Slide Rules

Re: Slide Rules

Dan Donaldson

>It has been a long time since I saw it, but if I can find it, I have a pamphlet that is the best tutorial I have seen on the slide rule. I still have two of them, a 6 inch, and a 10 inch K & E, still with the leather cases. I used them in school until my senior year in College, when the calculators became a bit more available. (My first real calculator was an HP45 in the leather case, which I still have)

With calculators so readily available now, it probably is not going to be a lot of use for you, especially given that it is limited in the significant digits that it can handle. That said, it is an excellent way to understand logarithms and also to see many math relationships in a way that makes them understandable. I used to have fun racing guys with calculators. If they were constrained from using the built in functions and actually had to work the problem, I could have the answer to a rectangular to polar conversion before they could get it punched in;-)

Feh!

Michael R

>Big problem with slide rules is that they are only good to three significant figures. I grew up with them, and can see no earthly use for them any more. No faster than a calculator, and not nearly as accurate.

Michael R

Re: Slide Rules

Skip in Falls Church

>IMO, keep up with the slide rule - they're fun. I still have a couple of them although I haven't used them in years. (My dad gave me a round one a long time ago - that one is really fun.) It's really fun to do continuous operations by switching scales. I'll check and see if I still have a set of instructions somewhere if you want.

Skip

Re: Slide Rules

Dale Stansbery

>Notice how everyone says they're fun, but they don't use them any more? Same here, and there's a good reason. It's not quite the same as using hand tools (slide rule) verses power tools (calculators). It's been 25-30 years since I used one, and probably couldn't multiply two numbers any more.

Re: Slide Rules

Todd Stock

>I keep a Post Versalog in the office and a Faber at home just in case of local suppression of EMF; however, I almost never have to use them.

I do use a circular slide rule on a weekly basis...an E6-B flight computer. Used to love to see my students fumble with a calculator to do fuel burn or holding pattern calculations...the E6-B is way faster.

As to three sig figs...good enough for most engineering applications...that's what a safety factor is for, right?

I'm not a total Luddite...15C, 28C, 28S, 32S, 32SII, 41C, 41CV, 41CX, 42S, 48SX, and a 48GX. Never can tell when RPN calcs will no longer be available, so good to have a backup.

Re: Slide Rules

Jerry Nicholson

>I have two Post slide rules right here in the drawer and that is probably where they will stay! I was using one of them in college 50 years ago. You must worry about RPN even more than I do. I only have an HP11 (HPs first LCD scientific calculator), a HP32SII, and an HP33s. Prior to the HP11, I had an HP35, HP45, and an HP55. Actually, I still have the 55 but it quit working about 15 years ago.

Jerry

Re: Slide Rules

Todd Stock

>I've kept each of the calcs I purchased over the years, plus the 'give-aways' from retiring engineers.

Re: slide rules, even my dad - much more a working engineer than most - only used his slide rule for figuring his paycheck after the pocket calculators came out in the early '70s.

Re: Slide Rules

John Pappas

>Ray, I have a circular slide rule that I occassionally get out when I want to get a quick glance at proportions. Set 1 opposite 1.6 and you can quickly see some ratios that would work in designing a piece of furniture. In this case, faster than a calculator. I still have the instructions and would be happy to mail them to you if you would e-mail me your snail mail address. The essence is the same for a circular rule and a straight rule. Even if you didn't use it much you would have fun.

John

Napier's Bones!

Jorge Castaneda ~ Downeast Maine

>I grew up playing with them, you can do a lot with it and it never needs batteries and it is not affected by black outs. The main loss is that is a wonderful tool to help you think and to be proficient with it you need to develop you mental calculating muscle, you can get to the point that you are working with 4 decimals and think nothing of it, with the slide rule you have to understand the workings of trigonometry and logarithms and stuff that are not even taught anymore, but they are still valid tools; true the TI-89 OR Excel can do a lot but belive it or not the slide rule is a lot faster, the electronic calculators are great for complex calculations, but to help you think the slide rule excels. I still have one or two somewhere, I encourage you to learn to use it and have a good time doing it.

Jorge

Re: Slide Rules

Todd Hughes

>I'm way to much of a slow head to ever figure out how to use a Slide Rule or even to be to sure of what they do....I was smart enough last year when I saw an old K&E slide rule that I thought was a little different to throw it in a pile of tools at the auction at the last min. Got it for basicaly nothing......sold it on the ebay for $1,900 about a week later .....Todd

Re: Napier's Bones!

Jorge Castaneda ~ Downeast Maine

>Ray,

I just found yhe 6" one, (5" on the markings), it is a Uto Duplex, a danish job and it still has the instruction sheet with it, if you want,I can scan it and send it to you. Somewhere I also have a 10" K&E, if I find the instructions I can send them too, but they are going to be almost the same unless they have different scales. The advantage of the 6" one is that can go in your shirt pocket, the 10" one is more of a desk object, but it is easier to figure out the decimals more accurately.

Jorge

Re: Napier's Bones!

Jerry Nicholson

>When I was in college you hung your 10 inch slide rule in its leather case from your belt. Post also had a 20 inch but that was considered to be a bit much. I think I paid $20 for the 10 inch Post in 1954.

Jerry

Re: Napier's Bones!

Jorge Castaneda ~ Downeast Maine

>Jerry,

I got my first 6" K&E in 1949 and it cost $50.00 pesos, I did grow up in Mexico City, that one stayed with me through high school and into the service where I gave it to a friend after I got my first circular flight computer.

Yes 20" is too much of a whooper, even the 10" hanging from your belt must have felt like a dagger. I did work for a while as a land surveyor and the 6" in my shirt pocket was part of me, then I worked in a machine shop where you have to work in "tenths" 1/10 000" that was fun too.

Now I seldom have to compute anything... :(

Re: Slide Rules

Todd Stock

>So...flush and ready to buy $50 chisels, right?

Amazing what obsolete technology will go for on EBay. Ever since the $500 empty McIntosh Box, I've had to wonder.

Re: Slide Rules

Bob Hutchins in Central Texas

>Howdy Ray! (you whippersnapper, you!)

Google for 'slide rule instructions'. Some results are interesting, others not so very much.

Looked on eBay and found this:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=14018&item=6163265177&rd=1

Sorry, don't know how to 'snipurl' or 'tinyurl' this. If you do, please tell me.

HTH

BobH

Re: Slide Rules

Todd Stock

>The Post Versalog manual is still available from a number of used book sellers, and is a good guide to this sort of thing. Hard bound, and under $15 - even for a mint copy. Ordered a copy from Borders, and had it in a day.

Best thing about slide rules is that it requires the user to develop a clear sense of the magnitude of the result. Often, all that is required in a first order analysis is something like "...10,000 angels CAN dance on the head of a representative straight pin." Calculators and computers have deemphasized the skill; however, I consider it pretty useful.

Simple Instructions On Line:  *LINK*

Don Thompson - Cutler Ridge, Florida

>


Basic Slide Rule Instructions

Re: Slide Rules

Jorge Castaneda ~ Downeast Maine

>Todd,

Thanks for posting, I just ordered a copy of the Post Versalog under $6.00, That will help me remember stuff. Hey, I bet it is an excellent way to fight Alzenheimer's...

Re: Slide Rules

Ernie Miller Topeka

>I have a smale pile of the 6" one sitting on the sharpening bench if any one wants one give me a jingle and I'll drop one in the mail to you you will have to get the instructions on line or frome some one else though. it you go to sales these things are like ink pens that don't work in a junk drawer they just keep pileing up. I have sold some versalogs with the book for some pretty good money but the small plastic ones don't sell.

Re: Slide Rules

William Duffield, on the Cohansey

>They're great at multiplying and dividing, trig, exponents, etc., but severely limited at addition and subtraction, so you should look into obtaining and learning how to use an abacus as well as the slide rule. An abacus can be so much faster than an adding machine (calculator) it'll make your head spin. They don't have the three significant digits limitation, which can make a difference to those counting red and black beans.

Re: Slide Rules

Todd Stock

>Huh? What were we discussing?

Engineers and accountants

mike recchione

>Good point, Bill. For engineering, 3 significant figures was all you needed, and anything more precise than that was down in the noise. Doing mental addition and subtraction to 3 significant figures is pretty trivial, so I never found the addition/subtraction thing much of a limitation on the slide rule.

On the other hand, getting things right to the penny, even when the numbers being added/subtracted are orders of magnitude apart was/is very important to bean counter types.

I grew up using slide rules, but I didn't have much experience with abaci until my son got interested a couple of years ago. It turns out these simple tools are also very interesting and useful for many operations. I made him a couple of different kinds to play with, and we had some fun learning to use them.

One of the interesting things about using the abacus is that you do calculations from most significant to least significant digit, rather than the paper and pencil way of working from right to left. When you think about it, this is also the best way to do mental arithmetic. The answer gets more precise as the process is carried out, and you could theoretically stop whenever the answer got "close enough".

The point is that these old tools develop a feel for quantities and their inter-relations that is lost in the calculator age. It wouldn't be a bad thing for everyone to learn to use both the slide rule and the abacus. But I'm still not throwing away my old 15C (which sits on my workbench in the shop now, and is officially a naturalized neander tool), nor my MatLab either :-).

Re: Napier's Bones!

Don Thompson - Cutler Ridge, Florida

>My first year of college (1972), affordable calculators did not have trig functions, so I had a slide rule AND a calculator hanging from my belt.

Talk about geeked out...

Re: Question on abacus construction

William Duffield, on the Cohansey

>Mike, when you built the abacus, what methods did you use to get all the beads of consistent size and shape? Somehow, it seems that a very consistent feel for each bead would be essential for ease of use. If I were to make one, which I have been toying with for quite a while, I think I would use ebony for the beads, and wouldn't want to waste it making beads of different shapes and sizes.