Hammer Seeks Nail

People sometimes say “when you have a hammer, everything looks like a nail” as if that were a bad thing. Hitting up Wikipedia, they’re calling it the Law of the Instrument or Maslow’s Hammer and calling it a cognitive bias. But I like hammers…

I’m working on a new tool, a four-axis hot-wire foam cutter based roughly on this design, but built out of stuff in my basement so far. I want it primarily to turn out wings for RC airplanes so that I can play around with airfoils and construction methods and so on. But halfway through building this new “hammer”, I’m already getting funny ideas of other projects that could be built with it. Classic nail-seeking behavior.

And some of these thoughts are making me reconsider the design of my hammer. I originally wanted to build it low, because it’s not likely that I’ll ever want to cut wing sections taller than 50 mm or so. But as soon as cutting out giant letters to decorate my son’s room, or maybe parts for a boat hull enter my mind, that means a significantly taller cutter, with ensuing complications.

So here I am suffering simultaneously from Maslow’s Hammer and scope creep, but I’m not sad about either of these “ills”. Playing with a couple manual prototypes for the CNC hot-wire cutter has expanded my design vocabulary; I’ve thought of a couple cool projects that I simply wouldn’t have had the mental map for before. Having tools expands the possible ways you can build, cognitive bias or not.

One person’s scope creep is another’s “fully realizing the potential of a project”. I’m pretty sure that I’ll build a version two of this machine anyway, so maybe it’s not a big deal if the first draft were height-limited, but the process of thinking through the height problem has actually lead me to a better design even for the short cutter. (Tension provided by an external bow instead of born by the vertical CNC towers. I’ll write the project up when I’m done. But that’s not the point.)

Maybe instead of lamenting Maslow’s cognitive bias, we should be celebrating the other side of the same coin: that nails are tremendously useful, and that the simple fact of having a hammer can lead you to fully appreciate them, and in turn expand what you’re capable of. As for scope creep? As long as I get the project done over my vacation next week, all’s well, right?

22 thoughts on “Hammer Seeks Nail

        1. You have apparently not haunted the hardware section of local “Big Box Store” … those things are all over the place and that supposed “Soviet Linear Screw” is actually quite common on farms and in stables where a standard nail can be easily unseated from the pressures of a large animal…

          Basically, just because you “haven’t seen it” is not a valid reason to think it does not exist in the US There are wide varieties of hardware that are slightly more “specialized” or focused towards different markets and purposes…

          1. There is absolutely no reason to assume that I said “this doesn’t exist in the states”. I have been through the local big box store more times than I care to think about, and I’ve seen similar products screws with expanding inserts “lead heads” that you drive in with a hammer. If these are so common produce a link to one rather than deride someone on the internet.

  1. Don´t know how to enter a drawing here.
    We used to use an “H” made of wood, with the cutting wire between two legs on one side, and a spring in the other two, to keep the wire tensioned.

      1. A turnbuckle must allow for quick release. Heating elements shrink as they cool. A weight or spring is in a way, fancier. Really, a man requires several hammers. Several. I made one of mine with heads that unscrew to swap head material.

  2. Construction technique, OK. Airfoils are kinda meaningless at model scale, computer simulations or NACA wind tunnels aside since you’re never sure where the boundary layer is at: laminar, turbulent, whatever. I’ve never built one that left the critical Reynolds area.

    1. An engineer friend of mine says the same: The Reynolds effect is insignificant at this scale. We make RC planes using flat sheet using only AoA to generate lift. They’re lighter and they fly nicely.

  3. “…they’re calling it the Law of the Instrument or Maslow’s Hammer and calling it a cognitive bias…”

    I think it’s much better than that. You’ve introduced a new element to your world and your brain is busily integrating it into your universe and discovering new uses.

  4. “when you have a hammer, everything looks like a nail”

    I thought it was “when *all* you have is a hammer, everything looks like a nail”, which completely changes the meaning of the phrase as (mis)used in this article.

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