Understanding the 8/32 Helicoil: The Essential Guide to Tap and Drill Bits

When it comes to repairing or maintaining threaded holes, the 8/32 Helicoil is a popular choice. This type of thread repair is designed to restore the integrity of a damaged or worn-out hole. To ensure a successful repair, it’s crucial to use the correct tap and drill bits. In this article, we will delve into the details of the 8/32 Helicoil, including the appropriate tap and drill bit sizes.

Understanding the 8/32 Helicoil

The 8/32 Helicoil is a thread repair solution that involves inserting a helical spring into a pre-drilled hole. This spring is designed to restore the original thread size and strength. The “8/32” refers to the thread size, where “8” represents the diameter of the thread and “32” represents the pitch. This means that the thread has a diameter of 8mm and a pitch of 1mm.

Choosing the Right Tap

Selecting the correct tap for the 8/32 Helicoil is essential to ensure a proper fit and a successful repair. A tap is a cutting tool used to create internal threads. For the 8/32 Helicoil, you will need a 8-32 UNF (Unified National Fine) tap. This tap is specifically designed for creating threads with a diameter of 8mm and a pitch of 1mm.

When choosing a tap, consider the following factors:

• Material: Taps are available in various materials, such as high-speed steel, cobalt, and carbide. High-speed steel is suitable for general-purpose applications, while cobalt and carbide are better for harder materials.

• Coating: Some taps come with a coating, such as TiN (Titanium Nitride), which improves the tool’s life and reduces friction.

  

• Size: Ensure that the tap size matches the thread size of the Helicoil, which is 8-32 UNF.

Selecting the Correct Drill Bit

Before inserting the Helicoil, you need to drill a hole with the correct size and depth. For the 8/32 Helicoil, you will need a drill bit with a diameter of 8mm and a length that extends beyond the bottom of the hole by at least 1/4 inch. This ensures that the Helicoil has enough material to grip and restore the thread.

When selecting a drill bit, consider the following factors:

• Material: Drill bits are available in various materials, such as high-speed steel, cobalt, and carbide. High-speed steel is suitable for general-purpose applications, while cobalt and carbide are better for harder materials.

• Coating: Some drill bits come with a coating, such as TiN (Titanium Nitride), which improves the tool’s life and reduces friction.

• Size: Ensure that the drill bit size matches the thread diameter of the Helicoil, which is 8mm.

Drilling and Tapping the Hole

Once you have the correct tap and drill bit, follow these steps to drill and tap the hole for the 8/32 Helicoil:

1. Secure the workpiece in a vise or chuck.

2. Insert the drill bit into the drill and align it with the center of the workpiece.

3. Drill the hole to the desired depth, ensuring that the drill bit extends beyond the bottom of the hole by at least 1/4 inch.

4. Remove the drill bit and clean the hole to remove any debris.

5. Insert the tap into the drill and align it with the center of the hole.

6. Apply gentle pressure and tap the hole to create the threads.

7. Check the threads with a thread gauge to ensure they are properly formed.

Inserting the Helicoil

After tapping the hole, you can insert the Helicoil. Follow these steps:

1. Remove the Helicoil from its packaging and inspect it for any damage or bur