Torque Wrench Problems from avery

[osaleh]

i bought a CDI torque wrench from avery Tools

http://www.averytools.com/prodinfo.asp?number=4920

I put it to use on the bolts for the HS411 brackets which call for 20-25 in/lb. I am expecting a click once the torque is reached but i do not get that and after tightining too much one of the bolts actually breaks. Another bolt and a nut are now stuck becuase i tightened too much. Anywyas, i can take care of these issues but my questions is, did i miss something on how the torque wrench is upposed to work???? Or is it just defective?

 

[John Clark]

Torque

I would guess that the wrench did "click" but at a setting as low as that, the click can be rather subtle. In some wrenches it is more a feel issue than an audible one. 20 to 24 inch pounds is two pounds pressure on a 12" wrench, not much force. I would suggest a little practice on any old bolt held in a vise to get a feel for the tool.

John Clark ATP, CFI
FAA FAAST Team Member
EAA Flight Advisor
RV8 N18U "Sunshine"
KSBA

 

[UnPossible]

I have the same torque wrench and thought that it wasn't working at first.
It does not "click" like some other torque wrenches I have used.

When the set torque is reached, the head pivots... you do it more by feel than by sound. Once you get the hang of it, it becomes easy

 

[crabandy]

I have a similar torque wrench, it doesn't "click" when the selected torque is reached but the handle will breakover and pivot slightly just aft of the ratcheting head. Go slow when the nut gets tight and you'll feel it breakover....

 

[hendrik]

There is one more "subtlety" in addition to the pivoting head. The scale markings have steps so that you can see the whole number of the value you set the wrench to. This one for example is set to 20 in*lb, not to 15:

Probably not your issue, since you sound as if you used way too much torque. But something to keep in mind.

 

[Bob Kuykendall]

...I am expecting a click once the torque is reached but i do not get that and after tightining too much one of the bolts actually breaks...

Ditto what the others have said; a torque value of 25 in-lbs or so is too low to give a satisfying click. I use a tiny beam-type torque wrench for AN3 nuts and bolts when I need to.

Here's the thing that I suggest: break down the torque value and work from there. To get 25 in-lbs, you can apply 25 pounds of force 1" away from the axis of the bolt. Or, you can apply 1 lb of force 25" away from the axis. Or you can apply 2 lbs of force at a distance of 12.5".

See how that works? You take the target torque value, divide it by the length of the wrench you're using (assuming you're applying the force at the end of the wrench), and that's how much force you should expect to exert.

For example, to get 25 in-lbs with a 6" wrench, you evaluate 25/6, get 4.17, and know that you'll be applying a tad over 4 lbs at the end of the wrench.

From there, the only missing link is knowing what it feels like to apply 2 lbs or 15 lbs or whatever at the end of your wrench. And it just takes a bit of practice to get that kind of "mechanic's feel."

Regardless of whether or not you're using a torque wrench, you should always have this kind of understanding of how big the torque you're applying is. It will make sure that you're at least in the ballpark, and will serve as sort of an error-check for those times when there's an error in the instructions.

Thanks, Bob K.
http://www.hpaircraft.com/hp-24
HP-24 project on Facebook

 

[jmoylan]

Torque 101

Thanks for the Torque Wrench lessons, answered alot of my questions too!

 

[pgroell]

Ditto what others have said.
The only thing I might add is that if you torque down the nuts with a regular wrench before using the torque wrench you could well have torqued the nut already too much, so the torque wrench will never click (not exactly, it will click as soon as you apply torque and you may not notice it).
To avoid this, I use a short handle ratcheting wrench to install the nuts so as not to overtorque them.

 

[Charles in SC]

I bought a wrench like that from another supplier and sent three back before I figured out there is not a click like I was expecting but the head kinda clicks over. It works fine now. Do not forget to add the friction due to the elastic insert in the nut.