A center punch is a tool with a pointed end that makes a dimple in your piece of material right where you intend to drill a hole.
A center punch mark accomplishes two things:
- It gives a physical resting place for a drill bit so it stays right where you want your hole to be
- When you begin drilling, the recess of the dimple relieves pressure from the flat tip of the bit (the "chisel tip" or the "web".) This prevents bending, chipping, breaking.
- Consider center punching a REQUIREMENT for making holes in metal with drill bits
- Use a center punch for bits up to (arguably including) 1/2" in diameter.
For larger bits ( > 1/2"):
- make a center punch
- drill with a bit the size of your intended bit's chisel tip (this is called a "pilot hole")
- drill with your intended bit.
For this demonstration, I'm drilling a hole in a piece of mild ("hardware store") steel. Well, in the interest of full disclosure, I'm making a corner bracket. :)
And, naturally, I did all deez workins at Techshop Detroit! www.techshop.ws