How to Measure a Chamfer: Metalworking Guide

A chamfer is an angled surface machined along the edges or corners of a workpiece using different tools.

Depending on the application and purpose, these chamfers can be made of different sizes and dimensions.

But how exactly is a chamfer measured? What are the different types of chamfer, and what are some other geometries similar to chamfer?

Chamfer can be measured by using various tools like a chamfer gauge, optical comparator, or chamfering ruler. These tools are used to calculate the length of the chambered profile, also known as face width. You can also measure the chamfer by applying the Pythagorean theorem to its leg lengths.

This article will explain the process of measuring a chamfer by explaining its different terminologies and tools used for measuring.

In the end, I've also discussed different types of chamfers and compared chamfers with other similar geometries.

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Measuring a Chamfer

Chamfering is often done to remove any burrs present on a workpiece’s edges. Moreover, chamfered surfaces also facilitate the assembly of tight-fitting parts.

ISO 13715 specifies the standards for identifying and measuring undefined edges like chamfers on a workpiece, along with the symbols used for identifying them on 2D drawings.

The chamfer angles can be assumed to be 45 degrees if their magnitudes are unknown; however, it is better to compute or measure the exact value.

You can dimension the chamfers using the leg lengths or a combination of the chamfer angle and a leg length value.

For example, if a chamfer has an angle of 45 degrees and leg lengths of 0.010", then one way of dimensioning will be to use the convention 0.010" (0.25 mm) x 45°. 

Alternatively, you can use the convention 0.010" (0.25 mm) x 0.010" (0.25 mm), which will only state the leg length values.

Measuring Chamfer by Using a Chamfer Gauge

A chamfer gauge is a tool specially designed to measure the chamfer dimensions. 

It usually consists of a spring-loaded plunger housing an anvil that sits on the chamfered surface and measures the chamfer length and angle.

These tools come in analog and digital versions, with the latter being more accurate and easier to use. 

The analog version consists of an analog scale, while the digital model comprises a digital display.

Chamfer gauge can generally measure the dimensions with a precision of around 0.01 mm, with some advanced models that possess even higher precision and are used for research applications.

To calibrate the analog models, the base of the gauge is pushed against a flat surface, and a button is pressed to calibrate it, which brings the measuring needle to zero reading, as flat surfaces have zero chamfer angle.

This calibration process is to be repeated every time when you change the anvil of the chamfer gauge.

After calibrating the gauge, you can press the anvil against a chamfered opening to get the exact chamfer angle of that geometry.

Some chamfer gauges can also be automated by attaching them to a CNC-based robotic hand which moves and positions them accordingly to measure the chamfer dimensions and display them on a computer.

Measuring Chamfer by Using an Optical Comparator

Chamfers can also be measured by using an optical comparator that consists of a magnifying lens to zoom in and focus the chamfer geometry.

While manual comparators require you to trace that geometry and measure the chamfer dimensions manually, digital comparators provide you the ability to trace the geometry by using X and Y-axis controls.

Once you trace the required geometry, the comparator displays the dimensions of the selected geometry, i.e., chamfer.

Traditional comparators can only measure the angle of the chamfer, however, some newer models provide the ability to measure the length and angle.

These devices are commonly used in factories, research laboratories, and large mechanical workshops.

Measuring Chamfer by Using a Chamfering Ruler

A chamfering ruler is an L-shaped stainless steel scale that measures the leg lengths of a chamfered surface. 

Before use, you must ensure that both the scales are perpendicular to each other and their surface is smooth because even a slight deviation can result in inaccurate dimensions.

For this purpose, the ruler is positioned on a perfectly machined small metal block. If the scales completely block the passage of light, that would mean that the ruler is fit for use.

A thorough visual inspection can also help determine the working condition of the ruler.

Place this ruler in such a way that the scales perfectly sit on the horizontal and vertical sides of the workpiece that originate from the chamfered surface.

Then, carefully measure the horizontal and vertical leg lengths. These sides form an imaginary right-angled triangle on top of the chamfered surface.

After getting the exact leg length of the chamfer, you can use Pythagoras theorem and trigonometry to measure the length of the chamfered surface and calculate its angle.

Apart from that, you can also use a protractor to measure the chamfer angle and consequently save computation time.

However, this long and tedious method can result in inaccurate readings due to parallax and human error, but it is a cheap and simple way to measure the chamfer dimensions.

It is feasible for DIY users and beginners who want to learn the fundamentals of measuring, as it is cheap and easy to understand.  

Types of Chamfer

Chamfer types can be classified based on dimensions, tool type, and application.

Based On Dimensions

Leg lengths

A chamfer denoted in the design by its leg lengths is known as a leg length chamfer.

This method is also used when one leg length is known and the chamfer angle is assumed to be 45 degrees.

Leg length and Chamfer Angle

If the chamfer angle is known, then its value and leg length are stated while dimensioning.

This type of chamfer is referred to as leg length and chamfer angle.

Based On Tool Type and Application

Pointed

If the tool used for machining the chamfer onto the workpiece possesses a sharp pointy edge supported by at least two flutes, then a chamfered surface with a steep slope and a long depth is obtained.  

Such a cutter is ideal for machining precise chamfers on small geometries like holes, slots, and grooves.

Flat-End and Non-End Cutting

In this category, the tool cutter has a flat-surfaced end, but its remaining features are similar to a pointed chamfer cutter.

This cutter machines a chamfer geometry that is usually less steep and shorter than a pointed chamfer.

The periphery of the cutter performs the material removal and cutting action. Such chamfers are best suited for removing burrs around edges and slots.

Flat-End and End Cutting

These cutters are an optimized version of the flat-end, non-end cutting type. Their flutes meet at the center of the cutter’s bottom side, enabling some cutting action to occur at this point as well.

The chamfer geometry is similar to that of a flat-end non-end cutting type but more precise and accurate.

Other Geometries Similar to a Chamfer

Some geometries draw a resemblance to a chamfer.

Chamfer vs Fillet

Fillets are rounded edges on a workpiece that help reduce stress concentration and make it easier to hold. 

A fillet’s smooth and accurate geometry is generally more expensive and time-consuming to machine than a chamfer. 

Different cutters with different specifications are needed for machining different fillet sizes, whereas a single cutter can machine different chamfer sizes.

The completely rounded geometry significantly reduces any possibility of stress concentration.

In contrast, a chamfer still contains edges along its ends, which can act as stress raisers and deform the material over time. 

Fillets have a rounded shape, making objects easier and safer to handle, contrary to chamfered objects that contain edges that can cause injury.

Chamfer vs Bevel

Although a chamfer and a bevel are often considered the same in machining, a bevel is fundamentally different.

A bevel is a continuous sloping surface between two parallel sides of the workpiece, whereas a chamfer is a small tilted cut made around a surface’s edge. 

Bevel and chamfered surfaces are widely used in carpentry, metalworking, stoneworking, and woodworking.

Bevelling and chamfering tools differ in geometrical aspects, with bevelling tools being larger. However, you can also utilize a single tool can for both purposes.

When viewed from the sides, a completely chamfered object resembles an octagon, while a workpiece beveled from both ends looks like a rhombus.

Chamfering is only possible through material removal, contrary to bevelling, which is also possible by simply cutting a workpiece along an angle.

Frequently Asked Questions (FAQ)

What chamfer angle is commonly used in machining?

A chamfer angle of 45 degrees is commonly used in machining.

Can a radius be used to describe a chamfer on a 2D drawing?

No, a radius dimension can not describe a chamfer on a 2D drawing. Leg lengths and a chamfer angle are required for dimensioning a chamfer.

What mechanical advantage do chamfers offer?

The mechanical advantage of chamfers is reducing stress concentration by removing sharp edges.