# Drill Bit Sizes

Selecting the correct drill bit size is important for proper fastener fit, tapping, and hole accuracy in FRC fabrication.

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</div>## Common FRC Drill Bit Sizes

<table id="bkmrk-drill-bit-common-use"><tbody><tr><th>Drill Bit</th><th>Common Use</th></tr><tr><td>\#43 (0.089")</td><td>Tap drill for 4-40</td></tr><tr><td>\#36 (0.106")</td><td>Tap drill for 6-32</td></tr><tr><td>\#21 (0.159")</td><td>Tap drill for 10-32</td></tr><tr><td>\#7 (0.201")</td><td>Tap drill for 1/4-20</td></tr><tr><td>1/8"</td><td>Rivets and small hardware</td></tr><tr><td>3/16"</td><td>Large rivets</td></tr><tr><td>13/64"</td><td>Clearance hole for 10-32</td></tr><tr><td>17/64"</td><td>Clearance hole for 1/4-20</td></tr></tbody></table>

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</div>## Tap Drill vs. Clearance Drill

### Tap Drill

A tap drill creates the correct size hole for cutting threads with a tap.

Example:

- A 10-32 screw uses a **\#21 drill bit** before tapping.

### Clearance Drill

A clearance hole allows a fastener to pass through freely.

Example:

- A 10-32 bolt typically uses a **13/64" clearance hole**.

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</div>## Best Practices

- Verify the required drill size before drilling.
- Use a center punch to prevent drill wandering.
- Deburr holes after drilling.
- Label commonly used bits to prevent mistakes.

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</div>## Common Mistakes

- Using a clearance hole when tapping is required.
- Selecting the wrong drill bit size.
- Drilling oversized holes.
- Forgetting to deburr the finished hole.

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</div>## Key Idea

Using the correct drill bit size ensures proper fastener fit, accurate hole placement, and reliable assemblies on an FRC robot.