Extension Recommendations

[PugetDude]

Extension is essentially a solid shaft made of steel. If you want to calculate the "twist" also referred to as "angular deflection" - here is the formula for solid shafts.

https://www.engineeringtoolbox.com/torsion-shafts-d_947.html

Let's look at this formula and what it means.
L= length of the shaft - longer shaft, more twist.
T= torque - more torque, more twist.
J= is a geometrical factor calculated for shafts - bigger J, less twist
G= modulus of rigidity - bigger G, less twist


G is called - modulus of rigidity.

Here are all the examples of "steel" from the table in the link above;



Notice how similar the number is for different types of steel. In all likelihood the variation you find in steel used in extensions is so small it's impossible to detect or feel. Even difficult to measure with advanced equipment.

So basically, take a look at any extension, the only thing you need to know about it regarding twist is the diameter and length. And notice according to the formula above the twist or angular deflection is inversely proportional to the diameter in forth power. Meaning - small increase in diameter makes BIG difference in twist (less twist actually).

Ps
This formula is only valid in the elastic zone and tells you nothing about when your extension fails. Then different material properties come to play.

Olafur, good analysis, but you left out "snapunobtanium" the miracle alloy used in all Snapon tools. Snapnobtanium's unique ability to increase yield strength, notch toughness, torsional load, and corrosion resistance is only activated by special cryogenic conditioning bins on the ice cream truck. . , and continues to increase in direct proportion to the length of time the purchase is financed.

 

[Olafur]

Olafur, good analysis, but you left out "snapunobtanium" the miracle alloy used in all Snapon tools. Snapnobtanium's unique ability to increase yield strength, notch toughness, torsional load, and corrosion resistance is only activated by special cryogenic conditioning bins on the ice cream truck. . , and continues to increase in direct proportion to the length of time the purchase is financed.

Thanks!
Yes I have to rethink the whole situation.

Perhaps this formula works better: Aθ is perceived twist for extensions.

Aθ = T / (X*Y*Z)¹²

In this formula we still have torque T - more torque more twist.
Instead of length (L) and diameter (D) we got new variables:
X=Price in US dollars
Y=Number of tool trucks, selling said extensions in North America
Z=If made in USA=1; else =0

Thing to notice about this one is if X,Y or Z are zero - twist jumps to infinite number and the extension falls apart!
Because if X is zero - well, there is no such thing as free lunch!
We all know the only usable tools come out of tool trucks so Y can't be zero either.
Z is self exploratory, just can't be zero.

Finally if none of them are zero you will hardly feel any twist at all!

 

[nbpt100]

You guys are a hoot! LMAO

 

[noid]

Tried asiing this before but I am looking for extensions that don't or minimally twist over longer lengths, last thread turned into a debate about what was actually happening. I keep reading good reviews for Toptul, Genius, Nepro tools. How do these brands compare to say Carlyle? I'm ising Carlyle as the standard because I tried their extensions and they were similar in 'twist' to my harbor freights.

It wasnt a debate. Science is rarely debatable. Physics doesnt care what you think.

 

[JUNK-MAN]

I have older snap on knurled extensions, thay are much better than cheaper ones I've had. That's my suggestion.

Sent from my SM-G930V using Tapatalk

 

[Zewnten]

Sorry I don't suffer from"snapunobtanium", as noid said this is one thing where there is no debate (if this is not in reference to me then i apologize and you can ignore the following, but i cannot think of another way to take it) I only finished two years of mechanical engineering and blacksmith as a hobby on the side so I am not a metal expert by any means but I do know that when one taps two metal rods of similar dimensions with similar force and the rods produce separate notes/tunes/pitches, that is due to the different crystal structures in the two rods because of different metallurgy, forging, and heat treatment processes. Now that isn't to say one company can't come close to making a similar product as the first or that the first company is the only one that can. I was looking for those comparable products.

And I'm sorry Noid, but for me the other thread was a debate along the lines of not answering what was asked about comparable products. Your posts and others were not addressing the topic instead I was told I was using the wrong tool and then given a lesson in stress mechanics, especially the part when you were talking to T45, (but T45 addressed my question in his first post on the thread.) I do not like the "snap" I feel when an extension loads from the force I'm applying and twists and I want to avoid the twisting as much as possible, that was the extent of it. Instead i was told to go slower.

And I'm sorry if this comes across snippy but I don't care for threads turning into: off topic debates that have little to do with the thread, tool brand bashing (unless empirically deserved), or overly defensive posts, when the person may have been trying to go about the problem in a different way (this thread and the other). Because communication in typed word can easily be misconstrued by simply using the wrong word, I generally think that if what I type is not taken as I meant it, then I have done a poor job of communicating my thoughts or intentions and try to clarify it, the purpose of this thread.

 

[Zewnten]

And yes this is the internet and people will be ? and one must have thick skin in dealing with their posts but I came to this forum to learn from people smarter and/or more experienced than I, so that we are not all making the same mistakes over and over and can move on to our own new and original screw ups.

And thank you to everyone for their constructive responses, they were helpful.

 

[noid]

The reason your question is so hard to answer is because you cant have a high modulas of elastocity by just switching brands.

Either you have to change material or go thicker.

Depending on how much you want the twist to go away, you can design an extension in CAD (or pull an already designed piece) and get it machined from a tungsten rod.

It wont be cheap, but it will give you low flex for the same thickness of material.

 

[General Geoff]

The reason your question is so hard to answer is because you cant have a high modulas of elastocity by just switching brands.

Either you have to change material or go thicker.

Depending on how much you want the twist to go away, you can design an extension in CAD (or pull an already designed piece) and get it machined from a tungsten rod.

It wont be cheap, but it will give you low flex for the same thickness of material.

And it will give zero warning before it shatters into a thousand pieces under load.

 

[stercorarius]

The reason your question is so hard to answer is because you cant have a high modulas of elastocity by just switching brands.

Either you have to change material or go thicker.

Depending on how much you want the twist to go away, you can design an extension in CAD (or pull an already designed piece) and get it machined from a tungsten rod.

It wont be cheap, but it will give you low flex for the same thickness of material.

You can if one brand or the other has a thicker extension or a different material. Like you guys said even 1/32" makes a difference. Just make a recommendation of a solid extension. If you think every brand has identical extensions you have had a vastly different experience than me.

To answer your question OP. I don't recall which ones you have tried, but I have good luck with proto and SK. I work on semis and heavy equipment so I usually have bigger clearances to work. I can get an impact on most ****** bolts. I know that isn't an option for you so take my opinion with a grain of salt. The main reason I use these brands are the knurling and the eBay availability. I did notice some twist on a Honda crank pulley bolt the other day. Disclaimer: this only comes from using them. I didn't take them to a lab and have them test them and every other brand for me.

Maybe, since there seems to be an interest, we move the science of the matter outside of the thread to a new one. There everyone can go and post model numbers of extensions they own and get an exact diameter measurement and steel specs if so offered by the manufacturer. I know I'd be interested and willing to contribute my measurements. Then we can find out which extension truly is the theoretically "best' extension and leave this thread for extension recommendations?

 

[PugetDude]

If you want a scientific answer, round up a bunch of identical size extensions from the brands in question, and send them to a local materials test lab. They can test and record torsional, yield, and ultimate strengths and provide you with a matrix of measured values.

Or you can just ask random strangers on the internet, get a wide variety of subjective, brand-biased answers and then choose the answer that you like the best.

Good luck.