Tips from Sky

1. Select the Right Extrusion Profile

All extrusion profiles are not created equal. Rigidity of profiles with similar outer dimensions (e.g., 45 mm x 45mm) can significantly vary based on their moment of inertia with some profile geometries leading to a 40% stiffer beam. Another key aspect to consider is the cross-section’s area, which has a direct impact on the overall weight of the assembly. Given that the best profiles are highly rigid, yet lightweight, the best performance indicator is the moment of inertia to surface area ratio. The table below lists some of the key parameters for five well-known extrusions brands.

2. Carefully Select your Extrusion Joint Configuration

Selecting the right extrusion profile is only part of the work required to come up with effective structures. The assembly joint configuration can also substantially change the rigidity and structural integrity of a design.

One thing to avoid is assembly joints relying solely on friction to support the load. A better approach is to position one extrusion on top of another, as seen in the images below. Assembly plates then hold all of the pieces together, but only withstand a minimal amount of force.

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