Paper Resistor Calculator





Introduction: Paper Resistor Calculator

Here is a small resistor calculator with three dials that you can make out of card stock paper. This version does not include the tolerance band, but if there's enough interest drop me a line and I may modify the design to include one.

Step 1: Papercraft Tools

For this project you'll need a few tools, namely a scissors, razor knife, straight edge and glue. Additionally I often use an old chopstick to help nudge the paper when necessary and to press down tabs. Also a "self healing" mat will save your tabletop but is not required.

Step 2: The Raw Materials

To make the resistor calculator, download and print the attached .pdf. Printing onto thick white card stock seems to give the best results. YMMV.

Step 3: Cut Out the Main Body

After printing out the .pdf cut out the individual pieces. I first cut out the main body of the resistor calculator, then cut out the black shapes. Afterward I gently score (with the dull end of the razor knife) the lines denoting the flaps and the dotted line showing where to fold the main body. This step makes it very easy to get nice crisp folds.

Step 4: Cut Out the Wheels

Cutting the wheels may be the most tedious part of this project. But making a "knurled" edge makes it easy to operate the calculator when it's all completed. I actually don't mind making all these cuts, but a sharp blade sure makes it easier. The technique I use is to first cut around the edges one way, then the opposite way freeing the wheel from the paper. Don't forget to cut out the center hole as well!

Step 5: Cut Out the Axles

Cut the axles out using a scissors. I tried using the razor knife but the edges weren't as smooth. Afterward cut the black lines shown in the picture then fold up slightly.

Step 6: Glue Axles

This step may be the most fussy, but I think I've come up with a way to insure sufficient accuracy. First, on the main body, poke a hole with the razor knife through each of the spots marked "a", "b" and "c". Similarly poke a hole through the center of an axle. While holding the tabs out of the way add a bit of glue to the back of an axle. Then, with the point of the razor knife through the hole you just created, mount the axle to the main body by aligning holes. You might want to experiment with the tab alignment in your calculator, but I've found the operation to work a bit more smoothly if the tabs are glued vertically with respect to the main body.

Step 7: Attach Wheels

The color wheels are now ready to be attached. Each wheel is coded with a letter a, b, c and should be attached to the corresponding axle. Attach the wheels in the order: a, c, b. This isn't critical but I think it helps the wheels spin easier. Check the back of the main body to see which axle is which. By bending the axle tabs up then slipping the wheel over each tab you can finesse the wheel onto the axle. I found that threading one tab at a time, with the second tab helped into place with the chopstick seemed to work pretty well. Go slow, you're almost done!

Step 8: Close It All Up

Finally, with a bit of glue on each tab, press tabs down and seal the main body shut. All you need is a very thin layer of glue -- hardly wet at all. Then use a chopstick (or similar) to press the tabs down. This pressure and tacky nature of your thinly applied glue layer will adhere almost immediately. If you've used too much glue keep applying pressure to squeeze out the excess glue. Try not to let any glue work its way inside the main body where it might bind up the wheels.



    • Creative Misuse Contest

      Creative Misuse Contest
    • Water Contest

      Water Contest
    • Oil Contest

      Oil Contest

    13 Discussions

    there is a huge mistake in the pdf all numbers is wrong chick it again

    nice tool, but yesterday there was an instructable exactly like this(different print tho), now i'm not accusing you, but i do find it suspicious...

    2 replies

    Just *after* I posted this, my first instructible, I saw the other post (to my utter amazement). To be honest, I had my design floating around for months but wasn't ready for distribution. I had been actively using a prototype the whole time until it wore out. So yesterday I decided to fix the glitches, make another and document the process. The result is this instructible. The other design is very nicely done and simpler than mine, but this one doesn't require anything but a sheet of card stock.

    mkay, bad luck then, anyway, both instructables have there own quality's, your's has clever hinges, his looks a bit neater, your hinges will probably fail sometime soon, i have experience with those hinges, and they break after +/- a week most off the time, unless you use special non-tear paper...

    Not really. I realize that URL was in the photos and debated whether or not to Photoshop them out. Perhaps I was a bit hasty but wanted to get the darn thing posted so I didn't. If you download the accompanying PDF the URL on the back points to this instructable. Sorry for the confusion.

    No problem, I just thought I'd let you know I looked. L P.S. Having an animated "site under construction" gif doesn't do you many favours. I'd just tidy index.htm to show what is there, rather than suggest you're working on it (rather 90's as I remember them...)

    Heh, thanks for the suggestions. Yea, I've let that site stagnate for far too long. So I took your comments to heart and have cleaned things up a bit. Still not much content, even arguably less at the moment, but it definitely doesn't stink up the place like it did before! Maybe that little kick will give the site (i.e. me) enough energy to escape the orbit it's been stuck in for so long:-)