Name-Not-Applicable, to Sliderules
Name-Not-Applicable avatar

I went to IKEA today and found this: the UPPDATERA for 5 USD. It looks like it is intended for knife storage, but look how well it works to keep a few Slide Rules handy at your desk!

david_megginson, to Sliderules
@david_megginson@mstdn.ca avatar

Solving 2×2=4 is the for any slide rule with the basic D and C scales, including the :

  1. Adjust the wheels (or slide) to put 2 above 1
  2. Keeping the alignment, read 4 over 2.

Not so hard, was it? There's a lot of unnecessary mystification around , but they're simple tools at heart.

You can also try this with the online simulator at https://cardboard-computer.org

Closeup of a homemade circular slide rule showing 4 on the outer D scale above 2 on the inner C scale.

david_megginson,
@david_megginson@mstdn.ca avatar

Currency conversion with a slide rule (circular or straight) is also simple. For example, today 1 British pound is worth 20.9 Mexican pesos:

  1. Put 2.09 above 1.
  2. Keeping the same alignment, read pesos above pounds (or vice-versa) anywhere on the wheel

For example, 450 Mexican pesos is approximately £21.50.

Closeup of a homemade circular slide rule showing 4.5 on the outer D scale above 2.15 on the inner C scale.

david_megginson, to Sliderules
@david_megginson@mstdn.ca avatar

I tried a prototype of the with paper glued onto thick, corrugated box cardbord. It's easy to use, but looks messy.

https://cardboard-computer.org

deborahh,
@deborahh@mstdn.ca avatar

@david_megginson oh, just remembered: inkjet ink will blur if you apply with rubbing. So apply wax lightly, thin layer.

deborahh,
@deborahh@mstdn.ca avatar

@david_megginson it's more stable. Not soluble in water. Should be fine.

david_megginson, to Sliderules
@david_megginson@mstdn.ca avatar

prototype no. 2 (advanced version) solving the problem 5×25=75.

I cut the plastic cursor out of some stiff plastic "clamshell" packaging I pulled from the recycling bin.

Lessons from this iteration:

  1. Be more careful drawing the hairline on the cursor next time.
  2. Precise wheel alignment is very important, and I need to cover that more in the DiY instructions.

I'm going to glue these onto cardboard backings.

david_megginson,
@david_megginson@mstdn.ca avatar

@deborahh I get overwhelmed by notifications and clutter myself — modern apps are very noisy (literally and visually) and needy (please pay attention to ME!).

That's why I often make my windows fullscreen on my laptop, so that I won't see anything else, and why I use web sites rather than apps on my phone whenever possible.

deborahh,
@deborahh@mstdn.ca avatar

@david_megginson very few apps have permission to notify me on my smartphone 👍

david_megginson, to Sliderules
@david_megginson@mstdn.ca avatar

What's a Thursday without more news? 🙂

  1. There is now a home page with a virtual version that you can drag around manually to solve problems.
  2. The basic and advanced exercise pages now have help deeplinks directly to the relevant sections in the guide.

(I learned a bit making touch events work with SVG on mobile devices.)

https://cardboard-computer.org

david_megginson, to Sliderules
@david_megginson@mstdn.ca avatar

The is looking spiffy with the @creativecommons CC0 Public Domain Mark attached.

https://cardboard-computer.org

david_megginson, to Sliderules
@david_megginson@mstdn.ca avatar

First working prototype of the , calculating the Answer to Life, the Universe, and Everything.

https://cardboard-computer.org

david_megginson,
@david_megginson@mstdn.ca avatar

The printable templates for the are available now at

https://cardboard-computer.org/templates.html

(There are also PDFs in A4 and US Letter sizes, in case your browser doesn't print properly.)

david_megginson,
@david_megginson@mstdn.ca avatar

There is also a detailed guide, including a very short Quick Start for addition and multiplication:

https://cardboard-computer.org/guide.html#quick-start

david_megginson, to Sliderules
@david_megginson@mstdn.ca avatar

My DIY circular slide rule side project — an excuse to improve my knowledge of CSS3 transitions and SVG — progresseth apace.

There is now a simple version (just multiplication and subtraction) and an advanced version (square and cube roots). It will also animate the solutions to random basic problems on either.

Coming soon:

  • advanced problems
  • DIY printables and instructions for assembling your own
  • detailed instructions

https://davidmegginson.github.io/cardboard-computer/

electropict, to Futurology
@electropict@mastodon.scot avatar

Continuing the excavation...

I knew this was there, and have been thinking it should go back on a wall for the last year or so.

This is probably (1950s?) the oldest device in the house. (With feadan for scale.) No batteries required.

Formerly used at lews.uhi.ac.uk to teach their use, until these electric things came by.

enobacon, to Sliderules
@enobacon@urbanists.social avatar

Did you get a $15k quote for swap from your central furnace? Are heat load calculators really still this hard to use or are sales bros just not doing the work? We had cardboard that did it in the 80's. LMAO just wait for the coldest day and measure it @TechConnectify 🤣

https://www.youtube.com/watch?v=_hAuKtoRxJI

TechConnectify,
@TechConnectify@mas.to avatar

@trachelipus @enobacon This is sadly a real risk with mini-splits. However, if the leak isn't in the coils, that means it's in the lineset.

And if the leak is in the lineset, it's very likely it wasn't installed with due care.

enobacon,
@enobacon@urbanists.social avatar

@TechConnectify @trachelipus yeah unless it is a multi-zone system, you've practically reinstalled it by the time you've cut the lines and pressure-tested both sides of that. Whoever can't find the leak hasn't bothered to take the refrigerant out and test (there are often valves on the outdoor unit that trap the initial charge inside but I'm not sure if they're considered re-usable, they could stop using it for long enough to gauge which side of those valves it's on, assuming it leaks if off.

david_megginson, to Sliderules
@david_megginson@mstdn.ca avatar

Airplane altimeters over-read in colder-than-normal temperatures. If you were on a plane before the digital age and it had to clear a ridge, this is how the flight crew decided whether they were actually high enough to make it.

You don't need to have an E6B analogue flight computer (though it's fun); just hit any key to see the complex steps — one really hoped the navigator hadn't skipped their morning tea or coffee. 🙂

https://e6b.org/calc.html#true_altitude

david_megginson,
@david_megginson@mstdn.ca avatar

And yes, it was dangerous when propeller planes were already flying close to their service ceilings and margins were slim. The Allies lost nearly 600 cargo planes and over 1,600 crew supplying the Chinese army from India during (to the Himalayas. not enemy fire).

https://en.wikipedia.org/wiki/The_Hump

david_megginson, to analog
@david_megginson@mstdn.ca avatar

Among my hobbies, probably the weirdest one is circular slide rules. I was introduced to them 22 years ago when I started flying lessons, and have since branched out from the E6B to non-aviation circular rules. I like them because

  1. they're analogue, and
  2. they remind us of the correct level of precision.

Additionally, they make great fidget toys.

(See also my little website https://e6b.org/ )

nyrath, (edited )
@nyrath@spacey.space avatar

@david_megginson

I have a 1958 RAND circular slide rule that calculates rocket performance. At the link are PDF files one can use to make your own

https://www.projectrho.com/public_html/rocket/engines.php#mrslide

david_megginson,
@david_megginson@mstdn.ca avatar

@nyrath The DC-3 (designed exclusively using ) has never crashed due to a design defect, according to people I talked to at McDonnell-Douglas in the late 1990s. You can't say the same for Boeing's latest aircraft. I suspect there are two reasons for that:

  1. GIGO: People trust the output of computers and skip common-sense sanity checks.
  2. The DC-3 was overbuilt (to be on the safe side), while modern CAD allows companies to cut things closer to the margins for extra $$$.

Name-Not-Applicable, to Sliderules
Name-Not-Applicable avatar

My Pickett N1006-ES. A handy pocket rule!

Name-Not-Applicable, to Sliderules
Name-Not-Applicable avatar

Another of my favorite slide rules, the Aristo No. 867U System Darmstadt. This rule has a pleasant graphical design, and it's a very legible pocket rule. I like that it includes log-log scales, and the P scale is an interesting feature you don't see on a lot of rules. Having the trig scales on the body of the rule adds a wrinkle to using trig scales on a slide rule. You also don't see a BI (1/x²) scale on a lot of rules. This is also me experimenting with Kbin's Microblogging.

Name-Not-Applicable,
Name-Not-Applicable avatar

@_picklefork_ Like I say, I’m just experimenting with Kbin to see how things work, what gets better engagement, etc.

I meant for /m/Sliderules to be a continuation of r/Sliderules. I considered setting up a server for a slide rule community, but I don’t think it would get the exposure or discoverability that a social site like Reddit or Kbin gives it.

There really doesn’t seem to be an online slide rule community except for r/Sliderules. I don’t want to divide r/Sliderules, but I do want to give the community an alternate gathering place for those who don’t want to be on Reddit.

We’ll see what the future holds for the slide rule community. This might not get enough traction to make a difference. It also might be the beginning of something big!

Cthululemon, to random

I sure love slide rules. Endless things to relearn about logarithms. Beautiful to behold, pleasing to use and play with. Fun to collect. My favorite more modern one has to be the venerable Pickett N600-ES (it’s been to the moon! Kind of!), which I keep on me much of the time. Here it’s telling me that my voltage regulator was dissipating 5.6 watts before it died.

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