Designing a 3D‑Printed Tesla Turbine – Part 2: Bearing Housing Development

Introduction

In the second installment of our two‑part series, we explain how to retrofit a machined Tesla turbine with Markforged parts. The first article introduced Tesla turbines, identified components ideal for 3D printing, and replaced the turbine housing with a custom Markforged part. This entry focuses on the remaining printed element: the bearing housing.

The Tesla Turbine Bearing Housing

The turbine housing encases the shaft assembly but does not contact it directly. Instead, an intermediary component—the bearing housing—bolts onto the turbine housing and secures the shaft assembly with two perfectly concentric bearings. By cantilevering the rotor assembly on the bearing housing, the original designers allowed a machinist to verify bearing hole concentricity easily. This precision is critical; at 24,000 rpm, even a slight misalignment can cause catastrophic failure. In the original aluminum housing, the bearing fit tolerances were +0/‑0.0004 in, ensuring a snug press‑fit without hindering rotation. While a Markforged machine can produce this part, it presents a greater challenge than the turbine housing due to its tighter tolerances and critical function.

Additive Manufacturing Design Adjustments

Printing the bearing housing demands precision and concentricity. Fortunately, the reduced surface hardness of Onyx relaxes tolerances slightly—achieving +0/‑0.001 in is realistic compared to the aluminum requirement. We also needed to print retaining‑ring grooves and overhanging flanges with high accuracy; these features require significant support material, which is removed cleanly using Peel‑Off supports. Additionally, the part must accommodate a high volume of fiber, especially around the bearings, to maintain dimensional stability. The design allows six layers of fiber around each bearing, providing ample reinforcement.

Printing the Housing

To validate our approach, we printed two versions of the bearing housing: one on the Mark Two Enterprise and another on the Mark X, each evaluated with laser dimensional verification.

Mark Two Housing

On the Mark Two, tight tolerances rely on independently measured unit tests. By printing and measuring unit test rings for each bearing fit, we iterated twice, adjusted the CAD dimensions, and incorporated the refined dimensions into the full part. Only after verifying the complete housing did we insert the hardware. When successful, the bearings achieved a snug press‑fit and integrated seamlessly with the turbine housing.

Mark X Housing

Although the Mark X also relies on human validation, laser dimensional scanning simplifies the workflow. By scanning layers that contain the critical bearing fits, we verify tolerances in real time without calipers. We achieved both tolerances on the first attempt, eliminating the need for reprints. This hands‑off process is more efficient than unit testing.

Conclusion

Despite its complexity, the bearing housing demonstrates the viability of tight‑tolerance 3D printing for high‑performance components. We confirmed functional parts on both the Mark Two and Mark X with minimal design changes, and both housings enable flawless rotor spin.

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