Hi Phil how ya doing? <img src="/forums/images/graemlins/cheers.gif" alt="" />

I find this amusing. I-say, remeber that abrasives are disposable, tools aren't.

I personally find Frank's posts illuminating, which may be a commentary on my intelligence. I've always valued knowing something about everything, but don't value so much knowing everything about anything. The first makes you "educated", the second makes you too narrow gauge.

It's so much fun to watch naivete' in action.

BTW, all the good wheel tech's I ever saw set spoke tension by sound, and I've watched masters at work on Ferrari wire wheels....

Well, Scotty û

Now youÆve gone and gotten my curiosity engaged û not because I really want to know what formula is correct for front-end extensions on a torque wrench (I donÆt really care to know some things until I have a specific purpose) û but because I wondered how a guy on a bicycle could make a statement that multiple internet site references indicating how to do the calculations could be wrong and how he could be so certain his self-derived formula was right. But recognizing that Orville and Wilbur Wright were also bicycle folks û and pretty smart ones û I did want to be fair about it and withhold judgment until I could find out exactly where truth might lie.

So, I found a website from ôTorque Specialties Division, AKO, Inc.ö. They are in the business of building very expensive computerized torque wrench calibration machines as well as torque multiplier test and calibration systems, so I thought they might be a reliable source of factual information:

http://www.akotorque.com

There is indeed some useful information on their site. As an example, hereÆs the formula they put forth as the method for determining torque settings with adapter extensions. It appears to be another variation in nomenclature of the same formula found elsewhere on the internet:

TT = TA x IT / L

TT = Torque setting of wrench
TA = Torque exerted at extension
IA = Extension length (inches) measured from center of socket to center of drive square
IT = Wrench length (inches) measured from the middle of the handle to the center of the tang
L = IT + IA (for straight in-line extensions)

http://www.akotorque.com/usefull.htm

continued in next post

I decided to put some hypothetical numbers into their formula and yours to see if the results were similar and set up a test. If I want 100 ft/lbs of torque on a fastener and am using a 6ö extension, your formula indicates the following setting on the wrench scale would be needed:

I = A / 1+E

I = 100 / 1+.5
I = 100 / 1.5
I = 66.67 ft/lbs.

The same numbers into their formula and using my torque wrench handle length of 13ö:

TT = TA x IT / L

TT = 100 x 13 / 19
TT = 1300 / 19
TT = 68.42

Now, both answers can be wrong, but both answers canÆt be correct û although in that example they appear close. But if I used a torque wrench with a different length handle (say 24ö) and the same 6ö extension, it looks like this:

TT = 100 x 24 / 30
TT = 2400 / 30
TT = 80 ft/lbs.

So, how can that be? It does seem counter-intuitive that a longer length torque wrench would require a higher indicated setting to apply the same force to a fastener through identical extensions.

The reason for the need to include the torque wrench handle length in the calculation appears to be because of the relationship between the handle length in proportion to the length of the extension adapter as well as the internal design that includes 2 levers operating on a fulcrum or pivot. As the handle gets longer, the multiplying effect of the extension is reduced, since as a percentage of overall length, it has become less. Looking at it from the other way æround, if the extension was gradually reduced to the point of nearly zero length, the mechanical advantage provided by the extension is negligible and the wrench setting is dialed in to the original torque desired at the fastener.

All of the foregoing applies to ôclick-styleö torque wrenches û further, not only is the calibration of this type wrench affected by a forward extension, a handle extension will also affect indicated values. A handle extension will not affect values on a beam-type wrench.

continued

Now for beam torque wrenches:

According to Gary Fitzhugh, Engineer at ôSDI Torque Productsö (makers of all sorts of torque wrenches and testing equipment), the adjustment formula for beam-type and dial-type wrench forward extensions is as follows:

TW = TA x L / L + A

TW = Wrench setting
TA = Desired torque at the fastener
L = Effective wrench length
A = Added length of the adapter extension

http://www.cditorque.com/main.html

So, for a beam wrench in the above calculations, the following is determined:

TW = TA x L / L + A
TW = 100 x 13 / 13 + 6
TW = 1300 / 19
TW = 68.42

ThatÆs the exact same number derived above using the other published formula. Notice the example given on their page for a dial-type wrench of 18.75ö with a 2ö extension and a desire to know the correct torque setting needed to achieve 250 ft/lbs at the fastener. The answer they show is 226 ft/lbs indicated. LetÆs try your formula which doesnÆt allow for handle length:

I = A / 1 + E

I = 250 / 1 + .1667
I = 250 / 1.1667
I = 214 ft/lbs.

Close, but not quite the same. Your formula appears adequate for some things, but not for others, and certainly not for ôclick-styleö torque wrenches which depend on a fulcrum and levers for operation and which must be allowed for in extension calculations. By the way, you can download a lot of good information from that site.

I was considering buying a 6ö extension and running the experiment by the various formulae and removing the adapter extension to check actual torque, but IÆll leave that exercise to anyone else who is interestedà. IÆve spent enough time on it.

One last thought û you might want to recheck the fasteners on your bicycle if theyÆre that critical. Wouldn't want you to hurt yourself. <img src="/forums/images/graemlins/wink.gif" alt="" /> <img src="/forums/images/graemlins/cheers.gif" alt="" />

Frank

I find this amusing fasteddy,you say I'm disposable,abrasive,narrow gauge and naive.I say I'm helpful,accurate and specific.I can't be helpful unless I'm accurate and I can't be accurate unless I'm specific.I suspect people want accurate, specific answers when they ask questions.Magoo asked a question and I gave him a "narrow gauage" kind of answer.He liked it.I like my posts to have a logical progression.

As to your implied advice to set my spokes by sound,I do not claim to be a wheel tech,much less a "master".I could learn from one,but to blindly imitate, armed with little specific knowledge would be folly.They learned their craft over many years and countless wheels.They have accrued skills that make it look easy.I doubt it would be so for someone unskilled like myself.Seems logical, doesn't it? I have to get it right the first time I do it and that quest led me to this forum and specifically to this thread.I think LeeN and Magoo are logical,intelligent members of this forum,I'm sure there must be others.

Scotty

P.S. If this post seems narcissistic,it is.Hopefully I will stay out of Phil's dog house.

<img src="/forums/images/graemlins/rolleyes.gif" alt="" />

Hope that was a veiled reference back to the fire hydrant. <img src="/forums/images/graemlins/lol.gif" alt="" /> <img src="/forums/images/graemlins/lol.gif" alt="" /> <img src="/forums/images/graemlins/lol.gif" alt="" />

You know, this whole discussion, while elucidating a few myths and improperly applied formulae, also showed a huge lack of common sense for several parties...

As a money saving measure, the only way you're going to know exactly how much force you are applying to an extension of the handle is by keeping it perfectly perpendicular and adding weights, thereby circumventing your ability to tighten it (lack of rotation of your tightening lever), or by knowing exactly how much force you can generate--not likely. I've hand-tightened bolts before and tested them with a torque wrench out of curiosity. I've been well over 100lbs of torque with a 10-12" wrench. We're talking servo motors or hydraulics, maybe even a pneumatic system, with a very good control system. You can't touch a system like that for the cost of a good torque wrench.

Further, by adding an extension to the torque wrench, you lose a percentage of the torque, but who cares? You know it's going to be a loss of torque, and you are given a range to torque a fastener to. Set your wrench just above the top value, and keep the wrench as parallel to the fastener as you possibly can. You'll eliminate as much torque loss as possible. Double check it with the formula, if you don't feel comfortable. If you need more than a foot of extension, you probably need a better access point or further disassembly to do the job correctly.

Geez-us! Post the theoretical crap on the Talk side. Let's talk practical apps and real work on the Tech page. <img src="/forums/images/graemlins/rolleyes.gif" alt="" />

More repetition of others formulae and not one enlightening thought,frankly Frank I expected as much.You slam my dirt bike? My granny could drive your vehicle, I doubt she has the physical attributes or skill set to ride my "bicycle".I do aver that torque wrench length matters WHEN the extension is other than inline with the torque wrench. <img src="/forums/images/graemlins/cheers.gif" alt="" />

Scotty

Phil, can we vote?