The first wrench patent in the United States went to Soloman Merrick in 1835 and ever since, man has skinned his knuckles on a regular basis. You need the right-sized wrench for a proper fit and to get a good grip on each surface of the nut -- or it'll slip. A cheap wrench will wear quickly and lose its bite -- and will slip. A dirty wrench can make you lose your grip -- and will slip. If you push on the wrench instead of pulling, it can slip and mash your fingers. If you do have to push, use your palm and keep fingers out of the way. The nut on your end of the wrench causes most scrapes. And that's the On The House tip for today.