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?

29 thoughts on “Sliding Wrench Leaves A Little To Be Desired

    1. I know some people have the ability to look at a bolt and accurately determine the size. Also, some people seem to have an array of wrenches within reach, so they don’t have to go somewhere to get one.

      I have neither of these things on my side, so an adjustable wrench is a good solution.

      1. Look into the ‘Knipex pliers wrench’, it’s pliers and the perfect adjustable wrench because you don’t have to remove the wrench from the bolt/nut, you simply relax your hand and it ‘ratchets’ in a way. Plus the jaws stay perfectly parallel.

      2. The problem with adjustable wrenches is they have a lot more tendancy to round off the corners of a tight bolt. Then saving a few minutes of guessing and trying different wrenches turns into several hours of trying to remove a bolt with a messed up head.

        Also, tools are a lot less expensive these days than they used to be.

      1. According to Wikipedia, North American usage is different to UK, Ireland, Australia and New Zealand where the usual term is a spanner/adjustable spanners, with a wrench being a specialised tool e.g., tap wrench.
        My father who was a scientific instrument maker, always used (adjustable)spanner for what you in the US call a wrench. He only used wrench when referring to a tap wrench (as in tap and die for cutting threads)

  1. One look at it says the mechanical advantage is horrible. The mechanical advantage of a normal wrench is obviously better, and even a nut driver gains leverage from the difference between the diameter of the handle and the diameter of the shank of the bolt or screw. Whoever designed this thing was not an engineer.

    1. I have a new crescent brand one, not the original they bought out, but for me, it works awesome for holding nuts you can’t see. The quick one hand adjustment let’s you find the size quickly without fuss. It even locks at the end of you give the adjuster a little extra push, locks better than a classic cresent. Right tool for the right job, this thing is not for high torque driving, not any adjustable is, but in my life it’s made things like assembling pre built stuff, especially steeldeck platforms, easier and smoother.

  2. If you want a proper adjustable wrench that slides to fit the nut or bolt, and grips tighter as you apply force to tighten or loosen the nut/bolt, look at the Knipex pliers-wrench. They never round off the corners, and don’t need to be readjusted (or maybe better to say they automatically readjust) with every fractional turn of the nut/bolt.

      1. I have a couple of these and they’re awesome. Not just as pliers, but I tend to use them as a little portable arbor-press too. Flattening metal, pressing inserts into parts, punching, you name it. I’m about to weld a gap jaw onto one pair to enhance that functionality because it’s just so useful compared to a bulky stationary press.

    1. I haven’t used this particular tool, but Knipex brand snap-ring (circlip) pliers that I finally broke down and bought are an order of magnitude better than the ones typically found in a big-box or hardware store. Knipex is more expensive of course, but you definitely get what you pay for.

      Although my adjustable wrenches are decent quality, and I don’t anticipate needing a new one in the near future, nonetheless the next one I buy will be a Knipex.

  3. Weeeel I have one and it sort of works with a little coaxing and cursing. When I bought it I noticed that it was a poor design. I still wanted one so I went through several of them and picked the best one there. Still not good, but doable.

  4. When the local Sears department store was having their going out of business sale I bought a couple tools that look like an adjustable crescent wrench mated with vice grip pliers. How it works is you open the vice grip. Then you adjust the wrench on the bolt head just like you would a normal crescant wrench. Once you have it finger tight though instead of starting to turn the bolt you first close the pliers. This tightens the jaws of the crescant wrench an almost imperceptable amout further. But it’s enough to get a very tight grip on the bolt that you would never get with your finger alone.

    I still prefer to use the proper non-adjustable wrench when possible. But there have been a few times I just didn’t have that available and had to use these adjustable tools instead. I’ve losened tight bolts with them that I was sure I would have rounded the corners off the heads with a regular adjustable crescant wrench.

    Anyway, I am thinking that maybe combining these two ideas could get a best-of-both-worlds tool. The speed of adjustment from the sliding mechanism but still a nice tight fit so as not to round off the heads.

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