Key smiths have a bench filing machine that makes duplicating keys a quick and simple job. What usually goes on when you leave the original key to a key smith is a simple process and all it takes is a large file and some patience.
To start with, key smiths would need to begin by clamping down the original and blank key side by side that can be used to duplicate the pattern onto the blank key. Both keys must be lined up tightly and perfectly in the vice holder before starting the machine. Next, this is where you’ll need patience as you start filing down the blank key. Key smiths often begin filing the blank to the height of the tallest point of the original key first, but it is important to remember to be careful not to scrape any part of the original as this can potentially destroy the key. Filing the key valleys can be tricky as key smiths would be required to check every time if the keys are still lined up tightly as they should be. But if you don’t want to send your keys out to someone else, you can file your own keys at home with a solid metal filer, a strong grip, and a lot of time and patience. You’ll need to be able to figure out which areas of the new duplicate to tune if it doesn’t fit into the key slot properly.
Duplicating keys can be a really handy skill to have especially if you’re constantly on the bridge of fear of a key smith duplicating an extra key without your knowledge and using it to break in through your locks. While the possibility of that happening is quite low, there is no doubt that you’ll be able to learn other values as you try and learn how to file and duplicate keys on your own.