Slide rules live! 3

[oldfieldguy]

I was working with my fifteen year old son on a computer problem this weekend and he found an old slide rule on my shelf.

"What's this, dad?"

"It's a slide rule."

"What's it do?"

"Puts men into outer space. Breaks the sound barrier. Builds the interstate highway system. Let me show you how it works..."

And he thinks it's neat. He may never use it, but he knows it exists.

old field guy

 

[j79guy]

I use my Curta Type-I mechanical calculator daily. My (younger) guys in the shop just shake their heads.
Hard to explain what the heck that thing is in my briefcase though, when clearing airport security.

Robin.

 

[ScottyUK]

Bernard,

I did have my father's Commodore SR-4190 (I had to look on the 'net to find out the model no.) prior to that but it looked a little dated among the sleek new types of the late 80's. Image mattered when I was young! It would be worth a bit now I should think.

I've just surprised myself at how little a slide rule costs on eBay - I may have to get one just to remind myself how things used to be done.


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If we learn from our mistakes I'm getting a great education!

 

[WHEngineer]

My high school physics class started with instruction on the use of a slide rule. That was the last time I used a slide rule as I went to college with a HP-65 mag card programmable calculator. I remember trying to program formulas into the calculator during tests, but the professor was always alerted by the buzz as I fed the card through the reader.

 

[plasgears]

As an exercise to those who don't know slide rules:

- Get log paper.
- cut two strips; mark numbers: 1,2,3, etc.
- To multiply, add logs, that is, align one strip with another. 2 x 3 is indicated by setting the one of one stip at the 2 on the other. Read the answer opposite the 3: 6.
Division is by subtracting logs.

The slide rule helps you add logs. You can also read squares and cubes opposite your scale. Square roots and cube roots are read in reverse. Raising to any power is easy but beyond the scope of this intro. Clear?

 

[SomptingGuy]

Should I use two-ply or quilted log paper?

- Steve

 

[IRstuff]

That depends on whether you want to imitate a cheap plastic slide rule or a nice, sturdy, aluminum one.

TTFN

FAQ731-376

 

[ScottyUK]

Which presumably depends on the nature of the job at hand...


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If we learn from our mistakes I'm getting a great education!

 

[C2it]

I chucked my slide rule into the attic when I graduated in 1974 and moved to the Sinclair calculator .. inaccurate and ate batteries. expensive at the time too, so pretty rubbish. Imagine my surprise when 30 years later I found the slide rule, checked it out and a fluids exam cheat sheet floated out from under the slide, covered in tiny equations. Those the bad old days before open book exams !

 

[monkeydog]

Graduating in 1974 would put your eyes in the bi-focal/progressive stage. Just wondering if you could read the tiny equations.

 

[C2it]

Read them .... I could even apply one or two of them !!

 

[djack77494]

I remember seeing an electronic calculator for the first time during my senior year in college. We called it an electronic slide rule, and it could barely do what a good slide rule did. A few years later, I got a metal hydraulic slide rule. One side for liquids and the other for gases. Boy, was I on top of the world.

 

[rmw]

As I sit there day after day and use all kinds of computer software that just zips through calculations, it is kind of hard to remember that it all began for me when I had to do all that with a slide rule. Slide rules could do a lot of things, but they couldn't keep up with units and decimal places.

We've come a long way baby.

rmw

 

[IRstuff]

They're an amusing anachronism, but they can't compare with Mathcad or Excel.

TTFN

FAQ731-376

 

[KENAT]

"They're an amusing anachronism", hmm, I'm not touching that one.

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[IRstuff]

Speaking of anachronsisms, see:

http://www.antikythera-mechanism.gr/project/overview

THAT's an awesome piece of instrumentation, built over 2000 yrs ago. What's even more fascinating is that it took about one thousand yrs before anything comparable was built.

TTFN

FAQ731-376

 

[joyboy]

In 1999 I put a slide rule between two sheets of acrylic with a label on front stating 'YK2 COMPLIANT - IN CASE OF EMERGENCY BREAK GLASS' Left it on my desk for months after.

It is still on my bookcase behind my desk. All the grads want to know what it is, many of them don't even recall a threat when rolling over to the year 2000.

Mike

 

[PeterCharles]

I strongly object to the phrase cheap plastic slide rule!! I just found my old 10" Faber-Castell Duplex 2/82. Cheap it was not!! Reading top to bottom, front to back the scales are -
lgX, tan 0.1X. tan X, X^2, X^2, 100:X^2, 10:X, X, X, arc 0.01X, sin 0.1X, (can't type this one), e^-X, e^-0.1X, e^-0.01X, X^3, X^3, X, 10iX, piX, piX, e^0.01X, e^0.1X, e^X
And to think I used to know what all the scales did!!

I've also got a 5" 62/83, it's very similar to the 2/82 but with "folded" 10" scales on the back.

Of course for accurate work there was always "Inskips Combined Tables" (log tables based on 1ft).

Those were the days

 

[unclesyd]

Nostalgia Week.

rmw,
I once took a class on carrying the decimal point while working with a slide rule. I think I still have the class material, if I can locate it. It was like using an old un-dampened ?Chain-O-Matic? analytical balance when you had to get the 4th decimal place, count the moves to the left and to the right.

This last Wednesday I ran into an old co-worker who could and would use this technique to locate the decimal point. The odd part is the he is not an engineer, but a biochemist and was taught this method in advanced analytical chemistry.

SlideRuleEra,
About two weeks ago I was attending to some business where I met a friend of my brother's who was showing me some pictures of his basement shop, where in his radio room sits a working Collins R390A, the last of the great tube type radio receivers, with a set of Trimm headphones attached. I spent two years in the Army with Trim headphones locked to my head. The next trip up I gave him a box of probably 100 different types of gold labeled RCA vacuum tubes. When he opened the box of tubes I thought he was going to have a heart attack. He said that the majority of the tubes were ones that were getting hard to find.
I am working on a project to recomission my old Raytheon recording fathometer since a friend found a case of paper for it. It is all vacuum tubes and uses a vibrator to generate AC from a 32 DC volt input. All the tubes have been repalced with the above mentioned gold label tubes with the exception of the 2D21 diode. Over the years I have reworked this machine to where it uses no OEM part with the exception of the stylus drive belt, The vibrator is from a GM car, The carbon paper pots are now 3 turn wire wound, the two switches now have gold contacts, the stylus belt drive motor is now a sealed, The chart drive motor has been repalced with a much more robust one, the two contact rails are now solid silver, The warp spring clutch on the stylus belt drive motor has been changed to SS and made a little more robust. the stylus is now Tungsten instead of Steel.

All I have to do now is to find some fish. The last trip this machine made we caught around 2000 lbs of Red Snapper the worth about $2000.00 one weekend. Now you can only have two fish per person if the season is open.

 

[SlideRuleEra]

unclesyd - That is quite an accomplishment. There are so many parts that are no longer available... I can appreciate the "inventiveness" necessary to substitute similar items that will work.

http://www.SlideRuleEra.net

http://www.VacuumTubeEra.net

 

[70AARCUDA]

...my question to calculator users: "What are you gonna do when there aren't anymore batteries for your calculators?"

...my answer: "...go back to using our sliderulers!"