrier between the magnets and any ferromagnetic material it attracts.

Uses for Countersunk Magnets

There are plenty of uses for countersunk magnets, especially if you’re creative.

One of the most popular uses for countersinks is to keep doors open. To hold them open, people will screw a countersunk magnet into the floor at the edge of a door’s opening radius. When the door is swung open, it bumps against the countersunk, which it latches to either because the door itself is ferromagnetic or because a ferromagnetic material is attached to the door.

Some people also use countersunk magnets to hold furniture in place on the floor or behind artwork to keep them attached to the wall.

One of the most interesting uses of countersunk magnets we’ve seen is in workshops. Some people will cover a wall with outward-facing countersunk magnets to hold up objects they need to work on.

Purchasing and Installing Countersunk Magnets

Before purchasing a countersunk magnet, there are two questions you should ask:

  1. How much weight will the magnet need to hold? This will let you know how big of a countersunk you need.
  2. What size screw does it require? This will let you get the right equipment before you install.

 

Installation is simple: Drive the screw through the hole in the countersunk magnet, drilling it flush with the top of the countersunk so there’s no chance of the magnet shifting or snagging anything nearby. Finally, be careful not to over-tighten the screw, especially when using an all-magnet countersunk. The added pressure could break the brittle magnet. Once the countersunk’s in place, it’s ready for use!

Countersinks from Apex Magnets

Whether you want to call them countersink or countersunk, Apex Magnets has you covered. With a huge variety of strengths and designs, you’ll find exactly what you need. Questions? Contact our dedicated customer service team for help picking the best fit.