Wearable Slide Rule Bangle Bracelet




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Slide rules are simple devices that can do some very complex mathematical calculations. They put into use some of the theory you learned about logarithms in high-school algebra.

Hmmm, will they allow this for use on the Regents or SAT?

The Slide Rule Museum has a template to make a model slide rule. I took that and transformed it into a piece of functional jewelry.

This will be made entirely from paper/cardstock. Advanced crafters can apply the same concept to wood and wood veneers, machined metals, or formed plastics.

This project can be adapted to make a wood, metal, plastic or ceramic bangle/bracelet. Since the scale markings are intricate, it may require a laser cutter or other method to print directly on the material used.

Note that accuracy of the instrument is limited to the medium, construction method, and skill of the operator.

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Step 1: Do This at Your Desk...

This project illustrates creating a large bangle. The prototype just turned out that size. You can scale the PDF of the slide rule graphic to be smaller if you want a thinner bangle or sized for a man's bracelet.

To make this papercraft, you will only need to print out the slide rule template on cardstock and glue up the parts.

So at the office or home,  have ready:

printer to print PDF file

several sheets of cardstock, thin cardboard

straight paper trimmer


Download the PDF to make a papercraft slide rule from the Slide Rule Museum site.

Look for the "Scales to make a Mannheim Slide Rule - K,A,B,L,C,D - Kinsman" and click on the image to access the PDF in your browser.

Print out on regular letter size paper. The graphic will also be our guide to construct the bangle.

Step 2: Round It Up...

Make a bangle big enough for your hand to pass through and small enough so it does not fall off.

You need a round form to create the cardboard tube that is the basis for the bangle.

I am using a large peanut butter jar, 4 inches in diameter, as my form. Soup cans were way too small and I couldn't find any PVC pipe that was ideally about 3 1/2 inches outside diameter.

You could take a soup can and start wrapping newspaper around it to get the right diameter needed.

Start the prepwork for the project. Cut the cardstock into strips that are the height of the papercraft slide rule.

I used several colors of cardstock. When laminated, it will give a multi-colored layer look at the edges.

Step 3: Go Tubing...

Wrap the jar in plastic wrap. This keeps it clean from the glue. I wrapped it several times to even out the surface so that the cardboard tube could slide off of the jar past the ridge it had at the bottom of the jar.

Glue two strips by overlapping on the end about an inch. A single strip did not wrap entirely around the jar and this helps to glue the strips in place.

Glue a layer of cardstock around the jar. Don't snug it up too tight but keep it close enough to conform to the jar.

Continue gluing on the cardstock strips but butting the end to the last edge glued down. This will prevent bumps in the cardboard tube. Coat the entire strip with glue to laminate it to the previous strip. Smooth over to get rid of air and glue pockets.

When you have two or three layers, slide off to test that you can get it off the jar.

Position back on the jar and continue adding layers of cardstock. I think I had about a 9 layer lamination. You get a feel for how thick your lamination should be if it is fairly stiff when it is removed from the jar. It will become stiffer as the glue dries.

When the tube is still wet, you can work the edges with something like a marker barrel or tool to burnish the edge so it has a smoother finish.

Step 4: Strip Down...

While the main tube is drying, you can start cutting out the bottom portion of the slide rule graphic.

Use that to size the strips that will form the bottom rim of the slide rule bangle.

From now on, the construction needs to be fairly neat so that you line up all the edges of your strips when glued down. It will increase the accuracy of your final product.

Build up the bottom rim till it is about double the thickness of the main tube.

Step 5: Collar It In...

From the template cut out cardstock strips sized to match the slide rule middle slider part.

This time, we need to make a ring that will be free from the main tube so it can rotate. With the lamination strip, glue only at the point where it makes a ring onto itself and allows it to move freely.

Continue to laminate cardstock strips until it reaches the thickness of the base rim.

Step 6: Lord of the Rings...

From the template, cut cardstock strips the size of the top portion of the slide rule model.

Glue on to the main tube to form the top rim of the bangle. This is also the locking ring for the middle slider ring.

I used a painter's tool to burnish the joint and edges where the middle ring slides. This is to make the middle ring turn more smoothly.

Apply the middle slider graphic to the middle ring.

I had some space on the ring where the graphic did not cover. I put on a thumbtab to help with sliding the ring. It is just several layers of cardstock folded over and glued.

Step 7:

Apply the graphic for the bottom portion of the slide rule.

Line up the middle slider ring.

Apply the graphic for the top portion of the slide rule.

Cut out a piece of plastic from some scrap packaging that will be the clear marker slider.

Use a screw tip or awl to scratch a straight line into the plastic.

Mark it with a marker. Wipe away the excess ink so that the scratched line is highlighted.

Fold over the bangle and tape to secure ends on the back. The indicator marker should be able to slide on the bangle.

Step 8: Run Around With It...

Stuck at a boring party and need to calculate your escape trajectory? Use your handy slide rule bangle bracelet.

You can always be fashion-forward with this slide rule bangle.

Go and make the more advanced slide rules with other scales.

Use this technique to make a cryptex bangle bracelet. Wear an enigma.

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    11 Discussions


    4 years ago on Introduction

    Okay, okay...that's just plain cool in a totally nerdy way I never thought of. One "attaboy" is hereby allotted in your name. =)


    7 years ago on Introduction

    OMG, I used slide rules in the 1950's at High School in the UK at 13 years old.We got to 2 decimal points accuracy on them, and got used to using the 10 to the minus or 10 to the plus way of treating big or small numbers. Too many kids and Wall Street traders can't do this today.
    This is just wonderful, I have a crazy, much younger friend who makes her own jewelry, usually oiut of cast off computer boartds, diodes, tubes etc. This will be my Christmas challenge for her! In response to caitlandsdad,(Aug 23) the ones pilots used are flat, not cylindical, but for the same reason, like elbow room!l.

    1 reply

    Reply 7 years ago on Introduction

    Slide rules got people on the moon and back. Do have your friend take do an instructable on what she made. Bonus geek cred points.


    7 years ago on Introduction

    That is a lovely piece of work and useful too.

    Slide rules are not used enough, they help us understand how the numbers relate and mitigate against the fallacy of accuracy. As a chemist I often used them for making estimates so I knew when to concentrate on a measurement.

    You did miss a simple trick you know... Bring the 1 and 10 to meet one another it means you can calculate huge numbers and the exponent is just how many times you went around the wrist. That's why there used to be a lot of circular slide rules.

    Well done

    1 reply

    Reply 7 years ago on Introduction

    Thanks. I did no know that about circular slide rules. I thought pilots used them just for the size limitation in a cramped cockpit.


    7 years ago on Introduction

    I didn't get to read your instructable completely through just now, but consider yourself "bookmarked".
    I stumbled over an old slide rule from my brother in law, but never knew how to use it properly. But as an engineer, I think something like this is awesome, considering a lot of construction has been done without calculators and just using slide rules. With this knowledge, I always wanted to know how this works and your instructable seems like a great opportunity to actually make on myself (maybe over the weekend, although my daughter's room is waiting for a makeover as she shifts from being a child into teenage-hood). I think my next instructable will be my daughter's room as we intend to maximize the available room size. Maybe I will use a slide rule to make all the calculations.

    5 replies
    Phil BMike73

    Reply 7 years ago on Introduction

    I did a rather complete Instructable on using a slide rule. It is linked above at the right side of the page, or you can click on this orange hot linked word to see it. I am not able to tell from what you wrote if you have had some prior experience with a slide rule or not. A little time and practice is needed to use a slide rule well. If your printer is not completely precise and consistent in its paper feed rate, the paper slide rule you print out will be somewhat inaccurate. You may want to watch eBay for an acceptable deal on a vintage slide rule. I bought a nice Dietzgen rule there and described refurbishing missing pieces in this Instructable, which is also linked above at the right.

    Mike73Phil B

    Reply 7 years ago on Introduction

    Phil, I started reading your instructable because I don't have any experience with a slide rule. But still, being an engineer I was always amazed about all the stuff (bridges, procucts, high rises) that was constructed way before a calculator as we know it today was available. So far I could follow through real well and I really like your link to the online slide rule :-)
    Thanks for pointing to your instructable.

    Phil BMike73

    Reply 7 years ago on Introduction

    Mike, in the days before 1972 and the first scientific calculator engineering students would have made frequent heavy use of the log-log scales. Unfortunately, even though I once thought I wanted to be an engineer, I never learned more than a few basic things about logarithms. I wish I could have given better guidance on the use of those log-log scales. Still, many people have never seen a slide rule. You will be able to have some fun when you pull out a slide rule and work a problem without a calculator. Thank you for looking at my Instructable on using a slide rule. I wish I had more reasons to use one regularly. I wish you well with learning and practicing solving problems on a slide rule.


    Reply 7 years ago on Introduction

    A giant slide rule makes a great room accessory. It is easy to print out the template and fool around with it. I don't know if I am lucky but basic electronic calculators became affordable by the time I needed them in college. I think a slide rule forces you to think more with your brain than just pushing a few buttons. I think you just gave me the idea to work on a giant lightup abacus sometime. Thanks.


    Reply 7 years ago on Introduction

    Sounds great. I'm subscribed to you, so I'll definitely know when you've done the abacus :-)
    A giant slide rule for the wall sounds great. I think I'll probably try one.