3D Printed Trammel of Archimedes

Hey! One cool project I've worked is the Trammel of Archimedes or more commonly known as the "Do-Nothing Machine" because it literally does nothing. However, it is a fun first project to design for 3D printing and allows you to explore dimensioning in Tinkercad and helps you learn how to use joints and fillets in Fusion 360.

Access to Tinkercad and Fusion 360 (they're both free for students!).

Cura (or equivalent slicer) (this is also free!)

Any 3D printer (this is not free, but you may be able to access one for free at local MakerSpaces)

Create two intersecting equally sized boxes. Try to make them longer and ensure that they equally intersect to ensure an even base.

Use the trapezoid shape and extend it to the length of the rectangles. Make sure to set the trapezoid to hole and then group the trapezoids and rectangular boxes together. This is your first part!

Use a trapezoid with the same sized hole as in the base. Then sketch a cylinder in the exact center of the top of the trapezoid, approximately 5mm. Like the previous part, group the cylindrical pin and trapezoid together. This pin will help you attach the slider to the handle, which we will soon make.

This handle will allow us to make the elliptical motion of the Trammel of Archimedes. However, we will need to do some quick geometry. To calculate this distance between the pin holes we need sqrt(2(length of the base/2)^2). If we insert the length of the base in the equation, we can make two pin holes, with their centers that distance apart. Then, we can add a hole for the finger. Remember, you need to group all these holes together to make one part.

We will now need to transfer our Tinkercad parts to Fusion 360 as Tinkercad does not have certain functions, such as filleting and assemblies. Fusion 360 is a more powerful tool that will allow us to test our parts and make them better.

Here is a guide: https://www.tinkercad.com/projects/Send-Your-Tinkercad-Design-to-Fusion-360

Since there is more than one part in our file, we will need to convert the bodies into components by right clicking the body and clicking "Convert to component."

In Fusion 360, click fillet and select an appropriate fillet diameter like 5mm. Click the edges that you would like to fillet. It is up to your taste, but I selected the inner top edges. You can also fillet the other parts, like the handle and slider.

Although you do not need to use joints to join the parts together, it provides a nice visual and ensures you created a functioning product. To use joints, press the shortcut key "J" on your keyboard. Use revolute joints between the pin holes in the handle and the pins of the sliders. Then, use slider joins between the inner face of the base and outer face of the slider. Make sure the axis of sliding is correct.

To get your files to 3D printer, right click each component and click "Save as mesh", with the format "STL (ASCII)". Repeat this for each component. Once you are done, you can upload your files into Cura slicer. I would suggest making the size of the sliders 99% of their usual size, as 3D printers are not perfectly accurate. Decreasing the size allows the holes in the handle and the base allows it to slide more smoothly.

Filament: Inland PLA

Temperature: 200C

Bed: 60C

Layer Height: 0.16mm

Infill: 20%

Supports: Off

Adhesion: Skirt

Feel free to edit the settings to fit your own printer. You can now slice the file.

Your files are ready for printing! Put the gcode files into a microSD card and put it in your 3D printer. The printer should recognize the file and will allow you to start the print. Once the printing is done, place the sliders in the base and place the hand into the slider. Have fun with your new toy!