Why Do I Need 1000+ ft lbs in an Impact?

[Mandres]

Hey Bull, imo there's no need for a non-professional to spend big bucks on a fancy new impact gun.

Grab an old IR 231c for $50 on ebay or CL. They were the gold standard for many years and mine has yet to come across a bolt it couldn't remove, but I'm just a shadetree hack. In the unlikely event I ever have to deal with a Honda crank pulley I have a breaker bar and an 8ft. cheater pipe to jump up and down on...

 

[jvitez]

I had no idea 90 psi max meant no load/full speed either. This is an excellent thread: two bits of very useful info I didn't know. I love GJ! Thanks guys.

 

[zkling]

Since we all like pics.

Friend called me on the way home today, said his brakes were making a funny noise. Stopped by and I used old faithful below to zip the lugs off without hesitation.

One of these days when I find a good deal on an older USA made 231 I would like to upgrade, but for now this has not let me down, except for that honda crank bolt. Probably one of the best $10 (new clearance at Lowe's) I spent for the garage. Yes I realize the Matco socket is probably worth more than the impact itself. That is from a very generous member on this forum.

Just showing that you don't need a $200+ impact to get things done, like some folks seem to think on here.

 

[TwoInch]

i recently used a buddies CH that looked very similar, if not identical to that gun, and it did everything i asked of it. i wasnt busting axle nuts or crank bolts, but i felt it had plenty of power, and i was very surprised. i expected it to be terrible and weak. seemed much more powerful than my cheapo Cman rated for 450ftlbs or whatever it is.

 

[zkling]

Yea, I have been very happy with it for considering what I paid. I do keep it oiled and properly fed (3/8 line, high flow couplings and ~18cfm comp) so that probably helps. It is really a time saver. I would say ~65% of the time I use it for rusty bolts on misc stuff, other ~35% lugs and the like. Very rarely do I use it in right hand mode. Has yet to really let me down. Just throwing it out there for those like me that can't spend $200+ on an impact.

 

[TwoInch]

i have been watching locally for a "good" impact to show up at a decent price. i also cant afford/wont justify spending 200+ bucks on an impact. i will spend $75 for the same impact in good used condition though. i am not a pro though, and i surely would be buying a top of the line impact if i were.

i may also end up with an earthquake. i have been back and forth with a used IR or similar, or a brand new earthquake for some time. i am sure either would fit and exceed my needs just fine. i am sure bull would be completely satisfied with those same options.

 

[CWP1616L]

My next impact is gonna have an extended anvil so I can use my Matco flip socket that I never get to use.

 

[b7labelle]

Eh, not really. Torsional rigidity is a function of the length of the shaft. Although the reaction force is the same at the opposing end, with an impact, the impulse is lost along the length of the shaft due to the short duration impulse, basically the shaft is acting as a torsional spring (as mentioned above) causing the impacts to appear less. Which is the first place why you use the impact. So those that say they notice a reduced performance with extensions, that makes sense.

do you even know what impulse is? It is the integral of a force with respect to time. Yes, the shaft acts as a spring, but it does not rob torque. If the reaction force is the same at both ends, so is the applied torque. The actual force may not be the same, since that is dependent on the radius of the torque arm.

 

[CWP1616L]

do you even know what impulse is? It is the integral of a force with respect to time. Yes, the shaft acts as a spring, but it does not rob torque. If the reaction force is the same at both ends, so is the applied torque. The actual force may not be the same, since that is dependent on the radius of the torque arm.

Dude.....that's some seriously technical stuff. You oughtta be teaching a physics class somewhere.

 

[b7labelle]

Dude.....that's some seriously technical stuff. You oughtta be teaching a physics class somewhere.

Not trying to sound pompous, but I have a mechanical engineering degree. And a strong interest in tools.

This topic drives me insane.

 

[volvo92906]

Just showing that you don't need a $200+ impact to get things done, like some folks seem to think on here.

... Lucky if those lugs are torqued to 100lbft.

You need a $200+ impact to get things done if you use it the majority of a 40 hour work week breaking bolts that are torqued to a few hundred foot pounds. There are quality impacts for a reason. Marketed toward professionals.

Those cheap little flex joint pipe like socket wrenches that come with an OEM tire changing kit get the job done too... But they wont last very long with every day use.

To each his own, really.

 

[CWP1616L]

That NitroCat Mini looks interesting. 1/2 inch drive in a 3/8 body. 900 ft-lbs.

 

[firebox40dash5]

Not trying to sound pompous, but I have a mechanical engineering degree. And a strong interest in tools.

This topic drives me insane.

It can drive you nuts all you want, but the fact remains that in the real world, using an extension = loss of power transmitted to the fastener, and the longer and skinnier the extension, the more noticeable the difference.

 

[zkling]

do you even know what impulse is? It is the integral of a force with respect to time. Yes, the shaft acts as a spring, but it does not rob torque. If the reaction force is the same at both ends, so is the applied torque. The actual force may not be the same, since that is dependent on the radius of the torque arm.

EDITED, even if is the truth.

Not trying to sound pompous, but I have a mechanical engineering degree. And a strong interest in tools.

EDITED, even if is the truth.

If constant torque was applied to the shaft (Ie with a breaker bar). Since you like to talk in differentials. Df/Dt=0 since f is constant with respect to time. Yes you would be getting all of the toque at the reaction force (nut end) no matter how much angular deflection you put into the shaft (extension).

NOW the issue with the impact wrench is.....

Specifically under the section "Effects of Impact drive"
http://en.wikipedia.org/wiki/Impact_wrench

EDITED, even if is the truth.

The actual force may not be the same, since that is dependent on the radius of the torque arm.

Toque transmitted along a shaft is the same NO MATTER THE SHAFT DIAMETER. Now the angular deflection and thus stress will be different, but you could use a 1/4" or 1" extension and still transmit the same torque. Obviously the 1/4" is going to twist like a pretzel much sooner than the 1" will.

It can drive you nuts all you want, but the fact remains that in the real world, using an extension = loss of power transmitted to the fastener, and the longer and skinnier the extension, the more noticeable the difference.

It is very easy to calculate. What you are experiencing is expected. No surprise there.

 

[zkling]

... Lucky if those lugs are torqued to 100lbft.

You need a $200+ impact to get things done if you use it the majority of a 40 hour work week breaking bolts that are torqued to a few hundred foot pounds. There are quality impacts for a reason. Marketed toward professionals.

Yea and I am sure my little impact wrench wouldn't work for you application. When I pull a front end loader or other large equipment in my driveway for a tire rotation I will then probably have to upgrade. Untill then I was just providing a suggestion for those that can't spend that much on a impact, nor do they need that much torque for taking the lug nuts off of their 4 door economy car. Different tools for different applications. I typically don't use a sledge to hang a picture frame, likewise I usually don't use a tack hammer to put stakes in the ground.

 

[Bull]

Holy ****. Do I have to lock my own thread?

Now, zkling, a cardinal rule here is that no personal insults are allowed. Any of us lose the upper hand if we come across as being unable to disagree without being insulting and, you know, coarse.

 

[zkling]

Holy ****. Do I have to lock my own thread?

Now, zkling, a cardinal rule here is that no personal insults are allowed. Any of us lose the upper hand if we come across as being unable to disagree without being insulting and, you know, coarse.

I'm sorry, I just get irritated when people try to "call me out" and really have no clue what they are talking about. Would you like me to edit the above response?

I edited the above post. Again I apologize, just got a bit hot under the collar for a moment. If you want me to further edit it just let me know.

 

[crewchief888]

It can drive you nuts all you want, but the fact remains that in the real world, using an extension = loss of power transmitted to the fastener, and the longer and skinnier the extension, the more noticeable the difference.

as does the use of impact wobble sockets


sorry i dont have a degree in anything.

only 30 years of experience

 

[purplezr2]

Yea and I am sure my little impact wrench wouldn't work for you application. When I pull a front end loader or other large equipment in my driveway for a tire rotation I will then probably have to upgrade. Untill then I was just providing a suggestion for those that can't spend that much on a impact, nor do they need that much torque for taking the lug nuts off of their 4 door economy car. Different tools for different applications. I typically don't use a sledge to hang a picture frame, likewise I usually don't use a tack hammer to put stakes in the ground.

I have seen my 2135TI IR fall to take off lugs that are suppose to be torque to 90 ft-lb, but even if they were at 200Ft-lbs if should have had no problem, that is the effects of rust and never getting a tire rotation. (I was not the owner of the car).

 

[Bull]

I'm sorry, I just get irritated when people try to "call me out" and really have no clue what they are talking about. Would you like me to edit the above response?

I edited the above post. Again I apologize, just got a bit hot under the collar for a moment. If you want me to further edit it just let me know.

Maybe just edit the whole thing so that it reads more like a higher-road approach to demonstrating superior knowledge or divergent views or whatever. Because you know, a good teacher can't belittle or insult when he is trying to teach.

Also, the other fellow appears to use a large fax machine as a cell phone for muscular selfies, so tread carefully!

 

[zkling]

I have seen my 2135TI IR fall to take off lugs that are suppose to be torque to 90 ft-lb, but even if they were at 200Ft-lbs if should have had no problem, that is the effects of rust and never getting a tire rotation. (I was not the owner of the car).

Look, y'all can hate on my cheap little impact wrench all you want. I am just reporting my personal experience with it. That is all. Not telling you to go out and buy one because somehow I get kickback on it. Just putting my opinion out there. That is it. Maybe I got one built on Tuesday by the top assembler. All I can say for certainty is that for $10 I spent on it, I have got great service out of it for the past ~5 years. I actually want to upgrade to a nice used USA made IR wrench, but I really don't NEED to if this one will do all I need it to.

 

[redwrench60]

LOL, good lord guys. Sometimes all the education in the world won't match real world experience. Listen to me: I spend all day every day using 3/8' and 1/2' drive impacts, air ratchets, die grinders, cutoff wheels, air chisels and more and I'm telling you with absolute certainty that the use of extensions and wobble sockets reduces an impacts ability to break loose fasteners. I'm not saying this based on any degrees or theorys I have, I know this because I live it every day.

 

[KinzeMech]

I think part of the confusion here comes from the layperson using physics terms. Many don't know the physics definitions of force, work, and power, and which one is a derivative or integral of which other one, yet the does not stop them from using these terms in common speech.

For example, the claim that impact extensions "rob torque". Before you analyze a statement like that, you have to realize if that statement is not coming from an engineering literate person, you cannot interpret it as strictly literal engineering terminology.

I think what is meant here is the phenomenon we have all seen, where with an extension, or several, an impact is unable to loosen a fastener. Removal of extensions results in the impact then being able to loosen the fastener.

In physics terms, what has happened that has resulted in the difference? It is not correct to say "extensions rob torque" as if the extensions/sockets are not undergoing an acceleration, then the torque applied at one end must be equal and opposite the torque applied at the other end, but something has happened to make the difference. Something about removing the extra extensions has had an effect that allows the impact wrench to remove a fastener it otherwise couldn't (does anyone hold this statement in dispute?)

 

[redwrench60]

No dispute, Kinze. I've even seen a difference with extensions with different diameters. The thinner the extension the more it flexes torsionally. Switch to one thicker and you get some power back, quite often it's just enough to get it done. That's why i got away from Snap On's 1/2'-3/8' reducing extensions, they're too thin and soak up too much torque.

 

[The Ratchet Man]

1. An extension that flexes at all can transfer the energy to both ends. Some energy will go to the fastener and some will return to the impact. Put one end of a torsion bar in a vise and affix a bar to the other end. Hit the bar with a hammer and some of the energy will be transfered to the vise while the rest of the energy will be transfered back to the hammer.

2. We all know that when hammering on a stubborn bolt with an impact for an extended period of time that the socket and attachments get hot. This is due to flexing and clearances at each point of connection. Stacking clearances was mentioned a while back but those clearances also create heat when the male and female ends move back and forth against easy other, creating friction. When heat is created, energy is used. Any energy being used to create heat is not being used to remove the fastener. If you were to weld all connections solid you would have a much more efficient extension, but that's not feasible. The tighter the joints, the more efficient the extension.

While the argument that extensions don't cause energy loss might be somewhat true its only because the wrong point is being argued. I say somewhat because any extension that flexes causes heat internally from the particles rubbing against each other, again, using energy to create heat.

Bull, to answer your original request, i have never used an Air Cat. The Earthquake from HF is a nice gun though and can be had for $69 if you find the right coupon. It should take care of most of your needs.

 

[firebox40dash5]

as does the use of impact wobble sockets


sorry i dont have a degree in anything.

only 30 years of experience

There's gotta be a good reason why a bigass hand sledge is called an engineer's hammer.

 

[zkling]

I think part of the confusion here comes from the layperson using physics terms.

For example, the claim that impact extensions "rob torque". Before you analyze a statement like that, you have to realize if that statement is not coming from an engineering literate person, you cannot interpret it as strictly literal engineering terminology.

No confusion here. Just one person that thinks mentioning the mathematical definition of impulse and stating their education background is reasoning for their wrong explanation.

Extensions do not rob torque to say, they DAMPEN (dissipate) the impact/impulse/hammering action that the impact uses to loosen the fastener in the first place. Any bar of any length that follows hooke's law is a spring. This is why people notice a dramatic reduction in performance when adding extensions and other fitting between the output of an impact and the fastener to be removed. I mentioned this quite a few pages back.

So the impact / extension is the rotating component. If we were to think of this in a more linear or straight line manner it would be like using a hammer and hitting a surface, then adding a spring or multiple springs and then hitting the spring that rest on the surface. Add in a few gaps to simulate the connection of extensions and now the intensity of the impact at the surface is greatly reduced, especially when frequency is increased.

 

[zkling]

There's gotta be a good reason why a bigass hand sledge is called an engineer's hammer.

Yea, because it solves all the problems.

 

[TwoInch]

Not trying to sound pompous, but I have a mechanical engineering degree. And a strong interest in tools.

This topic drives me insane.

how do you explain torque sticks?


im curious...

 

[kriwoel]

"Why Do I Need 1000+ ft lbs in an Impact?"
I don't need that , but somebody else do and even go higher rate... hydraulic
http://www.tjtools.com.au/hydraulic_torque_wrench.html

 

[rodm1]

harmonic balancer bolts and Pinion Yokes.

 

[b7labelle]

EDITED, even if is the truth.



EDITED, even if is the truth.

If constant torque was applied to the shaft (Ie with a breaker bar). Since you like to talk in differentials. Df/Dt=0 since f is constant with respect to time. Yes you would be getting all of the toque at the reaction force (nut end) no matter how much angular deflection you put into the shaft (extension).

NOW the issue with the impact wrench is.....

Specifically under the section "Effects of Impact drive"
http://en.wikipedia.org/wiki/Impact_wrench

EDITED, even if is the truth.



Toque transmitted along a shaft is the same NO MATTER THE SHAFT DIAMETER. Now the angular deflection and thus stress will be different, but you could use a 1/4" or 1" extension and still transmit the same torque. Obviously the 1/4" is going to twist like a pretzel much sooner than the 1" will.



It is very easy to calculate. What you are experiencing is expected. No surprise there.

Thank you for referencing a Wikipedia article with some solid source information.

DT/dt is an average, or the slope of the torque increase upon strike or when the anvils pass..should be pretty high value. You are still applying torque.

I want to apologize for upsetting you. Obviously this is a very critical discussion and everyone's emotions are running high.

After think about this some more, I do not believe the loss of torque comes from the gun, extension, or the color if the impact. It comes down to how STILL you can keep that gun. Doesn't matter how long the extension is, you need to be able to hold the gun still for all the torque to be transferred. Like you mentioned, a breaker bar is the ideal tool, as there is no recoil causing the users arms to flop. A thicker extension should have less deflection.

So to conclude...hold the gun still.

Come on boys!

 

[volvo92906]

how do you explain torque sticks? im curious...

Torque sticks are made to spring at a desired torque setting. The theory of their design, their twist, and their torque are built into the little package you know of as a 'torque stick'.

 

[b7labelle]

Also, the other fellow appears to use a large fax machine as a cell phone for muscular selfies, so tread carefully!

Should see the one I took with a copying machine.

 

[Wakefield]

The hammer impulse or kick or whatever from the gun does not finish winding the torque stick or extension up all of the way before the gun starts to relax before the next kick. So full torque with full windup never happens.
(My take on why the airgun doesn't act like a constant sustained torque source like a steady pull on a breaker bar when coupled through something that acts like a twisting spring)
Jumping on a springing bouncing breaker bar might have a little of the same effect?

If you were to run an airgun for a long time through a torque stick would the torque stick warm up just a little bit?

(Edit) the thought occurs that if the anvil is not held very rigidly,that is if it doesn't encounter resistance that keeps it from turning even part of a degree or so against springy resistance perhaps it doesn't develop full torque.

 

[zkling]

Thank you for referencing a Wikipedia article with some solid source information.


So to conclude...hold the gun still.

Come on boys!

No you are just wrong, plain an simple. That is all there is too it. I would have been fine, but when you had to bring up the BSME or is it BSMET? that put me over the edge. You still didn't answer the "how do torque sticks work" question.

1.) You don't know
2.) It goes against what you said earlier.

Which one is it?

So far I don't think you have said one intelligent, correct or useful thing in this thread.

Started with the wrong

Swivel sockets yes, straight extensions...not so much.

Kept going

The actual force may not be the same, since that is dependent on the radius of the torque arm.

And finished off

So to conclude...hold the gun still.

Congrats it takes talent to be wrong in almost every post in one thread.

 

[SuzukiGS750EZ]

I say get an impact and use it. The
HF earthquake will serve you well. When I went to buy an impact gun (albeit I worked in a shop), I weighed options. Price, weight, power, reliability and use ability all were visited in my decision. It was basically between IR and SO. I've seen a few snap on guns have to go back (mg725) due to things beig broken. My grandfather sold his because they would wear out. Two of the experienced mechs in the shop rocked ingersoll ti guns, but I didn't let that determine for me. Having used a snap on gun of one of the other guys it was bulky, loud and top heavy. The IR guns were less loud and balanced. I got teased all the time by the snap on fan boys telling me to "get a real gun". In reality it was them justifying spending 3x the amount I did and regretting it. I do like the anvil brake on them, I'll give them that. They would also remove the baffling to make it louder, basically saying "hey, look over here at my gun". I bought the 2135 timax (quiet version). It's served me well and I've lent it to the snap on guys once in a while. When I was going to buy my cordless, I also was back to snap on vs ir. Having used snap on cordless and an ir in shop I had a pretty good idea of them. I liked the snap on 3/8 with the light on it, a ton of power, solid built and a pleasure to use. The IR was light but didn't have the same power as the snap on. So then I sat and thought about what I wanted to do with it. I got the IR W7150 vs the snap on. Price was better, power was better and what the heck, I already have a deep and shallow metric IR socket set as well as the air impact, mays well complete the collection. I kind of want to sell the air impact and buy the 3/8 cordless.

 

[TwoInch]

Torque sticks are made to spring at a desired torque setting. The theory of their design, their twist, and their torque are built into the little package you know of as a 'torque stick'.

i completely understand how they work, i am simply asking this b7labelle character to explain them, how they work, and how a regular extension does not do the same thing, only at an unspecified rate.

how bout it b7labelle?

how does a torque stick reduce applied torque when used on an impact, but transfer 100% when used on a breaker bar?its well understood concept, but i just gotta hear it.

 

[Conductor562]

 

[TwoInch]