Torque wrench extensions

[Heatnbeat]

Does anybody have a formula to calculate the reduced settings for using extensions with a clicker wrench? All of the ones I've found reference the length from the center of the drive to the center of the handle. Two problems there; for one the length varies depending on the setting although leverage doesn't . Secondly although that center of handle works on beam type, on clickers it makes no damn difference. I put my hand as close as I could to the flex joint and then used a 3 ft cheater bar and it made no difference to the torque. So it seems to me that I need a formula that reduces the torque setting by a percentage based on the length of the extension.
I'm good with questions, but not so good with math. :-)

[Rockout Rocker Products]

There are various calculators online. The easiest way... always keep the extension 90 degrees to the torque wrench beam.... no correction factor needed. 

[Heatnbeat]

Yeah I know the extension at 90degrees doesn't require any calculations but this is more of an intellectual quest.

There are calculators on line but I really do think they are wrong for a clicker style. It's damn hard for me to believe they are all wrong and this dumb old welder is right but I need to understand it before I can concede.

If the length of the handle made any difference then my 3 ft cheater bar would change the torque, but it doesn't.

[FSG]

If the length of the handle made any difference then my 3 ft cheater bar would change the torque, but it doesn't.

It has to, post a pic of your torque wrench with the cheater bar fitted

http://www.harleytechtalk.com/htt/index.php?topic=1215.msg

[Karl H.]

...If the length of the handle made any difference then my 3 ft cheater bar would change the torque, but it doesn't...

As long as you do not use any torque adaptor the lengt of the handle makes no difference. But as soon as you use a torque adaptor the situation changes! Might this be the point where you're hanging?

Karl

[Heatnbeat]

 Just to be clear ALL of this applies only to clicker type wrenches. Bending beam are a different animal.

OK, so here's what I did so far. I mounted an old clicker wrench in a fixture ( made by Chas Parker Meridian CT LOL)
and set it for 190 in/lbs. I took a second wrench and upped the setting until they both clicked at almost the same time ( as close as I could get) then I took the wand from my shop vac which is a good 3'+ and slid it over the handle, Exactly the same as before, so the length of the handle on a clicker makes no difference.

As near as I could figure out my 3" extension reduces my setting by 20%on my 1/4 drive wrench but the calculators say it would change if I used it on my 3/8 wrench which is longer. I don't believe it.

Oh one other thing. Since the center of the grip area moves when you adjust it. If those calculators are right you have to re calculate your torque for the extension every time you adjust the wrench.  Does this make sense??

[Rockout Rocker Products]

The reason the length of the beam doesn't matter on the click type is all you're really doing by turning the handle is adjusting spring pressure on the mechanism. If it was 3" long I'm guessing it would still read the same.

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[Heatnbeat]

YES Rockout, you are correct. That's why the calculators on the internet and even the ones supplied by the wrench are wrong.

Maybe I'm missing something but I don't think so..

[Coyote]

Added length before the measurement head does not matter (at 90 deg). If off 90 degs, it follows the calculators.

[Heatnbeat]

Well I just did some more experimenting.


  According to the online calculator (https://www.belknaptools.com/support-library/extensions-calculator/)
To get 120 in/lb with my 8" long 1/4 drive torque wrench and a 3 inch extension I need to set the wrench at 87.3 but if I run the calculation with my 13" long 3/8 wrench I need to set the wrench at 97.5. But my 1/4 and my 3/8 with the 3" extension and set at the same setting give the exact same torque.

And Coyote, with all due respect that isn't true either. I didn't believe it so I made an 18" extension. I put my old wrench in the Chas Parker fixture and set both wrenches to 120 in/lb. With the 18" extension at 90deg I could not set the old wrench low enough to make it click.

If you guys don't believe me try it. Make a long extension and try to torque something with it. I admit an 18" extension is a bit absurd. But if it really did not matter then 18" wouldn't matter either.

Now if you guys will excuse me I have an engine install to finish up.

( why the heck does everything take so danged long. LOL)

[chaos901]

An extension (cheater pipe) on the handle of the torque wrench does not make any difference to the torque applied.  Just makes it easier to apply.  As previously stated, an extension from the drive (at other than 90 degrees) does make a difference.

[Coyote]

An extension (cheater pipe) on the handle of the torque wrench does not make any difference to the torque applied.  Just makes it easier to apply.  As previously stated, an extension from the drive (at other than 90 degrees) does make a difference.

I agree but to do the calculation you do need to use the wrenches spec'd handle length.

So the Wrench TQ setting =  Desired TQ x  ( handle length/  (handle length + added length))

So if you have a 12" wrench and you add 2 inches and you desire 100ft-lbs you should set your wrench to

100 * 12 / (12+2)  = 85.7 ft-lbs    adding a cheater bar changes nothing on this.

[Rockout Rocker Products]

The click mechanism in a click type torque wrench doesn't know inch pounds from metric tons. It knows to click when the force overcomes the spring pressure applied to the mechanism. Apply that force from a foot away, two feet away, it knows no difference. It makes a difference on how it feels to you.

[Coyote]

True, that's what I said above...

[Panzer]

Now my head hurts.

[cheetah]

I think when speaking of "length," they are speaking about http://www.sears.com/stanley-proto-stanley-proto-j5100-3-8-inch-drive/p-SPM8849389223?plpSellerId=Edealszone LLC&prdN  not the length of the handle of the wrench.
When using an adapter as above, the overall length is extended, and one must use a calculator.
If using a pipe extension  without using an adapter on the wrench,  no calculations needed.
C

[Dan89flstc]

When you say extension, you are actually referring to what is known as a cheater bar (a length of pipe slipped over the wrench to make it easier to turn).

All you are doing is making it easier to turn the torque wrench, the wrench does not know if it is being turned by hand, or a 50 foot long pipe.

For a clicker type, it really doesn`t matter where the wrench is pushed from, the handle does not have a pivot point, it measures torque at the pivot point up near the head of the wrench.

The cheater bar does not change the effective length of the clicker type wrench.

On a deflecting beam torque wrench, the force must be applied at the pivot point in the handle.

The online torque formulas are correct, they have nothing to do with adding a cheater bar extension, they give the calculation for adding to the effective length of the wrench when using a torque adapter.

But...there is no reason to use a cheater bar on a torque wrench, the wrench is plenty long enough to pull the max torque the wrench can indicate.

[Heatnbeat]

No Dan, maybe I wasn't clear. No cheater bar on the wrench, I only used my shop vac wand to prove out an idea. Anybody that would use a cheaterbar on a torque wrench needs there tools taken away from them.

My extension is what you refer to as a torque adapter. And no the online formulas are as far as I can see not correct for clicker style wrenches, but correct for the bending beam type.

If you don';t believe they are incorrect try this experiment for yourself.
Use a torque adapter on your short handled 1/4" clicker and run the calculation. Then check force exerted. Use a 1/4x3/8 adapter and put the torque adapter on your longer handled 3/8 torque wrench, run the calculation and check exerted force. I get 2 different forces. if I set the 3/8 wrench to the same setting as the 1/4 I get the same exerted force.

[Karl H.]

...Use a torque adapter on your short handled 1/4" clicker and run the calculation. Then check force exerted. Use a 1/4x3/8 adapter and put the torque adapter on your longer handled 3/8 torque wrench, run the calculation and check exerted force. I get 2 different forces. if I set the 3/8 wrench to the same setting as the 1/4 I get the same exerted force.

I don't understand the logic yet. Could you sketch your setup please?!

Karl

[Dan89flstc]

You may not understand what is going on, but I have used these formulas in the aviation world for over 43 years as a jet engine mechanic, the formula is correct.

The formula is correct for any type hand torque wrench, be it deflecting beam, dial torque meter or micrometer type clicker.

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[Karl H.]

 

[Coyote]

Exactly the same as I posted above. 

[FSG]

Exactly the same as I posted above. 

and the same as http://www.harleytechtalk.com/htt/index.php?topic=1215.0 which has been around since 2008

[Coyote]

Exactly the same as I posted above. 

and the same as http://www.harleytechtalk.com/htt/index.php?topic=1215.0 which has been around since 2008

Good formulas stand the test of time.   

[Heatnbeat]

Dan,

I know, we've all been using them. I've used them for 50 years.

But answer me one question.

If as you state (and we agree!)


"For a clicker type, it really doesn`t matter where the wrench is pushed from, the handle does not have a pivot point, it measures torque at the pivot point up near the head of the wrench.

The cheater bar does not change the effective length of the clicker type wrench."


How can a formula that references the handle length work?
I do not think it does since handle length does not change the effective length of a clicker wrench.
It works for a breaker bar, or a bending beam torque wrench. But I can not see how it possibly can.

I'm not trying to be stubborn (my ex said I didn't have to try to be stubborn, it came naturally) and I really don't want to tie up the forum so if anyone would like to continue this via messages I'm all "ears".


Update:

I've been looking and I may have a better way to explain my issue.

Lets say you have 2 torque wrenches, 1- 12 in long and 1- 24in long. Torque 2 bolts to 50lb/ft and they will be equally tight. Correct? Now put your 2"  torque adapter on both wrenches, tighten both bolts to the original setting. They will both still be equally tight. Correct? But the calculators tell you to use different settings.