How to Use an Adjustable Crescent Wrench?

I was taught exactly what you are saying... (I.E. the book is wrong) and that the force applied to the movable jaw of an adjustable wrench should be on the "low end".

--.- Dave

What should be "intuitive" is that resulting torque is applied in a direction that draws the work back into the jaws rather than away from them. Bob Swinney

I was taught that you should turn the nut so the force is on the inside end of the adjustable jaw, as you were.

Remember: With rare exceptions a Really Good textbook writer will make significantly less money than plain old good mechanic. Unless you have a good mechanic who's also a good book writer, you're going to get a book with poor writing or poor content. If you find a technical book with good writing and good content it's because someone was donating his or her time to humanity, not because they were making out like a bandit.

This applies to my book, too. It's been in print for a bit under a year, and I think my earnings from it are in South America or Mexico (i.e., at this point I've probably earned 50 cents for every hour I've spent). I doubt that I'll ever be able to point to it and say that I made minimum wage for writing it.

So why'd I write it? First, because my dad and brother are (or were) both volunteer firefighters, which I will never be. So it's my small way to contribute to society at large. Second, because I get some marketing out of it. Third, because for some people authorship is a disease, and I'm one of them.

Wikipedia gives both viewpoints without really favoring either one. Intuitively it seems to me that the fixed jaw should lead the direction of rotation but I remember reading an explanation furnished by a wrench manufacturer (maybe Diamond) that with this position there was a greater tendency for the movable jaw to pull out of it's channel.

My intuition is that it's a totally symmetric situation. The forces applied by both jaws are the same and applied at the same angles. Otherwise they'd move due to the unequal forces. Assuming the force acting on the handle is strictly normal (perpendicular).

Imagine this: you put the wrench on and snug it. Apply force on the handle and the jaws spring a little. Which jaw "moves" is totally irrelevant, the only thing relevant is that they are a little further apart and a little out of parallel, so contact is more toward the corners. With the slop out and everything rigid, it "looks" just like an open end wrench.

It doesn't matter which orientation is used.

That's my story and I'm sticking to it, Bob

Ohhh, I'm wrong! Tim Wescott has the answer: contact on the adjustable jaw should be at its base. Assuming that the adjustable jaw is springier than the fixed jaw. Contact on the outer end of the fixed jaw will cause less spring than contact on the outer end of the adjustable jaw.

Eating his words, Bob

I agree with Robert Swinney. If you think there is a problem because you are putting more stress on the moveable jaw, you need to use a bigger wrench. Think about 15 degree open end wrenches where both jaws are fixed. Use those so there is no tendency to have the wrench slip off the nut ( unless of course you need to use it the other way because it is the only way you can get the wrench in that awkward space ).

Dan

I'm not seeing where that "drawing back into the jaws" comes from Bob. Can you elucidate please?

I've always found Stillson wrenches much more understandable.

Always remember to hammer with the round edge and not the pointy one.

Steve

Use it as a hammer on a combination wrench.

Is that a variation on the old saw:

"Those that can, do. Those that can't, teach"

In fact, is doesn't matter. Some guy a Notre Dame, I think, made an entire copy of a Crescent wrench out of Plexiglas and put it in a Schlieren camera. This allows you to see stress on the material as fringes of color. He showed the peak stress in the wrench was pretty much the same either way, although in different spots. So, there really isn't a whole lot of difference, at least if the wrench is patterned pretty much the same as the old Crescent design. I think they showed this in Scientific American sometime in the 1970's, but my memory might be faulty. It sounds more like a Popolar Science sort of article.

Jon

I can see the theory that you'd want the force close-in on the movable jaw, but I was always more influenced by my experience with bent-nose slip-joint pliers.

When used with the handles past the angle of the jaws, they seem to self-tighten onto the work and provide much more torque. You are pushing on the handle that is supporting what would be the movable jaw of a Crescent wrench, and very little squeezing force is required on the other handle with its jaw hooked around the work.

My newest 12" Crescent brand wrench from maybe 15 years ago came with a rotation arrow cast into the handle, which clinched the argument for me. It suggests the same direction as your textbook and my slip-joint pliers.

On a possibly related note... Is there a similar advantage to the pipe wrench design where the movable jaw slides diagonally through the handle and the jaws end up at a 90 -15 degree angle relative to the handle, over the design where the sliding jaw moves parallel to the handle and the jaws are at 90 degrees?

Loren

Loren sez:

"> My newest 12" Crescent brand wrench from maybe 15 years ago came with

Naw ! That little arrow is a tiny clock symbol which states how many milliseconds it takes you to say "S*IT" after you bust your knuckles with the damn thing.

Bob Swinney

Ditto what Loren said. It's the same effect with Channellocks or pipe wrenches, one way they grip, the other they don't.

Pete Keillor

And those that can't teach teach teachers. Per my wife that has an M Ed. ...lew...

I've checked all 4 of my adjustable wrenches and none of them have that arrow. Now I'm feeling jealous!

I use mine when I shut off the water at the meter. I slip the wrench over the valve and then use the other one on the handle of the first one to apply the torque. One of these wrenches is a cheap import and I can get a really good twist in the handle this way.:>)

Well, that's right from the horse's mouth I guess.

I visited:

Jeff