MEASURING TOOL MAINTENANCE
I was once in a shop where the Sunnen dial bore gauge setting standards were so worn on their Sunnen CF1126 that it messed up every job in the boring department and no one noticed. The ends of the changeable standards had divots worn in them from years of rubbing by the carbide balls in the dial bore gauge. The Sunnen rep was called and he said he had never seen such a worn out set. He took our set until he got the new standards for our set and had the dial setting fixture calibration checked. It’s just a matter of watching the needle when dropping the dial bore gauge into the cylinder. If it jumps just before the gauge is seated, you have wear. Everyone should know this, but everybody in that shop missed it. The 3 torque wrenches in the assembly department were 10, 15, and 20 pounds low at 65 foot pounds when I checked them against a craftsman beam type torque wrench just for fun one morning. I verified it against an almost new craftsman wrench. This is such an issue that ARP fasteners actually has a torque wrench tester on the mobile trailer that they take to NHRA races, to verify the torque wrench settings for racers using their fasteners. I believe these problems exist in shops all over the country. When was the last time you checked the calibration of your tools?
Wayne Petty
Wayne’s Auto Works
Los Angeles, CA
October, 2015
