Rivet Nut Drill Size Chart
Choosing the correct drill size is critical for the proper installation of rivet nuts. This Rivet Nut Drill Size Chart provides recommended drill bit sizes for both metric and inch-threaded rivet nuts, helping ensure a secure fit and reliable performance. Whether you’re working with aluminum, steel, or plastic, accurate hole preparation is the first step toward a strong and lasting fastener connection.
| Nut OD | Thread (Metric/Inch) | Body Diameter (mm) | Recommended Drill Size | Grip Range (mm) |
| M3 | M3 × 0.5 | 4.8 | 5.0 mm | 0.5 – 1.5 |
| M4 | M4 × 0.7 | 6.1 | 6.3 mm | 0.5 – 2.0 |
| M5 | M5 × 0.8 | 7.1 | 7.3 mm | 0.5 – 3.0 |
| M6 | M6 × 1.0 | 8.9 | 9.0 mm | 0.5 – 3.5 |
| M8 | M8 × 1.25 | 11.0 | 11.1 mm | 0.5 – 4.5 |
| M10 | M10 × 1.5 | 13.1 | 13.3 mm | 1.0 – 5.0 |
| M12 | M12 × 1.75 | 15.1 | 15.3 mm | 1.0 – 6.0 |
| #6-32 | Unified Fine | 4.8 | #17 (4.93 mm) | 0.5 – 1.5 |
| #8-32 | Unified Fine | 6.1 | #11 (5.9 mm) | 0.5 – 2.0 |
| #10-24 | Unified Coarse | 7.1 | F drill (7.14 mm) | 0.5 – 2.5 |
| #10-32 | Unified Fine | 7.1 | F drill (7.14 mm) | 0.5 – 2.5 |
| 1/4″-20 | Unified Coarse | 9.3 | 3/8″ (9.5 mm) | 0.5 – 3.0 |
| 5/16″-18 | Unified Coarse | 11.0 | 7/16″ (11.1 mm) | 0.5 – 4.0 |
| 3/8″-16 | Unified Coarse | 13.1 | 33/64″ (13.1 mm) | 1.0 – 5.0 |
| 1/2″-13 | Unified Coarse | 17.0 | 43/64″ (17.06 mm) | 1.0 – 6.0 |
✅ Note:
The recommended drill size is slightly larger than the rivet nut body diameter to allow smooth insertion without being too loose.
For imperial drill sizes (e.g., #11, F drill), refer to a standard drill size chart to select the correct drill bit.
If using hex or knurled body rivet nuts, be sure to verify the required hole shape and tolerance accordingly.
When installing rivet nuts, choosing the correct drill size is crucial to ensure proper fastening quality. A hole that is either too large or too small can affect the insertion ease, locking strength, and long-term stability. Here are the key points to consider when selecting the appropriate drill size:
1. The hole should be slightly larger than the rivet nut body diameter
To allow smooth insertion and ensure a secure fit, the recommended drill hole size is generally about 0.1mm to 0.3mm larger than the rivet nut’s body diameter. This helps the nut fit properly without being too loose, which could otherwise lead to spinning or loosening.
2. Adjust drill size based on material type
- Steel plates: As steel is harder and less likely to deform after drilling, you can follow the standard recommended drill size.
- Aluminum or plastic: These softer materials are more prone to thermal expansion or edge deformation during drilling. In such cases, using a slightly smaller drill bit may help maintain precise hole dimensions.
Why Is Choosing the Right Drill Size Important?
Selecting the correct drill size is critical in the installation of rivet nuts, as it directly impacts the quality of the fastening, structural strength, and long-term durability. Improper hole size can lead to installation failures and pose long-term safety risks. Here is a detailed explanation of why choosing the right drill size is so important:
1. Ensures Smooth Insertion of the Rivet Nut
If the drill hole is too small, the rivet nut may not fit into the hole or may require excessive force, which can damage the nut or the hole wall, reduce assembly efficiency, and even cause part failure.
2. Achieves a Secure and Strong Installation
The correct hole size creates a proper interference fit between the rivet nut and the panel. This allows the body of the nut to expand fully during installation, ensuring that the nut is firmly fixed without spinning or falling out, providing a stable and reliable connection.
3. Prevents Loosening or Spinning Due to Oversized Holes
If the drill hole is too large, the rivet nut will lack sufficient contact with the wall, leading to looseness or slippage after installation. Under tensile load or vibration, the nut may rotate or come off, which compromises structural safety.
4. Improves Assembly Consistency and Product Quality
Consistently controlling hole size helps maintain uniform installation results. This is especially important in automated or high-volume production, where tight tolerances reduce defect rates and enhance overall product quality.
5. Extends Service Life
When properly installed, rivet nuts can withstand repeated tightening, pulling, or vibration, helping to extend the service life of the fastened structure.
Does the Material Affect the Drill Size Selection?
Yes, the type of base material has a significant impact on the selection of drill size. It plays a key role in ensuring a secure and reliable installation of rivet nuts. Different materials have varying physical properties during the drilling process, which affect the actual hole diameter and stability.
1. Steel Sheets: Standard Drill Sizes Recommended
When properly installed, rivet nuts can withstand repeated tightening, pulling, or vibration, helping to extend the service life of the fastened structure.
2. Aluminum Sheets: Slightly Smaller Drill Size Suggested
Aluminum is softer and more prone to slight burrs, hole expansion, or thermal swelling during drilling. These factors can cause the actual hole to be slightly larger than the drill bit size. Therefore, when installing rivet nuts in aluminum, it’s advisable to use a drill bit approximately 0.1mm smaller than the standard size to ensure a snug fit and prevent nut loosening.
3. Plastics or Composite Materials: Special Attention to Hole Precision
Non-metallic materials such as plastic have a high thermal expansion rate and are prone to deformation, melting, or edge damage during drilling, which can result in irregular or oversized holes. In this case, it is recommended to:
- Use special drill bits designed for plastics to reduce burring;
- Drill at low speeds to prevent heat buildup and melting;
- Test drill holes in advance to confirm the proper drill size and tolerance.
4. Stainless Steel Sheets: Use High-Quality Drill Bits and Replace Regularly
Stainless steel is very hard and abrasive, making drilling more difficult and likely to wear down drill bits quickly, affecting hole accuracy. To ensure consistency:
- Use high-strength drill bits (e.g., cobalt or carbide-tipped);
- Replace worn bits frequently;
- Apply cutting fluid or coolant to reduce heat and deformation.
Can I Use Standard Drill Bits for All Rivet Nut Types?
Not always. While standard round drill bits are suitable for most smooth body rivet nuts, other types—such as knurled body and hex body rivet nuts—may require special hole shapes or tighter hole tolerance. Here’s a detailed explanation:
a. Smooth Body – ✅ Standard Drill Bits Applicable
This type has a plain cylindrical outer surface and does not require special hole shapes. As long as the hole diameter is within the recommended range (typically 0.1–0.3 mm larger than the nut body), installation will be smooth and secure. Therefore:
- Standard metal drill bits are sufficient;
- Commonly used for aluminum sheets, thin steel panels, and general applications.
b. Knurled Body – ⚠️ Requires Tighter Hole Tolerance
Knurled rivet nuts feature longitudinal ridges that grip the base material through friction. If the hole is too large, the knurls won’t bite properly, reducing anti-rotation performance. Recommendations:
- Standard drill bits can be used but require precise control of the hole diameter;
- Use in softer or medium-hard materials for optimal knurl engagement;
- Avoid oversized holes or rough edges (burrs).
c. Hex Body – ❌ Not Suitable for Standard Round Holes
Hexagonal rivet nuts are designed to prevent rotation and must be installed in hex-shaped holes or slots. Using a standard round drill bit will result in:
- Inability to lock the nut in place;
- Poor joint strength;
- Compromised performance.
For hex body rivet nuts, laser cutting, stamping, or milling is recommended to achieve accurate hex holes.
What Tools Are Recommended for Drilling and Installing Rivet Nuts?
1. Recommended Drilling Tools
a. Handheld Electric Drill
- Suitable for drilling common metals, plastics, and composite panels;
- Compatible with various drill bit sizes, ideal for small batches or mobile work;
- Pay attention to maintaining drill perpendicularity and feed speed to avoid misaligned holes.
b. Drill Press / Bench Drill
- Recommended for applications requiring higher precision;
- Ensures vertical stability and consistent hole diameter;
- Better suited for batch processing or drilling tougher materials.
c. Specialized Drill Bits
- For metals: Use high-speed steel (HSS) or cobalt drill bits;
- For plastics or aluminum: Use sharp specialized drill bits to minimize burrs and edge tears;
- For inch-threaded rivet nuts (e.g., #10-24, 1/4”-20), refer to drill size charts and use corresponding inch drill bits (such as #7, F drill).
2. Recommended Installation Tools
a. Hand Rivet Nut Tool
- Easy to operate, suitable for repair work or small batches;
- Compact design fits tight spaces and outdoor jobs;
- Lacks torque control, so tightening depends on operator’s feel.
b. Cordless Electric Rivet Nut Gun
- Suitable for medium to small batch assembly;
- Battery-powered for flexible movement and labor saving;
- Some models have adjustable torque settings for consistent installation.
c. Pneumatic Rivet Nut Gun
- Ideal for large-scale production and assembly lines;
- Provides high pulling force and stable operation, allowing fast installation;
- Requires an air compressor, mainly used in factories or workshops.
d. Torque and Stroke Control
- Tools with torque adjustment or stroke setting are recommended to avoid over- or under-installation;
- Helps improve installation consistency and reduce rework.
FAQs
1. What If the Drill Hole Is Too Big or Too Small?
If the drill hole is too small, the rivet nut will be difficult or impossible to insert, which may damage the external knurls or splines of the nut and compromise its locking ability. Forcing insertion can also deform or crack the base material, especially if it is soft like aluminum or plastic.
If the hole is too large, the rivet nut will not grip tightly after installation, causing looseness or rotation. This can lead to the nut coming loose or falling out under vibration or load, significantly reducing the joint’s strength and reliability. Therefore, it is crucial to drill a hole size slightly larger than the rivet nut’s body diameter within the recommended tolerance.
2. Is There a One-to-One Correspondence Between Drill Bit Size and Thread Size?
No, drill bit size does not directly match thread size because the drill hole must be slightly larger than the rivet nut’s outer diameter (body diameter), not the thread diameter. The drill size allows the rivet nut to fit smoothly into the hole before installation. Different rivet nut types and materials may require slight adjustments in drill size to ensure proper fit and secure fastening. Always refer to the manufacturer’s recommended drill size chart rather than using thread size as the drill bit diameter.
3. How to Choose Metric Drill Bits When Using Inch-Threaded Rivet Nuts?
When using inch-threaded rivet nuts (e.g., #10-24, 1/4”-20), it’s common to select drill bits in metric units due to availability or convenience. In this case, refer to an inch-to-metric drill bit conversion chart to find the closest metric drill size recommended for the specific inch-thread rivet nut. Using the correct drill size ensures the rivet nut fits properly and is installed securely, even if the drill bit is metric. Always verify with manufacturer specifications or trusted conversion tables for accuracy.
4. Can I Reuse a Rivet Nut Once Installed?
No, rivet nuts are typically designed for one-time use. Once installed and crimped into place, their body deforms to grip the material. Removing them often damages the nut or the base material. If removal is necessary, it’s best to replace with a new rivet nut to ensure structural integrity.
5. What If I Don’t Have the Exact Recommended Drill Bit Size?
If you don’t have the exact recommended size, use the closest drill size without exceeding the upper tolerance limit. It’s safer to use a slightly smaller bit and ream to size if needed. Using a drill bit that’s too large may compromise the fit and lead to weak fastening.
6. Can I Install Rivet Nuts Without a Special Tool?
It is possible but not recommended. Some DIY methods involve using bolts and washers to compress the nut manually, but this can lead to inconsistent installation and damage. For best results, use a rivet nut tool—either manual, pneumatic, or electric—for proper crimping and grip.
