Torque Wrenches

jnmeade

jnmeade

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Jim Meade
I'm in the market for a new torque wrench. Electronic and digital torque wrenches are new to me - what should I know about them? It would be nice to switch easily between Nm, in/lbs and ft/lbs. The use is on the very light load side. Probably nothing bigger than 200 in/lbs and I could probably do with something even smaller.

Can I get anything any good for $200? Suggestions?

TIA
 
Snap on off craigslist
 
We only have standard click type with Nm on one side and in. lb. or ft. lb. on the other side, and dial gauge torque wrenches. I don't see a need for anything else.
 
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Beam type[edit]

Beam-type torque wrench. The indicator bar remains straight while the main shaft bends proportionally to the force applied at the handle.

Detailed view of the torque display scale on a beam type torque wrench. This shows a torque of about 160 in.lbf or 18 N·m.
The simplest form of torque wrench consists of a long lever arm between the handle and the wrench head, made of a material which bends elastically in response to applied torque. The deflection at the handle is proportional to the applied torque and material constants of the cantilever arm. A second, smaller bar with integral mechanical indicator is also connected to the head; this is never subjected to torque and thus maintains a constant position with respect to the head. When no torque is applied to the lever arm the indicator rests parallel to the lever arm. A calibrated scale is fitted to the handle so that applied torque, and the associated deflection scaled as torque of the main lever, causes the scale to move under the indicator. When the desired torque is reached (as shown by the indicator), the operator stops applying force. This type of wrench is simple, inherently accurate, and inexpensive.

The beam type torque wrench was developed in the late 1920s/early 1930s by Walter Percy Chrysler for the Chrysler Corporation and a company known as Micromatic Hone. Paul Allen Sturtevant—a sales representative for the Cedar Rapids Engineering Company at that time—was licensed by Chrysler to manufacture his invention. Sturtevant patented the torque wrench in 1938 and became the first individual to sell torque wrenches.

A more sophisticated variation of the beam type torque wrench has a dial gauge indicator on its body that can be configured to give a visual indication, or electrical indication, or both when a preset torque is reached.

The only one that doesn't require re-calibration.
 
As you can see in the picture, the one that doesn't require calibration, needs to be calibrated, reading over 150 inch pounds with no load on it.
 
Probably going to have to go with two wrenches to cover the range. 50-180 in/# is pretty standard. We cover 1-60, with a torque driver and 50 and up with various handles and heads. Once we get past 750, it's off to the tool crib for the big ones.

Clicker types for most stuff and the dial type for when you need running torque information. An example of the running info....We have some latches that have opening and closeing requirements, so the mechanic has to measure the torque to open or close the latch and a dial unit is the only way.
 
I bought a CDI 3/8 socket torque wrench off amazon for a $100 or so last December. Have used to to torque out AN3 and 4 bolts on my plane project and it's worked well. Once I get to firewall forward I may get something more fancy for ft lbs.
 
I bought a 1/2 drive one on sale at Harbor Freight for <$20, use it only to torque my spark plugs.

If it's a tool you will use often, don't shop there . . .
 
Hank S said:
I bought a 1/2 drive one on sale at Harbor Freight for <$20, use it only to torque my spark plugs.

If it's a tool you will use often, don't shop there . . .
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Did you check it against anything reasonably accurate? Even another torque wrench?

The click style torque wrenches can be way off if they are not treated properly - we had one at work that delivered about 60% of the indicated torque when I checked it.

My new Craftsman click and 70's vintage Craftsman beam wrench match up nicely.
 
Let'sgoflying! said:
Would you calibrate and adjust your clicktype torque wrench this way?

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It's simply a load cell, If you have one of them you don't need a torque wrench. simply use a breaker bar and the load cell.
 
Let'sgoflying! said:
Would you calibrate and adjust your clicktype torque wrench this way?
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I wouldn't use something from harbor freight without first having it checked against a known standard - which this guy did. Having done that, this is fine.

The big problem is when you only have one device - what do you check it against? I check my wrenches (different technology, different age) against each other - the chances that they would both be wrong by the same amount is minimal. If they turn out to not agree, then the problem is "which one is wrong?".
 
One foot long with a 10 pound weight on it is 10 foot pounds. Have any bar bells? Have a tape measure? Just hang a weight off the arm of the torque wrench.
 
I actually have used 'the known weight to verify a digital scale', then used the digital scale, 12.0" from center of the torque wrench's 'center of action' as a rough guide to double check one...worked out pretty well.
 
I have three torque wrenches, all for car projects but I'd be confident using them on a plane. They're all Snap On and I bought them all on eBay. One is a 1/4" drive mechanical wrench that I haven't used much but love for the small torque jobs. The other two are digital. The 3/8" drive is the TechAngle one that can measure angle of rotation after applying torque, useful for those "torque to X Nm and then turn 90 degrees" tasks, and the 1/2" drive is just the digital torque wrench.

I like the digital wrenches but I wish I had bought their mechanical cousins. The mechanical version gives a positive click when you reach your torque. The digital version beeps and vibrates. It is easy to over-torque if you react too slowly to the soft vibration or the digital beep. A mechanical click is a sharp, instantaneous feeling and sound that happens precisely when you should stop pushing on the wrench. It may happen a few Nm on either side of your target, but is probably more accurate than your reaction to a vibrating handle. Another problem is that the wrench makes the same vibration and beep when it turns on, which also happens when the batteries are weak and it resets during operation or when the plastic battery cover is worn a bit and not holding the batteries as perfectly still as they were when the wrench was new. There is no sound or vibration warning when the wrench turns itself off because the batteries died or were temporarily disconnected. So, did it just vibrate and beep at you because you reached your torque, because you upset the batteries and are well past your torque by now, or because it needs new batteries?

I don't use torque wrenches very often. They are a tool that I recommend buying quality regardless of how often you will use it. I had a Craftsman that self-destructed after one valve adjustment and spark plug change on my car. The Snap On wrenches are good quality. But if you will use it a lot, get the mechanical kind. The digital ones just aren't tough or positive enough to get it done every day.
 
We have aircraft specific tool carts with calibration certified torque wrenches on them, as well as numerous other "calibrated" torque wrenches in the tool room and in special kits, such as engine change. I knew we have Snap-on an others, but I just went out and verified, there are 10 torque wrenches total, on 4 carts, they are either Snap-on or CDI, 10-50 in.lb., 40-200 in.lb., and 200-1000 in.lb.
 
Cap'n Jack said:
If he weighed it first on a calibrated scale, it will be quite accurate. Even if the 10 pounds is dropped, it probably won't be off by enough to notice for this purpose.
Click to expand...

Exactly. Easy to weigh 5, 10, and 20 lb plates to the nearest gram on a calibrated lab top loading balance, hold the drive of the wrench in a vise with the bar horizontal, and hang a plate from a measured spot on the bar with safety wire (weigh the wire and add it to the weight of the plate). Then change the setting of the wrench until it just clicks when the weight of the plate is loaded onto the bar. The applied torque is simply the weight of the plate plus wire (in lbs) times the distance of the wire from the center of the drive in either inches or feet depending upon the range..

Considering how much the load cell readout in the video was jumping as torque was applied with the wrench, I suspect that the static method using weights gives a more precise and accurate result than the load cell.

Adjust the calibration of the wrench until the wrench clicks at the appropriate setting for an applied torque near the center of the range. Then check other readings using one or more lighter or heavier weights, and/or positions nearer or further from the drive.
 
I use a Craftsman model 1019 Laboratory Edition Signature Series torque wrench. The kind used by Caltech high energy physicists and NASA engineers.
A split second before the torque wrench was applied to the faucet handle, it had been calibrated by top members of the state AND federal Department of Weights and Measures... to be dead on balls accurate!
 
bkspero said:
Exactly. Easy to weigh 5, 10, and 20 lb plates to the nearest gram on a calibrated lab top loading balance, hold the drive of the wrench in a vise with the bar horizontal, and hang a plate from a measured spot on the bar with safety wire (weigh the wire and add it to the weight of the plate). Then change the setting of the wrench until it just clicks when the weight of the plate is loaded onto the bar. The applied torque is simply the weight of the plate plus wire (in lbs) times the distance of the wire from the center of the drive in either inches or feet depending upon the range..

Considering how much the load cell readout in the video was jumping as torque was applied with the wrench, I suspect that the static method using weights gives a more precise and accurate result than the load cell.

Adjust the calibration of the wrench until the wrench clicks at the appropriate setting for an applied torque near the center of the range. Then check other readings using one or more lighter or heavier weights, and/or positions nearer or further from the drive.
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How accurate do you want to be? You figuring in a latitude and elevation weight correction?
 
flyingron said:
I use a Craftsman model 1019 Laboratory Edition Signature Series torque wrench. The kind used by Caltech high energy physicists and NASA engineers.
A split second before the torque wrench was applied to the faucet handle, it had been calibrated by top members of the state AND federal Department of Weights and Measures... to be dead on balls accurate!
Click to expand...
Is that a drip I hear?
 
[QUOTE="GlennAB1, ]Every latch check I can think of, we use a spring (fish type) push/pull scale.[/QUOTE]

Hard to use a push-pull scale on a rotary type latch. :)

Had a good one this morning...torque value called out was 82.5 oz./ in. Had to get online and convert that one to inch/ pounds, then head to the tool crib for something that would work that low. I have had occasion to use a 0-10 oz./ in. torque watch before.
 
Note that the units are inch-pounds, foot-pounds and ounce-inches NOT ounce/inches or inch/pounds. Torque is measured in FORCE x DISTANCE. not FORCE/DISTANCE (or vice versa). To convert from 82.5 ounce-inches conversion is easy. There are 16 (avoirdupois) ounces in a pound. 82.5 ounce-inches is 5.15 inches-pounds or a touch under a half of a foot-pound. No computer is necessary, just simple division by 16 (ounces to pounds) and 12 (inches to feet).
 
Craig said:
Hard to use a push-pull scale on a rotary type latch. :)
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Yeah, I caught that after I posted it... we do thousands more cowling latch checks than cabin door latching checks (that is correct terminology, also). Cabin doors I've done have max latching and min unlatching forces, so a "click" type torque wrench can be used. The difference is: cowling latches are checked individually and the cabin door latching check takes into account all of the latches and door mechanism.
 
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GlennAB1 said:
Yeah, I caught that after I posted it... we do thousands more cowling latch checks than cabin door latching checks (that is correct terminology, also).
Click to expand...

No cabin doors for us....single seat ordinance tosser...All of our exterior panels have either screws or rotary type latches. The other model ordinance truck I work on has some external panels that use Hartwell style latches, so no tools to open it up, and it comes in both single and family models...:p
 
flyingron said:
Note that the units are inch-pounds, foot-pounds and ounce-inches NOT ounce/inches or inch/pounds. /QUOTE]

Yeah, I know Ron, but the slash is the only symbol that will consistently work on that page of the keyboard on my iphone without having a stick to type. If I have to send any equation stuff on the phone, I have to spell out the operand, or waste a bunch of time typing and correcting. Touch screens and I do not get along. I have trouble with the tool boxes at work, the ones in the airplane and the one on my Yaesu FTM-400 in the car. I can wear all cotton clothes and walk barefooted across a conductive floor and generate an arc when I touch a grounding bar... And to think I handle sensitive hardware and explosives for my job...:eek:

As to checking the torque values on an online conversion, it's an oddball set of values with a tiny allowable window for a set of electrical connections that are submerged in fuel. At many AMUs for a messed up fuel sending unit or harness, I take no chances on doing the non-normal conversions in my head. For most of the ones I need, I do it mentally. I normally do sub 10 inch-pound torques only a couple times a year, so I run the numbers on the computer to be safe.
Click to expand...
 
Craig said:
No cabin doors for us....single seat ordinance tosser...All of our exterior panels have either screws or rotary type latches. The other model ordinance truck I work on has some external panels that use Hartwell style latches, so no tools to open it up, and it comes in both single and family models...:p
Click to expand...
When I worked on ordinance tossers, someone else took care of panels... ;)
P.S. Hartwell makes several types of latches.
 
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Not a torque wrench but I have a digital caliper and EVERY TIME I tried to use it the battery was dead. So I don't use it anymore.
 
I prefer clickers, sometimes it is very hard to be able to read a scale or display.
 
I'm cheap but do like the non-electronic SnapOn click-type enough to fork over the $$$. It also matters if you ever move from FBO/MRO to FBO/MRO and they set up a schedule to calibrate them on company $. Oddballs may not be eligible for the company program.
 
I have a click type. It is pretty much impossible to read, not sure why I haven't tossed it. Anyone have one they could not read? Lines not matching up with any values or line up at low torque but not high torque.
 
bnt83 said:
I'm cheap but do like the non-electronic SnapOn click-type enough to fork over the $$$. It also matters if you ever move from FBO/MRO to FBO/MRO and they set up a schedule to calibrate them on company $. Oddballs may not be eligible for the company program.
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We have our own calibration shop for torque wrenches and pressure gauges.
 
When I worked for the Army, I had a friend who worked in the calibration department. They gave him an ID and a badge. I always referred to him as the calibration cop.
 
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