Torque wrench school is in session:

After some chasing around I got one of those cheap $20 (on sale for $10) 1/4" drive Harbor Freight torque wrenches. I so seldomly use one I cannot justify a $100+ wrench. The handle shifts to the side when the set torque is met. Not exactly a click sound or feel like it should. Be that as it may, I measured the accuracy of the wrench. Here is what I did. Feel free to correct me if I did something wrong.

Measured exactly 10" down the handle from the center point of the socket drive. Marked the spot. Filled a jug of water on a digital kitchen scale to exactly 8 pounds. Set the wrench for 80 in-lbs. Placed the socket drive in a vise and tightened such that the wrench was horizontal. Hung the jug with string on the handle at the point at which it first shifted to the side. Came up with 8.8" from the center of the socket drive. This tells me my wrench is off to the light side by 12%. Am I understanding this correctly?

FYI: I have a 400 gram weight that is used for calibrating a smaller digital scale I use for measuring e-liquid. My kitchen scale has an 11 pound capacity. I put the 400 gram weight on my kitchen scale and it registered 401 grams (and 14.1 ounces) so this tells me my kitchen scale is accurate (on the low end anyway).

 

It's only accurate at the end of the torque wrench handle.

So I'd take the length in inches, multiply that by 8, and set the torque wrench to that.

Also, maximum accuracy is in the middle of the wrench scale. So if it's a 0-120 lb/inch wrench, then you should test at 60 lb/inch .

RwP

 

I was fairly close. I was within an inch of the end of the handle (less the locking ****). And the upper limit of the wrench is 150 in-lbs. So 80 is close to the middle. Wonder if I should add a little to my setting to compensate for the wrench being off 12%??

 

Got to thinking. I have to add at least part of the weight of the handle to my calculation. That's significant enough to reduce the 12% error to be more in line with the +/- 4% spec of the wrench. I don't think I have to compensate at all.

 

After all these years, I go by the "Gudentite" way of torquing down small bolts. I do use torque wrenches for heavier bolts, especially at higher ratings.

 

That's a common misconception. Gutentights are for German cars, these American vehicles use Ugga Duggas.

Seriously though, I only use torque wrench on super delicate things, like transmission internals, or things holding bearings in that you don't want too tight (axle nuts, lug nuts, etc). Most everything else can go tight enough by feel.

 

And I needed the torque wrench to adjust my transmission bands. Tighten to 72 in-lbs and unscrew specific number of turns. I was prepared to guess the torque but then Ralph gave me a Harbor Freight coupon for a $10 torque wrench. I had no excuses to guess after that.

 

JMO, But if I was to buy a cheap torque wrench, I would go with the beam style...
FWIW I have one of those cheap clicker style from harbor freight. The adjustment is very rough. sometimes have to back off and then try to go foward again,
BTW always back down to zero when finished.

 

There's a heavy German presence around here. My first job that paid me to work on vehicles, rather than fixing my own junk, was on Amish buggies. A small local community had an arrangement to swap out deep cycle batteries for the lights and 8 track players on the buggies that the young Amish drove during their Rumspringa (SP?)

I remember when I had to get a torque angle gauge for torque to yield head bolts. That seriously messed with my head.

 

My $10 Harbor Freight torque wrench turned into an adventure but it ended well...fortunately.