Q: I have been using a flex-shaft and a small (#60) drill bit to drill holes in 20 gauge copper. I ding the center of the hole first, but it seems to take forever to get through the metal on most occasions. Am I doing something wrong?
A: High quality drill bits generally will give better results than cheap ones. Be sure you’re getting good high speed steel bits, and preferably, from a major manufacturer. I bought some once on ebay that seemed a great deal. They were made with good steel, but didn’t get a good grind nor were they well-sharpened. Worthless drills for a bargain price aren’t a bargain. So get high quality drill bits, keep them sharp, and you’ll see much faster drilling.
Also, be sure to use a lubricant of some sort. Bur Life, bees’ wax, ordinary machine oil, or even saliva will all not only help to keep the bit cool, but will speed up the cutting markedly. Dinging the metal first may not be quite enough to give the bit a good start. Use a center punch, which puts an actual conical depression in the metal. This makes for a solidly located hole, since the bit will be less likely to wander around before biting into the metal.
If, while drilling, the “feel” changes, seeming coarser, or the bit seems to be slowing down, pull it back slightly to allow more lube to get into the hole before resuming. This also allows the chip to break free, and the hole to clear out a bit before you continue, again helping the lubricant to get into the hole. If the drill bit heats up and discolors during use, you’re either not using lube, or more likely the drill is dull and needs resharpening or replacing. I’d expect that your holes might take somewhere in the area of ten seconds each to drill, if all the above conditions are met.
by Peter W. Rowe M.F.A., G.G.