Torque wrench left in mid range for long term.

[snickers muncher]

Hey guys, I just received a CDI 3/8 torque wrench 10-75 ft lb made in USA from Harry J Epstein. It is appears to be New Old Stock but may also be a factory seconds since the numbers by the head are etched askew and some chrome is flaking off of the head on the 3/8 side. Judging by the stickers and manual it is several years old.

When I examined it the wrench was set to 32ft/lbs instead of it's lowest setting of ten. If this wrench has been sitting at the middle of it's range for who knows how many years, could the spring be damaged? Do I need to contact HJE or CDI? I don't care if it's a seconds as long as it isn't damaged. It's my first purchase from them and it's not instilling confidence.

Thanks for any advice,

John

 

[plinker]

You could check it against a known good wrench as a basic test.

I want to say those were military surplus or similar, dont remember where I'd seen/read it off hand.

 

[fordnut85]

It can damage it but you need to test it. Most tool trucks like snap on have a torque comparator on the truck for testing accuracy

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[850xpeps]

I always thought they needed to be set to zero. On our large 3/4” I was recommended by a mechanic who was told by his snapon dealer to leave it midrange. Not sure if it is the same for the small ones.


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[plinker]

Some torque wrenches can be left in mid range (or anywhere for that matter) depends on the style. Precision instruments split beams are this way.
https://www.tooltopia.com/precision-instruments-c3fr250f.aspx

I always set mine to the lowest setting marked on the tool, no matter what type it is.

 

[matt_i]

It seems wrong to me (defying materials science) that a steel compression spring could ever take a plastic "set" at midrange of compression, no matter how long you ever leave it.

I leave them at lowest too. I did find out on a recent project that a Proto clicker I took out of a drawer after about a 2 year nap would not click on any torque (with square drive in the vise jaws). Not seeing how I could disassemble it, I doused the top end in LPS2 spray lube and it started working correctly again. So I would say the lubrication of the mechanism to reduce friction is actually more important.

If you want to rough-test it, make an arm by welding a socket to flat or other, and hang a barbell out at a measured distance from center and see if the wrench is close to clicking. Keep arm perpendicular to vertical ratchet handle for greatest accuracy.

 

[ishiboo]

I always thought they needed to be set to zero. On our large 3/4” I was recommended by a mechanic who was told by his snapon dealer to leave it midrange. Not sure if it is the same for the small ones.


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I believe it is supposed to be left at the bottom of its scale, NOT zero.

Either way... it's a several year old torque wrench. It needs to be taken to a metrology lab for calibration either way.

 

[snickers muncher]

Thanks for the advise so far. I'm just a guy at home doing basic and intermediate repairs on the family vehicles to save everyone money. This one was supposed to replace the harbor freight torque wrenches I've been using. I've always been told to store at lowest setting and the manual for this torque wrench also states this.

The easiest way I have to test it out would be using weights on a car's lug nuts. I'm more concerned about premature wear.

Thanks,


John

 

[seber]

The problem is creep deformation of the compressed spring. The amount of creep will be based on temperature, vibration, and most of all stress. The lower the stress and the shorter the stress time, the lower the creep. Therefor the recommendation for compressed spring type torque wrenches will always be to keep the setting as low as possible when not in use.

 

[guy48065]

I would NEVER recommend this but "a friend" bought a HF digital torque adapter for $30 and used it (in peak mode) to capture the actual peak torque of his clicker at various settings. Then he returned it to the store.

If it doesn't pass then you still have to decide whether to put some money into your purchase to make it right.

 

[dnschmidt]

I've always thought this return to zero thing was a bit overblown. When you consider the beating the valve springs in an ICE take being slightly compressed shouldn't be that big of a deal to a spring. My opinion is that it doesn't hurt to return them to zero but that it probably doesn't matter very much. That's why a spring is a spring.

 

[Vantastic]

Split beam for life! Lol

 

[sberry]

Do a little comparison and see if it seems to be working. Probably not building the space shuttle and torque can be a rather crude measurement anyway.

 

[DadsTools]

May sound like a silly question, but anyone care much for the old beam and needle?

 

[dnschmidt]

The only use of the "old beam and needle" that I can think of is for measuring bearing pre-load. For that purpose they are often the best way to go.

 

[jdoe213]

Good info.

 

[Lonnies Performance]

The best way to preserve your calibration is to take off all tension when not in use.

All springs tend take a "set" over time... meaning the spring gets shorter due to being held in a compressed state. What this means is the wrench can end up being 10ft./lb. off across the entire range from leaving the spring compressed.

A division of the company I worked for calibrated instruments, including torque wrenches. Almost all (good quality wrenches) that were off needed the preload readjusted to make them accurate across the range. The cheap ones were all over the place as the quality control on the spring & its corresponding lb./in. rating varies, but there is no adjustment for the numbers on the side of the wrench.

Since there was also a comment about valve springs, I'll state they do the same thing. You install at a certain height to get a specific installed seat pressure & after running them for a while the seat pressure will slightly drop off. They will lose a slight amount of free length (preload) & you can re-shim them back to the proper pressure setting. On critical builds, we often made a few dyno pulls & then checked all springs for pressure & shimmed accordingly. Seems most took only a thin .015-.030" shim to bring them back to spec.

Springs typically do not typically get weaker as far as the lb./in. rating to compress them unless fatigued by repeated compression or substantial heat. This is where valve springs also show their age.

 

[Treeman]

The best way to preserve your calibration is to take off all tension when not in use.

All springs tend take a "set" over time... meaning the spring gets shorter due to being held in a compressed state. What this means is the wrench can end up being 10ft./lb. off across the entire range from leaving the spring compressed. .........

Since we tend to be ****-retentive about torque wrenches...

Sturdevant Richmont takes exception to your statement, as shown in this article: http://www.srtorque.com/error-proof...may-be-quietly-sabotaging-your-quality-score/

The key word is "may":

Why Your Best Practice May Be Quietly Sabotaging Your Quality Score

"When taking pressure off the spring, the design may allow the wrench to relieve pressure on the torque block. This can allow the torque block to disorient, shift. Some wrenches can be set to zero pressure on the spring or have the handle further away from the spring. Not only can the torque block disorient, it can even fall out of place in the wrench.

If the torque block disorients, calibration is lost. Repeatability becomes an issue because the block no longer functions as designed. Typically in the tilt block design, the block itself is not square. That means when the tilt block is reoriented and is on it's side, the torque value has changed without you knowlege. The scale still reads the same torque value, but what wrench says, and what it does, are two entirely differnt things. The difference in torque could be 20% or it could be 50%. It depends on the dimensions of the torque block. "

 

[Lonnies Performance]

I guess if you buy junk you get questionable results....

If the design allows the parts to move & separate erratically, the torque setting should be limited by the manufacturer to prevent this from happening.

All I know is my torque wrenches have always been the same every time I had the shop check them, except for the 1 time I accidentally left the setting cranked up for a few months. My mistake & my lesson learned.

Your results may vary, but I'll stick with my proven results.

 

[6PTsocket]

It seems wrong to me (defying materials science) that a steel compression spring could ever take a plastic "set" at midrange of compression, no matter how long you ever leave it.

I leave them at lowest too. I did find out on a recent project that a Proto clicker I took out of a drawer after about a 2 year nap would not click on any torque (with square drive in the vise jaws). Not seeing how I could disassemble it, I doused the top end in LPS2 spray lube and it started working correctly again. So I would say the lubrication of the mechanism to reduce friction is actually more important.

If you want to rough-test it, make an arm by welding a socket to flat or other, and hang a barbell out at a measured distance from center and see if the wrench is close to clicking. Keep arm perpendicular to vertical ratchet handle for greatest accuracy.

Have you ever seen a car or truck that needed new springs because the old ones sagged under the long term weight of rhe vehicle? I have replaced dish washer springs because the would no longer counterbalance the door. Before that the springs were moved to farther holes in the frame to make up for lost tension. Springs under compression or tension definitely stretch or compress with time. I'm just going in emperical evidence. I know zip about metalurgy.

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[matt_i]

Have you ever seen a car or truck that needed new springs because the old ones sagged under the long term weight of rhe vehicle? I have replaced dish washer springs because the would no longer counterbalance the door. Before that the springs were moved to farther holes in the frame to make up for lost tension. Springs under compression or tension definitely stretch or compress with time. I'm just going in emperical evidence. I know zip about metalurgy.

Never have observed this in a vehicle, neither coil springs nor leaves, but I am not precision-measuring the ride-height either, and I have yet to see one go all the way to start dragging the pavement . I can understand creep happening up close to the yield point (sort of a poorly defined yield point) or if the temp is significantly elevated...meaning get a bar red hot and it can deflect under its own weight. It is quite possible that sketchy heat-treating in a spring leaves it with localized soft spots that can be locally yielded due to the torsion, especially if its under a heavy load or into a lot of deflection. Maybe torque wrenches are trying to wring as much range out of the spring as possible.

 

[guy48065]

I have seen the problem described in the above link/quote (tilt block shifting position) several times and that's why I object whenever I see the advice to turn the handle "all the way down". All the manuals say to "turn the handle down to the minimum setting". Many will continue to turn way past the end of the stamped digits.

There's one numb-nut at work that refuses to follow this simple advice so his wrench keeps going out of spec. WAY out. By policy I have to halve the Due Date each time this occurs. If he keeps it up I'll end up having to confiscate his wrench and force him to buy a new one.

 

[maico]

There is no conventional spring in the Stahlwille torsion bar type torque wrench and nothing is under load when not in use. http://www.stahlwille.co.uk/wp-content/uploads/2014/02/MANOSKOP-730N.pdf