10. Every company and expert agrees your wrench should be calibrated from time to time. For sure if it has been dropped or you suspect someone has used it improperly. Also, if you just get the feeling it is off. Finding a place to calibrate it is a different matter. If you have Mac, Snap-on or similar professional tools, then you shouldn't have much trouble. Snap-on's Western Service Center said the average calibration charge is around $60. Every company I checked required shipping your wrench to them. Sears claims every store can send in your Craftsman wrench. At my local store the guys in the service department looked baffled when I asked about the service. The quoted price was $90, so it would be about the same as buying a new micrometer-style unit. The calibration is a good deal if you have a more expensive push-button, split-beam-type wrench.
11. My wrench is claimed to be good for 5,000 uses before calibration (if taken care of), so you start to see the wisdom in caring for the tool. Cheaper off-shore wrenches may be difficult to calibrate, and you may not find a company willing to do the work. Also, just because a tool says it is has a certain range does not mean it's certified. Make sure the tool you buy is certified, so that at least it starts out accurate.