Torque wrench (re)calibration
 

In preparation for the spring/fall maintenance season I decided to treat myself to a 3/8" Sears "digitorque" wrench ($100), to use in place of the $15 torque wrenches that sometimes do not click when they are supposed to. Sears says they will recalibrate their torque wrenches for free (actually just give you a new one, salesman said) within the warranty period. But how would you know if your wrench needs calibrating unless you have an accurate one to compare it to?
Snap-on torque wrenches are going for amazingly high prices on eBay - but how would you know that they would not need recalibrating?

Don't know the answer to your question, but fyi, the Craftsman lifetime hand tool warranty applies to their beam-type torque wrenches. I just brought my 25+ year old one in two weeks ago - walked out with the identical one (same model number!) - absolutely no questions asked.

Does Sears even calibrate torque wrenches. I walked in and ask them this, and the tools sales person said they don't offer any recalibration service.

---anthony

I've had two of their 1/2" click style wrenches go bad on me and they gave me a hard time on both occasions when returning??

I am lucky, I work in aerospace and a friend of mine runs the cal lab. If you are near Austin Tx let me know and I will take your wrench in for a checkup. My click styles had been stored corectly with the tension off for 15 years and they were dead on. (one proto one snap on) From what I have seen it really pays to buy a snap on. I sure felt better after checking mine.....

My experience has shown that beam types keep their cal forever. You can use them as a standard to check and adjust if necessary your clicker.

MACHINEMON... what brand do you guys use?

We use snap on's. The only time I have seen them fail is when they are abused. As in thrown across the shop. We had a guy flip his lid one day....

Also work around airplanes and we have to calibrate them every 6 months. On my home tools its done every year or two.

Also use Snap On torque wrenches. They work, they work forever and the way they should. The cost per day or use is nothing compared to one of the other brands that fails or does not pass calibration.

JoeA

How could you put a 10.000 motor together wondering if the values were correct?

Calibration at home:

Put the business end of the torque wrench in a vise so it does not move.
Keep the wrench at horizontal level
Hang a known weight, in my case 15 lbs from a string on the handle
Measure the distance from where the string is to the "business" end of the wrench.
Multiply that distace in foot to the weight in lbs, that is your setting,
Set the wrench at that setting, it should click if it is accurate
If not, remove the handle, twist the adjusting screw and recheck.

I agree 100% with JoeA....

IMHO...purchase the best wrench you can afford. Albeit, snap-on's are in the range of $200.00 and up depending on the type.

Yelcab1, that is the method i am thinking of. Except I plan on putting a bolt in the vise, put the wrench on the bolt, set the wrench on 25 ft-lbs. Then hang a 25 lbs off the wrench to see if it clicks.

I think does matter and it is very important where you put the string on the wrench. I will put it in the exact middle of the handle grip since I assume the design calls for an even force spread over the handle grip.

---anthony

I put the body of the clicker type wrench in the vice to hold the wrench still. Then I put a socket on my precision beam type wrench. I forget the size but its a 12 pt that will (sort of) fit over the square drive of the clicker. Then I pull on the beam type and see if the clicker "clicks" when it should.

Snap-On/Bahco came out with a (relatively) low priced digital torque wrench a couple of years ago. It's as handy as a clicker but without the clicker drawbacks. It's got some nice features like switching between different units and recording the actual torque applied. One of the nicest features is it's wide range. The one I have has a range of 5-100 ftlbs and an accuracy of 2%. (TECH2FR100 $300 new/$200 Ebay)

-Chris

I have 3 Craftsman clickers and have used this method to calibrate them to be dead nuts on. For tires, who cares? But before an engine rebuild, I would recalibrate my wrenches, for nothing, and at home.

I know this is old, but I wanted to add- Make sure the weight is accurate. I just took a 5lb weight to a known scale and it came out to 5lbs 5ozs, thus throwing off my accuracy by about 6%.

FYI, Snap-on's torque wrenches are made by either Precision Instruments or CDI. You can buy the same ones, just not as pretty, from those companies for around half the Snap-on price.

It doesn't matter where you put the string. Obviously it would be the most simple to measure exactly 12" from the center of your bolt and put the string there.
Try to use a weight which would result in a torque near the middle of your wrench's range.

I just got a 1/2 inch drive CDI torque wrench in the last year. I picked it up after learning they were the company that builds the Snap On Torque wrench. They are made the US, very heavy duty and come in a nice case. I will debate the not pretty part of the above quote :) I can post pics later if anyone is interested.

I got a CDI electronic wrench for Christmas....what a piece of junk. It came in a nice box missing the back cover for the head with screw threads stripped. Returned, never to return.

Dennis