Drilling out a lock is a way to gain entry to locks which can’t be opened by other means but it is considered to be a last-resort approach. It can be very efficient method which will save you from destroying the door, or breaking the glass, or even save you money if you need to drill out ignition lock cylinders. The good side in drilling out a lock is that if it is done properly, the tumblers in the lock’s keyway are drilled out of the way, allowing the keyway to be turned with a straight-slot screwdriver or similar tool.
So first you need to examine the lock, see if it has a center pin made of hardened steel, or a ball bearing in the middle pin to prevent drilling. In these cases, the drilling would be useless.
When drilling out a lock i.e. a lock cylinder you will fist need a drill (electric or battery-powered) with variable speed; several sizes of drill bits because you want to match the drill bit to the size of the lock, 3/16 inch or 7/32 inch offers the best cut because of the size of the tumblers. Anything bigger might catch on the tumblers or shavings, jamming the drill bit; anything smaller might not cut through the tumblers.
The recommend bits are masonry bits or HSS drill bits. The same goes if you are drilling out a mailbox lock. But if you are drilling out ignition lock cylinder you might consider taking titanium bits because the IC is made of very hardened metal and it is going to take some work to get it drilled out.
When drilling out a lock you will require some kind a lubricant, a spray-on is fine, except when you are drilling out ignition lock cylinder, electronics and water do not work well together.
Also prepare a hammer and a straight-slot screwdriver small enough to fit in the lock’s keyway or a key tool.
Let’s do it!
Primarily you need to create a guidance point for drilling. You will achieve this by hammering a center punch at a point directly above the keyhole. It should be high enough to effectively drill through the pin tumblers. Set the drill in place and start drilling at moderate speed, spraying the lubricant occasionally on the drill bit where it meets the lock cylinder. Without the lubricant there is a great possibility that the cylinder would heat up to a point of melting. While drilling you will feel the drill bit cut through the pins that make up the tumbler (usually you have five or six pins). When you are drilling out a mailbox lock just drill into the middle of the cylinder a few times, and go in slowly with a bit that is at least 3/16. As far as drilling a deadbolt lock, you need to cover the entire drill bit with lubricant and spray it also inside the deadbolt and around the outer edge of the key hole. Drilling out an ignition lock cylinders require a bit smaller than a cylinder. Start the drilling at a low speed and create a groove in the end of the lock cylinder (no need for deep holes), as you go increase the speed and drill out the lock cylinder. Take it easy because if you force the drill into the lock cylinder, you could burn out the rotor inside the drill motor. I will also mention, that if you are drilling out an ordinary lock, after breaking through with a smaller bit, you can attach a larger one later 1/4-inch (6.5mm), and go through the lock again in order to break up the pins more.
After drilling, insert the blade of a flat-headed screwdriver into the lock head. Turn it in the same direction as the key goes, if you done everything right, you will gain your entry.