Assignment 3: The Pascaline


  1. Watch the video above.

  2. This is a team project. Talk with your partner about how to divide responsibility for the work.

  3. Download the SolidWorks design and extract all the files to your file server directory. Note: also see the updated file, which contains the modifications discussed in class: large nylon spacers, and a modified backstop pawl. But it does not contain the SLDDRW files.

  4. In SolidWorks, load the file Pascaline.SLDASM. This will in turn load all the other assembly and parts files. SolidWorks will try to find the files using a directory path that doesn't work on your computer. Simply tell it you will search for the file, and direct it to the version7 directory. Once you help it find one file it will know where to look for the rest.

  5. In addition to the assembly and parts files, there are also drawing files that you can use to create DXF files and laser cut your parts once you've modified the design.

Part 1: The Design

  1. The first part of the assignment is to modify the Pascaline design to make it more artistic.
  2. Start by spending some time exploring the Pascaline in SolidWorks so you understand how the various assemblies are put together.

  3. Last semester, many people added artwork they engraved into the front, back, and side panels of their Pascaline. One group even added wooden ornamentation; see the picture below (click for larger versions):

  4. Another way to play with the design is to change the shapes of some of the components. For example, the accumulator gear uses a circle of screws, but the plastic itself does not have to be circular. What if it had a more irregular shape, or had designs cut into it? What other component shapes could you play with?

  5. Yet another way to change the design is to change the color selections for parts. (But you'll need to do more than just that to earn a good grade on this part.)

  6. Be careful when modifying parts that you don't break the mechanism by causing collisions/interference with other parts.

  7. When you've completed your design, load the drawing files (they'll update automatically) and save them as DXF files. Color them appropriately using the tool of your choice.

  8. Make a zip file containing your DXF files, two screenshots of your modified Pascaline viewed in SolidWorks, and a short note (as a plain text file) describing the modifications you made to the Pascaline design. This will be your hand-in for Part 1.

Part 2: Construction

  1. Cut your parts on the Rabbit Laser. You can get acrylic sheets from the usual place.

  2. Follow these assembly instructions to build and test your Pascaline.

  3. Your hand-in for part 2 will be the physical Pascaline. We will examine them and grade them. Then you can keep yours if you want to.

Parts List

Click here for a complete parts list. Your metal parts will be available in your project bins. Take acrylic from the piles in the lab; try not to waste any.

Construction Tips

  1. Use the right screw for the job so you don't have excess metal sticking out past the nut. Here's how to calculate the correct length. Each plastic part is 1/8 inch thick. The nut or standoff requires 1/8 inch of thread. So if you're attaching a threaded standoff to a piece of plastic, you'll need need a 1/4 inch screw (1/8 inch for the plastic piece and 1/8 inch to thread into the standoff.) Similarly, if you're screwing two plastic pieces together using a nut, you need 1+1+1 = 3/8 inches of thread: use a 3/8 inch screw.

  2. Don't rip open your screw and nut packs. Cut a tiny opening in one corner, and squeeze out the parts as you need them. This keeps things neat and protects you from having all your parts spill on the floor if you drop a pack.

  3. Use the thread locking fluid! If you don't, your screws will quickly come loose and your Pascaline will not work properly. Eventually it will start falling apart.

  4. Don't coat the entire screw with thread locker. Just squeeze one tiny drop onto the screw at the point where the nut will rest. Wipe up any spillage so it doesn't discolor your parts.

  5. Use pliers, not your fingers, to hold the nut as you tighten the screw down. You'll get a tighter fit that way.

What to Hand In

  • Hand in your DXF files, two rendering images, and a brief description of what design modifications you made, via Autolab.

  • We will have a "Pascaline checkpoint" session in which Adam or Meg will check your Pascalines to identify any problems with the assembly, answer any questions you have, and verify that your mechanism is operating properly. Check the syllabus for the date and time.

  • Your physical Pascalines are due shortly after the Pascaline checkpoint. Check the syllabus for the official due date.


  • 7 points for customization and properly laid out drawing files
  • 3 points for properly colored DXF files
  • 3 points for cutting the plastic
  • 7 points for correct assembly and demonstrating a fully working replica

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Last modified: Thu Feb 4 18:00:34 EST 2016