H-Arm Fixturing

September 2024-January 2025

The Baja SAE vehicle's suspension H-arms are complex welded assemblies that require extreme precision to ensure proper vehicle kinematics. My challenge was to design a high-precision fixture that would rigidly hold all individual steel tubes in their exact, final positions, enabling the team's welders to produce accurate and repeatable components. The fixture needed to be designed and fabricated on an accelerated timeline.

CAD Design & Digital Assembly

The entire fixture was designed and validated virtually in a SOLIDWORKS assembly before any material was cut. My process was to:

Create a base plate and import the finished H-arm model as a fixed reference.

Digitally place standard locating components (collets and brackets) around the H-arm.

Use a series of precise mates to lock the collets onto the base plate, effectively creating a "cage" that perfectly constrained the H-arm's geometry.

Design custom support bars and specify the correct shoulder bolts to provide additional constraints, ensuring the part would not warp from the heat of welding.

The final deliverable was not just a CAD model, but a complete set of instructions for fabrication. I created detailed engineering drawings for the base plate, specifying the exact locations for drilled and tapped holes, and drawings for the custom support bars. This data package ensured that the manufacturing team could quickly and accurately produce the fixture

Outcome & Key Learnings

The resulting fixture provided a robust platform for the welding team to work from. While post-welding inspection revealed a slight deviation in the final H-arm geometry (approx. ¼”), the project was a critical lesson in tolerance stack-up and the immense precision required for manufacturing tooling. This experience was invaluable for mastering SOLIDWORKS assembly tools and understanding how to design for the needs of a manufacturing team. It demonstrated that even a "simple" fixture requires a rigorous design process to ensure the quality of the final product.

Tools & Skills: SOLIDWORKS CAD, Assembly Mates, Measurement Tools, Design for Manufacturing (DFM), Manufacturing Tooling, Fixture Design, Engineering Drawings, Tolerance Analysis.