This is a 1/8″ point Starrett center punch with knurled body.
Instructions: After scribing a hole location, carefully align the center punch over the mark and lightly tap it with a hammer. Now check to make sure the mark is exactly where you want it to be. If the mark is off slightly, you can angle the punch slightly when you strike again to correct its position. Strike the punch fairly hard when the initial dimple from lightly tapping is on target.
The goal of using a center punch is to give the drill bit a large enough dimple so that the cutting lips of the bit can engage the hole and lock it into position. If you look carefully, you’ll notice that the very end of a drill bit isn’t a point, but is a flat edge called a “chisel edge.” This edge needs to fit inside the mark created by the center punch. With a 1/8″ center punch, you should be able start bits up to at least 3/8″, mileage will vary based on the bits.
How is a center punch different from a prick punch? A prick punch has a steeper angle (60 deg or less) compared to about a 90 degree tip on center punches. The center punch’s goal is to create a large enough hole to capture the cutting edges of a drill bit. The goal of a prick punch is to leave a small, precisely placed hole that can be used to make further measurements or markings from, such as scribing a circumference with a divider (compass). For holes that require a fair amount of precision, the prick punch can be used to make a starter dimple that is then enlarged with the center punch. It’s slightly easier to align the smaller point on a prick punch.
Tip: If your punch dulls over time, a grinder can be used to re-sharpen it. Grind the tip so that the resulting grinding lines run parallel to the length of the punch. Grinding the other way (around the circumference) will leave lines that resist the punch from entering metal. Note: Safety glass are not overkill when using a punch. Anytime two relatively hard pieces of metal (hammer and punch for instance) are struck together there is a chance that a shard of metal will fly off.