Re: Lying Torque Wrenchs
Posted by Fish'n Jim On 2023/11/5 22:17:39
I suspect since the "throw away" wrench read higher, the spring was 'stretched'. This happens from not backing off the tension setting after use to the lowest scale number and over time it stretches/relaxes. You don't want to go past the numbers and take all tension off.
Using calibrated instruments is an art. Without a calibration certificate, you're guessing that the unit is correct. Torque is only about 2-5% of full scale accurate because varies by measuring and use technique. Check your manufacturer's statement. DIY wrench turners tend to buy on price since we don't use them as much as a certified tech/engine builder. A real quality certified wrench is costly. You really need more than one to cover the normal SAE bolt schedule. Those torq "protectors" fit into spaces the wrench won't so have utility. I think with enough practice/years, most people can tell how much pressure to apply to most non-critical bolts but I won't go into the 'wet v dry' arguments. Don't use the impact wrench for tightening! They're too quick and too powerful for most auto fasteners and rechargeables get more powerful every year!
Torq measurement is necessary when a sealing/structural task is performed, that requires uniform clamping force. Bolts apply force by stretching, so that's why it has to be measured to get the right amount of stretch. Not needed for most tasks, low grades.
But since the device checks out with more than one other, it's probably 'accurate'. Need to test more than a few times to establish the 'precision'.
I have more trouble with the digitals not because of accuracy, but because it doesn't get enough use and when needed, the batteries are shot.(just the other day doing alloy wheel lug nuts) I usually take the batts out but they're button type and can still go bad in the case. Left in they corrode the connections. Same with my micrometer but it's LCD. The price of small batteries is thru the roof like most things now.
Below is what Snap-on says. Search the subject from bona-fide sources, not wiki this or that or Utube video for more info. Get a handy fastener size torq chart and post on your wall next to your thread tap/drill bit chart.
Attach file:
TorqueWrench08.pdf Size: 37.01 KB; Hits: 40
Using calibrated instruments is an art. Without a calibration certificate, you're guessing that the unit is correct. Torque is only about 2-5% of full scale accurate because varies by measuring and use technique. Check your manufacturer's statement. DIY wrench turners tend to buy on price since we don't use them as much as a certified tech/engine builder. A real quality certified wrench is costly. You really need more than one to cover the normal SAE bolt schedule. Those torq "protectors" fit into spaces the wrench won't so have utility. I think with enough practice/years, most people can tell how much pressure to apply to most non-critical bolts but I won't go into the 'wet v dry' arguments. Don't use the impact wrench for tightening! They're too quick and too powerful for most auto fasteners and rechargeables get more powerful every year!
Torq measurement is necessary when a sealing/structural task is performed, that requires uniform clamping force. Bolts apply force by stretching, so that's why it has to be measured to get the right amount of stretch. Not needed for most tasks, low grades.
But since the device checks out with more than one other, it's probably 'accurate'. Need to test more than a few times to establish the 'precision'.
I have more trouble with the digitals not because of accuracy, but because it doesn't get enough use and when needed, the batteries are shot.(just the other day doing alloy wheel lug nuts) I usually take the batts out but they're button type and can still go bad in the case. Left in they corrode the connections. Same with my micrometer but it's LCD. The price of small batteries is thru the roof like most things now.
Below is what Snap-on says. Search the subject from bona-fide sources, not wiki this or that or Utube video for more info. Get a handy fastener size torq chart and post on your wall next to your thread tap/drill bit chart.
Attach file:
TorqueWrench08.pdf Size: 37.01 KB; Hits: 40This Post was from: https://packardinfo.com/xoops/html/modules/newbb/viewtopic.php?post_id=263973