Taps make threaded holes so that they’re ready for fasteners like screws and bolts to be inserted or tightened with a drill or appropriate hand tool. Turning the tap by hand creates threads inside pre-drilled holes. They’re found in manufacturing parts, like vehicles and structures, and they’re also in flat-packed furniture—handy for those putting it together as they won’t have to manually make these holes.
There are tons of different types of thread taps with many varying endpoints, tapers, and flutings. Let’s look at 13 of them to help you decide on the right one for your needs—because, let’s face it, knowing which one to use is a total shot in the dark.
Hand taps are multifunctional and work either by hand or with a power tool. They’re used for machine tapping in general and most materials with blind or through holes. These have straight flutes used in shallow blind or through holes. A standard hand tap set has three separate types, which we’ll discuss below.
A plug tap has a five-thread cutting chamfer that slowly cuts away material to create the thread, starting with the smaller diameter. They’re used when there is enough space at a blind hole’s bottom part, or to make through-holes. They make a more complete set of threads compared to taper taps, but aren’t as well suited to finishing threads in blind-holes as bottoming taps.
Also known as fluteless taps or rolled threads, these taps don’t actually cut threads; they cold-form them instead, during which the metal isn’t cut, but moved away before being compressed into position. No chips are formed in the process, meaning you don’t have to remove any. These taps make stronger threads that are less likely to break.
We suggest using form taps instead of cutting taps whenever you can, as long as the material isn’t too hard. Lots of people think that these are only good for soft materials like aluminum, but they work with any material with a hardness of 36 HRC (or 340 BHN). That covers a bunch of materials, including a lot of steel types.
Taps have marks on the shank, so you can tell with just a look what type of thread tap you’re working with. The markings include the nominal size, which is the thread size that the tap will take. There’s also the thread form symbol, which identifies the thread family. There’s also tap material, which is usually carbide or HSS. It also typically shows the pitch diameter limit, which tells what tolerance thread will be made.
Here is a quick guide for threads with a diameter of less than an inch:
Note: You can find these limits in G-Wizard’s thread database as well.
When you’re choosing which thread tap to use, there are four main factors to think about so you can up your chances of success:
Workpiece material: Various materials have different levels of firmness and there will be a tap suitable for each level. Some will work better than others on different materials, i.e., a machine tap works well on harder materials, but a fluteless tap is best for soft materials.
Tap material: You’ll have to choose this according to the material of the piece you want to work on, e.g., carbide steel taps can cut threads quickly, and are strong enough to handle hard materials like cast iron.
Hole type: Depending on what hole you need to make, there will be a tap up to the task. Taps with 1–3 thread chamfers can create deeper holes, for instance.
Cutting speed: Some taps, i.e., spiral flute, are designed for high-speed work, while others not so much, so you’ll have to know the speed of cutting before choosing your taps.
Contact us to discuss your requirements of custom taps and dies. Our experienced sales team can help you identify the options that best suit your needs.