# Introduction to FRC Extrusion

Rectangular aluminum extrusion is used in FRC to build robot frames and structural mechanisms. The strength, stiffness, and weight depend on both size and wall thickness.

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</div>## Common Extrusion Sizes

### 1" × 1"

- Small, lightweight structural member
- Used for mechanisms and compact structures

### 2" × 1"

- Most common FRC structural extrusion
- High stiffness in the 2" direction
- Used for drivetrains and main frames

### 2" × 2"

- Heavy-duty, very rigid
- Used for high-load structures
- Heavier, used only when needed

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</div>## Wall Thickness (WCP Options)

West Coast Products (WCP) commonly offers:

- **0.063"** — Lightweight, lower strength
- **0.090"** — Balanced strength and weight (most common)
- **0.125"** — Maximum strength and stiffness

Thicker walls increase strength but also add weight.

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</div>## 0.5 Inch Hole Spacing

Many FRC designs use a **0.5 inch grid pattern** when drilling extrusion.

This means holes are placed every half inch (0.5", 1.0", 1.5", etc.) to create consistent mounting locations.

This system:

- Matches CAD layouts
- Improves alignment between parts
- Makes fabrication repeatable and accurate
- Helps standardize robot construction

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</div>## Key Idea

Different extrusion sizes and wall thicknesses control strength and weight, while the 0.5 inch grid system ensures accurate and repeatable assembly.