school me on torque wrenches

[SGT4677]

Best way to ruin the calibration on your torque wrench is to not back it off to "zero" after you're finished with it. By "zero" I mean whatever the lowest value on the wrench is, not cranked all the way down to wherever it stops.

Second best way to ruin the cal is to drop it.

Third best way to ruin the cal is to use it as a breaker bar.

At work, calibration is checked weekly. I think a 4% variance is allowed, and once they're outside of that range they're sent to Pylon Electronics to be re-calibrated.
I think the cal expires after 1 year (not 100%) but at any given time 10-25% of ours are out for cal.

They don't always come back re-calibrated either. Sometimes they're just too worn out and they get destroyed and tossed in the scrap bin. Snap-On, Westward, and many other brands, it doesn't really matter. They aren't made to last forever.

That said, some of these are used daily, so they see much more use and abuse than someone's personal tool.

We have a similar system, they are sent out for calibration yearly and we use a torque checking fixture before each use on the aircraft. My personal torque wrenches are under the same system. My Snap-on 1/2 drive 0-250 ft./lb. unit is over 30 years old, and rolled back to 0 after each use and kept in its case.

Just buy a quality name brand tool and take care of it and it will last a long time. Regular calibration is peace of mind for you.

[Northern]

We have a similar system, they are sent out for calibration yearly and we use a torque checking fixture before each use on the aircraft. My personal torque wrenches are under the same system. My Snap-on 1/2 drive 0-250 ft./lb. unit is over 30 years old, and rolled back to 0 after each use and kept in its case.

We used to check before each use. Sometime in the past few years they switched to having the stores guys check weekly. I think they were concerned that techs wouldn't check and just make up a value to save time or something weird. There's a lot of paranoia around here.

We don't have personal tools at work, but at home my personal torque wrenches are about 2 years old. I treat them well, but I've never had them calibrated since new(yet). My 1/2" (30-300ftlb) pretty much only gets used for hubs/axles/wheel nuts, so I'm not really concerned with how far it's off. My 3/8" one has been used maybe 10 times, so I'm still pretty confident in it. If I ever built an engine, I'd either have them cal'd or buy nicer ones.

[Bearmw]

I just redid much of the steering on myE28 with a beam type and it was a pain. If I had an assistant during the processs it would have been easier no doubt. A good click type is generally easier I think.

[SGT4677]

We had a torque wrench fail Cal a while back and traced its usage back to some critical torques. We ended up self reporting it and asking the customer to recheck the work in the field. Now we check them, our stores people can't perform maintenance actions.
I really prefer to use my own tools so I own most of what I need, but I run an Avionics shop so they don't get used much anymore. A butterfly net and a cattle prod are my best tools most days.

[Northern]

A butterfly net and a cattle prod are my best tools most days.

:rofl:

[AndrewBird]

You can check calibration at home by mounting the torque wrench in a vise and hanging weight off of the handle. You just have to calculate how much weight to hang at a certain distance. This will get you close enough for things like lug bolts, though getting it professionally calibrated is always a good idea.

[e30onBBSs]

Hey guys how often would you use something like the one AndrewBird posted? I know for lots of projects a torque wrench is needed, and I see myself working on my own cars at least for a long time. This is the wrench

http://www.amazon.com/Precision-Instruments-PREC3FR250F-Torque-Wrench/dp/B002XMSFIM

I'm on the edge of investing in it because I know how important it is to torque everything, and it seems like a really great tool that I will be able to rely on. I won't be using it everyday, and it should last right? Right now I have this crappy one that is in inch pounds and only goes to like 85 foot pounds

[gwb72tii]

so here is a follow on question/opinion
i know the importance of torquing bolts/nuts to their specs because of the type of load the respective pieces are subject to.
but is it really that important to get a hypothetical torque to exactly 20ft/lb or is close ok, meaning 20 or over but not too far over? in the e30 world?

[AndrewBird]

Depends on the bolt. Some bolts have a torque rating so you don't over torque them and strip them, others are stretch bolts and require a specific torque to be set correctly. Other bolts have one so that you make sure you get them tight enough so they don't come undone. Then there are things like head bolts that also require even torque on all the bolts, otherwise you won't get an even seal.

Anything under 50ft. lbs, I don't bother with a torque wrench as I have a good enough feel to not over torque things. Things like oil pan bolts don't really need a torque wrench, unless you are ham fisted and can't tell when a bolt is tight.