Here's a couple more choice pieces from that torque wrench discussion:
"Never use your torque wrench to loosen a bolt, that's not what it was designed for. Even if the wrench is designed to be used in the CCW direction, it will cause excess wear on the internals."
"....Extreme cold and hot temperatures will throw off their accuracy."
"Craftsman wrenches, especially the type with the setting window were absolute junk. Not only did most of them not meet their specs out of the box, but they would not adjust within specs on the high and low end of the scale. They were typically non-linear (low on the low setting, and high on the high setting) which resulted in having to send them back to Sears for replacement. And lots of torque wrenches are not accurate out of the box. They actually need re-calibrating before you even use it for the first time!"
"....If you hold the wrench by a part other than the center of the handle (like the metal body, or if you are for some reason using a pipe to extend the handle) it can throw off the accuracy greatly. Any kind of extension will reduce the applied torque value due to flex, and also extreme cold and hot temperatures will throw off their accuracy."
Here's LS1's complete post:
"I've been a Calibration Technician for almost 8 year now. During that time I've verified the accuracy of and repaired/adjusted hundreds of torque wrenches in both the military and civilian sectors. Here are my comments based on what I've experienced:
Snap-On makes a very durable torque wrench that can be accurate and remain so after it is adjusted correctly. They tend to be reliable over time, but I would not trust the accuracy of the wrench when it is first purchased. Most of the wrenches that we cal'd for the Air Force were spec'd at +/-4% CW and +/-6% CCW, and I would say that only about 50% of them met this spec out of the box. After we adjusted them initially to our CDI standard, they held the adjustment great and performed accurately. Almost all of these were the click-type.
Craftsman wrenches, especially the type with the setting window were absolute junk. Not only did most of them not meet their specs out of the box, but they would not adjust within specs on the high and low end of the scale. They were typically non-linear (low on the low setting, and high on the high setting) which resulted in having to send them back to Sears for replacement.
I don't remember having too many problems with Proto wrenches... nothing that stands out in my mind anyways.
I have only dealt with two Husky wrenches, both were 250# click-types. I bought one and my brother-in-law bought one from Home Depot at the same time. I checked the accuracy of both of them before use, and they were both within
2% CW, I didn't check either of them CCW since we weren't going to use them in that direction. I pulled my wrench out of the shed where it had been sitting for 2 years without being used, and took it in to work to make sure it was still accurate and found that the handle retaining nuts had come loose so the handle was spinning freely instead of adjusting the torque setting. The fix was as simple as jamming a flat-headed screwdriver inside the back of the handle to hold the nut in place, then back the Allen head adjustment screw out against it. This tightened it back up so I could set the torque, so I checked the accuracy and it is still within
+/-2%!. I think we paid $40 each for these wrenches, and they're one of the best values I have found yet.
The beam style wrenches are usually very accurate throughout their useable lives, but are not always the easiest to use. No wrench can be expected to be more accurate than its manufacturer's specifications though, even though some of them are.
For storage purposes with all torque wrenches, you should return the wrench to its lowest setting before putting it away. There is a spring inside that can get damaged if you don't.
Never use your torque wrench to loosen a bolt, that's not what it was designed for. Even if the wrench is designed to be used in the CCW direction, it will cause excess wear on the internals. Why not use a cheap breaker bar that has no accuracy requirements instead?
I personally will never again use a Husky TQ wrech due to the awful accuracy of the units I have personally handled. Out of curiosity, how did you verify the accuracy of your Husky torque wrenches? Based on their constuction and the readings that I've taken with mine and my brother-in-law's torque wrench, they should be pretty reliable and accurate.
There are several factors related to the way it is used that can influence the accuracy of a torque wrench. If you aren't holding the handle level while trying to tighten the fastener, I've seen it throw off readings by 10-15%. Also if you hold the wrench by a part other than the center of the handle (like the metal body, or if you are for some reason using a pipe to extend the handle) it can throw off the accuracy greatly. Any kind of extension will reduce the applied torque value due to flex, and also extreme cold and hot temperatures will throw off their accuracy.
Torque wrenches should definitely have their accuracy verified on a regular interval though. Most of our customers use a 12 month interval, people who use them very often might use a 6 month interval, and most of the Air Force departments sent theirs in every 3 months! Verifying accuracy is important for all measuring tools though, torque wrenches, DMMs, oscilloscopes, etc.
Let me know if you have any other questions! I covered everything that came to the top of my mind. :cheers: