Ever had your torque wrench tested?

I tested my 3 craftsman wrenches at home, and adjusted them to within 5%. Good enough for me.

 

[QUOTE I was lucky, and had a auto service center test mine for free, they purchased the machine, as they must test each of their torque wrenches once per month, and log it in a book.[/QUOTE]

Wow once a month is very strict, all our torque wrenches, vernier guages, micrometers, etc have to be tested and calibrated only once a year.

 

I've seen wrenches checked once a week at a subassembly manufacturing plant.

 

GM uses Subout Wright torque wrenches that never need calibrating!

 

where can I buy one of these?

 

What the heck is "Subout Wright" I couldn't find a single Google reference to this phrase, and how do they make a measurement device that never needs calibrating? I suppose I could say that my torque wrench in my garage never needs calibrating, either, but that's only because in my garage I'm not ISO certified...

 

Slightly off topic. I was in the Snap-On truck last week, and asked the dealer how they checked the accuracy of tire pressure gauges. How do they know which is correct, the $3.00 gauge or the $50.00 gauge? He told me that he was not aware of any way to calibrate a tire gauge. I find that hard to believe. I think I paid about $25 for my tire gauge, I'd like to know if it's accurate!

 

Close, but no cookie.

That's about right

 

I check mine by clamping the square drive in a vice horizontally and hanging a (known weight) bucket from the end of the bar and filling it with measured quantities of water. Its ok up to about 50 ft-lbs. After that you can get very wet if the wrench slips in the vice!

 

I have been told that while the old style Needle Torque wrench are slightly less precise they are less likely to lose calibration than the modern "click type" - any truth in that?

 

But Paul, how do you calibrate the scale used to give you the known weight of the bucket? And what about the level of minerals in the water that affect its weight vs. volume?

Birdman

 

I cant recall absolutely, but I was positive I seen a pressure calibration tester in a snap on catalog. All it was was a block of metal, guage, a pressure regulator, and a schrader valve. But then, how do you know if the other guage your checking it with is right on? More test equipment? Test equipment for the test equipment? That would be a test equipment tester? Who tests that?

I to have questioned these thoughts. I figure a beam torque wrench cant change to much if its not used a lot. It is a spring, and springs do lose thier temper after long periods of use and with continuous load on them, but a beam wrench sitting in your tool box isnt stressed very much. I test my click type against the beam just to be sure I'm rocket science close, and just do em up.

There was a guy on F chat years back, and if your here I applogise, he spole about electric bolts used in the space program. Some kind of bolts that had wires coming out, and by hooking up a resistance meter, you could "read> the torque as you tightened this bolt. It pi$$ed me off, and it still does. I am not stupid, I understand it works, maybe very accurately. Nut we will never get into space trying to re-invent the wheel. The problem with the space people is they are all hung up on rocket science instead of just calling it a machine. What I mean to say is, checking stuff is good, but enjoy the ride. Enzo would have liked it that way.

 

A company I once owned had an Air Lab.; I had them calibrate my tyre pressure gauges quarterly(every 3 months).

 

Do a quick search of fchat & old fchat for 'torque wrench' and 'calibration'.

There's a LOOONNGGGG thread including several calibrate it yourself alternatives. I like the way I described there.

 

Birdman

I use distilled water at standard temperature and pressure and then Subout Wright scales to weigh it out!

I've just tightened a crank pulley bolt onto a UK Vauxhall (GM) 2 litre race engine. 184 ft-lbs then another 45 deg. That's tight. I can't believe a percent or two either way will make too much difference as to whether it comes off or not.

Paul

 

I have an old needle type wrench that I have checked the calibration out myself using simple mechancical means. It is nice and close and is never used other than as a calibration implement. I take my click type wrench and hook it to the needle wrench and see at what reading of the needle the corresponding click occurs. Works well and is fully repeatable.

 

Google "phonetics" instead.
(Did you really Google that before stopping to consider that it was a joke?)

 

Yes, I really did.
I wanted to see what whizbang new technology GM was supposed to be using. I'm still not sure I get the humor of it all. Call me a dense engineering type.... :|