Drill & Tap Charts: A Comprehensive Guide

When it comes to drilling and tapping holes, precision is key. Whether you’re working with fractional, pipe, or metric threads, having a drill and tap chart is important, and it’s almost impossible to create a hole without one. These charts serve as a roadmap, guiding you to the right size drill bit and tap to cut out the perfect threaded hole.

In this guide, we’ll break down the essentials, starting with the tools and accessories you’ll need to get the job done right. From selecting the correct drill bit to choosing the right tap with our handy charts we have available, we’ll cover everything you need to know to avoid stripping the threads and breaking the tap for a clean, precise fit every time.

When it comes to drilling and tapping a hole, the right tools make all the difference. First off, you’ll need a good set of T-handle tap wrenches. These are essential for manual threading, providing the control and precision needed to start and finish your threads without damaging the material. The Irwin 12401 is ideal for smaller taps ranging from No. 0 to 1/4", while the Irwin TR-1E is perfect for larger taps between 1/4" and 1/2". Both wrenches are adjustable and offer the sturdy construction needed to handle a variety of materials.

On the power tools front, the Milwaukee 3696-22 M18 FUEL 2-Tool Combo Kit with ONE-KEY is a powerhouse for drilling and tapping tasks. This kit includes an M18 FUEL 1/2" Hammer Drill and a 1/4" Hex Impact Driver, both equipped with the POWERSTATE Brushless Motor for unmatched power and efficiency. The hammer drill is compact yet powerful, perfect for drilling your initial holes with precision. 

When tackling those heavy-duty jobs, the Jet JDP20VST 20" Variable Speed Tapping Drill Press is a solid choice. With its robust steel column, heavy-duty cast iron construction, and variable speed settings, this drill press offers the precision and control needed for larger holes and deeper threads.

Before you start threading, you’ll need a tap and die set to ensure you’re creating clean, precise threads. A set like the Irwin 26317 Metric Tap & Hex Die Set or the GearWrench 82812 Ratcheting Tap and Die Set offers a variety of sizes and types to tackle different threading tasks, whether you’re working with new material or repairing old threads. To prepare the hole for tapping, using a chamfer tool like the Reed DEB3 Deburring Tool for aluminum, copper, and steel to ensure that the edges are smooth and ready for threading.

Lastly, don’t forget the cutting fluid. Using a high-quality product like Relton Rapid Tap is crucial. Cutting fluid reduces friction and heat buildup, extending the life of your tools and preventing damage to the workpiece. It also helps produce a smoother surface finish and makes it easier to remove chips from the hole, which is particularly important when working with tougher materials. Applying cutting fluid before drilling and tapping is key to achieving a clean, precise finish and ensuring your tools last longer.

Using one of these charts is pretty straightforward. Let's break it down:

1. Identify Your Tap Size: Start by knowing the size of the tap you plan to use. This could be a standard size, like 1/4-20, or a metric size, like M6x1.

2. Find the Corresponding Drill Bit: Look at the chart, find your tap size, and trace it across the chart to find the correct drill bit size. For example, if you're working with a 1/4-20 tap, the chart will tell you to use a #7 drill bit.

3. Check the material: Different materials may require slight adjustments, so be sure to consider what you’re drilling into.

Using the wrong drill bit size can lead to a number of issues:

1. Stripped Threads: If the hole is too small, your tap might strip the threads, making them too weak to hold anything.
2. Loose Fit: On the other hand, if the hole is too large, the threads will be too loose, and your fasteners will not hold securely.
3. Broken Tools: Using the wrong size can also put unnecessary stress on your drill bits and taps, increasing the chances of breakage.

A drill and tap chart eliminates these problems by giving you the correct pairing every time.

To start, let’s take a look at the Fractional Drill Tap Chart below. This drill tap chart lists tap sizes with their corresponding fractional drill sizes, decimal equivalents, and threads per inch (TPI). By following this chart, professionals can ensure accurate drilling, which is crucial for creating clean, precise threads that fit correctly and function properly.

Next up on our charts is the Pipe Thread Drill Tap Chart . This chart is essential for professionals needing precision in threading pipes. The chart below outlines each pipe thread size and is listed with it’s threads per inch (TPI), with the correct drill bit size to use before tapping threads.

For instance, a ¼”-18 thread requires a 7/16” drill bit, while a ½”-14 thread needs a 23/32” bit. Make it easy on yourself and increase productivity time by keeping this chart handy. 

Our last chart is the Metric Thread Drill Tap Chart . A metric thread drill tap chart is crucial for professionals working with metric fasteners, ensuring precision and consistency when tapping threads. The chart pairs each metric tap size, indicated with its thread pitch, to the correct drill size in millimeters, alongside its decimal inch equivalent.

For example, an M5X0.8 tap requires a 4.20 mm drill bit, while an M10X1.5 tap needs an 8.50 mm bit. Professionals use these charts to guarantee that threads fit accurately, reducing the risk of damaging components and maintaining consistent quality across various projects, from automotive work to manufacturing.

Here are a few examples of tap sizes and the corresponding drill bit you'll need:

1. 1/4-20 Tap: Use a #7 drill bit (0.201” diameter).
2. 3/8-16 Tap: Use a 5/16” drill bit (0.3125” diameter).
3. M6x1 Tap: Use a 5mm drill bit.

1. Use Cutting Fluid: This reduces friction and heat, making your taps last longer.
2. Go Slow: Especially with harder materials, take your time. A slower speed ensures cleaner threads.
3. Back Off: Every few turns, back the tap out slightly to clear the chips and prevent binding.

Understanding and using a Drill & Tap Chart is essential for precision in your drilling and tapping tasks. These charts are more than just handy tools—they're vital for ensuring that every hole you create matches the exact size needed for threading, reducing the risk of stripped threads, loose fits, or broken tools.

We’ve covered the basics, from selecting the right tools and accessories to the specifics of using a Drill & Tap Chart effectively. Remember, whether you’re working with fractional, pipe, or metric threads, having the correct drill bit and tap size will make your job smoother and more accurate.

For best results, always refer to a Drill & Tap Chart to avoid costly mistakes and ensure professional outcomes.