Fab-in-a-Box Spinning Tops: Deep Dive

A variety of stackable tops with interchangeable parts should be available for learners to examine. Facilitators can lead a discussion on the challenges of designing parts that fit together and how stacking might influence spin performance. Learners will sketch modular profiles, such as bases, mid-sections, and caps, and add a z-axis line to each drawing. They will trace the portion that will revole to visualize how each part becomes a 3D object. The optional paper fan-art activity can be used again to reinforce the concept of revolution, especially in the context of modular design. This setup encourages learners to think critically about precision, balance, and the physics of rotational motion.

Welcome:

Welcome learners, and introduce the session: designing modular, stackable spinning tops using CAD and 3D printing. Explain that they’ll be creating parts that fit together precisely, just like in real-world product design. Reinforce the importance of CAD in engineering and manufacturing, especially when designing components that must align and interact. Show examples of stackable tops and interchangeable parts, and ask, “How do you think changing just one part might affect the way a top spins?” Set the tone for a session focused on precision, testing, and creative problem solving.

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.

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 is 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:

Sketch some ideas for your stackable tops in three dimensions. Label the features or characteristics you think will help both your tops perform well (brim width, spindle length, etc.) Think about how they will stack on top of one another and how the weight of the one above will impact the spin.

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 half. That’s fine! Just make sure it doesn’t intersect with the dotted axis line more than twice for each top: once at the top and once at the bottom. Anything more than that will create multiple bodies on both tops.)

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. Consider how the tops will interlock.

Design:

Draw your profile.

For xDesign Steps Click Here

xDesign steps can also be found:

In xDesign under Content

Prepare & Slice Files:

Open your slicing software: Bambu Studio

What is slicing software? Often called “slicers,” they 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 top is now ready to print!

Launch Print:

You have two options to launch your print:

1) Send it wirelessly.

2) Use 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 tops off the bed. If they seem stuck, you can either use 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!

Assemble your stackable tops, and do a test spin! You may have more luck spinning them just a few millimeters above your test surface and dropping them.

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?

Discussion questions:

What was the most challenging part of designing stackable components?

Which combination of parts spun best? Why do you think that is?

How did weight and balance affect your tops’ performance?

What would you improve in your next modular design?

Optional Tie-ins:

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.

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.

Career Connections:

Learning to design and fabricate 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 the ability to produce professional-quality work.

Physics: 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 Engineering: 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.