You forgot your keys. Your roommate is in parts unknown and can’t come by to let you back in. What are you going to do? Lurk outside your door until someone with a key comes by? That could be hours. No; you need to take action. You need to pick the lock.

First off, you’ll need a tension wrench and a pick. Assuming you don’t have a set of professional lock picks, you’ll have to jury-rig your own tools. A tension wrench can be anything that doesn’t break when you apply pressure to the lock’s cylinder, but is thin enough to actually fit in the end of the keyhole. A small filed-down Allen wrench could work, or a thin flathead screwdriver. Picks are easier—you can make them out of safety pins, paperclips, bobby pins, hacksaw blades, whatever you have. You need something that you can take and bend a small portion of the end up 90 degrees, but is strong enough that it won’t keep bending when you’re trying to use it.

Jai Kamat

The lock on your door right now is probably a standard pin-and-tumbler lock. It has a cylinder that can rotate inside the housing, which is secured by pairs of pins when locked — usually five pairs — which are held in place by springs. American locks tend to have the pins on top. When a key is put in the lock, the ridges and grooves push the pins to the correct height so that the upper pins are completely out of the cylinder, the lock can turn and the door can open. What you need to do to pick the lock is get all of those pins out of the cylinder without using the key.

Jai Kamat

First, put your tension wrench in the lower portion of the keyhole. Try turning the lock just using the wrench. The direction that the lock is supposed to turn should have a little more give in it. Start putting light pressure on that direction, and hold it. The force required will vary from lock to lock, and even from pin to pin, so you’ll have to go through some trial and error to figure out the exact amount of pressure, but it’s best to start lightly. Put your pick in the upper part of the lock and feel the pins. You should be able to push them up and feel them get pushed back down by the springs. Find the pin that is hardest to push up. If all of them are easy, apply more torque with the wrench, and if one of them doesn’t move at all, apply less.

Now try to “set” the pin. Push the hardest pin up with just enough pressure to counteract the spring. Each pin you’re feeling with your pick is actually a pair of pins; your goal is to push the upper pin out of the cylinder. When you stop pushing the lower pin should fall back down, but the pressure from your wrench should cause the upper pin to be out of alignment with the hole in the cylinder. You should hear a faint click as it falls down and hits the top of the cylinder, and should be able to push the lower pin up a bit without any pressure.

Now do the same thing for the rest of the pins in the lock. You may have to make adjustments in torque to set the rest of the pins, but remember to always keep up some pressure with the wrench so that the already set pins don’t fall back down. Once all the pins are set, use the tension wrench to turn the lock. Hopefully you chose the right direction to apply pressure, otherwise you’ll have to reset all those pins and start again from the other direction. Assuming that you did everything properly, though (and that no one saw you and started asking awkward questions about why you need to break into your own apartment), you’re in. Step through the threshold, hang up your coat, and feel proud that you were able to use your new found abilities for good.