Making Your Own Slide Rule

I have thought about making my own slide rule, and finally did.  This Instructable is partially a description of how I did it and partially an evaluation of the effort.

Step 1

Back in 2008 Instructables member legionlabs published "How to use a slide rule."  In the comment section Instructables member Mr ross made reference to a May 2006 article in Scientific American magazine titled "When Slide Rules Ruled."  Once that article was available on-line in PDF, but has since been removed.  Scientific American still makes it available, but at a cost of about $7 US.  The article included a downloadable PDF file pictured in the graphic for this step.  It is a printout for a fold-up paper slide rule.  I decided I wanted to make one of these just for fun, but mount it on wood and Plexiglass.  After printing the PDF file, I enlarged it with a copy machine to about 150%.  The idea was that the scales would be larger, easier to read, and more precise. 

Comments

[snideprime]

I still have the slide rule I used in college in the 60s...I tried to sell it at a yard sale, but few people knew what it was, and no one wanted it. Even when I marked it down. So I will probably own the thing 'til I die, even as I use the much easier calculator!

[pheenix42]

Do you still have said slide rule? If so, I'd like to give it a new home, if you don't mind! =D

[escher7]

Keep it. It's a classic and they are hard to find new.

[Phil B]

eBay does a brisk business in used slide rules. There are several sites that buy and sell slide rules. A lot depends on what you have and its condition.

[snideprime]

Actually, it makes a good conversation piece. Maybe I'm glad it didn't sell, it brings back memories of a simpler time when I was young and life was in front of me. And, it might be worth more in the future as a relic!

[Phil B]

I am curious. What make and model of slide rule do you have?

I have thought about buying a (used) slide rule for each of my kids and showing them how to use it, but that is also not very realistic. Still, it is fun to show younger people who have never seen one what they are and how they work. I do enjoy reaching for a slide rule and doing a calculation on it.

[snideprime]

I just came across it in a drawer in the shed....it's a Post 1447, in a case/sleeve of fake leather. Still has the instruction book with it. Someday it will be worth a fortune as an antique... a hardly-used antique. I do like the feel of it, even if I never calculate with it.

[Phil B]

Thank you for taking the time to post again with information on your slide rule. At this link you can read some of the details on your rule, and you can click on the small images in the upper left corner to see an enlarged view of it. Although POST was a US company, that rule was made in Japan by Hemmi for POST. That is true of several rules from several companies.

[TheOmegaGears]

a bit to complex

[Phil B]

What about it is too complex?

[Landon Sullivan]

I think it's too complex because it's analog. I personally dislike technology, only use it cause I have to, and I like a few computer games. We sent men to the moon with these things, no reason we can't send them to Mars.

[Phil B]

Digital is great until something does not work. A friend served in an Army Reserve artillery unit. They went out one weekend for drills and all of the fancy computer equipment that does the calculations to aim the guns did not work. The younger guys from the digital gaming generation were dead in the water. My friend and a couple of other old school guys knew how to do the calculations by hand on a specialized slide rule that someone had the good sense to bring along together with the necessary tables and charts. Yes, it was only an exercise, but it could also have been a battle situation just as easily.

[bikerbob2005]

eon ago by internet standards i found a pickett sliderule manual.scanned it and posted it to yahoo groups,it still is online,might be the only one out there.
http://groups.yahoo.com/group/pickett_slide_rule/
do not have to join to view.

[Phil B]

Check the link to my previous Instructable (above). There you can find links to quite a number of manuals anyone can download free, and without joining any group.

[angler]

I love slide rules. I still have my Faber Castell 57/87 in good working order. It took years before the slide & cursor moved really smoothly. Unfortunately my kids glaze over when I produce the device!

[Phil B]

Thank you for your comment and for looking. If you have not seen it, check my other Instructable on slide rules linked in this one. It contains more links you would enjoy. Your Faber Castell rule is very much like the Nestler 23 rule that Albert Einstein, Werner von Braun, and the head of the Russian space program all used for the space race in the 1950s and 1960s.

I know the feeling about one's kids glazing over when you try to show them things like these. I have shown a slide rule to people the same age as my grown kids and they were interested. 

[blkhawk]

Thank you for posting! Back before the modern electronic calculators this was the fastest way to calculate large numbers. Mechanical calculators were made like the famous Curta , but the slide rule is one of the simplest way to perform calculations after the invention of the abacus. During the space missions to the moon you could see the engineers referring to their slide rules and safely bringing those men to earth.

[Phil B]

Thank you for looking and for commenting. I still enjoy the challenge of using a slide rule rather than a calculator for working out a mathematical problem. If you have not looked already, you would probably enjoy my Instructable on refurbishing an old slide rule. It is linked in step 7. It also includes a lot of general information.

[Foxtrot70]

I have had my "Post" slide rule for the last 45 years. When I was a Freshman in High School an engineer friend of the family gave this Brand New slide rule to me. I was so grateful as I was one of the few in the school to have a slide rule. Jump ahead to 1985 or so my nephew who was a freshman and taking lots of math I showed him my slide rule. He asked what it was and I explained, "This was the calculator that got the first manned space flight to the moon!" I remember when digital calculators from HP came out they could only do addition, subtraction, multiplication and division, they cost $400 at the time. Also gasoline was about $0.25 per gallon!

[Phil B]

You would enjoy the article from the May 10, 2006 Scientific American. You can probably find it in a local library. The HP calculator that was the first serious contender with the slide rule was the HP-35. It got that name because it had 35 keys. It appeared in 1972 and cost $395. Within six years Texas Instruments came out with the TI-30. It competed head to head with the HP-35 and cost only $25. Although calculators are everywhere and cheap, I think it would not hurt for advanced mathematics students to know how to use a slide rule, perhaps even more people. it is a little like military people at various levels knowing Morse Code. You never know when you might need it. Slide Rules would still function after a serious electro-magnetic pulse took out unprotected digital devices,like pocket calculators. Thanks for your comment.

[monkz0390]

Think Geek sells a good slide rule but its all plastic
www.thinkgeek.com
regular price is 29.99

I am eighteen and when i heard about slide rules i searched everywhere trying to make one out of paper.  After a while i decided to buy one. It gets a little stuck sometimes then all you do is separate the non-moving parts a bit and it works great.

Link
http://www.thinkgeek.com/gadgets/tools/be12/

[Thav]

For the ThinkGeek slide rule, do not try to use graphite lube, it just makes life worse!

Instead, I took an exacto and shaved down some of the areas I found were rubbing, and now it slides very smoothly. It might be worth trying the wax as well.

[Phil B]

Thanks. From the things I was reading about that slide rule, it sounded like the problem on some, but not all units was more in keeping with an Exacto knife than simple lubrication with paraffin. From what I could see in the photos, it appears the marking lines are not as fine as they are on quality vintage slide rules. I could be wrong.

[ijibang]

When the slide-piece gets a little "stuck", just slide it out and apply a thin layer of wax (a household candle will do).

[Phil B]

That is a good suggestion. I did use a little paraffin between the plywood and the Plexiglass slider on this rule. I also mentioned using paraffin as a lubricant in my other Instructable that I linked above in this one: Refurbish an Old Slide Rule.  The plastic slide rules sold as trainers back before electronic calculators were not adjustable, but better slide rules are, and that allows the user to set how easily and how smoothly the slider moves, as I mentioned in step 3.  Thank you for looking and for commenting.

[Phil B]

The Think Geek slide rule appears to be basically a replica of the Pickett 120 Trainer I bought in 1960. Some people have had trouble with a sticking slider. For the new price of the plastic Think Geek rule you can buy a nice vintage aluminum PIckett slide rule on eBay. The Think Geek rule is the only one still in production. Thanks for your comment and your interest. I am glad to see someone 18 years old has an interest in slide rules.

[mikeasaurus]

Way to keep the spirit of vintage technology alive. Awesome job, Phil.

[mole1]

Speaking of keeping technology alive, Slide Rule (autobiographical) by Nevil Shute puts it in context. Trustee From The Toolroom is one of his novels that I think most of this group could relate to.

[Phil B]

Thanks, Mike. It might be good to try a slide rule with a different download for the scales in order to see if it would be more accurate.

A few weeks ago I showed my new old Dietzgen rule to the preschool teachers at our church. Basic slide rule is a little advanced for 4 year olds, but the kids like anything that has moving parts. Just a few minutes ago I gave the slide rule I made to the preschool teachers. They plan to have it laying around when parents come for conferences, but doubt any of the parents will know what it is.

[mtdna]

You mention showing slide rules to kids. Have you considered getting a demonstration slide rule? It's a giant slide rule that you hang on the wall so you can show a whole class how to use it. Plus, they look awesome in your living room!

[Phil B]

We had one of those on the wall at my school during my high school years. They come up for sale on eBay periodically. Right now I am downsizing. My wife would not approve were I to buy a demonstration rule. Thank you for the comment.

[rimar2000]

Great work as always Phil!
In step 6, I understand you want say "1,99 is the square root of 4 (no 2)"
When you print or scan a graphic, there are possibilities to have distortions, in this case they mean calc error.
You will say I am a copier, now I want to make a slide ruler!!

[Phil B]

I did not make a scan, myself, but printed a file someone else produced. It might be interesting if someone else downloaded this file and made the slide rule from folded paper. He could check to see if the error is in my printer or if there is a problem with the file. Some of the other links I gave appear to offer better master files from which to make a slide rule. But, I already had this one on my desk and wanted to try it.

I do not remember if you have a router. If you do and if you have a dovetail bit, trimming the Plexiglass with it to make a beveled edge worked very, very well. The action was smooth and held the slider in place very nicely. If you make one, show us a photo.

As i mentioned in response to PurplePeople, the C and D scales seem to be very accurate. If the problem were with my printer or the copy machine, I would expect distortion in those scales, too. They were printed at the same time as the A and B scales, only on a different edge of the same piece of paper.

[PurplePeople]

The inaccuracy of your rule might be due to your printer and/or the enlargement by photocopier.

[Phil B]

I considered that, but the C and D scales print at the same time as the A and B scales. The two sets are parallel to each other in the layout. Distortion on the copier or in the printer of one set would result in a corresponding distortion on the other, but I can find distortion only on the A and B scales. In addition, when I have seen printer or copier distortion in the past, things elongated. They did not shorten. The error I mentioned is in keeping with a shortening.