The Experts’ Guide to CNC Engraving

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CNC engraving is a process that removes a small amount of material to create detailed images or shapes. Many manufacturers use this method for labeling parts or creating complex designs; however, not everyone is aware of the key techniques necessary for optimal results. When using an engraving tool, it is essential to consider several challenges that could affect both the tool and the operation.

Advantages of CNC Engraving

Compared to other engraving methods, CNC engraving is fast, consistent, and cost-effective. Thanks to their repeatability, CNC machines deliver consistent results when paired with a high-quality engraving tool. We suggest running the tool at a minimum of 6,000 RPM.

If your machine supports it, increasing the RPM can lead to even greater results. Running at lower speeds can negatively impact tool life. Choosing the right engraving tool requires considering production volume and tool engagement time. Key factors such as tip design, angle, and coating play a crucial role in maximizing efficiency and durability.

Proper Engraver Tool Selection

Most machinists understand that a square-corner end mill does not last as long as a corner-radius or ball-end mill due to its fragile cutting edge.

The same principle applies to CNC engraving tools. An engraver that comes to a sharp point is more fragile than one with a tipped-off or radius tip. For long production runs, consider using a tip-off or rounded tip design, as these geometries distribute cutting forces more evenly across the cutting edge, improving tool longevity. A tip-flat design will last longer than a pointed tip but not as long as a radius tip. If high-detail work is required, a pointed tip is preferable because it provides greater precision.

Pointed Tip Engraving Cutters
Tipped Off Engraving Cutters
Tip Radius Engraving Cutters

Environment and Detail Considerations

Similar to tip geometry, the engraving angle plays a critical role in visibility. The environment in which the engraving is used affects how well it can be seen. If the engraving is exposed to harsh conditions with elements like snow, mud, or dirt, debris can accumulate in the grooves, making it difficult to see and clean. A larger angle creates a wider groove, improving visibility and ease of cleaning.

The image below illustrates three different engraving angles offered by Harvey: the leftmost groove is 30° included, the middle groove is 60° included, and the rightmost groove is 120° included. Each of these engravings is only 0.009 inches deep.

Notice that the 120° engraving is more visible at a distance due to increased surface exposure. If a job requires precision and detail, a smaller angle is preferable. While geometry significantly impacts engraving visibility and tool longevity, another key factor in tool performance is the choice of coating.

Choosing a Tool Coating

A coated engraving tool will last longer than an uncoated one because the coating provides a protective barrier between the tool and the workpiece. Additionally, coatings help reduce heat absorption, increase lubricity, and decrease tool wear. Selecting the right coating depends on the material being machined.

For example, our AlTiN and AlTiN-Nano coatings perform best in stainless steel and nickel alloys. For non-ferrous materials such as aluminum or copper, our Amorphous Diamond coating is ideal. As an alternative to our Amorphous Diamond coating, we also offer ZrN or TiB2 coatings.

A common misconception is that diamond-coated tools can be used on ferrous materials. Instead, this leads to rapid heat generation and premature tool failure.

Successfully Running Your Engraver

Selecting the correct engraving tool is just as important as understanding how to operate it properly. Even the highest-quality tool will be wasted if not used correctly. As with any machining operation, you must consider depth of cut, work holding methods, and appropriate speeds and feeds

Cutting Speeds and Feeds for Engraving 

The tip is the most delicate area of the tool which makes running at the correct speed and feed rate crucial. Running at an incorrect speed and feed rate can cause deflection, which will lead to an inaccurate engraving, chipping, breaking, or a poor surface finish.

At Harvey, we recommend a minimum spindle speed of 6,000 RPM. Operating at higher RPMs, when possible, offers even better support for tool tip integrity.

Higher speeds ensure tool stability as it will be less likely to cause vibration and reduces heat buildup during operation. Running too slowly generates excess heat and vibration leading to chipping, breakage, or having a poor surface finish. To help maintain tool tip integrity, it is important to follow the recommended depth of cut and consider the way the engraver enters the material.

Determining Depth of Cut

Many machinists are unaware that taking cuts deeper than 0.009 inches can shorten the lifespan of a Harvey engraving tool. For depth of cut ranging from 0.001 inch to 0.009 inches, you can operate within our stated speed and feed guidelines. If the operation requires a deeper groove, the chip load must be reduced accordingly. For depths between 0.010 inches and 0.015 inches, reduce the chip load by 20%. For depths ranging from 0.016 inches to 0.020 inches, reduce the chip load by 30%. Depth of cut also influences visibility. A deeper cut made with a tool that has a smaller angle can provide similar visibility to a shallower cut made with a tool that has a larger angle.

The image below illustrates different engraving depths using a 30° included angle. From left to right, the depths are 0.009 inches, 0.015 inches, and 0.020 inches. As depth increases, visibility improves. When engaging the tool with the workpiece, it is best to ramp into the material to protect the tool tip.

We recommend a ramp angle of 1° to 3° for ferrous materials such as stainless steel, and 3° to 10° for non-ferrous materials like aluminum or copper. If ramping is not an option, you may plunge the tool into the material. However, the chip load must be reduced by 50% during entry. Once the desired depth is reached, you can return to the recommended running parameters. Another key consideration is ensuring the workpiece is securely held in place.

Workholding Considerations

Runout or vibration during engraving can result in uneven cuts and tool failure. To prevent this, ensure that engraving tools are held in a sturdy toolholder and that the workpiece is secured. A shrink-fit toolholder minimizes runout and provides excellent stability. While ER collets are acceptable, they wear overtime. To verify an ER collet’s suitability, place an indicator on the tool shank and rotate the tool within the collet. The goal is to achieve the least possible runout, ideally no more than 0.0003 inches.

The workpiece should also be properly secured, either in a vise or a fixture. To detect vibrations during operation, listen for irregular noise or feel for vibrations through the CNC machine door. For cooling, coolants are recommended for metallic workpieces, while an air blast is preferable for non-metallic materials such as plastic.

Conclusion

When selecting an engraving tool, it is essential to choose the correct geometry for the operation, as well as the appropriate coating for the material being machined. Regardless of tip geometry, the engraving tool’s tip is its most fragile part. Proper speed, feed rate, and depth of cut are crucial for maximizing tool life.

For metallic workpieces, a cooling method such as coolant is necessary, while non-metallic workpieces require an air blast. Before starting a new engraving operation, double-check tool runout and ensure that the workpiece is securely held in place.

By following these best practices, CNC engraving operations can achieve high precision, longevity, and optimal tool performance.

Are You Ready to Put Your Engraving Knowledge to Use?

Browse Harvey Tool’s full selection of precision engravers, coatings, and geometries designed for optimal performance in a wide range of materials.

Supporting Precision in Mold, Tool & Die Applications

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Mold, Tool, and Die manufacturing demands a high level of precision. Whether you’re machining hardened tool steels, creating detailed mold cavities, or producing dies with complex geometries, the tooling used plays a critical role in ensuring consistent, repeatable results. To explore the full selection of tools relevant to this industry, including application-specific geometries and coatings, visit Harvey Tool’s Mold, Tool & Die Featured Solutions page.

Harvey Tool offers a comprehensive range of tools specifically engineered to meet the unique challenges of the Mold, Tool & Die industry. From tools designed to reach deep cavities to those that maintain surface finish in demanding materials, this offering is built to support precision and reliability throughout the machining process.

Tools included in this lineup are:

  • CVD Diamond End Mills– This Harvey Tool lineup of Diamond Tooling for Non-Ferrous Materials features true crystalline CVD diamond on a solid carbide substrate, making it ideal for machining graphite, composites, green carbide, and green ceramics.
  • End Mills for Hardened Steels– Engineered for hardened steels from 46Rc to 68Rc, this tool includes the latest generation AlTiN Nano coating for enhanced hardness and thermal resistance.

  • End Mills for Aluminum Alloys– We know a part is only as successful as its finish. That’s why our aluminum finishing solutions are crafted for mirror-like surface quality.   

  • End Mills for Medium Alloy Steels– Engineered for versatility, these CNC-ground, AlTiN-coated tools excel in machining stainless, tool, and medium alloy steels.
  • Miniature Tapered End Mills– Tackling deep part features? Harvey Tool’s tapered Miniature End Mills offer unique geometries that take the challenge out of tough-to-reach cuts.

Diamond End Mills for Abrasive and Non-Ferrous Materials

Diamond tooling is essential to many moldmaking processes, particularly during electrode production and when machining non-metallic materials. Harvey Tool’s offering includes a wide selection of Diamond End Mills designed for use in abrasive and non-ferrous materials such as graphite, green carbide, green ceramics, and composites—materials commonly encountered in mold and die work.

These tools feature a CVD (Chemical Vapor Deposition) coating to promote longer tool life and uphold tight tolerances over extended machining cycles.

Highlighted tooling includes:

Diamond End Mills are frequently used in electrode machining for EDM (Electrical Discharge Machining), where precision in non-metallic workpieces directly influences final mold quality.

All tools in the Mold, Tool & Die offering are fully stocked and available to ship same day, helping to reduce lead times and keep your production on schedule.

To view the full offering, including tools with specialized geometries and coatings, visit the Mold, Tool & Die Solutions page.

A Closer Look at Helical Solutions’ Tapered End Mills

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Helical Solutions offers a variety of Tapered End Mills designed to enhance performance and efficiency in tapered wall applications. In this blog post, we’ll dive into the geometry of tapered end mills and explore their common applications to understand when they could be utilized to optimize your CNC machining application.

Tapered End Mill Geometry

Tapered End Mills bring many advantages to machining compared to standard end mills, but what is a Tapered End Mill? A standard end mill will have the same cutting diameter throughout the whole length of cut, whereas a taper mills starts at the shank or neck at a larger diameter and tapers down at a specific angle.

The angle of the taper can vary, but Helical Solutions’ tools feature angles ranging from .05° to 5°, which allows for a broad spectrum of cutting operations. A tapered length of cut or tapered neck can also provide increased strength and rigidity, compared to that of a standard end mill. Having a tapered length of cut makes it easier to create flat tapered walls on 3-axis machines and leads to a better finish.

Tapered End Mill

Standard End Mill

Common Taper Mill Applications

Tapered End Mills are used in any machining process that requires an angled surface. These tools are engineered for light profiling and finishing applications in mold and die pockets and other tapered wall applications.

Mold & Die Applications

Mold and die applications are a mass production manufacturing method that consists of shaping different types of metals and other materials. Molds are used to shape metals, allowing them to become solid in the mold, while dies use a mechanical force to cut the material into the desired shape.

A couple examples of mold and die applications are plastic bottles, car body parts, electronic components, cutlery, coins, and metal stamping parts.

Mold Tool & Die Example

Tapered End Mills Profiles

Taper mills are great for profiling with the ball nose version, and for light finishing and creating required draft angles with the square version. Which style is right for you?

Ball Nose Taper Mills

Ball Nose Tapered End Mills are great for profiling because the full radius at the bottom eliminates sharp edges, which leads to a smoother process.

Square Profile Tooling

The square version of the tapered end mill has a higher flute count and helix angle with a sharp cutting edge. This is better for light finishes on the walls of tools.

The draft angle determined in the design process is the amount of mold design can be tapered. A draft angle is a strategic angle or slope designed in the mold. The tapered angle in the tool allows for the draft angle to be formed easier compared to a straight shanked end mill. Having a draft angle in the mold allows for easier removal of the part so it does not get stuck to the mold.

Helical Solutions’ Tapered End Mills

Helical Solutions’ offering of Tapered End Mills feature a tapered profile design, variable pitch geometry for reduced harmonics and increased feed rates, and Aplus coating for increased performance in Cast Iron, Steel, and even Stainless Steel. These tools are offered in a 4 Flute Ball style, and a 5 Flute Square style, so you can select the end profile that best suits your specific toolpath.

Helical’s Tapered End Mills

4 Flute Ball (HTPR-4)

Helical’s 4 Flute Ball Tapered End Mills (HTPR-4) are fully stocked in 6 different angles per side (0.5°, 1°, 1.5°, 2°, 3°, 5°), and in 3 different cutter diameters (1/8”, 3/16”, ¼”). These tools feature a ball nose profile, allowing them to excel in a variety of different applications from 3D contouring and profiling to slotting. A Ball Nose End Mill has a full form radius, allowing machinists to utilize the entire radius when contouring and finishing a 3D surface.

5 Flute Square (HPTR-5)

Helical’s 5 Flute Square Tapered End Mills (HTPR-5) is also is also fully stocked 6 different angles per side (0.5°, 1°, 1.5°, 2°, 3°, 5°), and in 3 different cutter diameters (1/8”, 3/16”, ¼”). These tools feature a square profile for more precise finishing and the 5 flute design creates a larger core, allowing for better tool strength in roughing applications.

Taper Mill Tooling Wrapped-up

By understanding the unique features and advantages of this tooling, machinists can make informed decisions and achieve superior results in their projects. These feature unique geometry that enhances machining capabilities and ensures reliability and accuracy across a range of tapered wall applications.

Save Time With Quick Change Tooling

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Making a manual tool change on any CNC machine is never a timely or rewarding process. Typically, a tool change in a standard holder can take up to 5 minutes. Add that up a few times, and suddenly you have added significant minutes to your production time.

As CNC machine tool and cutting tool technology has advanced, there are more multi-functional tools available to help you avoid tool changes. However, sometimes it just isn’t feasible, and multiple tool changes are needed. Luckily, Micro 100 has developed a revolutionary new method to speed up tool changes significantly.

What is the Micro-Quik Tooling System?

Developed in Micro 100’s world-class grinding facility in Meridian, Idaho, the Micro 100 Micro-Quik tooling system is held to the same standards and tight tolerances as all of the Micro 100 carbide tooling.

The quick change tooling system allows for highly repeatable tool changes that save countless hours without sacrificing performance. This system combines a unique tool holder with a unique tool design to deliver highly repeatable and accurate results.

Each quick change tool holder features a locating/locking set screw to secure the tool and a locating pin which helps align the tool for repeatability. Removing a tool is as simple as loosening the set screw and inserting its replacement.

depiction of removing tool from quick change system

During tool changes, the precision ground bevel on the rear of the tool aligns with a locating pin inside the tool holder. The distance from this locational point to the tip of the tool is highly controlled under tight tolerances, meaning that the Micro-Quik tooling system ensures a very high degree of tool length and centerline repeatability. The “L4” dimension on all of our quick change tools, as seen in the image above, remains consistent across the entire product line. Check out the video below for a demonstration of the Micro 100 Micro-Quik system in action!

Quick Change Tooling Benefits

quick change system with micro 100 boring bar close up image

The most obvious benefit to using Micro 100’s Micro-Quik Quick Change Tooling System is the time savings that come with easier tool changes. By using the quick change holders in combination with quick change tooling, it is easy to reduce tool changes from 5 minutes to under 30 seconds, resulting in a 90% decrease in time spent swapping out tools. This is a significant benefit to the system, but there are benefits once the tool is in the machine as well.

As mentioned above, the distance from the locational point on each tool shank to the tip of the tool is highly controlled, meaning that regardless of which type of tool you insert into the holder, your stick out will remain the same. This allows you to have confidence in the tooling and does not require additional touch offs, which is another major time saver.

assortment of boring bars with quick change system

By removing additional touch-offs and tool changes from your workflow, you also reduce the chances for human or machine error. Improper touch-offs or tool change errors can cause costly machine crashes and result in serious repairs and downtime. With the Micro 100 Micro-Quik Quick Change Tooling System, initial setups become much easier, allowing you to hit the cycle start button with total confidence for each run.

By making a few simple changes to your tool holding configurations and adopting the Micro-Quik system, your shop can save thousands in time saved, with less machine downtime and increased part production. To learn more about the Micro 100 Micro-Quik cutting tools and tool holders, please visit Micro 100.

Selecting the Right Chamfer Cutter Tip Geometry

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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.

Harvey Tool Chamfer Cutters

Pointed and Flat End Chamfer Cutters

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 I Chamfer Cutter overview

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 II Chamfer Cutter overview

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.

Type III Chamfer Cutter overview

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.

When to and Not to Use Drop Hole Allowance

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Dovetail Cutters are cutting tools that create a trapezoidal-type shape, or a dovetail groove, in a part. Due to the form of these tools, special considerations need to be made in order to achieve long tool life and superior results. This is particularly true when machining O-ring grooves, as this operation requires the tool to drop into the part to begin cutting. Using an appropriate tool entry method, specifically understanding when drop hole allowance is (and is not) needed, is important to keep common dovetail mishaps from occurring.

What is a Drop-Hole?

When designing parts featuring O-ring grooves, the consideration of drop-hole allowance is a pivotal first step. A drop-hole is an off-center hole milled during the roughing/slotting operation. This feature allows for a significantly larger, more rigid tool to be used. This is because the cutter no longer has to fit into the slot, but into a hole with a diameter larger than its cutter diameter.

graphic showing holes with and without drop hole allowance

Why consider adding a Drop-Hole?

When compared to tools without drop-hole allowance, tools with drop-hole allowance have a much larger neck diameter-to-cutter diameter ratio. This makes the drop-hole tools far stronger, permitting the tool to take heavy radial depths of cut and fewer step-overs. Using a drop-hole will allow the use of the stronger tool, which will increase production rate and improve tool life.

Machining Operation with Drop-Hole Allowance

5 unique machining operations with drop hole allowance

A maximum of 4 radial passes per side are needed.

When Not to Drop Hole

Drop-holes are sometimes not permitted in a design due to the added stress concentration point it leaves. Common examples for where a drop-hole would not be allowed include:

  • In high pressure applications
  • In seals requiring a high reliability
  • Where dangerous or hazardous fluids are being used

The issue with drop-hole allowance is that the additional clearance used for tool entry can create a weak spot in the seal, which can then become compromised under certain conditions. Ultimately, drop-hole allowance requires approval from the customer to ensure the application allows for it.

Machining Operation Without Drop-Hole Allowance

machining operations without drop hole allowance

A maximum of 20 radial passes per side are needed.

Drop-Hole Placement

When adding a drop-hole to your part, it is important to ensure that the feature is placed correctly to maximize seal integrity. Per the below figure, the drop-hole should be placed off center of the groove, ensuring that only one side of the groove is affected.

proper placement of hole when using drop hole allowance

It is also necessary to ensure that drop-hole features are put on the correct side of the groove. Since O-rings are used as a seal between pressures, it is important to have the drop-hole bordering the high pressure zone. As pressure moves from high to low, the O-ring will be forced into the fully supported side, allowing for a proper seal (See image below).

graphic showing the use of a drop hole for o-ring seals between high and low pressure areas

Main Differences Between Engravers & Marking Cutters

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Understanding the Distinctions

While similar on the surface, Half-round Engraving Cutters and Marking Cutters are actually very different. Both tools are unique in the geometries they possess, the benefits they offer, and the specific purposes they’re used for. Below are the key differences that all machinists must know, as the engraving on a part is often a critical step in the machining process.

harvey tool marking cutters ad

Engravers & Marking Cutters Serve Different Purposes

All Marking Cutters are Engraving Cutters, but not all Engraving Cutters are Marking Cutters. This is because Marking Cutters are a “type” of engraving tool. By virtue of their sturdier geometry, these tools are suited for applications requiring repetition such as the engraving of serial numbers onto parts. Harvey Tool has been able to customize specific tool geometries for ferrous and non-ferrous applications, offering Marking Cutters for material specific purposes.

harvey tool marking cutter

Engraving Cutters, on the other hand, are meant for finer detailed applications that require intricate designs such as engraving a wedding band or a complex brand design.

harvey tool doubled ended engraving cutter

These Tools Have Unique Geometry Features

Historically, Engraving Cutters have been made as a half round style tool. This tool allows for a true point, which is better for fine detail, but can easily break if not run correctly. Because of this, these tools have performed well in softer materials such as aluminum and wood, especially for jobs that require an artistic engraving with fine detail.

Marking cutters are not as widely seen throughout the industry, however. These tools hold up in harder-to-machine materials exceedingly well. Marking Cutters are a form of Engraving Cutter that contain 2 flutes and a web at the tip, meaning that the tool has a stronger tip and is less susceptible to breakage.

tip details of an engraver versus marking cutter

While these tools do not contain a true point (due to their web), they do feature shear flutes for better cutting action and the ability to evacuate chips easier when compared to a half-round engraver.

Harvey Tool Product Offering

Harvey Tool offers a wide variety of both Engraving Cutters and Marking Cutters. Choose from a selection of pointed, double-ended, tip radius, and tipped-off Engraving Cutter styles in 15 included angles ranging from 10° to 120°.

types of cnc engraver tips, pointed, radiused, and tipped-off

Marking Cutters are fully stocked in tip radius or tipped-off options, and are designed specifically for either ferrous or non-ferrous materials. They are are offered in included angles from 20° to 120°.

While Engraving Cutters are offered uncoated or in AlTiN, AlTiN Nano, or Amorphous Diamond coatings, Marking Cutters are fully stocked in uncoated, AlTiN, or TiB2 coated styles.

Add Fine Details to Your Parts With Harvey Tool’s Expansive Selection of Marking Cutters

Choosing the Right Tool

While both Engraving Cutters and Marking Cutters can accomplish similar tasks, each tool has its own advantages and purpose. Selecting the correct tool is based largely on preference and applicability to the job at hand. Factors that could impact your selection would be final Depth of Cut, Width of Cut, the angle needing to be achieved, and the desired detail of the engraving.

4 Essential Corner Rounding End Mill Decisions

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A Corner Rounding End Mill is typically used to add a specific radius to a workpiece, or in a finishing operation to remove a sharp edge or burr. Prior to selecting your tool, mull the following considerations over. Choosing the right tool will result in a strong tool with a long usable life, and the desired dimensional qualities on your part. Choosing wrong could result in part inaccuracies and a subpar experience.

Selecting the Right Pilot Diameter for Your Corner Rounding End Mill

Corner Rounding End Mill with dimension callouts

The pilot diameter (D1 in the image above) determines the tool’s limitations. When pilot diameters are larger, the tool is able to be run at lower speeds. But with smaller pilot diameters, the tool can be run faster because of its larger effective cutter radius. The effective cutter diameter is determined by the following equations depending on the radius to pilot ratio:

For a Radius/Pilot Ratio < 2.5, Effective Cutter Diameter = Pilot Diameter + Radius
For a Radius/Pilot Ratio ≥ 2.5, Effective Cutter Diameter = Pilot Diameter + .7x Radius

Larger pilot diameters also have more strength than smaller pilot diameters due to the added material behind the radius. A smaller pilot may be necessary for clearance when working in narrow slots or holes. Smaller pilots also allow for tighter turns when machining an inside corner.

Flared or Unflared Corner Rounder

Putting a full radius on a part has the potential to leave a step or an over-cut on a workpiece. This can happen if the tool isn’t completely dialed in or if there is minor runout or vibration. A slight 5° flare on the pilot and shoulder blends the radius smoothly on the workpiece and avoids leaving an over-cut.

A flared Corner Rounding End Mill leaves an incomplete radius but allows for more forgiveness. Additionally, this tool leaves a clean surface finish and does not require a second finishing operation to clean leftover marks. An unflared corner radius leaves a complete radius on the workpiece, but requires more set-up time to make sure there is no step.

2 flute and 4 flute corner rounding end mills with 5° flares

Front or Back

Choosing between a Corner Rounding End Mill and a Back Corner tool boils down to the location on the part you’re machining. A Back Corner Rounding End Mill should be utilized to put a radius on an area of the part facing the opposite direction as the spindle. While the material could be rotated, and a front Corner Rounding End Mill used, this adds to unnecessary time spent and increased cycle times. When using a Back Corner Rounding End Mill, ensure that you have proper clearance for the head diameter, and that the right reach length is used. If there is not enough clearance, the workpiece will need to be adjusted.

harvey tool back Corner Rounding End Mill

Flute Count

These tools are often offered in 2, 3, and 4 flute styles.  2 flute styles are normally used for aluminum and non-ferrous materials, although 3 flutes is quickly becoming a more popular choice for these materials, as they are softer than steels so a larger chip can be taken without an impact on tool life. 4 flutes should be chosen when machining steels to extend tool life by spreading out the wear over multiple teeth. 4 flute versions can also be run at higher feeds compared to 2 or 3 flute tools.

Corner Rounding End Mill Selection Summarized

The best corner rounding end mill varies from job-to-job. Generally speaking, opting for a tool with the largest pilot diameter possible is your best bet, as it has the most strength and requires less power due to its larger effective cutter diameter. A flared Corner Rounder is preferred for blending purposes if the workpiece is allowed to have an incomplete radius as this allows more forgiveness and can save on set up time. If not, however, an unflared Corner Rounder should be utilized. As is often the case, choosing between number of flutes boils down to user preference, largely. Softer materials usually require fewer flutes. As material gets harder, the number of flutes on your tool should increase.

Why You Should Stop Deburring by Hand

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Deburring is a process in which sharp edges and burrs are removed from a part to create a more aesthetically pleasing final product. After milling, parts are typically taken off the machine and sent off to the Deburring Department. Here, the burrs and sharp points are removed, traditionally by hand. However, an operation that takes an hour by hand can be reduced to mere minutes by deburring parts right in the machine with high precision CNC deburring tools, making hand deburring a thing of the past.

High Precision Tools

Hand deburring tools often have a sharp hook-shaped blade on the end, which is used to scrape/slice off the burrs as it passes along the edge of the part. These tools are fairly simple and easy to use, but much less efficient and precise than CNC deburring tools.

red hand deburring tool
Image Source: https://upload.wikimedia.org/wikipedia/commons/0/03/Deburring_tool.jpg

CNC deburring tools are also held to much tighter tolerances than traditional hand-deburring tools. Traditional cylindrical deburring tools typically have a diameter-tolerance window of +/- .008 versus a CNC deburring end mill which has a diameter tolerance of +/-.0005. The tighter tolerance design eliminates the location issues found in traditional deburring tools with loose tolerances, allowing them to be programmed like a traditional end mill.

While hand deburring tools often have just a single blade, CNC deburring tools feature double cut patterns and a high number of flutes. The double cut pattern contains both right hand and left hand teeth, which results in an improved finish. These tools leave completed parts looking far superior to their hand-deburred counterparts, with more consistent and controlled edge breaks. Additionally, there is a large variety of CNC deburring tools available today which can take full advantage of multi-axis machines and the most complex tool paths. For example, Harvey Tool’s 270° Undercutting End Mill is a great choice for multi-axis and more complex deburring options. Further, Deburring Chamfer Cutters are multi-use tools that can perform both chamfering and deburring accurately with no need for a tool change.

examples of cnc undercutters and chamfer mills

Reduce Production Costs and Increase Profits

Having an entire department dedicated to deburring can be costly, and many smaller businesses may have pulled employees off other jobs to help with deburring, which hampers production. Taking employees off the deburring station and asking them to run more parts or man another department can help keep labor costs low while still increasing production rates.

machinist hand deburring with a motorized hand tool
Stop Deburring By Hand and Increase Your Profits

By deburring right in the CNC machine, parts can be completed in one machining operation. The double-cut pattern found on many deburring tools also allows for increased speeds and feeds. This helps to reduce cycle times even further, saving hours of work and increasing production efficiency. Deburring in the machine is a highly repeatable process that reduces overall cycle times and allows for more efficient finishing of a part. In addition, CNC machines are going to be more accurate than manual operations, leading to fewer scrapped parts due to human error and inconsistencies.

STOP Deburring by Hand With Harvey Tool’s Wide Selection of Deburring Solutions

Simply put, the precision and accuracy of the CNC machine, along with the cost and time savings associated with keeping the part in the machine from start to finish, makes deburring in the CNC machine one of the easiest way to increase your shop’s efficiency.

Undercutting End Mills for Maximum Versatility

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Undercutting end mills, also known as lollipop cutters or spherical ball end mills, are a common choice for machining undercuts. An undercut is a common part feature characterized by one part of a workpiece “hanging” over another. Undercuts are typically difficult, or even impossible, to machine with a standard tool, especially on 3-axis machines. In many cases, a specialty tool is needed to tackle this feature. Although they are frequently associated with a singular use, undercutters are actually very versatile tools that are worth keeping on hand for a variety of operations.

Undercutting

undercutting end mill ideal operations in machining

Unsurprisingly, these tools are very well suited to undercutting operations. Creating an undercut on a part can be tricky and time consuming, especially when forced to rotate the workpiece. Fortunately, this can be greatly simplified with an undercutter.

Exactly what tool to use depends on the geometry of the feature and the part. These tools are available with a range of wrap angles like 220°, 270°, and 300°. Greater wrap angles are the result of a thinner neck and create a more spherical cutting end. This style offers more clearance at the cost of rigidity. Likewise, undercutting end mills with lower wrap angles sacrifice clearance for greater rigidity.

Deburring & Edgebreaking

deburring with undercutting end mills

Since undercuts have a wrap angle that is greater than 180°, they are very well-suited to deburring or edgebreaking anywhere on your workpiece, including the underside. Deburring your parts by hand can be inefficient for your shop – using an undercutting end mill instead will save you time and money. Edgebreaking operations are often a critical final step to create a part that looks and feels like a finished product and that is safe to handle.

All undercutting end mills can be used to deburr and edgebreak, which makes them a useful tool to have on hand in any shop. Some manufacturers also offer specialized deburring tools that are designed with a right and left hand flute orientation, giving them “teeth” that make them particularly useful for deburring complex shapes. Using a deburring tool in a 5-axis machine often makes it possible to deburr or edgebreak an entire workpiece in one shot.

Slotting

slotting uses of undercutting end mill

Most machinists might not think of undercutting end mills for slotting, but they are fully capable of this operation. An equivalent slot can be machined with a regular ball end mill, but doing so might not be feasible due to clearance issues – an undercutter has a reduced neck, unlike a standard ball end mill. Additionally, using an undercutter to slot can save time switching to an equivalent ball end mill.

Harvey Tool Stocks a Wide Variety of Undercutting End Mills Perfect for Your Next Machining Job

Since only 180° of the cutting end can be used to slot, undercutting end mills with lower wrap angles and thicker necks are best suited to slotting. However, high helix undercutting tools may be ideal if improved finish and increased chip removal are important to the operation.

Contouring & Profiling

contouring and profiling illustration with lollipop end mill

With their wrap angle and increased clearance, undercutting end mills are very useful for both simple and complicated contouring and profiling operations. Their versatility means that it is sometimes possible to accomplish the entire operation with a single tool, rather than several, especially when 5-axis milling.

Reduced shank tools offer the most versatility in complex contouring and profiling operations. The ability to chuck these tools at any depth means that they are capable of maximum clearance.

Choosing An Undercutting End Mill

While most undercutting end mills are conceptually similar, there are a few key differences that must be considered when picking the right tool for your job. Harvey Tool offers the following styles as stock standard tools.

selection undercutting end mills sizes and styles