Gyrobob
Serious Thumper
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Posers ain't motorcyclists
Posts: 2571
Newnan, GA
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You can calibrate a torque wrench pretty easily if you just want to make sure it is in the ballpark. The following is not real precise. There are shops that do this for real and will charge maybe $50 to calibrate and adjust a torque wrench. Just put the drive side in a vise (with some soft metal sheet to keep from putting vise marks on your wrench) and make sure the handle is level. Tie a cord or safety wire 12" (that's one foot, bill) from the center of the drive. -- for a clicker, set it on a weight in the midrange of the scale,.. say 40 pounds. -- attach 40 pounds of something (I use lead ingots stored for bullet casting) to the safety wire and see if it clicks. Barbell weights are handy for this if you are confident in the weight being accurate. Go up or down a pound or two or three to see where the actual click point is. -- for a beam wrench it is easier. Just attach the safety wire at the 12" point, and attach a known weight to the wire. If the scale reads the weight properly, you're golden. If not, you'll have to start carrying a correction every time you use that wrench.
A lot of our fasteners use inch-pounds. So, if you want to test your smaller wrench graduated in inch-pounds, find two one-gallon plastic milk jugs (they weigh only a couple ounces each), fill them with exactly one gallon of water each, tie them together and you'll have a weight that is really close to 17 pounds. Put the drive end of the wrench in the vise, set it on 102 inch pounds, and tie the two jugs on the wrench at a point 6" from the center of the piece clamped in the vise. If it just clicks,.. marvy.
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