Accurate Torque Wrench range

Sonoma Coma · Mar 6, 2017

I am looking to purchase two torque wrenches to cover a wide range of torque specs. I found them at Precision Instruments has them... I think?
3/8" is 15-100 Ft. Lbs.
1/2" is 40-250 Ft. Lbs.
What is the actual accurate operating range of these torque wrenches? How do I determine the bottom 20% of each one? And what is the maximum setting on the scale for accuracy?
It seems like the two are spaced apart quite a bit to cover accuracy for torquing something like Head Bolts.

T45 · Mar 6, 2017

tax the max and the 1/5 of the max

100=max
20= min

should be calibrated OK between 20-100

...etc :thumbup:

Sonoma Coma · Mar 6, 2017

So the 3/8" is good from 20Ft. Lbs. on up and the 1/2" is good from 45Ft. Lbs. and up. Not try and figure out what is 20% between the 40-250 Ft. LB range.

Sonoma Coma · Mar 6, 2017

Now to determine between the Precision Instruments and CDI.
I called Precision and they said I can send it back to them to get re-calibrated and they can repair it if it needs it. CDI said I would have to send it to a different company for re-calibration or repairs, once it leaves their facility it is out of their hands - see ya later by bye. (Except for the one year warranty of course.)

zakmartin · Mar 6, 2017

I have three PI torque wrenches. On the one that scales out in in-lbs, I bought the 3/8" version (they offered an identical wrench in 1/4"). I called PI because I wanted to get a kit to change my 3/8 out to 1/4, since the 1/4" sockets were more likely to get used on the in-lb application. They HAPPILY sent me the conversion parts for free and they were at my doorstep in 3 days. They succeed as a company with flying colors, as far as I'm concerned.

dnschmidt · Mar 6, 2017

The problem with operating a "clicker" style torque wrench at the lower end of its range is that it can be very difficult to detect the click. Unless I'm using a digital - which since I sell them I actually do most of the time - I try to use clicker torque wrenches at the higher end of their scale. There the "click" is much more pronounced.

The biggest offender in this regard is the Harbor Freight torque wrenches. I have found these to be accurate but very hard to tell if they have in fact clicked at the low end of their range. The Precision Instruments split beams have this problem as well. At their lowest setting you have got to really feel for the click and be in a quiet environment to hear it. This can lead to damaging over torquing as you blow right past the click and keep on going. I've done this myself a couple of times and that's why I don't do it any longer. If I'm torquing to 75 ft-lb I'm using a 20-100 ft-lb wrench for that not a 60-250 ft-lb wrench.

Sonoma Coma · Mar 6, 2017

Yea, I'm trying to decide between the CDI and Precision Instruments models. I have already called my Snap-On dealer and he said a 3/8" micrometer click-type and a digital 1/2" with the angle finder together would be approx. $800.00 together!
I have bee reading reviews, found most on Amazon, and not many about the PI. What reviews there are people say it feels mushy and hard to detect the click. The Snap-On dealer admitted they own CDI but they are two totally different torque wrenches. Snappy obviously the better quality but also lots of moo-lah.

kd3pc · Mar 6, 2017

I am another very happy Precision Instruments user. No issues whatsoever. 1/2" drive and 3/8" drive

L.Cheapo · Mar 6, 2017

Sonoma Coma said:
Yea, I'm trying to decide between the CDI and Precision Instruments models. I have already called my Snap-On dealer and he said a 3/8" micrometer click-type and a digital 1/2" with the angle finder together would be approx. $800.00 together!
I have bee reading reviews, found most on Amazon, and not many about the PI. What reviews there are people say it feels mushy and hard to detect the click. The Snap-On dealer admitted they own CDI but they are two totally different torque wrenches. Snappy obviously the better quality but also lots of moo-lah.

The nice thing about the Snap-Ons is that if something ever goes wrong with it, or it needs calibration, they take care if it all for a very reasonable flat fee, something like $60 including return shipping. You'll pay more than that just to get most others calibrated. You also get a certificate of accuracy.

As far as accuracy, I believe (maybe I'm wrong?) that most torque wrenches state accuracy from 20-100% of scale. So if the wrench has a range of 15-100, thats a scale of 85. That would mean advertised accuracy from 32-100. Snap On publishes their accuracy for Techangles from 5-9% and 10-19% also. Technique will result in more error than the small percentage variances of a Techangle.

kd3pc · Mar 6, 2017

I think the accuracy of these style torque wrenches is more of:

if you set it to 40 pounds of torque...the actual range of torque would be 36-44ft/lbs. I tested a brand new high end digital snap on and my 30 year old beam wrench from Sears craftsman. And both were identical on the test gear.

So unless you are using these 2-4 hours a day on the same fasteners....the best you can hope for is hitting the preset torque number 75-80% of the time.

guy48065 · Mar 7, 2017

Ignore the previous 2 Ministers of Misinformation! Nearly all click-type torque wrenches are certified accurate from 20% to 100% of FULL SCALE. So a 10-150 ft-lbs wrench would be guaranteed to torque ALL fasteners within the specified tolerance (usually ±4% CW direction) when set anywhere in the range of 30 to 150 ft-lbs.

WittHay · Mar 7, 2017

One of my local tool stores has specials on Proto and GearWrench. The 1/2" Proto I have is a good US built torque wrench. The 3/8" GearWrench is made in China.

You might want to read the reviews on GearWrench and see if it is suitable for your needs. The GearWrench seems okay and is available everywere

bmwpowere36m3 · Mar 7, 2017

For most clicker-type wrenches, the guaranteed accuracy range is 20-100% of full scale. Some strain-gauge, electronic, wrenches have a larger range and higher accuracy as well.

country83 · Mar 7, 2017

Sonoma Coma said:
So the 3/8" is good from 20Ft. Lbs. on up and the 1/2" is good from 45Ft. Lbs. and up. Not try and figure out what is 20% between the 40-250 Ft. LB range.

Should be accurate from 50 to 250 ft-lb (50 is 20% of full scale which is 250 in this case).

dnschmidt · Mar 7, 2017

Normally, as I posted above, accuracy isn't the problem. Even the cheapest HF torque wrenches have been within spec when I've tested them on my torque gauge. The problem is realizing when they have "snapped" over since at the low end of the range you can barley feel this happening. A friend of mine broke off three studs on Monroe Quick-Struts during an install using a Harbor Freight 1/2" drive torque wrench at 30 ft-lbs. I tested the wrench afterwards and it was within 4% of perfection. The problem he had was he couldn't tell when the wrench snapped over and just kept going until the studs broke off. I don't care how accurate your torque wrench is if you can't feel when it's released it's entirely useless. People get hung up on the wrong issue. There is enough of slop in torque measurements inherently (bolt lube, quality of thread friction, and a million other variables) that a wrench being off 10% will very seldom truly matter. Not being able to tell if the wrench has snapped over and over torquing to the point of bolt failure is a far more serious concern. We often worry about the wrong things.

txvwnut · Mar 7, 2017

Just go with Precision Instruments and don't look back. I had nothing but the micrometer type torque wrenches in my box. I tried a PI split beam and now have replaced the micrometer type with PI and will use nothing else. They are remarkably affordable for a torque wrench plus made in America.

Accurate Torque Wrench range

Sonoma Coma

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T45

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