Selecting the Right Chamfer Cutter Tip Geometry

A chamfer cutter, or a chamfer mill, can be found at any machine shop, assembly floor, or hobbyist’s garage. These cutters are simple tools that are used for chamfering or beveling any part in a wide variety of materials. There are many reasons to chamfer a part, ranging from fluid flow and safety, to part aesthetics.

Due to the diversity of needs, tooling manufacturers offer many different angles and sizes of chamfer cutters, and as well as different types of chamfer cutter tip geometries. Harvey Tool, for instance, offers 21 different angles per side, ranging from 15° to 80°, flute counts of 2 to 6, and shank diameters starting at 1/8” up to 1 inch.

After finding a tool with the exact angle they’re looking for, a customer may have to choose a certain chamfer cutter tip that would best suit their operation. Common types of chamfer cutter tips include pointed, flat end, and end cutting. The following three types of chamfer cutter tip styles, offered by Harvey Tool, each serve a unique purpose.

Three Types of Harvey Tool Chamfer Cutters

Type I: Pointed

This style of chamfer cutter is the only Harvey Tool option that comes to a sharp point. The pointed tip allows the cutter to perform in smaller grooves, slots, and holes, relative to the other two types. This style also allows for easier programming and touch-offs, since the point can be easily located. It’s due to its tip that this version of the cutter has the longest length of cut (with the tool coming to a finished point), compared to the flat end of the other types of chamfer cutters. With only a 2 flute option, this is the most straightforward version of a chamfer cutter offered by Harvey Tool.

Type II: Flat End, Non-End Cutting

Type II chamfer cutters are very similar to the type I style, but feature an end that’s ground down to a flat, non-cutting tip. This flat “tip” removes the pointed part of the chamfer, which is the weakest part of the tool. Due to this change in tool geometry, this tool is given an additional measurement for how much longer the tool would be if it came to a point. This measurement is known as “distance to theoretical sharp corner,” which helps with the programming of the tool. The advantage of the flat end of the cutter now allows for multiple flutes to exist on the tapered profile of the chamfer cutter. With more flutes, this chamfer has improved tool life and finish. The flat, non-end cutting tip flat does limit its use in narrow slots, but another advantage is a lower profile angle with better angular velocity at the tip.

Type III: Flat End, End Cutting

Type III chamfer cutters are an improved and more advanced version of the type II style. The type III boasts a flat end tip with 2 flutes meeting at the center, creating a center cutting-capable version of the type II cutter. The center cutting geometry of this cutter makes it possible to cut with its flat tip. This cutting allows the chamfer cutter to lightly cut into the top of a part to the bottom of it, rather than leave material behind when cutting a chamfer. There are many situations where blending of a tapered wall and floor is needed, and this is where these chamfer cutters shine. The tip diameter is also held to a tight tolerance, which significantly helps with programing it.

In conclusion, there could be many suitable cutters for a single job, and there are many questions you must ask prior to picking your ideal tool. Choosing the right angle comes down to making sure that the angle on the chamfer cutter matches the angle on the part. One needs to be cautious of how the angles are called out, as well. Is the angle an “included angle” or “angle per side?” Is the angle called off of the vertical or horizontal? Next, the larger the shank diameter, the stronger the chamfer and the longer the length of cut, but now, interference with walls or fixtures need to be considered. Flute count comes down to material and finish. Softer materials tend to want less flutes for better chip evacuation, while more flutes will help with finish. After addressing each of these considerations, the correct style of chamfer for your job should be abundantly clear.

The Multiple Uses of a Chamfer Mill

A chamfer mill, or a chamfer cutter, is one of the most common tools used by machinists daily. When creating a part, machining operations can oftentimes leave a sharp edge on a workpiece. A chamfer mill eliminates sharp edges, leaving a sloped surface, or a chamfer, instead. In doing so, the part will be stronger and more aesthetically appealing to its eventual user.

This singular tool can provide many cost-saving benefits to machinists. Aside from the namesake operation it performs on a part, a chamfer mill can be used for several machining operations including beveling, deburring, countersinking, and spotting.

Chamfer Mill for Beveling

The terms “chamfer” and “bevel” are often used interchangeably. These two features, while similar, actually have two different definitions. While a chamfer impacts a portion of the side of a workpiece – specifically the edge of a part, a bevel angles the entire side of what was a squared-off part feature. Thus, the side of a part can feature two chamfers, or only one bevel (Figure 1).

A chamfer mill, however, can perform both operations. The two features are equivalent in both geometry, and how they are machined.  A chamfer mill will create both part features in the exact same fashion; a bevel just may use a larger portion of the cutting surface, or may require multiple passes to create a large part feature.

Chamfer Mill for Deburring

Like many other versatile tools, a chamfer mill can be used to easily and swiftly deburr a part during the CNC machining process. In doing so, efficiency is maintained as manual deburring – a time exhaustive process – isn’t necessary.

A chamfer mill’s angled cutting surface makes it a great tool for deburring workpiece edges.  Because a very small amount of the chamfer cutter’s cutting face will be used, a simple adjustment to running parameters will allow for simple deburring operations using a very light cut depth.

Chamfer Mill for Spotting & Countersinking

Drilling precise, clean, and aesthetically appealing holes into a part is not a one-step process. In fact, some use up to four different tools to machine a perfect hole: spotting drill, drill, flat bottom counterbore, and countersink. However, a chamfer cutter is often used to perform two of these operations simultaneously.

By using a pointed chamfer cutter with a diameter larger than that of the hole being drilled, a machinist can spot and countersink the hole in one operation prior to its creation. Tipped-off Chamfer  Cutters are unable to perform a spotting operation because they are non-center cutting. By spotting a hole, the drill has a clear starting point. This works to alleviate walking during the drilling process, which in turn drastically reduces the chance of misaligned holes. By countersinking a hole, the screw sits flush with the part, which is often a requirement for many parts in the aerospace industry.

One consideration to keep in mind is that a carbide spot drill should always have an angle larger than that of the drill following it. However, many countersinks have angles that are smaller than most drill points.  This creates a dilemma in choosing a chamfer tool for both spotting and countersinking, as they can reduce the number of tools needed, but do not see the full benefit of a spot drill with a proper angle.

Key Takeaways

A chamfer mill, also known as a chamfer cutter, is a tool that can perform several machining operations including chamfering, beveling, deburring, spotting, and countersinking. Due to this versatility, chamfer mills are an essential part of every machinist’s arsenal.  All that’s needed to run them is these various operations is a slight change to running parameters and depth of cut.