Torque wrench ??

[vossman]

I have a few Crafstman torque wrenches that are a few years old. Sears said the torque value accuracy is only good for a year and then it must be reset. How much will the values actually be off after a year or more. Is it that big of an issue?

[maldos]

You actually have to measure the torque wrench at several settings and make a chart to actually know. The values will differ through the scale. Once you know these it's simple math to dial in the proper torque. Reset the wrench, that I've not seen, however, some sellers like www.Griotsgarage.com offer lifetime testing service which makes it easy, but their wrenches are expensive. I'm not sure about digital but I'm sure someone else will chime in.

[Byron]

The only way to know is to put it on a tester. If if makes you feel any better I still use mine and it is at least 20 years old and never been recalibrated.

[Blrfl]

You might try these guys if you want to get them calibrated: http://www.teamtorque.com

--Mark

[nm6r]

I have no idea how accurate torque wrenches are when they are brand new.

I could see the calibration only being good for a year if the torque wrench is used daily. Even less if it's not treated with the utmost of care.

I don't see our torque wrenches going out of calibration from sitting in the tool box if they are left on the lowest setting.

Once again, how accurate are they ever? I'm guessing within a few percent is close enough. Quite often, consistency or repeatability is most important.

Ray
http://www.frontiernet.net/~st1300rider/smile04Bikerwheelie.gif

[Highrider]

The ratchet design torque wrenches should be stored for long periods with the setting dialed down to close to minimum, even if they are used frequently,like a few times per week. Checking is easy if you have a small 50 lb pull scale laying around - similar to the kind used to weigh larger fish. This is the proceedure I use on a 0 - 120 ft/lb wrench.
1. Clamp a large bolt (1/2" - 3/4" Hex head) vertical in a vise with the head on top.
2. Set the torque wrench to a low setting ( say 20 ft/lbs.) and install on the bolt using the appropriate socket.
3. Attach the pull scale to a repeatable point on the handle and measure the distance from the center of the socket to the attachment point.
4. Pull on the wrench and record the weight at which the torque wrench is triggered.
5. Divide the pull distance by 12" and multiply that by the weight recorded on the scale.
Example: Scale attached 16" from socket center and torque wrench set to 20 ft/lbs.
The wrench triggers at 15 pounds of pull.
16" / 12" = 1.333
1.333 x 15 pounds = 20 ft lbs

6. If the torque wrench is right the 2 numbers should match.
7. Repeat steps 1 thru 6 at 40 and 60 ft/lb settings and record the results.

This should give you a good indication of how well the wrench is calibrated. It also works well for digital and flex bar torque wrench designs.

[BigTom]

Of course, Highrider has the right way. I used to have to set torque values on air wrenches, I needed my clicker type to be accurate. I would:

1. Clamp the clicker (or digital) in a vise
2. Put an adapter between the clicker (set to a known value) and a beam type torque wrench.
3. Pull the beam wrench to the specified torque, and over if needed. If it was within 10% it was close enough for my purposes. Quick and easy check.

I would give each wrench multiple checks, took just minutes.