Hi, this is Wayne again with a topic “Make Inventions: Pin Tumbler Lock”.
As long as people have owned property, they’ve looked for ways to keep it secure. The idea of a lock and key dates back to the earliest civilizations and the history of invention is littered with countless failed designs. The most widely used lock today is the pin tumbler lock, invented by linus yale senior and his son linus yale jr in 1848. The senior yale patented the basic premise, but later in 1861, linus jr refined his father’s invention into the enduring design that we still use today. The pin tumbler lock gets its name from the pins that line the keyway they’re split in various locations and springs hold them in place when the right key is inserted.
The pins align to put the split exactly between the plug in the center and the shell around the outside. When everything lines up the plug can turn i’m building this lock out of acrylic. So we can see the inner workings. It also comes in a variety of useful shapes and can be worked with common tools.
The plug is a bit too large for the shell to get it down to size. I find the center of the plug and then drill a hole for the circular key. I thread a bolt through the middle and use a drill to quickly and evenly sand it to size when it fits smoothly. I restore the polish using successively finer, grained sandpaper and finish with plastic polish and a non-abrasive cloth. I drill the holes for the pins through the case and the shell at the same time to make sure they’re aligned with each other after they’re drilled. It’S time for more polishing. Cutting a groove in a cylindrical key is more complicated than modern, flat keys, but a narrow grinding wheel and a rotary tool makes it go quickly.
Next, i cut the pins that right along the key i round the end next to the key, so it will easily slide into its groove. Each pin should be flush with the plug when the correct key is inserted. The wrong key will misalign them and keep the plug from turning.
Pin chambers hold the other half of the pins and springs to push them against the key. I make them from smaller tubes that are shaped to match the curve of the shell and attached with acrylic glue. The springs are salvaged from retractable pins and each pin assembly is held in place with small screws. Finally, i cut a face plate flame polish, the edges and glue it to the rest of the lock, fully assembled. We can see if it works when i use an incorrect key. The pins fail to line up on the shear line and the plug won’t rotate using the correct key aligns the pins, the bottom half in the pin chamber, the top half and the plug, and the lock rotates.
No lock is foolproof, but many other lock designs have come and gone since 1861.. Meanwhile, the pin tumbler lock has been consistently popular remaining nearly unchanged for more than 150 years. I’M steve hofer for make inventions. You .