Slide rule

gpoehlein said:

Anyone remember the old HP calculators with reverse Polish notation? (I'm not making that up and it ISN'T an ethnic joke!)

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I still use (and love) my HP15C. I even bought the App to have on my iphone (although the real one is so much better). Those calculators without RPN still screw me up

I seem to recall Seymour Cray mentioning somewhere that he used a "circular" slide rule....I'll have to see if I can find mention of the make and model.

Said he could solve ANY problem with that and Laplace Transforms :grin:

If like me you have read a lot of old science fiction you will at one point have run across the “Hero of the Intergalactic Empire” whipping out his SLIDERULE when he needs to solve some equation.

Clarke, Asimov, Heinlein, J.W. Campbell, Van Vogt, none of them foresaw the coming of the micro-electronic revolution. Faster Than Light Travel; check. Time Travel; check. Force Fields; check. Laser Beam Weapons; check. Nuclear Power in a Bottle or better still Fusion!!!; check Yet no pocket calculators apparent.

jpummil said:

...a "circular" slide rule....I'll have to see if I can find mention of the make and model.

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Look up an E6B.

jpummil said:

I seem to recall Seymour Cray mentioning somewhere that he used a "circular" slide rule....I'll have to see if I can find mention of the make and model.

Said he could solve ANY problem with that and Laplace Transforms :grin:

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Pictures

The biggest advantage is the slide spirals around making it effectively longer. On my binary slide rule, the primary scale is 4 feet long. Of course, I don't know how to use it though.

Back when dinosaurs roamed the earth, (aka 5 years ago) I used a slide rule in high school calculus class.

Because everyone had programmable graphing calculators, my teacher said "No electronic computational devices allowed."

I was the only one who took him up on that, using one of my dad's old slide rules. Nobody even attempted to use an abacus, however.

sandman said:

Back in the 60's when I was an engineering student at Michigan State all of the engineering students, me included, had a slide rule in a leather belt sheath.

We were cool!

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Indeed you were! My roommate had a 20" slide rule in college. Claimed he could get 4 significant digits of accuracy! Scoffed as users of substandard 10" slide rules. His mother sewed him a quiver for it and he wore it to class like he was Robin Hood. He truly pegged the geek meter on that one. (And I think I was jealous of his ... I guess it was slide rule envy?)

I had a Pickett metal slide rule in that wild yellow-green color (I think it was marketed as easier to read in 5600 Angstrom Green ...). Traded it to a friend for his wood and laminate Post. Still have it.

I posted to another thread tonight when someone suggested having an app to do upscales of designs. The slide rule is a great tool for that. Put your tube diameters aligned on the C and D scale to set the ratio, then get current and new tube lengths by sliding he cursor.

Or you could use a spreadsheet ...

JAL3 said:

When in private practice as an engineer, I kept mine in a glass case on the wall with a sign: "in case of emergency, break glass".

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:rofl: That made my day!

You people are a bad influence! I found a circular slide rule on ebay today and just couldn't pass it up. Kind of a birthday present to myself!

I inherited my grandfathers slip sticks and some drafting stuff, they are fun. I had to program a RPN in my C course in college, I never got it to work quite right. I remember my dad being impressed by the giant slide rule in one of the labs where I went when we did a visit day, looks about the same size as the one Sandman posted.

mjennings said:

I inherited my grandfathers slip sticks and some drafting stuff, they are fun. I had to program a RPN in my C course in college, I never got it to work quite right. I remember my dad being impressed by the giant slide rule in one of the labs where I went when we did a visit day, looks about the same size as the one Sandman posted.

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I like the idea of increased accuracy through giant slide rules. Something like a 50 foot mechanized slide rule would be cool, with markings down to millionths or billionths of a unit. Maybe some neat 50's era control panel with dials and knobs to move the components and with catwalks all around the slide rule itself.

This one is close - 9m scale!

shrox said:

I like the idea of increased accuracy through giant slide rules. Something like a 50 foot mechanized slide rule would be cool, with markings down to millionths or billionths of a unit. Maybe some neat 50's era control panel with dials and knobs to move the components and with catwalks all around the slide rule itself.

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kruland said:

This one is close - 9m scale!

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That's cool too, but I was thinking along dieselpunk lines. A big machine run by guys in white lab coats and safety helmets. Maybe even flashing yellow lights and a klaxon to let you know it's in operation. Something a college or the government would build.

It has to be on rails and be steam powered!

shrox said:

That's cool too, but I was thinking along dieselpunk lines. A big machine run by guys in white lab coats and safety helmets. Maybe even flashing yellow lights and a klaxon to let you know it's in operation. Something a college or the government would build.

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kruland said:

It has to be on rails and be steam powered!

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Diesel. It has to be diesel, with Bakelite handles and moldings. Although it could be powered by a hydroelectric dam, built specifically to run the slide rule. I'd accept that.

I just found this Versatrig 1450 with belt loop sheath at a local used stuff store for fifty cents.
I have'nt the slightest Idea how to use one, and the mere mention of doing math sets my mind a reelin' but I recognized it as a thing of beauty, and wonderfully constructed too, so I had to have it.
Sadly, it had seen some rough handling, as the lens on the back side was cracked, so before I did anything else I threw some clear tape on that to atleast keep all the pieces, lest a replacement not be available. I can mend it with a clear finishing epoxy if I have to.
The front lens bracket was bent slightly, as someone had shoved it into the leather case with the slide down far enough that it was dragged on the way out of the case, so I carefully removed the screws and then the bracket and lens. I cleaned the lens up, then carefully bent the bracket back to straight. It is obviously old, as the case would likely have never been fitted so poorly in it's original state, and the leather, while intact, must have shrunk considerably.
I would like to learn to perform at least one operation with it, and hopefully something related to rocketry, like a scaling equation or something, but I have no Idea what it does, even after reading this thread.
I see them on Ebay for anywhere from $8-$30, but this one looks like it just needs a new rear glass, so I'll try to source that.
Even if I never learn use it, I just love everything about it. It is so nicely made, and you would never guess it is made from bamboo.
It almost looks like they used some form of composite to finish it, as I sense a slight weave pattern on it's surface if the light hits it just right.

I still have mine, too..

Sandman, that giant one in the picture is an instructor's model that hung in the front of a classroom to teach folks how to use slide rules. I recall taking such a class. The thing was crazy accurate, since the scales were so large, they could be lined up precisely.

I found a complete replacement cursor for $40 and the window for $16. I can't get either today, but it's good to see they are available so I can have this one back to original condition when I get around to it.
https://srtco.us/PartsHemmi.htm
On Ebay there are also complete units like the one I got, so I'll keep my eyes open there too.

I have my dad's slide rule. I think he gave it to me in 1964-65.

TopRamen said:

I just found this Versatrig 1450 with belt loop sheath at a local used stuff store for fifty cents.

View attachment 289971View attachment 289972

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Holy cow, that looks just like my dad's. But that one looks in newer shape...I'll have to post pictures later when I dig it up.

o1d_dude said:

I have my dad's slide rule. I think he gave it to me in 1964-65.

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My dad started teaching me how to use a slide rule when I was about 7 years old, to "get a leg up on the other kids." Well, handheld calculators all of a sudden got very affordable, and that never really came to fruition. I've always wanted to really learn how to use a slide rule...maybe when the drought season is fully on us, and I've run out of kits to build (not going to happen soon).

The_Lone_Beagle said:

My dad started teaching me how to use a slide rule when I was about 7 years old, to "get a leg up on the other kids." Well, handheld calculators all of a sudden got very affordable, and that never really came to fruition. I've always wanted to really learn how to use a slide rule...maybe when the drought season is fully on us, and I've run out of kits to build (not going to happen soon).

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My Mom learned to use these in School, as back in her day you went to "Trade Schools" and the like.
She said she was taught the slide rule in 5th, 6th, and 7th grade, before she even was pegged for Art School, where she used some kind of slide rule sometimes in Architectural Drawing.
Nowadays, kids are just told they are smart, even if they are not. They are told they can be anything, even if they really have no talent at anything specific. Society is garbage compared to the days where you were taught to use slide rules, and I often find myself wishing I had been born into this world at an earlier time.

Mike Konshak, CD of NARAM 52 is into slide rules big time.

https://sliderulemuseum.com/

How to use a slide rule by Mike Konshak

https://www.oughtred.org/flyers/OS-ISRM_SlideRuleSeminar.pdf


John Boren

I was well past the slide rule generation, although my mom remembered the first calculators that could do square roots. In my class, it was always a fight between RPN and not. We couldn't borrow each others' calculators. A couple of calculator stories:

In engineering class in college, the prof asks if he can borrow a calculator. Someone in the front row passes him an HP48G. He looks at it for a moment, then says, "Does anyone have a simpler calculator?"

A few years after graduation, a classmate of mine asks me what I thought of an engineer who asked the secretary to buy him a calculator on his first day on the job. The secretary (who knew engineers and their calculators) froze like a rabbit seeing a hawk and asked what kind. The new guy said it didn't matter. I told my friend that the new guy should be fired on the spot for incompetence. He said it took them three months to figure that out.

Slide rules were great. They gave accurate enough results and you never had to worry about dead batteries....... :blush:

Bob

These are pictures of my dad's slide rule, as well as the book I will (eventually) read to learn how to use it.

In all the pictures I see of slide rules and the holders, nobody *ever* mentions the belt loop! Why?

Imagine how cool you would look, showing up at school/work/a night on the town, wearing your slide rule on your belt! "Hey is that a slide rule on your belt...or are you just happy to see me?" LOL

They had a couple of von Braun's slide rules on display at the US Rocket and Missile Museum:
is one

I still have mine. It was a Post made of bamboo. It got me through high school and college. They didn't have digital calculators then.

The_Lone_Beagle said:

In all the pictures I see of slide rules and the holders, nobody *ever* mentions the belt loop! Why?

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Heh. Didn't realize there was such a thing, but it makes sense. The only slide rule I've ever held/used was my dad's (his engineering career started in 1969), but it's one of the round ones. It's not quite like the 'typical' circular rule pictured on google searches I did that are just the wheel, this one's wheel & dial are mounted to a rectangular card, as I recall the card has additional data on it, either for unit conversions or popular engineering constants/equations or something like that (lots of tiny text). Might have had a slot for a booklet (manual or more equations) as well. It was clearly sized to fit in a shirt pocket. So no belt loop for his.

I'm of the calculator age, but could never stand RPN and wasn't too keen on graphing calculators either (the TI-89 seemed to be the popular choice). The calculator I used throughout high school and college was a Casio FX-5000F, which was a great scientific calculator that let you define complex equations, it would ask you to enter each variable then give you one or more results, and had a bunch of built-in formulas as well (for example the quadratic equation, so you enter a, b and c and it returned both the "x1" and "x2" values). At the time it was the only non-graphing calculator banned from use on the standard tests I took that let you use calculators, presumably because of the formula/storage. I somehow managed to lose it on my very last final in college (I used it during the test, and had no idea what happened to it by the time I was back at my dorm). Once I was working during a trip to Taiwan I visited an electronics market and spotted a stall selling the chinese version, the unit itself was identical but the manual was in chinese, so I bought it. Used it for a bunch of years at work but something eventually went wrong with it, even with new batteries it would run fine until you tried to execute a calculation and then the screen would go out. These days I use Spotlight for most calculations, and usually have a Terminal window open running lua so I use that as an interactive session for more complex calculations/equations.

woferry said:

Heh. Didn't realize there was such a thing, but it makes sense. The only slide rule I've ever held/used was my dad's (his engineering career started in 1969), but it's one of the round ones. It's not quite like the 'typical' circular rule pictured on google searches I did that are just the wheel, this one's wheel & dial are mounted to a rectangular card, as I recall the card has additional data on it, either for unit conversions or popular engineering constants/equations or something like that (lots of tiny text). Might have had a slot for a booklet (manual or more equations) as well. It was clearly sized to fit in a shirt pocket. So no belt loop for his.

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Just thinking out loud...you could have a *huge* round slide rule, and carry it around like a shield on your back...kinda like a nerdy Viking raider, ha ha.

re: RPN, the first calculator I ever used was an HP-67 (?) I think it was...my dad had it for work. It was cool, to solve the problem of limited memory, you could save your program on a little magnetic strip (about the size of an address return label) and run it through a strip reader in the calculator. In any event, I learned RPN first, and trying to use a "regular" calculator always takes more effort for me.