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Slide Rules. Collecting and discussing. 13

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Skogsgurra

Electrical
Mar 31, 2003
11,815
SE
Hello all,

You are invited to share views and thoughts about slide rules. I have been collecting these devices on a rather small scale and had fifteen of them when my collection took a quantum jump. I was visiting the local book store to buy a book on flowers (yes, flowers) when I happened to ask the store-keeper if he perhaps had any slide rules. He gave me a puzzled look and then said "Yes, I found a box with some forty old slide rules yesterday. I haven't decided what to do with them yet".

Need I say that I saved them from the scrapheap? I got a substantial addition to my collection at a price that we both were very pleased with. He because he got anything at all and I because I paid about a tenth of what I had expected to pay.

I have mostly European and Japanese slide rules. Faber-Castell, Aristo, Sun-Hemmi and some less known makes like Graphoplex (French), Diwa (Danish), Royal Slide Rule (British) and Eco Bra (can't make out from where it comes).

There is a certain standardisation among slide rules. There are the scale systems; Mannheim, Rietz, Darmstadt, Electro, Disponent and some other special systems. There is one that intrigues me. It is called Tachymeter and seems to have been used by surveyors. And there are probably many more that I haven't discovered yet.

The slide rules from the BHP era look very much the same except for the introduction of the Duplex slide rules in the late fifties/early sixties. That was also when some colour was added - except for the "reversed" scales (increasing from right to left instead of from left to right) which seems to have been coloured red for a very long time.

It was only AHP that design people started to make the slide rules more and more attractive. Mild colour coding, more scales and cursor lines, extra functions, friction areas to ease handling, table stands and more was added to keep a market that everyone probably already knew was lost. The last slide rules produced were sometimes monsters - or beauties - depending on your personal preferences. I, myself, think that the Faber-Castell 2/83 N (the N is important here) is a beauty. It is the longest 1 foot SR produced, I think. It has 30 scales and it even smells good!

Another favourite is the little FC 67/38b 400 grad Tachymeter. It is a favourite mostly because it is so enigmatic. What are sin.cos and cos2 scales used for? They are probably there for some very valid reason - as is the 1-cos2 scale. Anyone that has information about these scales?

Collecting slide rules appears to be the retired engineer's perfect hobby. We know a lot, but not all, about the objects. We can appreciate the good workmanship, the precision, the artistery and the ingenuity that went into their design and production. And we know how to use them!

There are a few other reasons that make them ideal collector's objects: They are no more produced. They are still available - although in limited quantity. They are not bulky - can be carried with you when meeting like-minded. There will probably never be a fake slide rule - it takes a very complex production facility to make slide rules and the last factory was closed in 1975.

It is a little like collecting Fabergé eggs - only so much cheaper and more interesting.

Comments and answers invited! Do you collect slide rules? Do you have specific knowledge about any special slide rule? What makes do you know about? How do you find them?

BHP = Before HP.

Gunnar Englund
 
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Were your model numbers different? The Teletype model ASR 33 is what I remember to be 110 baud and paper tape.

We had a Macrodata MD-104 memory tester that was programmed via paper tape. We'd sit on the ASR 33 and type in the codes, but if we made ANY mistake, we started all over again. Thank goodness we finally found a way to do electronic editing on a different paper tape puncher.

Anyway, senior yr in high school, we had something called Engineer's Week, and I got an honorable mention (not sure what I did to compete, tho.), which was rewarded with a brand-spanking new Pickett aluminum slide rule in a faux leather case. Really nice... Unfortunately, I had already pestered my mother into sinking $150 for a TI SR-50. Whoa, momma!!!

Of course, merely 1 yr later, I was pestering her for another $150 for an HP-27, which was programmable, and therefore, infinitely better.

TTFN



 
No, same model numbers. I just had forgotten about the Automatic Send Receive and used the generic TTY for Teletype.

Yes, a mother's love used to be an infinite source of new gadgets. And still is. Although it is my children's mom we are talking about nowadays.

Gunnar Englund
 
One thing a lot of people miss in discussions about the slide rule days and the days before a slide rule became practical and inexpensive(???) was the use of graphics in solving problems. This applied to both real and theoretical problems.

Looking at some of my fathers books from the 20's very complex mechanical problems are resolved by a graphical solution using only algebra, trigonometry, and geometry and of course the logs. He had solved some very complex mechanical motion problems using graphics and plotting some of the results.

f you carry this theme further to when you and I began our careers the slide had became more readily available and usable, but the one thing left out of most discussions is the profusion and availability of good technical graph papers. A slide rule and the proper graph paper were a potent combination in resolving fairly complex problems. The engineering group had a very large cabinet with every conceivable type graph paper and in another area the process group had another cabinet with a slightly different inventory. Graphing was the spreadsheet of the day. Every engineer had to attend a production chart (graphs) meeting at least once a week where as the production group went everyday. After accounting the quality control group got the first shot at all new computer technology and really went wild when they could start doing some statistical control functions. Changing the scales and limits to fit the data and making their point.

As I’ve stated my first engineering application on a main frame was the expansion of the McCabe-Thiel diagram. To develop the data to have punched into the computer we took numbers off an existing diagram, used a slide rule to verify that point, ran the program, reploted the diagram, then took more numbers off the new diagram and then took the slide rule to convert them to useful engineering functions.

You see a lot of recommendations on this site recommending that a particular problem be modeled. Well we sometimes modeled a problem graphically by using multiple axis and scales to see where two functions converged or diverged. I have extrapolated data by eyeballing a curve through a raft of plotted data and then using the resultant curve for data points in slide rule calculations. All with what must have been pretty good accuracy as some of the equipment is still running after 40 years.

I just visited an office supply store and they had exactly two types of graph paper. Up to the mid 80's our companies standard engineering work sheets and log books were printed on grid pattern paper. By this time we were telling new engineers that the grids were to make them write legibly.

You probably remember that the 6" pocket slide rule stayed around for a few years after the larger rules dropped out. They didn’t start disappearing until the personal multifunction calculators could extract a square root. They were all gone when the nat log scales came on the scene.
 
Oooohh yeah...

We've got a beaut of a nomograph for one particular problem in TV performance modelling against an airborne target. There are actually 9 (yes, nine) 2-d graphs on a single 11x17 sheet of paper. You start on one graph and follow the directions through the other 8 in sequence to determine the design requirements given the target and atmospheric transmission. There's log-log, semi-log and linear graphs all in the same nomograph. It's truly a thing of beauty...

It's also quite sad to see those 5 and 6 place logarithm tables languishing in the used book stores.

TTFN



 
Graph Papers... Yes. They demended some sort of artistery from the user. And the funny thing is that the user turned into an artist - sort of.

I once had a very good shareware program named "GraphWriter" in one of my computers. I had even paid a small registration fee for it. But now I cannot find it out there. Wasn't it GraphWriter? Or was it something else? I loved it. Could do anything - and is probably a lot more universal today. Anyone knows about it?

Gunnar Englund
 
Thanks IR,

No. Not one of those. This, I think, was a Swiss or French guy that had made a very nice program for all kinds of graph papers. For calendars, music, smith charts, lin/log, log/log, weibull and what have you. I may be mistaken abiut the name. Will search more some other day. Now we are off to search for slide rules in the flea markets of western Sweden. Wish us luck!

Gunnar Englund
 
Hello all;

Here is an intersting link, they have a rule on a wrist watch.
I have a K & E, 68-1251 Log Log Duplex Decitrig Rule with leather that I recently aquired. Willing to depart with it if anybody wants to barter.

When I was in college we were restricted to calculators with no more than two memory registers, A and B. What a comparison to current mobile computers and yesterdays slides.

Today you will have to pry TK Solver "from my cold dead hands"!

_______________________________________
Feeling frisky.........
 
Well, I didn't previously frequent this forum, and only came over here because of SlideRuleEra's thread on the New Orleans pumps. Didn't know what fun I was missing.

My main sliderule in college was a 10" K&E Decilon plastic rule. Plastic was very good in the humid and hot deep south. Nothing like going to a test, and it rained that day, and your bamboo slide rule was swollen and stuck.

I transferred to the university from which I graduated from a military academy where I had been issued the K&E. The predominant rule where I finished was Post with a smattering of Picketts. I could work circles around the Post guys with my K&E. Those natural log scales were wonderful. (not that I could use them today)

When I graduated I did not want to carry that 10" on construction jobs, so I got a 5" K&E Decilon in a pocket carrier with clip. I used it until I got my first HP which was a 35 or a 55, I can't remember. It had a 10 step programmer. Thought I had died and gone to heaven.

Wnen I bought the HP, it cost a months salary, and wouldn't really fit into any pocket except the inside pocket in a suit jacket. I didn't wear suits to work, but I did wear a tie.

The company wouldn't buy us the calculator, so those that had one in our engineering dep't used their own personal equipment. So, when we had a really big crunch project, I would show up with my slide rule. It infuriated the chief engineer that I did not bring in my calculator that day, but since they wouldn't issue me one, it was my choice.

Now, an interesting story: when at a Plate Hx conference once in the early '90's, I made a statement contrasting some design differences between them and shell and tube Hx's that had to be remembered, mentioning in the process that I had had some shell and tube design experience in a previous life.

At the dinner that followed, a young engineer sitting next to me made the statement; 'I remember you...you were the one who said he had a S&T design background. Did you use B-Jack?' To which I answered "no, I used a slide rule." He replied 'I have heard of those.'

I have a client about my age who commented to me once "every now and again I get my slide rule out of the drawer and throw it up on my desk just to remind me of who the heck I am." I now do the same from time to time.

I also have a simple Post slide rule that I used in High School, and one other one that I could not find which is a 4" or a 5", again, with very few scales.

I also have a Fisher valve sizing slide rule. Remember those?

rmw



 
Valve sizing slide rule. I have one, but I don't use it much anymore, it sits next to my Pump-jack sizing rule, and my "choke calculator" rule.

I also have a circular compressor-sizing slide rule that I still use every day. I've never thought of it as a "slide rule", but it is. I've got the arithmetic that it uses built into a MathCad file, but I find the slide rule a lot easier to get right.

David

David Simpson, PE
MuleShoe Engineering
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

The harder I work, the luckier I seem
 
Slide rules come in all styöes and sizes. I found a "mug rule" today. A Jorgensen designed mug which can best be described as a cylinder with graduated rotating rings around it. A very nice thing - but it cost me more than fifty bucks. I still think it is worth it. Never seen anything like it before. What is the weirdest slide rule you have met?

Gunnar Englund
 
I have three, all purchased for my own use.

One is from high school. It is only a little 6” long plastic one. I kept it and later used it to calculate gas mileage. (That was when we still thought of gas mileage in MPG and bought the stuff in liters and had the odometer in kms, so a little conversion was in order.) Many a gas pump attendant looked on in disbelief that a stick could be used to do calculations.

I have a cheap circular one from when I took my pilot’s license. It has the basic scales on the perimeter and can do vector addition on the circular part. (wind and velocity vectors to give true ground speed and heading)

Finally I have a Geotec Versalog, a true engineering slide rule. I bought it when I started university in 1973, paid $CDN 100 for it and used it until Christmas when I got my first calculation, a Commodore model that only had the basic four functions plus square root. I still carried my slide rule and used it to look up trig functions, until I got a full featured calculator a year later.


Rick Kitson MBA P.Eng

Construction Project Management
From conception to completion
 
Thanks Rick, I think that mastery of that circular slide rule is still needed if you want to be a pilot - the Breitling and similar watches seem to reflect that.

I am still curious about strange slide rules that you may have - or have used.

I have one circular one (square plastic with circular scales and a "hand" that serves as a cursor. It has a scale system that goes from 0.01 up to 1000000. Yes, one hundredth to one million and you can do calculations on it without having to keep track of the decimal point. At least as long as you do not leave the 0.01 - 1000000 range.

It is marked IWA 1638 system Wern. You guys ever seen one of those? Any historical data?

Gunnar Englund
 
Interesting discussion about sliderules. I actually use two sliderules at work for doing calculations for the forging shop. I have a big sliderule that I use at my office and a smaller one that can be used on the shop floor for fast calculations. I use the sliderules for calculating weight, length etc for large forgings. The ingots we use here are octagonal or 16-sided. We also forge things with octagonal shape or similar. To make the calculations faster I have made some marks on the rule for “square”, “octagonal”, 16-sided, circular etc. I have tried to use my HP48SX for these calculations but it’s much slower than the “real thing”. I even made some programming in the 48SX to speed things up, but still the rule is faster. At the moment I’m doing a VBA Excel application to see if that’s the right way to gain speed, but I still believe the rule will win the competition. By the way I would like to mention that I’m just 29 years old and graduated this spring. The first thing I learnt at my first “real” job was to use the rules to make fast calculations… I work as a process- and production developer in the steel industry in the middle of Sweden.
 
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