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A nice casual use case for a slide rule is metric conversion: https://americanhistory.si.edu/collections/search/object/nmah_1215014#:~:text=This%20ten%2Dinch%2

A nice casual use case for a slide rule is metric conversion: https://americanhistory.si.edu/collections/search/object/nmah_1215014#:~:text=This%20ten%2Dinch%2C%20one%2D,of%20metric%20and%20conventional%20units https://americanhistory.si.edu/collections/search/object/nma.... Consider that this slide is doing two things for you: it remembers the conversion factor (for a bunch of difference conversions), and it does the multiplication or division.

ddingus 5y ago
I want one of these. Right now, I do this conversion a lot more than usual. Over time, I have mapped many of my familiar Imperial unit touchstone type references onto Standard International units, so I am largely good to go, but this would have been very useful during the process. And what I mean here is just ones sense of scale and ability to mentally estimate and work with familiar ratios to arrive at solid first order approximations. These are important, in that one can set expectations about the answer quickly and accurately. Doing that is a great check on the problem overall and or makes mental analysis quick and robust. It is all the little things, like a sheet of paper being 0.004" or 0.1mm. Looking at something, say to understand whether it can be manufactured, or maybe features are too small or large and fall outside process limits. Or, given a force, something happening, or one suspects may have happened, working backward to arrive at root cause of failure, having that kind of info "in head", useable directly in that internal way, knowing how it might appear, feel, be seen, sound like, is high value. Tools like this really help with all that. Combining the data with motions, the slide, how far, etc all build robust mental connections. It just starts happening. For me at least, I just begin to "know" whether it make sense, will fit, break, etc...
- spc476 5y ago
  I have four slide rulers, and all of them I picked up at various antique shops. The latest one I bought is the same type that the Apollo astronauts took to the moon (Picket N600-ES, about 6" (15.5cm) long). I paid about US$5 for it.
  - ddingus 5y ago
    I will have to go looking. The conversion one would go great with my analog dial metrology gear, most of which was made with imperial units.

ddingus 5y ago

I want one of these. Right now, I do this conversion a lot more than usual. Over time, I have mapped many of my familiar Imperial unit touchstone type references onto Standard International units, so I am largely good to go, but this would have been very useful during the process. And what I mean here is just ones sense of scale and ability to mentally estimate and work with familiar ratios to arrive at solid first order approximations. These are important, in that one can set expectations about the answer quickly and accurately. Doing that is a great check on the problem overall and or makes mental analysis quick and robust. It is all the little things, like a sheet of paper being 0.004" or 0.1mm. Looking at something, say to understand whether it can be manufactured, or maybe features are too small or large and fall outside process limits. Or, given a force, something happening, or one suspects may have happened, working backward to arrive at root cause of failure, having that kind of info "in head", useable directly in that internal way, knowing how it might appear, feel, be seen, sound like, is high value. Tools like this really help with all that. Combining the data with motions, the slide, how far, etc all build robust mental connections. It just starts happening. For me at least, I just begin to "know" whether it make sense, will fit, break, etc...

spc476 5y ago
I have four slide rulers, and all of them I picked up at various antique shops. The latest one I bought is the same type that the Apollo astronauts took to the moon (Picket N600-ES, about 6" (15.5cm) long). I paid about US$5 for it.
- ddingus 5y ago
  I will have to go looking. The conversion one would go great with my analog dial metrology gear, most of which was made with imperial units.