torque wrench review

[Cam3512]

Okay, another dumb question.  How does using an extension on a torque wrench effect torque values?

Or does it?

[rboe]

It's difficult to hold the extension straight up from the fastener so it will add a moment arm to the torque wrench will render errors in the final figure.

Also, at high torque values the extension can twist, affecting the torque value. And both can happen.

[lucky phil]

Okay, another dumb question.  How does using an extension on a torque wrench effect torque values?

Or does it?

An extension, (from the socket attach point on the wrench to the fastener point) does change the wrench setting. Its dependent on the distance from the wrench socket attach point and the fastener point of the extension and also the angle at which the extension is in relation to the center line of the wrench. Its a basic formula which you will be able to find on line. Never bothered to commit to memory.
If you mean a straight ratchet extension, no impact on wrench setting.
Try http://www.engineersedge.com/manufacturing_spec/calculator/torque_adapter_extension.htm
Ciao     

[Chuck in Indiana]

Sorry if I missed something Chuck, but why didn't Matco give you a new one?  Warranty should mean something....

Mark

Matco Man (Steve) *gave* me that wrench 30 or so years ago. It was in my original post. I'd have felt a little funny asking him to warrant it.. 

[Markcarovilli]

well then that makes sense....

Glad you got good service out of it then and it more than lived its life I'm sure.

Mark

[Ronkom]

Chuck,
Thanks for the reply, unfortunately I passed my old bean wrench on to my Son when I got my fancy click wrench.
FYI, When I retired from the R&D lab & no longer had access to precision balances for checking piston/rod weights etc.   I bought a Harbor Freight "compact scale". I had a friend back at the lab make me up a plastic bottle w/lead shot to an exact weight, to calibrate my new scale. Bummer report, the thing would not consistently repeat readings to near the accuracy I wanted. I hope HF is using better Chinese electronics in their electronic torque wrench.
ronkom   

[Kiwi_Roy]

It's difficult to hold the extension straight up from the fastener so it will add a moment arm to the torque wrench will render errors in the final figure.

Also, at high torque values the extension can twist, affecting the torque value. And both can happen.

From the original post

Chuck said " plus having a swivel head"

I wondered how that effects the torque setting?

[Chuck in Indiana]

From the original post

Chuck said " plus having a swivel head"

I wondered how that effects the torque setting?

Ok, let's do the math. Say the effective length of the torque wrench is 14", and the head is swiveled 10 degrees. Let's pick a number, say 20 ft. lbs. Doing the trig, the effective perpendicular length is now 14" -.2127" .  .2127/14 = .015, so you'd have to add .015% to the 20 ft lb reading, which would be 20.3
At least that seems right to me. For all practical purposes, I never used to worry about it. The important thing with torque is to make all the fasteners the same. You would be surprised at how well an experienced mechanic can do that.

[twhitaker]

There is a fellow I know who took his torque wrench to work and chucked the half inch drive in a vice then started cranking. His foreman asked what he was doing and he answered, "Calibrating my torque wrench." which was his arm.