In applying a new hairspring to a watch, the centre coils are broken out, about a quarter of a turn at a time, until there is room for the collet. The effect of this upon the time of the watch can be neglected, as the actual length of spring removed is so small. Now bend a small Length sharply inwards for pinning into the collet. Place the collet, right way up, on a broach, and push it on tightly; hold the broach in the left hand, pass the hairspring down the broach, and with the tweezers in the right hand, insert the end of the spring into the hole in the collet. Lay the broach down, with the collet and spring on, and file up a brass pin to fit. Then fix it in and break off the pin, which should previously be half cut through with a pocket-knife.