PICTURE -- Big vs. small impact wrench

[Leon]

> I held it as hard as I could.

Do you have a better link? For me, that only played the sound.

[Leon]

The principal of the impact action is the same regardless of the size.

Precicely, but again that assumes tha tthe impact is operating properly.

I don't remember my mechanics very well, but I do recall that the mathematics of "impulse" is different from simple statics. Many shots from a BB gun can move a floating aircraft carrier but the shooter never feels more than a minor recoil VERY many times. The energy delivered is large but in tiny, rapid increments.

That breaks it down pretty well.

[Leon]

No, they are pretty simple tools, they make an electric drill look complicated.

Logic is correct but not for this particular tool. Take a look at a schematic of an impact.

[Leon]

impacts.

[Leon]

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

[Leon]

Yeah. ;~)

Badder than the latest "Hulk"

[Leon]

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.

[Leon]

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. ;~)

[Leon]

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

[B A R R Y]

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

18V impact drivers in the pits and garages than air versions.

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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[SteveB]

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

[SteveB]

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

[William Bagwell]

This the one?

[Robatoy]

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

[Tanus]

I've been watching this thread and figured I didn't have any real experience with the tools you guys are discussing. However, when I was

22, I also worked a tool that, while not identical, was similar in workings. I think. I worked underground in a mine and we used what were called "jack-legs". Similar to a jack hammer but with a pneumatic leg that ran out the bottom of the machine on a backward angle to plant itself in the ground, giving the machine forward thrust.

A bit on varying lengths of drill rod was attached to the front and the machine drilled holes in a rock face to allow explosives to blow the wall. We drilled 8-10 feet typically and then loaded with powder.

IIRC, the hardest part was similar to what Leon is saying; pick it up and get the hole started. Then try to catch your breath and replenish the quart of sweat you just lost. Turn the machine on and relax til the hole is finished. Torque on the leg (and the operator) was so minimal as to be insignificant. But man, did it drill.

Tanus

[Robatoy]

Meh... my grandfather discovered a machine that can take an entire tractor-trailer apart in 5 seconds. He calls it a locomotive.

[SteveB]

That be the one. Funny, and well done.

Steve

[Tim Douglass]

Hmmmm.... Learn something new every day. The only ones I have ever seen were basically just a turbine & gear reduction.

-- "We need to make a sacrifice to the gods, find me a young virgin... oh, and bring something to kill"

Tim Douglass

[Tim Douglass]

Sounds like a story behind that...

-- "We need to make a sacrifice to the gods, find me a young virgin... oh, and bring something to kill"

Tim Douglass

[Curt Welch]

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?