What is an M8 Tap Drill Size

m8 tap drill size

Ever wondered what an M8 tap drill size is? If so, you’re in the right place! In this blog post, we’ll be discussing everything you need to know about M8 tap drill size, including what it is and how to use it. So without further ado, let’s get started.

What is an M8 Tap Drill Size?

An M8 tap drill size refers to the specific diameter of a drill bit that is used to create threads in a workpiece. This size is typically used for metric-sized screws and bolts. The M8 tap drill size is 8 mm in diameter. When using this size tap drill, it is important to ensure that the workpiece is properly prepared. The surface should be clean and free of debris [1]. 


The threads should be cut at a 90-degree angle to the surface of the workpiece. In addition, it is important to use the proper lubricant when creating the threads. This will help to prevent damage to the tap drill and the workpiece.

What Size Hole Do You Drill for an M8 Tap?

When drilling a hole for an M8 tap, the general rule of thumb is to drill a hole that is slightly smaller than the tap’s diameter. For an M8 tap, this would be a 7.5 mm hole. This allows for a tight fit and helps to prevent the tap from slipping or becoming damaged. When drilling, it is also important to use a high-quality drill bit that is sharp and designed for metal. 

If the hole is not drilled correctly, it can cause the tap to break or damage the threading. With a little care and attention, however, it is easy to drill the perfect hole for an M8 tap.

What Size Drill Bit is an M8?

If you’re looking to install an M8 expansion bolt, you’ll need to first drill a small pilot hole. For this, you’ll need a small drill bit, between 4 and 5 mm in diameter. Once the pilot hole is drilled, you can then use a 12mm drill bit to create the hole for the expansion bolt itself. 

m8 tap drill size

This will ensure that the bolt is properly secured and can support whatever weight you’re looking to hang from it. With the right drill bits, installing an M8 expansion bolt is a relatively simple process.


The M8 tap drill size is a metric screw thread with an 8 mm diameter. The tap drill size for this thread is the same as the major diameter, or 8 mm. This tap drill size should be used when tapping holes that are smaller than the major diameter of the screw thread.

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