Lesson 2: Potting and Thermal Sealing (The Wax Process)

Why is toilet bowl wax (petroleum-based) better than candle wax for this application?

How does the wax handle the change in temperature when the motor runs?

What are the signs of a "leak path" in a potting compound?

Potting: Encasing electronic components in a solid or gelatinous compound to exclude moisture.

Hydrophobic: "Water-fearing"; substances that do not mix with water.

Non-Polar: Molecules that do not have a charge, such as wax, which prevents them from bonding with polar water molecules.

Void: An accidental air bubble trapped in the wax that could collapse under water pressure.

NGSS HS-PS1-3: Plan and conduct an investigation to gather evidence to compare the structure of substances at the bulk scale to infer the strength of electrical forces between particles (Polarity).

Description: Students pack the motor canister with toilet bowl wax. This can be done by melting the wax and pouring it (with heavy supervision) or by "cold-packing" the wax into the housing. They then seal the cap and apply a final layer of tape to the wire exit point.

Purpose: To provide the primary waterproof barrier for the DC motors.

DOK Level: Level 3 (Strategic Thinking). Students must monitor the consistency of the wax. If it's too cold, it won't fill the gaps (creating voids); if it's too hot, it could melt the tape or motor internals. They must make "real-time" adjustments to their technique based on the material's behavior.

In this course, we recognize that students enter the lab with varying levels of technical experience. Our differentiation strategy employs a 'Scaffolded Autonomy' approach. We provide structured, step-by-step guidance for foundational concepts while offering open-ended, 'Design Challenge' extensions for advanced learners. By utilizing peer-mentorship models, diverse instructional media (visual, tactile, and digital), and flexible project pathways, we ensure every student can move from consumer to creator at their own pace.

The "Immersion Bubble Test": Students submerge the completed thruster in a clear tank of water. They must watch for 2 minutes. If no air bubbles escape from the canister, the seal is deemed successful.