The need to check to torque wrenches at home

I've been thinking about this. How important is it for a home builder to have their torque wrenches checked for accuracy?

Reason I ask is that I picked up this gauge that Sears sold. It is a digital torgue wrench & it will also check the readings of existing torque wrenches.

Is this overkill or do these wrenches go far enough out of spec. that it will make a real difference in over/under torquing bolts?

Thanks.

 

Can't give you a difinitive answer, but I think for the most part the actual torque value isn't that imprtant, as long as it's within 10% of the specified value. I think it's more imprtant that you use the same torque wrench to tighten all the bolts, so that the torque is even across all bolts in an ***embly. That way, you prevent stress risers caused by bolts being tighter than others and cracking or causing some other such stress failure on the torqued item.
Just my pair'o'pennies...

 

A mechanic friend of mine also told me this.

 

Good question! I recall the dry thread imperative, so that the tightness is close to accurate, when the bolt is torqued. (yet I've used anti-seize on all wheel bolts for years now)The Sears wrench I use has a reset back to zero ft-lbs instruction when finished, so that the spring based mechanism doesn't take-a-set.

 

You need to check the tolerance accuracy of those types of wrenched.I owned a snap on digital torque wrench and hated it for this fact.Traded it back in on a click type which I've never had any issues with.

 

We regularily calibrate the torque wrenches at work - all part of GMP. BTW tightening abolt is a means to an end - the "end" is to get it to stretch. Think of it as a rubber band. A certain amount of stretch is good - not enough it is prone to loosen - too much it may yield and be prone to failure. Torquing it is actually a crummy method - much better to use a stretch guage other than the fact that THAT is impractical most of the time. That is one reason why "angle" torquing has become popular - in an effort to attain increased accuracy in tightening fasteners.

So given the fact that we know that torquing bolts is a crummy way why would we then think it's good so long as they are all the same??? Sorry not buying that one.

It's one of those areas - where those who get away with it will swear it's ok - while those who have experienced failure may seek increased accuracy.

Pick your poison.

 

i know in aviation you need to have your Tq wrenches checked for calibration every year. and according to the FAA all torques are are dry thread unless otherwise specified. I agree with the above about stretch, its something that msot people will never do though.

 

I can add to that as I was the guy who checked torque wrenches for United Air Lines overhaul base for about 5 years. Also there was a torque tester available at all times for mechanics use. I also checked that. been retired 10 years. Never check my wrenchs now.

 

Something that stuck with me, said in an interview with some NASCAR builder in Circle Track:
Bending beam wrenches sty correct til beam breaks...just make sure pointer stays bent to zero when static. All others require testing...he used the fancy ones for semi-critical stuff like head studs, where minor errors were not fatal, and did the killer stuff like bearing related bolts ONLY with old beam wrenches.

Another builder simply kept a nut welded to a pillar in his shop, and buckets filled with amounts of s**** equivalent to his commonly used torque sttings;
put wrench on nut, hang bucket o wrech checked. Sounded sensible.

 

Not a way to calibrate but an easy check is to compare torque wrenches with others. If they are within 10% then you're good to go.
This can be done by making a fixture to attach them to one another.
Two old sockets welded together usually works well.

 

I haven't tried the Sears digital torque gauge but I'm anxious to. Nice thing about it is that it is made in USA. Hard to find any electronic tool (beside Fluke meters) made in the USA still.

 

dont forget to correct for adding or subtracting length, like with a dogbone. most people will not do this either... here are links for the equations.
http://www.engineersedge.com/manufacturing_spec/torque_wrench_1.htm
http://www.engineersedge.com/manufacturing_spec/torque_wrench_2.htm