Sliding Wrench Leaves a Little to be Desired

[Ben Conrad] received an interesting tool as a gift that purported to be a better mousetrap. It was a crescent wrench (made by the Crescent company, even) that didn’t have a tiny adjusting wheel like a traditional wrench. Instead, it had a slide running down the length of the handle. The idea is that you would push the slide to snug the wrench jaws against the bolt or nut, and that would be fast and easy compared to a conventional wrench. As [Ben] notes, though, it doesn’t work very well. Most of us would have just dumped it in the back of the tool chest or regifted it. [Ben] tore his apart to find out what was wrong with it.

A typical adjustable wrench has four parts. This one has 19 parts and looks like a conventional wrench with an extra slide and screw running down the length of the handle. [Ben] found the parts were poorly made, but that wasn’t the main problem.

While the poor machining caused skipping and jamming of the mechanism, he also found that even with perfect machining, the design was not very good. The jaws of the wrench move about an inch, and the slide moves about 2.5 inches. So that should offer some mechanical advantage, right? It turns out the screw is inefficient and eats up any potential force gain.

On the face of it, the wrench seems like a good idea exhibiting “out of the box” thinking. But the execution seems flawed. You have to wonder, though, how many basic tools could be improved if we would stop and think through without a lifetime of preconceptions.

We’ve pointed out before that if you build a better mousetrap, it had better be better. Then again, why adjust a wrench when you can make one the right size?