If you’ve come here, you’re probably wondering what “taper” is. While it might initially seem like a confusing construct, it really isn’t. In this post we’re going to go over what it is, and what is is used for.

What is taper?

Taper is a gradual reduction in thickness along a workpiece’s length. In other words, it’s when a section of metal gradually becomes thinner as you move from one end to another.

A taper angle (t) is the ratio between the original width and height of an object before being tapered, divided by its new width and height after being tapered.

Taper angle formula

Now that we know what taper is, we can understand how to calculate its angle. The formula we are going to use is:

\theta = tan^{-1} \times ( \frac {T} {2})

In this formula, T stands for the taper. The formula for calculating T is:

T = \frac {Di - Ds}{TI}

Di is the major diameter, Ds is the minor diameter, and TI is the taper length.

Now that you know what the formula is, let’s get into how to use it.

The first thing you need to do is measure your taper length (L). You can either use a ruler or an online tape measure to do this. Then, determine where you want your taper to start by measuring from the small end of your rod or tube to where you want it to start tapering down. This measurement could be anywhere along its length, but it will affect how quickly or slowly your taper will get smaller as well as how long the overall piece will be when finished.

The diameter of the small end or large end is a value that you choose, and it’s related to the size of your shank. The number of threads per inch (tpi) is also a variable that you can change in this equation depending on how many threads per inch your tap has.

Types of taper

There are two types of tapers: parallel and fractional. Both have a different approach to controlling the rate of change.

Parallel tapers are used when you need to reduce the diameter of a shaft while maintaining its overall length and you want this reduction to occur in equal amounts on both sides of the centerline. Parallel tapers are specified by their rate of change, which is expressed as a ratio between the original diameter and reduced diameter (e.g., 10:1). For example, if you have a 1-inch shaft that needs to be tapered down to 3/4 inch over its entire length, it will be cut using an 8:1 parallel taper angle at each end.

Fractional bearings typically use parallel tapers because they require more accuracy than standard parallel ones due to higher loads placed upon them during operation (e.g., high-speed spinning).

Parallel taper

Parallel tapers – In this type, small and large diameters vary equally. For example, if 1 inch is reduced in large diameter then 1 inch will also be reduced from the small diameter. Here parallel lines are used to represent the cross section of a taper. The length of the parallel line represents the length of the tapered section and its thickness represents its width or height.

Parallel tapers are used for long tapers (L-shaped). They can also be used for short tapering which means changing diameter along with both axial directions at equal rates but with different amounts of change in each direction (C-shaped).

How to use the taper calculator

As we discussed before, all you need to know, are the two diameters (major and minor) and the taper length. Once you input their values into the calculator, it will give you the taper angle and the taper.


What is the use of taper?

There are many uses, some of which are plug-in adapters, mounting drill bits into chucks, toolholders, and self-holding circular objects.

What is tapering?

Tapering is the process of reducing the width of a component with respect to its length.

What are the types of tapers?

There are parallel and fractional tapers.