Torque Wrenches

[madizell]

Sorry to differ, but... calibration is a comparison of the alleged torque value offered by a tool versus a standard value known to be accurate. The only way to calibrate either a click style, a beep style, or a beam style wrench is to use that tool against a known value of resistance. Just because the beam pointer points to zero is no indication of the accuracy of the tool. I have never seen a calibrated beam wrench, and don't know of anyone who has attempted to calibrate one.

Moreover, a beam wrench requires interpretation and is highly susceptible to operator induced error. A click wrench may be accurate plus or minus 1 percent, but its repeatability is just as good or better. With a beam wrench, if you can hit 5 percent of the intended value, you are doing quite well, and if you can use one to hit the same value time after time (precision as opposed to accuracy) you are a practiced guru of torque wrenching. With a static torque load on a beam wrench, just a slight tilt of the operator's head will account for errors of more than 1 to 3 percent in reading the dial, which is about what most click wrenchs offer when in good repair, and they can be used in the dark, in spots where you can't get your head over the dial, or upside down in the mud, and they require little practice to use correctly. A beam wrench pointer that is 1/32 inch wide covers an area on the dial of more than 3 percent if 100 pounds of torque results in one inch of deflection over the dial.

You may well be more comfortable with a beam wrench, and I used them professionally way back when I was a mechanic in the 70's, but I still trust a click wrench to do a better job.

 

[ntsqd]

I didn't expect my position to be popular, and I was right. I have experienced engine failures due to a supposedly well cared for clicker of quality mfg (Snap-On). Your points are valid, but careful use will mitigate them. Asking for under 5% means that you're so far inside the tolerance stack of other variables in the assembly (unless working on mil-spec stuff) that it is extra work for no significant gain. I never said beams were easy, I said I'll take a beam over a clicker any day. The wrench itself is far more consistent than any clicker could ever be. It is up to the user to to not fail.

If consistant high precision is required I believe a load cell type wrench is necessary, but then you'd better stock up on batteries....

 

[The BN Guy]

I have the Craftsman and have zero complaints! Good wrench and absolutely no problems with it. Reasonably priced as well.

 

[madizell]

I didn't expect my position to be popular, and I was right. I have experienced engine failures due to a supposedly well cared for clicker of quality mfg (Snap-On). Your points are valid, but careful use will mitigate them. Asking for under 5% means that you're so far inside the tolerance stack of other variables in the assembly (unless working on mil-spec stuff) that it is extra work for no significant gain. I never said beams were easy, I said I'll take a beam over a clicker any day. The wrench itself is far more consistent than any clicker could ever be. It is up to the user to to not fail.

If consistant high precision is required I believe a load cell type wrench is necessary, but then you'd better stock up on batteries....

Your views are not unpopular, we simply have a different perspective.

If a beam wrench, even in the hands of a practiced user, can't get within 5% on a regular basis, and if both precision and accuracy are mandatory (military does not have a corner on this market and frankly I would not expect a military mechanic to be any better than any other well trained professional -- not the ones I have know anyway), then how is it that beam wrenches compare favorably to a wrench of whatever other construction that has the ability to work under 5% on a regular basis with minimal maintenance, is easier to use with repeatability by persons of various levels of expertise, and is at the least susceptible to calibration?

That an engine might have been assembled with a click wrench, and then failed, is not a proven fault of the wrench. As you say, stacked tolerances can cause assembly issues, as can faulty build techniques. Even if an engine failed because torque values delivered by a particular wrench were all over the map, the "fault" in such a case would be attributable to the use of a faulty device, not the design of the device itself. That is, if precision and accuracy are required, the tool needs to be verified before the job begins. If it was not verified and the tool was faulty, then the process was flawed from the start, which would be true as well of a beam wrench if its torque values were not verified prior to use, or was used by someone without adequate training and experience.

There is no guarantee that any type of torque wrench you want to use actually provides the torque value it says it does unless you have the wrench verified. Take any two wrenches you wish to choose, have them calibrated, and them put them into the hands of a mechanic, and the click style wrench will clearly and unambiguously provide torque values within its ability with little room for guess work, whereas the beam wrench requires patience, practice, and a consistent style (stroke rate and point of view over the dial) in order to provide consistent results. Because it is a far more demanding instrument, I personally believe it is not the best choice for the average user.

To say that a beam wrench is more consistent than another style may well be correct, but consistency, accuracy, and precision are different things. It could be quite consistent, but consistency is not enough. A torque wrench needs to be accurate (gives the correct answer in torque) and precise (capable of giving the right answer again and again). If a torque wrench is not accurate, even if consistent, it is consistently wrong, which won't get you anywhere. Worse, if it is susceptible to user induced variation, which it is, it can only provide consistency if used consistently, which requires expertise and practice. With a beam wrench, accuracy comes from a properly calibrated tool, and precision comes from the operator. If you can achieve this and trust the results, that makes you a stand out mechanic, something that you can take pride in. But because you are an expert with this tool, you also know that in inexperienced hands, a beam wrench won't give a consistent result.

Within the context of this forum, where most of us are not mechanics by trade, I would favor a click wrench under most circumstances, and if there is any doubt as to the accuracy of the tool, send it out to be calibrated.

 

[ntsqd]

The rod bolts were over-torqued. I watched the owner of the car torque those bolts. He stopped at the click/detent. They were new ARP bolts. It was the fault of the wrench. A well cared for, but none the less old wrench. That is my gripe with clickers. A beam doesn't "go out of tune" with age.

A simple reading of the instructions should illuminate how to use a beam wrench to it's best consistancy and precision. I contend that with a little care from the user that a beam's consistancy and precision is only limited by the resolution of the scale. Which admittedly usually isn't as fine as a clicker, at least not in the larger capacity units. However there is far less to go wrong with a beam either immediately or over time.

I would venture most do not know where they can get their torque wrenches calibrated. I know that Snap-On will do their own product as an engine builder friend has two torque wrenches in constant rotation. Beyond that I know of no local shop that offers the service.