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Keeping Your Torque Wrench Calibrated May Be the Simplest Way to Avoid Broken Fasteners

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Keeping Your Torque Wrench Calibrated May Be the Simplest Way to Avoid Broken Fasteners Foreign Service Keeping your torque wrench calibrated may be the simplest way to avoid broken fasteners. This month, Dan tells us about a company that does the job quickly and efficiently. s a kid, the first things I learned tion vs. a pound of cure. Doubt us? Then con- about wrenchin’ cars—good or sider the cost of labor to pull a job apart again bad—came from the older gear- to remove a busted fastener or repair stripped heads in the neighborhood. And threads caused by inaccurate torque! Dan the first time I ever thought To get the straight scoop on torque wrench about torque wrench accuracy calibration and maintenance, we sought out Marinucci was when one of those older guys broke a Ben Spurlock at Angle Repair and Calibration Ahead bolt while assembling an MG motor. Al- in Beckley, West Virginia (304-253-5720, though the problem generated some cussing, www.anglerepair.com). If this company’s name and a whole lot of theorizing about the cause, rings a bell, it should. If you own an Ameri- the issue went unresolved. Looking back, I can-made torque wrench, the owner’s manual doubt that mechanic thought seriously about for that wrench probably lists Angle Repair as having his torque wrench tested. a factory-authorized repair/calibration source. I don’t think attitudes have changed after all Typically, the first thing a tech wants to these years. That is, torque wrench accuracy know about torque wrench maintenance is and calibration are still probably the farthest how often a wrench needs to be checked. The things from a technician’s mind. But there’s no second thing is cost. Spurlock responded with denying that a torque wrench is a mechanical this rule of thumb: If you use a torque wrench device, and as such it can and does go out of three to four times a month, you should have whack with use. it checked at least once a year. (Hmm...sounds Today, having your torque wrench checked like most techs we know!) periodically amounts to an ounce of preven- Angle Repair charges 25 bucks to calibrate 1 any ⁄2-inch drive or smaller torque wrench, 45 3 bucks for ⁄4-inch jobs. Shipping is extra, and the turnaround time is usually a couple of days. If your torque wrench needs repairs be- fore it can be calibrated, Angle Repair phones or faxes an estimate to you. An interesting side note is that Angle Repair won’t touch anything but domestically built torque wrenches. Spurlock emphasized that his company has been servicing torque wrenches for more than 25 years. So they’ve learned what the typical failures are and have built up a massive inven- tory of repair parts to minimize torque wrench downtime. Based on the number of used and abused torque wrenches coming in the door, Spurlock said, tips on proper use and maintenance are of- ten ignored. But a handful of these tips can save you a bucketful of bucks. First of all, remember that a torque wrench Photos courtesy Angle Repair and Calibration Angle Repair courtesy Photos is a precision measuring instrument, so treat it In this photo, an Angle Repair technician is adjusting a torque accordingly. That means don’t drop it, pitch it wrench to the appropriate torque setting prior to a calibration test. into a toolbox drawer, slide it across the floor, continued on page 14 12 February 2002 Foreign Service leave it unprotected or hurl other tools on top of it. Never use a torque wrench as a breaker bar for loosening fasteners. Don’t try to tighten a fastener beyond the range of the wrench and never use a “cheater pipe” on a torque wrench. Ratcheting-head torque wrenches are a favorite of many techs because they’re very convenient. However, ratchets are designed for constant ratcheting, torque wrenches aren’t. Using a ratcheting torque wrench in place of a traditional torque wrench will wear out its ratchet mechanism prematurely. Sometimes, this ratchet mecha- nism slips because it’s dirty. Spurlock Here the technician is recording actual torque readings from the wrench af- reminds us that some ratchet mecha- ter the calibration test was completed. Remember that a torque wrench is a nisms are very easy to remove, clean precision instrument, so treat it with lots of tender, loving care. and lubricate. “A little bit of light oil or very light grease is all you need. Don’t pack the thing with wheel bearing grease,” he explained. Of course, some ratchet heads are not easy to service. Over the telephone, Spurlock has tried to coach more than one surprised tech- nician through reassemblying a dis- combobulated ratchet mechanism. Click-type or microadjustable torque wrenches dominate the marketplace. Spurlock said a smart way to preserve the calibration of these popular wrench- es is to always adjust the torque back to the lowest setting or increment on the barrel of the wrench before you put it back in its storage case. Suppose you have a click-type torque wrench and you haven’t used it for several weeks. If so, “prep” it Here a technician disassembles a torque wrench for repair. Angle Repair and for use by getting its parts moving Calibration stocks repair parts for most, if not all, brand-name wrenches. again. Adjust the torque setting to the middle of its range (for example, wrench so you’re constantly pulling in 50-ft-lb range, buy a 100-ft-lb torque about 50 ft-lb on a 100-ft-lb wrench). a level plane, not upward or pushing wrench. Next, put it on a fastener and make downward on the wrench as you pull Finally, remember that you get ex- the wrench click five or six times at the handle. actly what you pay for in a torque the 50-ft-lb setting. Then adjust it to Third, always avoid the uppermost wrench. Several years ago, I was the required torque for the job at and lowermost ranges of any given sending my trusty old Proto to Angle hand and you’re ready to go. torque wrench. Staying within the Repair for a regular checkup. A Regardless of the type of torque middle 60% of a wrench’s range friend asked me to send his bargain- wrench you use, Spurlock offers the yields the best and most accurate re- basement, offshore torque wrench following tips to enhance accuracy: sults. This also helps you decide along in the same package, so I First, always torque fasteners with a which range of wrench to buy. For obliged. Spurlock told me that they smooth, steady pull of the wrench. example, if most of the fasteners you calibrated my pal’s torque wrench, Never jerk or snap the handle abrupt- tighten are in the 70- to 90-ft-lb then let it sit overnight. When they ly; smooth and steady does it. range, buy a 150-ft-lb wrench. If retested it in the morning, it was al- Second, always position a torque most of your work falls in the 45- to ready out of calibration! ’Nuff said? 14 February 2002.
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