Post #16 Maglock Basics

If you are new to the world of escape rooms, either as a player and/or a designer, you’ve probably come across a maglock or two. As a player, you might not have even been aware of the device, only the result it produced. Doors, hidden or otherwise, that open as a result of players performing some action are the most common use of maglocks. They can be placed out of sight and only require a pair of wires to supply current to make them work. There are benefits and drawbacks to using maglocks in your design, so let’s take a look at these devices in detail.

If you were a kid with any interest in science at all, you probably made an electromagnet with a nail, some wire and a battery. Wrap the wire in a tight coil around the nail and attach each end of the wire to the poles of a battery. You can then use the nail to pick up small objects like paperclips or another nail. Disconnect the wire from the battery and the objects fall from the nail to the table. This is exactly how a maglock works. Current from the power supply (usually 12 or 24 volts) runs around an internal coil producing a magnetic field. When the armature (the metal plate attached to the door or other surface) comes in contact with the field, it is strongly attracted and sticks as if by magic. (Note: “Any sufficiently advanced technology is indistinguishable from magic.” – Arthur C. Clarke). Remove the current, usually by opening a switch and the maglock releases the armature allowing the door to open.

There are some great advantages to using maglocks. They are highly reliable. Supply current, they work; turn it off, they stop working. Also, you can put pressure on the door and they will still open without jamming or binding. There are maglocks that generate as much as 1200 pounds of holding force, far more that a human can generate pulling on a door. I’ve worked as a locksmith for almost forty years and have installed a large number of maglocks for use in access control systems. They’re great for exit doors. You can install any number of switches to interrupt the current flow and the door opens. A badge reader (really fancy switch with a brain), a switch bar, an infrared sensor, a red exit button next to the door or any combination of these devices will do the trick. Simply hook all of your switches in series (end to end like train cars) and any one of them can break the current flow and turn off the maglock. They will not jam, bind or otherwise fail to open. There was a concern years ago about “residual current” keeping the mag energized after the current was turned off but the technology has come a long ways in four decades. I’ve never personally seen this happen, so two big thumbs up for maglocks.

Nothing is perfect and there are some drawbacks to using maglocks. The biggest one I can think of is their constant current draw. They MUST have power all the time to function. If you are using mags make sure they are rated for continuous duty. If not, they can overheat and fail. This goes for your power supply and wiring. Don’t skimp to save money, it will come back to haunt you. Maglocks are often paired with relays (basically an electrically powered switch), especially when using an Arduino or other micro controller. This way the relay does the heavy lifting of turning the current off and on rather than running it through the Arduino. I’ll talk about this more in another post.

Having said all this, there is another type of maglock that works without power, and releases when power is applied. Obviously these would not be a good choice for an exit door, but for an escape room or escape game box they can be very useful. They simply sit patiently holding whatever door you want kept closed until you give them a little electric power and then release. The big downside of these maglocks (called permanent electromagnets) is their price. While I can buy a regular mag that’s over an inch in diameter for less that twenty dollars, the permanent mags I bought were about the size of a dime and cost over thirty dollars each. It’s a trade-off. You pay more up front but save on electricity or batteries.

While we’re discussing alternates to standard maglocks, any electromagnet can be used to secure a door, panel or other type of mechanism. A small mag attached to the inside of a cabinet with a washer used as an armature will often do the trick. And here’s a little tip, when you attach that washer, leave it just a little loose. It will line up with the mag easier and eliminate having to get your alignment perfect.

So, depending on the theme of your game you may have to put in a little work to disguise your magnets. Egyptian pyramids, old west, Victorian London and even the swinging 60s are too far in the past for players to see electromagnetic devices. The last room we played was set in the attic of an eclectic millionaire set in the 1930s. There were numerous mags and electronic devices but they worked very well with the story. There was even a huge crate on the floor that had an entire side that fell off when the maglocks were released. This then led to a tunnel, a very cool effect. Because of the size of the crate, there were two large mags holding the panel on and they were very visible, but by the time we noticed this we were too engrossed in the story and … Holy Crap Batman! A Tunnel! Not to mention the thundering crash of the panel falling to the floor. It worked well.

There’s no doubt, maglocks are the workhorses of escape rooms and puzzles. Besides doors and panels, they can be used to drop keys or other small items down a chute or hold an item tight to a table top, then release it when the puzzle is solved. A note on keys: almost all modern keys are made of brass and will NOT stick to magnet. If you want to hold a key with a maglock, attach it to a steel ring (most key rings will work), washer or other ferrous metal object. Also, I’ve found that the thicker the armature, the stronger the magnetic attraction. If your magnet is not holding as well as you’d like, use a thicker piece of metal or several washers instead of one. There’s no substitute for experience so experiment with different size magnets, armatures, springs (to make things open or move after the maglock releases) until you get a combination that works the way you want it to. When it comes to maglocks, you have to stick with it. (Insert audible groan here) Now go out and be nice to someone.