torque wrench recalibration

[lawsoncl]

Oh, yeah, Montanaman... if you'd read my first post you would have read into the fact that I work in a cal shop... an NIST traceable lab to be exact. I calibrate everything from physical/ dimentional to microwave equipment.

Yeah, meybe your method would be good for a wrench to use in an emergency, but for a rebuild or anything that is done other that to get back home, properly cal'd equipment is all that should be used.

Due to your job, I think you may be a bit more anal about calibrated equipment than most shop mechanics or the average shade-tree mechanic would be. Most people don't need a high precision/accuracy torque wrenches and are fine with medium quality (not the low end HF junk). On the other hand, it makes lots of sense to periodically check your tools to make sure they are in the ballpark. Personally, I'm not overly worried about the absolute accuracy of my own torque wrenches. I'm be happy if they are within 10% for most applications. Most torque specs have a 10% tolerance anyway and as pointed out earlier, a given fastener torque doesn't ensure a specific bolt tension due to variations in the bolt conditions. I think what's more important in many cases, such as tightening lugs or head bolts, is consistency. Odd fact, but in the absence of a proper torque wrench, most people over-tighten bolts.

 

[Rick Anderson]

I have a 3/8" and 1/2" wrench that is exactly 12" from center to center, open end/box end. I put the open end on the wrench, 3/8" for my in-lb torque wrench and 1/2" for my ft-lb torque wrench, then connect a fish scale to the box end. The critical part here is to make sure the fish scale is pulled perpendicular to the wrench it is connected to.

My 2 cents, a pro calibration may be a little better, but calibrating it yourself with the methods described is adequate for working on cars. Most agree, and you have to admit, its better than NOT calibrating at all.

 

[montanaman]

I have a 3/8" and 1/2" wrench that is exactly 12" from center to center, open end/box end. I put the open end on the wrench, 3/8" for my in-lb torque wrench and 1/2" for my ft-lb torque wrench, then connect a fish scale to the box end. The critical part here is to make sure the fish scale is pulled perpendicular to the wrench it is connected to.

My 2 cents, a pro calibration may be a little better, but calibrating it yourself with the methods described is adequate for working on cars. Most agree, and you have to admit, its better than NOT calibrating at all.

Yeah ... I think your way would work pretty well ... just have to make sure that the only wrench movement is the pivot action ... no sliding around or anthing. How do you hold the end of the wrench still?

 

[Rick Anderson]

In-Lb wrench, yes I held it still in my hand, the force is light enough also. The Ft-Lb, I used a Vice. Both of mine, the pivot point is past the handle. So far no adjustment necessary, clicks at the right force.

 

[tallbluexj]

In ever in Elkhart, IN stop by and we can calibrate on our analyzer. We calibrate our tools off it, which is sent out for calibration, and tracable to NIST. No charge,...well maybe lunch.

 

[gjxj]

Sear does not guarantee the accuracy of their torque wrenchs. ...... Home Deport did a straight swap for their much nicer 0-250ftlb torque wrench.

I think you learned that he chance of finding a clerk who doens't know the fine print is better in home depot!

 

[lawsoncl]

I think you learned that he chance of finding a clerk who doens't know the fine print is better in home depot!

Ironically, he was the tools department manager. At one time, Home Depot claimed to take broken Sears, Matco, Snap-On, etc in trade for new Husky. They've since dropped that. They also dropped their lifetime warranty, but apparently they bought it back recently. Too bad they seem to be downsizing their selection of handtools though.

 

[nick86]

has anyonone work on big motors as i do, torque to a spec than 90 degrees, what a pain in the ars. why can/t just give a final spec

 

[artsifrtsi]

TallBlue, what equipment do you use in your shop? We use King Neutronics load cells with an HBM MGC Plus amp.
Do you just do physical/dimensional, or do you also cal u-wave and DC & Low? We do all of that in the shop, my favorite place to work though is the u-wave equipment. Torque wrenches just are too boring... they take like 5 minutes to verify and adjust... all including the equipment setup.

 

[CODevilDog]

I'll put in my two cents. The Hangging weight meathod the Montanaman suggested should be more than enough to calibrate a wrench. The only thing I would add is if possable check it at (at least) 2 points perferably 1/3 and 2/3 of the wrenches range. This will give you some confidence that it is linier.