Fab-in-a-Box Spinning Tops

Setup / Pre-Preparation

Print optional handouts for each learner to help with brainstorming.

Compare different tops or spinners: ideally, several of different designs (tall and narrow, short and squat, etc.)

Ask learners why they think different tops spin at different speeds; why they spin for different lengths of time; and what factors they think affect a top’s stability while spinning.

Practice drawing profiles of three-dimensional objects.

Assemble a handful of irregularly shaped but rotationally symmetrical three-dimensional objects, like vases.

Ask learners to line-sketch front views (profiles) of these objects.

Ask learners to add a dotted line to their sketches to illustrate their z-axis.

Ask learners to trace over half of their drawings—the portion on just the right side of the vertical axis line—using a bolder pen stroke or different color. This shows the design that gets revolved.

Optional: practice paper fan-art to illustrate how revolving a shape around a central axis can result in a 3D object.

Welcome:

Greet the students and introduce the lesson topic: designing and fabricating custom spinning tops using CAD software and a 3D printer.

Briefly explain what CAD software is and its importance in design and manufacturing.

Show a few examples of spinning tops to spark interest and creativity.

Context:

Tops are more than just toys! They demonstrate physics and math in action.

As long as it’s spinning, a top can remain upright and stable. But eventually, it will begin to wobble and shake. As it comes to a rest, it will fall to its side. This is due to a delicate balance of forces: angular momentum works to keep the top spinning, while gravity and friction work to destabilize it.

At the most basic level, a spinning top works by converting linear motion (movement along a straight line) into rotational motion (movement around an axis). This conversion is facilitated by the shape and weight distribution of the top, as well as the forces acting upon it.

In the Real World

Spinning in Figure Skating: When a figure skater performs a spin, they draw their arms close to their chest to increase their rotational speed, much like how a spinning top’s angular momentum increases when you give it a quick twist. By pulling their arms in, the skater reduces their moment of inertia, which is a measure of how mass is distributed around an axis of rotation. This reduction in moment of inertia allows them to spin faster while conserving angular momentum, just like how a spinning top maintains its rotation despite external forces.

Spinning the International Space Station (ISS): The ISS, like a spinning top, utilizes the principles of angular momentum to maintain its orientation and stability in space. Much like how a spinning top experiences precession due to external forces, the ISS occasionally experiences outside gravitational forces, (as well as interference from solar radiation pressure and atmospheric drag), and requires adjustments to its orientation to counteract.

In both cases, whether in figure skating or in space, the conservation of angular momentum plays a crucial role. By manipulating their moment of inertia or making precise adjustments, individuals or spacecraft can control their rotation to maintain stability in their respective environments.

Key Terms:

Forces, forces everywhere! Several key physics concepts affecting a top’s performance:

Rotational motion: Rotational motion describes an object’s movement around a central axis. In this case: the top’s spinning motion around its central spindle.

Angular Momentum: Angular momentum describes the rotational motion of an object around a fixed axis. In this context, it refers to the measure of the top’s tendency to continue rotating about its central axis.

Gravity: Gravity’s force pulls a top downward. However, if the top spins quickly enough, it can generate enough angular momentum to counteract gravity’s force and remain upright.

Friction: Friction between the top and the surface upon which it spins does two things. First, it provides torque to keep the top spinning, opposing its tendency to topple over due to gravity. Second, it gradually opposes the spinning motion, slowing the top down.

Precession: Precession is a phenomenon where the axis of rotation of a spinning object gradually changes direction in response to an external torque. In the case of a spinning top, precession occurs as a result of gravity. This causes the top to “wobble” slightly as it spins and slows, eventually throwing it off balance.

Design Considerations

Center of gravity: The center of gravity plays a crucial role in determining the stability of a spinning top. For a top to spin smoothly and remain upright, its center of gravity must align with the axis of rotation. This alignment ensures that the gravitational force acting upon it balanced. A lower center of gravity can enhance stability. Engineers can design tops with features like weighted bases to help prolong spin times.

Balanced rotation: Symmetry can help contribute to balanced rotation. A symmetrically shaped top distributes its mass evenly around its axis of rotation, reducing wobbling and vibration during spinning.

Ideate (optional printable worksheet)

Sketch some ideas for tops in three dimensions. Label the features or characteristics you think will help your top perform well (brim width, spindle length, etc.)

Label approximate units for your tops features: brim and spindle height, width, etc.

Now translate your designs into profiles. First, draw a dotted line to represent your z-axis. Then, sketch a single line representing the half-profile view of your design. (You may find it easier to draw the whole silhouette rather than just half. That’s fine! Just make sure it doesn’t intersect with the dotted axis line more than twice: once at the top and once at the bottom. Anything more than that will create multiple bodies.)

Pay attention to the shape of your spindle’s bottom point. Too pointy a point, and it may be difficult for the top to balance with any stability; too flat, and it will experience too much friction with the surface you’re spinning it on. Tiny, round points work best.

Design

Draw your profile:

xDesign Steps

Click OPEN on the xDesign landing page

Click the “Minimize” icon in the upper right-hand corner of the Search results page

— the results will be repositioned to the right-hand side of your screen so you can see things alongside your xDesign session

[1] Type “Lesson7” in the Search field, [2] press Enter on the keyboard, then [3] click on the blue header bar (to dismiss the Search History panel)

— the Search results will update to show you the Spinning Top templates

[1] Drag one of the spinning top templates into your xDesign session and then [2] click “Cancel” in the lower right-hand corner of the Search results panel

Click SAVE AS… in the dialog that appears

[1] Type a new name for the component (perhaps add your initials) and then [2] click SAVE

Double-click the “HandleLength” parameter in the Design Manager

[1] Enter a new length in the “Value” field, [2]  Press “Apply” to update the model, [3] Click the OK checkmark to close the dialog

Experiment with changing other parameters to customize your top. Just double-click the parameter, change its value, click “Apply”, then click “OK”.

TIP: Make sure your “HandleDiameter” is smaller than your “TopDiameter”

NOTE: The “FlairAngle” supports a range from 30 deg to 70 deg

Click “Save” on the Action Bar to save your spinning top

BONUS

Draw your own spinning top design!

Click “Close” on the Action Bar

Click New Component on the xDesign landing page

[1] Name your design (perhaps add your initials) and then [2] click OK

[1] Select the YZ plane from the graphics area and then [2] click the “Create Sketch” button on the context menu

— your model will now look like this, where you are looking straight at a 2D sketch:

Click the “Line” tool on the Action Bar

[1] Click on the origin to place the first point of the line, and then [2] click again to sketch a vertical line of any length

Move your mouse to the right and down and [1] click again to sketch another line at a slight angle down from horizontal, then continue clicking [2], [3], [4] to sketch more lines in the chain

Sketch a shape that looks roughly like this. When your last line meets back up with the origin, the area you created will be shaded, letting you know the perimeter is closed

Sketch one more line of any length that starts at the origin and extends vertically downward, then press escape (Esc) on the keyboard to exit the line command

[1] Select the line you just drew, and then [2] click the “Construction” button on the context menu 

— this will turn the line from solid to dashed

Click the “Sketch Dimension” tool on the Action Bar

Select the first vertical line you sketched and place the dimension off to the left of the sketch, then type a value of 1.5 in. and press Enter on the keyboard

Select line [1] and place the dimension off to the right. Enter a value of 0.125 in.

Select line [2] and place the dimension off to the right. Enter a value of 0.25 in.

Select point [1] and then line [2]. Place the dimension off to the right and enter a value of 0.5 in.

Select line [1] and then line [2]. Place the angle dimension up and to the right, then enter a value of 45 deg.

Select line [1] and then line [2]. Before placing the dimension, move your mouse to the left and to the right of the dashed line. Notice how the dimension changes from a single (or radius) to a double (or diameter) dimension. Place the dimension to the left of the dashed line, creating a diameter dimension. Enter a value of 0.5 in.

Create a diameter dimension between lines [1] and [2]. Enter a value of 0.625 in.

Select line [1] and move your mouse around the screen. Because the line is neither horizontal nor vertical, xDesign will offer either of those solutions as well as the actual length of the line depending on where you click to place the dimension.  Place the dimension to define the vertical length of the line and enter a value of 0.125 in.

[1] Click the Features tab of the Action Bar and then click the “Revolve” command

Select the dashed line the revolve axis

— Sketch.1 should have prepopulated into the Profiles list (if it didn’t you can select it from the Design Manager), and Direction 1 should default to “Full Revolve”.

Click the OK checkmark in the Revolve dialog to complete the command

Click “Save” on the Action Bar to save your custom spinning top

Double-click Sketch.1 and change any dimensions you’d like

Click the “Accept Sketch” button to update your spinning top

Remember to Save your design when you’ve finished making changes

Save your file

Save your finished top as a .stl file. This is the file format most commonly used for 3D printing. Often referred to as a “mesh,” it is an intricate three-dimensional web made up of thousands upon thousands of tiny triangles. (STL stands for stereolithography, but you can think of it as “standard triangle language” or “standard tessellation language” instead.)

Prepare & Slice Files

Open your slicing software: Bambu Studio

What is slicing software? Slicing softwares, often called “slicers,” are used to prepare .stl files for 3D printing. They offer tools and workflows to help you lay out multiple bodies on a single print bed, add supports, and more.

Import your design into the slicer:

This is easy: you can just drag and drop!

Select the type of printer you’re using (P1S).

Select the bed type.

Select the filament type being used (PLA).

Select the slicing settings.

Click “slice.” This will create a .3mf file and take you to a preview window that shows you what your finished design looks. Your dice is now ready to print!

Launch Print 

You have two options to launch your print: 1) send it wirelessly, or 2) us an SD card.

The printer will likely run an automatic leveling check before printing. This usually takes a few minutes.

Retrieve Finished Tops

Once the printer is done, pop your dice off the bed. If they seem stuck, you can either: using a soft prying tool (a 3D printed one works well!), or remove the magnetic bed entirely and gently flex it to help the objects release.

Give ‘Em a Spin!

Give your finished tops a test spin! You may have more luck spinning them just a few millimeters above your test surface and dropping them.

Discussion questions:

Try them out on different surfaces. How do different textures affect their performance? Why?

Two tops of identical shape are set to spinning. One is lighter than the other. Which will stay spinning longer?

Shape/size comparison:

Design an experiment to test tops of different shapes (circle, square, triangle) or sizes (small, medium, large).

Make predictions about which will spin the longest, travel the farthest, or have the most stability.

Test out the different designs and compare the results to your predictions.

Why do you think the different designs perform differently?

Career Connections:

Learning to design and fabricate custom spinning tops using CAD software and a 3D printer opens up a variety of exciting career paths:

Graphic Design: Graphic designers use CAD software to create visually appealing and precise designs. The skills learned in this lesson can be applied to various projects, from branding and logo creation to product packaging and digital media, enhancing their ability to produce professional-quality work.

Physicist: Physicists study the fundamental principles of the universe, including energy, force, and momentum. Understanding how to design and fabricate spinning tops allows them to create experimental setups to explore these concepts in a hands-on manner, aiding in both research and education.

Mechanical Engineer: Mechanical engineers use CAD software to design and analyze mechanical systems. The experience of creating spinning tops helps in understanding the principles of balance, rotational dynamics, and material properties, which are crucial for designing efficient and innovative mechanical components.

Product Design: Product designers develop and prototype new products. The skills gained from designing and 3D printing spinning tops can be applied to creating functional and aesthetically pleasing products, from toys and gadgets to household items and tools.

These career connections highlight the versatility and applicability of the skills learned in this lesson, showing how they can be valuable in various professional fields.