Taps and Dies are essential for creating new or repairing old threads. But they aren’t always the most straightforward tool to use.

What’s the Difference Between a Tap and a Die?

First, you have to understand the difference between a tap and a die. Taps make internal threads in a hole, which allows a bolt to be screwed into it. Dies, on the other hand, make external threads on a rod. Both taps and dies are used to cut new threads.

But how do you know which one you need? Well, you need to start by identifying the thread and the size of the tap you need. This might sound easy, but mistakes are often made at this crucial step. When creating new threads, reference a tap chart to determine the tap-and-tap drill that works best for your required task. Before you begin, you’ll want to choose the tap based on the type of material you’ll be threading into. For example, the Procore High-Speed Steel Tap and Die Set are great for softer materials, whereas the Procore Carbon Steel Tap and Die Set are ideal for harder materials like stainless steel. The most common taps are made of High-Speed Steel (HSS).

How to Measure for a Tap and Die?

Measure what size of thread you are going to need can be done in 4 easy steps:

  • Measure the outside diameter of the thread
  • Count how many threads there are per inch
  • Find out if your thread is a national fine or a national coarse. By looking at an identification chart, you can find out what your thread is.
  • Lastly, compare the numbers and thread type you just gathered to the numbers written on the taps and dies. For example, if you had a tap stamped “1/4-20 N.C” that means you have a ¼ inch diameter, with 20 national coarse threads per inch. The same is true for a die

A Word of Caution

In order for taps and dies to cut, they need to be harder than the material they are cutting. The type of steel and heat treatment that taps go through can make them brittle, which means they can break. Something you want to avoid at all costs! After all, the hardened material of a tap means it is that much more difficult to remove from a hole once it has been broken. To keep your taps in tip-top shape, you’ll want to make sure you’re using the right tool for the job. The Walter 02-W100 t-handle or tap wrench is the most commonly used tool. But proper usage is key to ensure that you don’t break your tap. Take your time and go slow to make sure that you don’t make a mistake that could cost you time and money.

Three Basic Types of Taps

Taper Taps

A taper tap is the least common. They can start narrow and taper to a full thread width, hence their name. The taper on the SST+ taps is a lot longer than the plug style. This allows for an easy start when you’re threading a hole. However, these taps need to go deeper than a plug tap to form a fully threaded hole, which is why they are less common than the other two tap styles.

Plug Taps

Plug Taps are the most common and are often used for general-purpose applications. They have a straight taper that helps to start your threads. If you’re only purchasing one kind of tap, the plug tap is your best bet since you can complete threads almost to the bottom of a hole and can start the threads with just one style of tap.  

Bottoming Taps

Unlike plug and taper taps, bottoming taps have no threads ground down at the starting end. That means that these taps don’t do well at starting threads, so it’s recommended to use a taper or plug tap to start. However, the nice thing about bottoming taps is that they can thread all the way to the bottom of a blind hole, whereas a taper and plug tap stop between 3 to 10 threads shy of the bottom.

How to Prepare a Rod for Threading

To prepare a rod for threading, grind a bevel onto the end so it’s easier to turn the die onto the rod. Then, make sure to secure the rod in a vice. You always want to secure the material you’re threading, not the tool you’re using to do the job. This ensures you get the best, cleanest threads possible.

The process is just like creating internal threads: make sure the die and rod stay level and that you’re using lubrication where necessary. Always check your threads with the desired nut or screw, before putting them to the test. Even though there’s not a lot of heat build-up when cutting threads, lubricating the threads can help to reduce friction and aid in chip removal.

How to Clean up the Chips

Chip removal and break-up is a critical part of the tapping process since it helps to clear out the chips of metal that are created when you cut the threads. This will prevent jamming and breaking the tap. To clean up the chips in your tap or die, use a wire brush like the Ridgid Copper Clean Tool to remove the metal.

In many taps, there is a groove called a flute. It provides a clearance so that the metal chips are kept free from the cutting teeth and can be pushed out the top of the threading hole. It's important to break up these chips to keep the tap from jamming and potentially breaking. Remember, excess friction equals a broken tap! So, the best way to prevent this is to make sure that for every full turn of clockwise cutting action, you are turning the tap one half-turn counterclockwise. This will break up the chips and help clear the way!

Here at Gregg Distributors we’ve got a wide variety of taps and dies to meet your needs. Whether you need a fully stocked Viking Counter Display, a full Performance Tool tap and die set, or just a taper pipe tap, we’ve got you covered! If you have any questions feel free to contact us here and make sure to subscribe to our email list or follow us on social media to stay up to date with things happening here at Gregg Distributors!