PICTURE -- Big vs. small impact wrench

More likely if the big guy was off balance when he tried to pick the tool up. ;~)

Yeah. ;~)

Badder than the latest "Hulk"

That is correct. When I was operating the 1" impact drives I was 22 years old and a heafty 125 lbs. dripping wet with sweat. I will say that the first time I looked at it I was very intemidated. One of the mechanics told me that if I can simply lift it I would have no problem after that. After grabing and holding on for dear life I was shocked at how little effort was actually required.

In all seriousness, you should get your hands on a large impact and have your wife film the event. You will "look" like a he-man, then let your wife operate the tool and you do the filming. Don't show that one to your buddies. ;~)

Might I add, be sure to actually have the impact doing work vs. just spinning up.

A few weeks back at Lime Rock, I was surprised to see far, far more

I remember seeing DeWalt, Milwaukee, and Makita, with about 75% DeWalt.

There were a mixture of teams, ranging from Joe Gibbs, Roush, and various factory (Subaru, Acura, VW, BMW, MINI, etc...) road racing teams, to privateers with open trailers. The use of cordless drivers was pretty universal.

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As an aside, has anyone seen the Milwaukee .mwv file of the sports car racing, and pulling in for a pit stop? The mechanic takes off the wheel, and when he goes to retorque the wheel, the whole car flips over and slams on its roof. Very nicely done, and very realistic. I have it in my files, but don't know how to post it. It used to be a URL.

Steve

Yer right. My comments were just a general statement about power tools, and not any one in particular. But even if it's a simple pry bar, you have to admit someone who knows how to use it RIGHT will use less effort than some big Bubba who just uses force.

Steve

This the one?

Interesting thread.

The REALLY big bolts, are never tightened with an impact wrench. The two halves of a steam turbine casing in power generation (hundreds of thousands of horse-power) are held together with bolts. They are tightened by hand. Really. Just a small 2-3 foot spanner. No impact nonsense. Some bolts on the high pressure side are 3" to 4" in diameter x anywhere to 18" to 24" long. Tightened by hand. Un-done by hand. But there is a trick to it. A hole, in the middle of the bolt, runs length-wise and is about 3/4" in diameter. Therein lies the magic. Also, those bolts are polished at the ends, which are very flat... for yet another reason.

But alas, I said too much already...

oooweeeeooooo

rrrrrr

That be the one. Funny, and well done.

Steve

Yeah, I was just going to look to see if wikipedia had an article on them. Very interesting, thanks.

That last design they describe with the "rocking hammer" I couldn't really understand from the description they gave but it sounded a bit like what I was thinking including the idea of using two hammers.

On the standard design however, it's clear that the torque to spin up the hammer is constantly being transfered to the operator and the reason it doesn't produce as much torque as delivered to the nut is simply because the energy is stored up over a longer period of time as it spins up the hammer and then delivered in a very short period of time to the nut at a much higher torque. As was already said, it's just like using a hammer where the impact of the hammer creates a much greater force than the operator had to apply to the hammer.

Didn't NASA have to design powered wrenches that would work in space without causing the astronaut to spin in cycles?

I recall that they had come up with some designs, but it looks like what happens in the real world is that the astronaut secures himself somehow. The Hubble Space Telescope has special mounting points for the foot-braces that are used during servicing.

Yes, the same setup is often used on ship engines, for example to attach the cylinder head to the cylinder.

Indeed. Often without any form of gasket.

I didn't see the show, but I have to weigh in here. A heavy recovery vehicle doesn't have tires, it has tracks. ;-)

Your statement indicating that you've never looked at the design, explains why you don't understand the actions involved, and why the rest of your theories about the tools' actions are incorrect.

The rotational direction of the striking parts is not reversed, doesn't change direction (unless the user changes the direction of the output to reverse the direction of rotation of the fastener).

The striking parts work with other parts to deliver glancing blows to the driven parts (output shaft).

BTW, the impacting action doesn't start until the fastener exhibits some rotational resistance/opposition to the tool's output (the fastener being installed becomes seated, a self-locking fastener, rusted or damaged threads, or a seated fastener needs impacting force to loosen it). However, mechanics that frequently assemble threaded parts cross-threaded, will experience the impacting action more often.

The practice of starting the fastener for the first couple of turns with just finger power generally eliminates the possibility of cross-threading the fastener.

Normally, the tool acts like a rotational driver unless a high(er) driving force needs to be applied.

Typically, some torque can be felt by the user that holds an air-operated impact wrench not attached to a fastener, and gooses the trigger to wide-open repeatedly, just to hear the tool's exaust noise. This torque is caused by the tool's air motor rotor jumping from zero/low speed to full speed, and the counter force of compressed air acting between the tool housing and the air motor's moving parts.

WB ......... metalworking projects

...You must have missed the part where I said it was more of a joke than a serious post, right? I'm not going to debate the issue when I wasn't putting myself in the position to defend it in the first place.

However, you are right. Technique and proper use / skill does mean a heck of a lot more than some or maybe even most people know.

Regards, Joe Agro, Jr. (800) 871-5022

We agree on that.