gayler
Well-known member
Anyone here doing this at home like this guy?
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torque wrench calibration
- Thread starter gayler
- Start date
joe_padavano
Well-known member
I just calibrated one of my torque wrenches, which happens to have exactly the same adjustment feature as the one in the video. I agree that there is no guarantee that any scale like that is anywhere near accurate. I use known weights and gravity. Clamp the wrench in a vise 90 deg to the orientation shown, use a known weight at the correct distance, and do the math. For example, 20 lbs applied at 8 inches from the pivot point in the head is 8/12*20=13.3 ft lbs applied. Adjust until the wrench just clicks when you gently apply the load.
joe_padavano
Well-known member
Im not saying this guys $5 scale is accurate. If you had an accurate scale is this a useable method?
Yes, of course it is. All that matters during calibration is that you apply a known load at a known distance from the ratchet pivot. The rest is just math.
joe_padavano
Well-known member
I'll add that the problem with calibrating a torque wrench isn't applying a known load. It's knowing how to adjust the wrench when it turns out to be inaccurate. If you have a wrench with an adjustment feature like the one in the video, that's easy. Other wrenches that I have require some disassembly to get to the adjustment feature. How they come apart isn't always clear.
I'll add that the problem with calibrating a torque wrench isn't applying a known load. It's knowing how to adjust the wrench when it turns out to be inaccurate. If you have a wrench with an adjustment feature like the one in the video, that's easy. Other wrenches that I have require some disassembly to get to the adjustment feature. How they come apart isn't always clear.
Thanks. I just stumbled on his video and it looked like it should work.
guy48065
Well-known member
It would be better if the scale were of known accuracy AND if it could capture the peak weight. Sometimes digital scales are fairly slow responding and the reading you *thought* you saw was actually lagging behind and is too low.
The digital torque adapter at HF ($30) is a way better comparison.
The digital torque adapter at HF ($30) is a way better comparison.
joe_padavano
Well-known member
It would be better if the scale were of known accuracy AND if it could capture the peak weight. Sometimes digital scales are fairly slow responding and the reading you *thought* you saw was actually lagging behind and is too low.
The digital torque adapter at HF ($30) is a way better comparison.
And as I pointed out, a known weight at a known distance is even better. Gravity doesn't vary that much...
Just out of curiosity, how do you know that the Chinesium HF item is calibrated? Just because it's "digital"?
guy48065
Well-known member
See my profile.
Ok, how do you do it?
Guessing either an manual or automatic torque loader with a digital torque analyzer.
guy48065
Well-known member
Guessing either an manual or automatic torque loader with a digital torque analyzer.
Pretty much. A fast peak-capture meter is necessary. A cheap fish scale or luggage scale is intended to display static weight in real time and can't keep up with the fast break-over of a clicker wrench.
Also I get far more consistent results using a gear-reduction mechanical loader vs hand operated. Even with a simple lever loading mechanism it's possible to overshoot the "click" and get a 2nd hit that's higher than the initial break-over.
Nothing wrong with using a tape measure & a scale, or a bucket of rocks as an intermediate check ("sanity check") between calibrations.