Torque Wrench re-calibration?

[KE4AVB]

I have a torque wrench that has gotten out of calibration. Any ideas on how to re-calbrate it? I have found how it got out calibration and how make the adjustment.

Would I just use a known good torque wrench and tighten a bolt at near maximum range of the one that out and sneak up on that bolt's torque while fine tuning the one that is out until clicks at the test torque setting? Just curious if I can save the wrench; its is my fault it is out adjustment as I took it a part to see what made it work and if it could converted to left hand mode. I could sent it out for calibration but that will cost a lot more than I can replace it for.

No big deal if I can't as I already have my reversible torque wrenches (RH and LH torquing capable except the 3/4" 300 ft-lbs is RH only) coming in Tuesday.

[bgsengine]

what I would do for a DIY Calibration:

first, a contrasting color of pencil to the handle of your wrench, then measure out on the wrench to 12 inches (or 24 if you have the length of handle for it) from the center of the square drive and mark off a point on the handle for 12 (or 24) inches out, set your torque wrench to 240 inch Lbs or 20 Ft Lbs (or if using 24 inch wrench handle marker, half that) . find a 20 pound weight (or other known exact weight - adjust torque wrench setting to match) and tie off a strong string to it and tie that to your wrench handle "ahead" (closer in to the drive end) and then roll it back bit by bit until wrench clicks - if the string is in the place you marked, you're calibrated, otherwise you just do the math and see if your wrench clicks where it should

*edit* Oh yeah I see I didnt mention the fairly obvious - when setting things up, the above also assumes you have your square drive end chucked into a vise and the handle sticking out exactly 90 degrees (level to the floor)..)

[NO0C]

http://www.wikihow.com/Calibrate-a-Torque-Wrench

[KE4AVB]

Thanks guys for kick starting my brain. I see what I can do here about weighting potential counterweights here. I had to quit using the 3/8 drive wrench as it so far off it wasn't usable anymore.

I will need to adjust the weight between the different torque wrenches though as 20 lbs is way too much for the 1/4 drive (16.6 ft-lbs max) and way too little for the 3/4 drive (50 ft-lb minimum). I will need to do the math too because of handle lengths to check their calibration too as I would like to get scale marks to line up better. Two of the torque wrenches scales never had lined up properly from day one.

[KE4AVB]

You won't believe this. I must have done something right yesterday by accident as the 3/8 is on the mark. Even double check against my 1/2 and the 1/2 is off only by a width of an inscribed mark. Before the 3/8 was so far off that I couldn't even tighten a blade bolt earlier this year without it clicking just as the bolt made solid contact.