The impact of drilling concrete, to hold the drill, at any time will bring out the slag eye, to travel in a time not too long. Pay attention to the pipe line in the wall. Pay attention to the steel bar on the wall, it will drill body belt turn, wounding.
There are so many fake twist drills, you can only buy them and buy more.Steel plate drilling should be light pressure, at any time pouring oil or water cooling.
An angular grinder cannot grind a drill bit. You must grind a drill bit on a sander, and you are a layman, and you may not sharpen it even if you have it
