Drill Substrate Guide: HSS vs Cobalt vs Carbide

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Drilling applications require careful consideration of material, production volume, and machine setup to ensure optimal hole quality, tool life, and cost. Harvey Performance Company offers drills in three primary substrates: carbide, cobalt, and high-speed steel (HSS). This guide breaks down the differences between the drilling substrate options and helps you choose the right tool for your specific application.

Solid Carbide Drills

Advantages of Carbide Drills

  1. Extreme Hardness and Wear Resistance
    • Carbide drills maintain sharp cutting edges longer than HSS or cobalt, even in abrasive materials. This reduces tool changes and helps to maintain consistent hole quality.
  2. High Heat Tolerance
    • Carbide can withstand cutting temperatures above 2,100°F (1,150°C), allowing higher speeds and feeds for faster material removal and shorter cycle times.
  3. Precision Machining
    • Carbide maintains tight tolerances and excellent surface finish in hard steels, tool steels, ceramics, composites, and high-temperature alloys, making it ideal for precise, high-performance applications.
  4. Long-term Cost Efficiency
    • Although the initial cost is higher, carbide’s longer tool life reduces frequent tool changes, lowering overall costs in high-volume production.

Drawbacks of Carbide as a Drill Substrate

  1. Brittle Nature
    • Carbide is more prone to chipping or breaking if the machine setup is not rigid, feed rates are too aggressive, or vibration is present.
  2. Regrinding Requirements
    • Carbide usually requires CNC grinding equipment for precise sharpening, unlike HSS, which can often be reground using conventional machines.
  3. Initial Investment
    • Carbide has a higher upfront cost, which may not be justified for use in short runs or soft materials, where less expensive HSS or cobalt drills can provide adequate performance.

What are the Ideal Applications for Carbide Drills?

Carbide drills excel in:

  • Large production runs requiring consistent tool life
  • Hard materials above 45 HRC, such as tool steels and high-temperature alloys
  • Applications requiring high-speed cutting and maximum material removal
  • Situations demanding precise hole tolerances and surface finish

Example: Valor Holemaking High Performance Carbide Drills are engineered to provide unmatched precision and repeatability in difficult-to-machine materials. Material-specific geometries and coolant-through designs improve heat management and tool life in demanding applications.

High Speed Steel (HSS) Drills

Advantages of HSS Drills

  1. Tough and Durable
    • High Speed Steel is the least brittle of the three materials, reducing the risk of breakage during less rigid setups.
  2. Easier to Regrind
    • HSS Drills can be sharpened and reconditioned using conventional grinding equipment, which reduces shop complexity and cost.
  3. Cost-Effective
    • The lower cost-per-tool makes HSS ideal for small jobs or low-volume production where long-term tool life is less critical.
  4. Versatile for Soft Materials
    • HSS performs well in most non-ferrous metals providing reliable results for general-purpose machining without the higher cost of harder substrates.

Drawbacks of High Speed Steel Drills

  1. Limited Heat Tolerance
    • High Speed Steel Drills can only handle cutting temperatures up to 1,100°F (600°C), restricting cutting speeds and material removal rates.
  2. Shorter Tool Life
    • HSS Edges dull faster than cobalt or carbide, requiring more frequent replacement, affecting productivity.
  3. Not Ideal for Very Hard Materials
    • High speed steel tools cannot reliably machine steels above 45 HRC or high-temperature alloys.

What are the Ideal Applications for HSS Drills?

HSS drills are ideal for:

  • Soft materials like aluminum, brass, and other non-ferrous metals
  • Small production runs or one-off jobs where tool life is less critical
  • Shops without CNC grinding capability
  • Situations where cost and ease of regrind outweigh long-term performance

Example: Titan USA High Speed Steel Drills provide reliable performance for general-purpose machining and softer materials, offering versatility for low- to medium-volume operations.

Cobalt Drills

Advantages to Cobalt Drilling

  1. Intermediate Hardness
    • Cobalt is harder than HSS but less brittle than carbide, providing a balance of toughness and wear resistance.
  2. Higher Heat Resistance
    • Cutting temperatures up to 1,580–1,616°F (860–880°C) enable faster speeds and feeds than HSS.
  3. Moderate Cost
    • Cobalt drills offer longer tool life than HSS without the higher upfront cost of carbide.
  4. Capability for Harder Materials
    • Can machine steels up to 58 HRC, handling materials that high speed steel struggles with, while remaining more forgiving than carbide.

Cobalt Drill Disadvantages

  1. Less Wear-Resistant than Carbide
    • While cobalt drills are harder than HSS, they are still not as wear-resistant as carbide. In extremely abrasive materials, cobalt drills will wear much faster than solid carbide, which can increase tool changes and impact long-term cost in high-production runs.
  2. Slightly More Brittle than HSS
    • Cobalt is harder than HSS, making it more prone to chipping or breakage. Regrinding may require careful handling or CNC equipment to maintain geometry.
  3. Not Suitable for Extreme High-Temperature Alloys or Very Hard Materials
    • Cobalt cannot maintain performance in very hard steels or high-temperature alloys. Carbide is needed for materials above 60 HRC or extreme heat applications.

What Applications are Ideal for Cobalt Drills?

Cobalt drills work well for:

  • Medium-volume jobs with harder materials
  • Applications requiring more speed and heat tolerance than HSS
  • Shops seeking a balance of cost, tool life, and performance

Example: Titan USA Cobalt Drills are a solid choice for harder-to-machine materials that do not require carbide, providing longevity and moderate speed capabilities.

What Factors Influence What Drill Substrate to Choose?

Every drilling job is unique, and the optimal drill substrate depends on your specific requirements. Key considerations include:

  • Material Hardness
  • Production Volume and Job Size
  • Machine Rigidity
  • Budget
  • Regrinding Capabilities
  • Desired Cutting Speed and Material Removal Rate

No drill fits every job, and these factors are intended as a guide to help machinists choose the right substrate to improve efficiency, precision, and cost-effectiveness.

The Benefits of Combined Drill & Countersinks

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Two of the most frequently recurring operations across a variety of applications are CNC drilling and countersinking. Since these two processes are often interdependent, managing space in the tool crib and time lost on tool changes can become cumbersome when using dedicated tools for each operation. Using combined drill and countersinks eliminates these concerns and has become a go-to tool across machine shops.  

valor holemaking combined drill and countersink tools on a table with a slide caliper and ruler
Variety of Combined Drill & Countersinks

What is a Combination Drill & Countersink Tool?

A Combined Drill & Countersink is a specialized tool designed to perform two critical operations in one step: drilling a hole and creating a countersink. These tools are typically short and rigid, ideal for producing either a shallow conic or a center hole. Their double-ended design minimizes downtime by enabling quick transitions between tasks.

Valor Holemaking’s Combined Drill & Countersink

Key Features of Combined Drill & Countersinks

They feature a smaller drilling pilot and larger diameter countersink. The drill pilot resembles a spot drill, making it useful for predrilling applications. The stub length of the drill mitigates deflection and ensures accurate location of a hole’s center. When preparing a spot hole for a longer drill, it prevents walking or wobbling off-center. 

Common Applications for Combined Drill & Countersinks

Many holemaking applications begin with spotting and end with countersinking, making combination multi-functional tools cost-effective and time efficient. As the tool drills into the material, the larger countersink diameter chamfers the top edges, allowing fasteners to sit flush with the surface.

Where and How to Use a Combined Drill & Countersink

The primary use of a combined drill and countersink is to create center holes in materials that will be turned between two centers. These centers help accurately position a workpiece along its axis between a lathe chuck and tailstock. Live centers are used in applications requiring a high level of concentricity and support. They typically feature a 60° included angle, which is the angle most combined drills and countersinks are manufactured with. For this reason, combined drill and countersinks are often referred to as center drills.

Combined drill and countersinks are also essential in any application where screws need to sit flush in the workpiece. Holes need to be drilled and countersunk across all industries. Flush-mounted fasteners are required in applications such as aircraft panels and structural components, automotive engine components, boat hulls and marine components, electronic device housings, and covers of all types.

Example of countersunk hole

Types of Combination Drill/sinks: 60°, 82°, and 90° Angles

Harvey Tool and Valor Holemaking offer combined drill and countersinks in 60°, 82°, and 90° included angles. While 60° tools are most commonly used for center drilling, 82° and 90° included angles are designed to match the angles of the most popular flat and oval head screws. These tools allow users to create countersunk fastener holes in a single step.

Important Tips for Running Combination Drills

When running a combined drill-and-countersink, it is important to ensure that chiploads (IPR) are based on the drill diameter. Since the drill diameter is always smaller than the chamfer area, it is safer to use parameters designed for the drill portion of the tool rather than calculating an effective cutter diameter for the chamfer.

Valor Holemaking Combined Drill & Countersink in the Spindle
Valor Holemaking Combined Drill & Countersink in the Spindle

Why These Tools Are Essential in Machining

Combined drill & countersinks are cost-effective and efficient tools to have in your arsenal. Whether you’re preparing a workpiece for turning between centers, spot drilling, or creating countersunk holes for fasteners, these reliable tools complete the job quickly and effectively.

Mastering Precision: Pilot Drills in CNC Machining

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When it comes to achieving precision in CNC drilling applications, the choice of tools and techniques can make a significant difference in the outcome. One essential element that often doesn’t get the spotlight it deserves is the Pilot Drill. This blog post will explore the importance of pilot drills, their applications, and best practices for integrating them into your CNC machining processes.

What is a Pilot Drill?

A pilot drill is used to create a guide hole in deep drilling applications where precision is required. This guide hole keeps the drill on center, maintaining straightness throughout the cut. By creating a pilot hole, machinists can also improve the quality of the finished product and extend the life of their tools.

The Importance of Pilot Drills in CNC Machining

1. Enhanced Accuracy

The primary advantage of using a pilot drill is the enhanced accuracy it provides. When working with harder materials or complex geometries, a small pilot hole helps maintain the alignment of the longer drill, reducing the risk of misalignment and defects.

2. Extended Tool Life

Using a pilot drill can significantly extend the life of your deep-hole drilling tools. By first creating a pilot hole, the chasing drill experiences less stress, reducing wear and tear, and the chance of breakage, ultimately leading to cost savings from longer tool life.

3. Improved Chip Removal

Pilot drilling can enhance chip removal, particularly in deep-hole drilling scenarios. The smaller pilot hole allows for better coolant flow, which is crucial for effective chip evacuation and maintaining optimal cutting temperatures.

Applications of Pilot Drills

Pilot drills are versatile and can be used in various applications, including:

  1. Deep-hole Drilling: Pilot holes create a guide when drilling deep holes for improved centering and straightness.
  2. Tapping Operations: A pilot hole can facilitate easier and more accurate tapping.
  3. Reaming: When preparing for reaming operations, a pilot drill can ensure the hole is properly aligned and sized.
  4. Screw and Bolt Holes: Pilot holes are essential for ensuring screws and bolts are inserted correctly and securely.

Best Practices for Using Pilot Drills

1. Application      

Piloting is recommended for tighter tolerance holes when drilling at depths of 8xD or greater. Valor Holemaking provides a custom tolerance of +0.0002/+0.0005 (+0.005mm/+0.013mm) to create the perfect oversized guide hole for their traditional drill lines capable of drilling 8xD or greater. Valor Holemaking’s Pilot Drills also include a +2/+1 deg angle tolerance to ensure a larger angle than the chasing drill. Piloting depth is recommended as 3xD for all applications drilling 8xD or greater.

2. Choose the Right Size and Point Angle

Selecting the appropriate size for your pilot drill is crucial. As a rule of thumb, the diameter of the pilot hole should be slightly larger than the diameter of the final hole. This allows for optimal support for the chasing drill while preventing excessive material removal. The pilot drill’s point angle should be equal to or larger than the succeeding drill. This allows the tip of the succeeding drill to engage the material before the flank does (see figure below).

3. Optimize Feed Rates

When using a pilot drill, ensure that the feed rates are optimized for both the pilot and the larger drill. Adjusting the feed rate can improve performance and reduce the risk of tool breakage. Valor Holemaking’s downloadable speeds and feeds tables and Machining Adviser Pro are excellent resources, and you can always consult Valor Holemaking’s Tech Team for further assistance!

4. Use Proper Coolants

Effective cooling and lubrication are vital in metal machining. Ensure that your pilot drill is adequately cooled with flood coolant or adjust speeds and feeds to maintain tool integrity and enhance cutting performance.

5. Maintain Tool Condition

Regularly check the condition of your pilot drills. Worn or damaged pilot drills can lead to inaccuracies and affect the performance of subsequent operations.

6. Integrate with CNC Programming

Incorporate pilot drilling into your CNC programs to ensure that it’s executed at the right stage of your machining process. Program one revolution or brief dwell at the bottom of the pilot hole to ensure a clean surface. This will help streamline operations and improve overall efficiency.

 

Conclusion

Pilot drills may seem like a small detail in the larger scope of CNC machining, but their impact on precision, tool life, and overall efficiency is significant. By understanding their importance and implementing best practices, machinists can enhance their processes and achieve superior results. Whether you’re a seasoned CNC operator or just starting out, incorporating pilot drills into your workflow is a smart move that can lead to greater accuracy and success in metal machining.


Mastering CNC Drilling: Geometries and Key Factors

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Selecting the proper drill for a specific application is essential to ensuring a successful cnc drilling job. Achieving a perfectly machined hole can often be challenging. There are many machining woes that can occur when drilling into a material. These can greatly affect hole quality, and regardless of the material being machined, there is often zero margin for error to ensure all components meet specifications.

To ensure you are selecting and using the correct drill, you need not only a deep understanding of drill geometries, but also the factors that influence the performance of the drill and quality of the hole. In this comprehensive guide, we’ll dive into drill geometries, while also exploring the performance factors that determine CNC drilling results. Furthermore, we’ll connect these to the strategic decisions that drive the tool selection process, so you can gain a competitive edge at the spindle.

Performance Factors Influencing CNC Drilling Success

Part Material

Different materials require different drill geometries and cutting speeds to maintain hole quality and prevent excessive wear. With different types of materials, whether it be a softer non-ferrous material like aluminum or a harder ferrous material like stainless steels, you’ll face different challenges as you manufacture your part. To ensure that you’re getting the best performance and tool life possible features and geometries must be considered.

metal blocks that have many holes from cnc drilling operations

CNC Drill Geometries

It is important to understand the different geometries of a drill to understand how they affect an application. For an in depth dive into drill geometries, read 10 CNC Drill Geometries Every Machinist Must Know. This breaks down the unique aspects of geometries and how they affect the cnc drilling process.

Drill Geometries and Drill Walking

CNC drill walking occurs when a drill lacks sufficient engagement with the material. This causes it to deviate from its intended tool path, leading to inaccuracies in hole placement and dimensions. This occurs due to various factors, often including improper drill geometry choice. Understanding how different drill geometries influence drill walking is crucial to ensure you’re achieving precision and consistency in every hole.

Point Angles

The point angle dictates cutting forces and chip evacuation. Choosing the right angle, such as 118° or 135°, based on material hardness, ensures efficient drilling and prevents walking. The shallower the point angle, the better the distribution of cutting forces on the material. Higher angles walk less, as the point grabs into the material easier. Machinists must weight these options when choosing the proper drill.

Web Thickness

Web thickness is the distance between cutting edges or flutes at the face of the drill. This is where stability is generated in a tool. Webs that are too thin can increase the likelihood of breakages, while webs that are too thick will generate unnecessary cutting forces. Finding the proper blend of stability and cutting force is a common struggle for machinists.

CNC Drill Length Considerations

Flute and overall length impact stability and chip evacuation. Matching these lengths to drilling depth prevents deflection and enhances hole quality.

While it may be easiest to purchase a long drill that will work in a variety of scenarios, it is not the best choice to ensure precision. Machinists should best match their required depth to the effective depth of a drill. This ensures that the tool will be as rigid as possible, generating the straightest holes.

As tool length increases, rigidity decreases. Therefore, a properly matched drill will be as rigid as the situation allows. This affords the machinist with the best possible outcome for their unique drilling application.

Coolant-Through Drilling

Proper cooling and lubrication extends tool life and ensures excellent hole quality. If your machine is equipped with the option to run through spindle coolant tooling, it can be extremely beneficial to your application. Unlike an end mill, where chips often have the ability to evacuate outward from the tool, the chips in a drilling operating are held captive inside the feature as it’s being drilled. Here, chips are only able to evacuate through the drill fluting

Through spindle coolant not only cools and lubricates a drill at the point of material removal, but also forcibly evacuates the chips. This can increase your tool’s life while reducing or removing the need for peck cycles all together. This means faster cycle times and higher production rates for your product.

On the other hand, coolant can be fed externally, and sprayed onto the tooling. This will aid in cooling and lubricity. The downside is it is less efficient than utilizing a coolant-through drill. In deep hole drilling applications, external coolant is often ineffective for chip evacuation efforts, and is not the ideal choice for the best results.

Speeds & Feeds

Optimizing speeds & feeds is essential for efficient and accurate drilling. There is not a “one size fits all approach” for speeds & feeds, as all tools and materials require a slightly different approach.

Finding the right balance for each material prevents tool wear and ensures effective chip evacuation. Valor Holemaking offers comprehensive starting parameters in the form of Speeds & Feeds Charts and each tool is also supported by Machining Advisor Pro. This tool allows machinist to custom generate speeds & feeds based off the exact tool path, material, and machine setup.

Rigidity and Stability

A sturdy machining setup reduces vibrations during drilling, improving hole quality. The same can be said about the drill within. A rigid tool is a stable tool, especially as the depth requirements increase. Stability is especially important for drilling heavy-duty materials. This can be impacted by several factors, most importantly the quality of the tool and its design, as well as its chip management capabilities. High precision and high-performance solid carbide drills are designed for the utmost rigidity to ensure repeatability time after time and part after part.

Software and Programming

CNC programming software simplifies creating and editing drilling programs. Compatibility with common CAD/CAM software streamlines integration. Much like machine quality, proper programming is an important step in ensuring precision in CNC drilling applications. CAD/CAM integration ensures the correct dimensions are input to the software to best ensure the tool correctly fits the required parameters.

Exploring CNC Drilling Geometries & Key Factors: Wrapped Up

There are many different drill geometries and factors that can directly impact a drill’s performance and hole quality. Understanding these features can greatly assist in your tool selection process, allowing you to improve productivity and hole quality, so you can gain a competitive edge at the spindle. Drilling is often the most precise aspect of machining, so mastering geometries is critical to success.

Aerospace Drill Type Classifications Explained

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When browsing Titan USA’s selection of available drill bits, you may come across descriptions like “Type B,” “Type C,” or “Type J.” The following will serve to explain the origins of these designations and what each “Type” means; information that will help you when selecting the optimal drill bit for your operation.

Origin of Drill Type Classifications

The drill “Types” referenced above are creations of the National Aerospace Specification Committee (NASC), a subset of the Aerospace Industries Association (AIA). The Committee is responsible for the creation and maintenance of part standards for aerospace parts and components within AIA’s National Aerospace Standards (NAS) library. These part standards are recognized for meeting the high strength, close tolerance, and rigorous acceptance testing requirements of the aerospace industry.[1]

Aerospace Drill Standards & Types

The NASC identifies three different “standards” for drills: NAS907, NAS937, and NAS965. Each of these standards can be broken down into different “types.” The “standard” represents the size range and shank options, and the “type” represents a unique combination of other attributes including material, surface treatment, web construction, back taper, point type, and lengths. For example, NAS 937 drills have a size range of Ø1/8” through Ø1/2” and the following shank options: Straight, straight w/ tri flats, quick change, reduced shank, reduced shank with tri flats, and Tang. Type B within that same standard would indicate that the material is High Speed Steel (M2 or M7), that the drill has a bright finish, a web construction where thickness increases uniformly at 0.017” ± 0.003” per inch taper, a back taper of 0.0002” to 0.0005” per inch for all diameters, a P-3 (135°) split point, and a jobber or aircraft extension length.

All the drills that call out a type in Titan USA’s catalog are NAS907 standard drills as they all have drill diameters of 1/16” through 1/2” and straight shanks. Below are examples of Titan USA drills of types B, C, and J within that standard:

Type B

screenshot from titan cutting tools of an aerospace type b drill

Type C

Screenshot from Titan Cutting tools of an aerospace type c drill

Type J

Screenshot from Titan Cutting Tools of a Type J aerospace drill

Choosing the right drill bit for your job is key to ensuring accuracy and efficiency in any project, and knowing what these type designations represent can help you identify the size and material that’s right for you more quickly.

Do you have an application that requires a miniature drill? Learn about Selecting the Right Harvey Tool Miniature Drill.

  1. [1] National Aerospace Standards Committee (NASC). “About NASC.” Aerospace Industries Association, www.aia-aerospace.org/membership/committees/national-aerospace-standards-committee-nasc/. Accessed [April 26, 2024].

10 CNC Drill Geometries Every Machinist Must Know

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A CNC drill has many different features and geometries that directly impact the tool’s performance, productivity, and tool life in the specific material it’s machining. It is important to understand the different geometries of a drill to ensure you’re not only recognizing how they affect an application, but also which geometries you should be looking for when selecting your next drill. For continued success a machinist must know all aspects that goes into a cnc drill geometry.

1.    Point Angle

This drill geometry refers to the angle of the cutting edge of the drill. As the point angle increases on a drill, the radial forces decrease, making the angle size a huge factor in what type of material the drill is optimized for and what types of applications should be run. The smaller the point angle, the better it will perform in through hole applications. This is because the smaller angle reduces the axial forces, allowing less of the chip to be pushed out and more cutting to occur.

118° & 120° Point Angle

Many machinists opt for this angle when machining soft gummy materials.

135° Point Angle

This point angle size is an excellent choice for machining aluminum and stainless steels.

140° Point Angle

This larger point angle size is great for machining steels.

150° Point Angle

Large angles are often used for spot drilling applications, but the optimal spot drill angle is determined by the size of the angle of the final drill being used. Selecting the proper spot drill is essential to eliminating the chance of drill walking and ensuring a more accurate final product. Learn which spot angle should be used for your next drilling job in this in-depth guide.

2.    Chisel and Cutting Edges


Although the chisel edge of a CNC drill does not provide any cutting action, it is responsible for the centering of the drill, as it extrudes the material towards the cutting edges. The cutting edges are then able to start the process of producing chips, which then travel up the flutes of the drill.

3.    Flutes

The most recognizable part of a drill is its flutes. They are the deep grooves that allow for chip evacuation to occur. When one thinks of a drill, they are likely imagining a spiral flute drill. These spiral flutes complement the point angle, chisel edge, and the cutting edges. They work like an elevator system to lift the chips out of the hole, allowing them to provide excellent chip evacuation. They work great in most material types and provide good hole quality.

4.    Helix Angle

The helix angle is the angle formed by the leading edge of the land with a plane containing the axis of the drill. The main function of the helix angle is to transfer the chips out of the hole and a specific angle is relevant to the type of material that is being machined in and the particular application being run.

Low Helix

A low helix of 12° – 22° is recommended for materials like cast iron, brass, and hardened steels. In these “short chipping” materials, the chips move more freely, and the coolant provides enough assistance to properly evacuate the chips out of the hole.

Medium Helix

The most widely used helix angles are medium as they provide optimal chip evacuation and strength to the drill. Medium helix angles range from 28° – 32° and are recommended for any general purpose drilling applications.

High Helix

A high helix angle of 34° – 38° is recommended for long chipping material such as softer non-ferrous materials like brass, aluminum, and plastics. Drills with a high helix are also beneficial in deep hole applications as the chips can evacuate more easily.

5.    Web Thickness (Core)

The web is the core section of the drill body, which connects the two flutes. The thickness of the web determines the torsional strength of a drill. A drill with a larger web diameter will have more torsional strength than a drill with a smaller web diameter.

The proper web thickness is determined by the material type to be machined. Long chipping materials will require a drill with a smaller web thickness to provide adequate clearance for chip removal. When drilling short chipping materials such as cast iron, the drill web can be increased for additional strength.

6.    Corner Chamfer


A corner chamfer or radius is often added to eliminate the sharp edge at the intersection of the flutes and the outside diameter of a drill. This helps to eliminate material breakout when exiting a hole, while also helping to reduce the size of the entrance and exit burrs. This feature is also widely known to significantly extend tool life.

7.    Drill Margin

Margin(s) are the surfaces along the outer diameter of the drill which provide stability to the hole as they support the radial forces that are directed radially by the drill point.

Size of Drill Margin

The size of the margin will determine the overall quality of the hole. Wide marginswill stabilize the drill better, hold a tighter hole diameter tolerance, and improve the circularity of the hole. Narrow margins reduce friction and heat, eliminate work hardening, mitigate built-up edge, and provide better tool life.

Number of Drill Margins

The number of margins on a drill is usually determined by the type of hole being machined. Single margin drills are very common in non-interrupted holes. Double or triple margin drills are common in interrupted or intersecting holes. The more margins there are, the better the guidance is to help the drill stay straight through interrupted cuts, cross holes, and irregular or angled surfaces on exit. While adding margins does provide these benefits for irregular style cuts, they also increase friction, which causes the drill to produce more heat. This causes wear to be accelerated, reducing the life of the tool.

8.    Land of a Drill

The land is the outer portion of the body of the drill between two adjacent flutes. Land width will determine how much torsional force a drill can withstand before catastrophic failure. The smaller the land is, the more chip space there is, producing less torsional strength. The larger the land is, the less chip space there is, providing more torsional strength.

9.    Coolant-Through Channels


Not only do coolant-through channels offer any drilling application a multitude of benefits, but they are also highly recommended for hole depths that exceed 4XD (4 times diameter). Coolant-Through Drills allow for higher speed and feed rate capabilities, increased lubricity, better chip control, improved surface finish, and enhanced tool life.

10.  Shank

The shank is a very important yet overlooked drill geometry as it is the drive mechanism and is what is mounted into a Tool Holder. It is essential that the shank is held to proper diameter tolerance and considerations are being made depending on the holder being used. For example, a shank with an h6 tolerance is essential when a shrink fit style tool holder is being used.

Learning the different geometries of a CNC drill can greatly assist you in ensuring you are selecting the right drill for your next job, while understanding the functions of these features will allow you to trouble shoot any potential machining hiccups you may encounter in your future CNC drilling applications.

3 Tips for Avoiding Misaligned Holes

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One of the most common issues machinists face during a drilling operation is hole misalignment. Hole alignment is an essential step in any assembly or while mating cylindrical parts. When holes are properly aligned, the mating parts fit easily in each other. When one of the pieces to the puzzle is inaccurate, however, machinists run into issues and parts can be scrapped. The two types of common misalignment woes are Angular Misalignment and Offset Misalignment.

Angular Misalignment

Angular misalignment is the difference in slope of the centerlines of the holes. When the centerlines are not parallel, a shaft will not be able to fit through the hole properly.

Offset Misalignment

Offset misalignment is the distance between the centerlines of the hole. This is the position of the hole from its true position or mating part. Many CAD software programs will help to identify if holes are misaligned, but proper technique is still paramount to creating perfect holes.

1.    Utilize a Spotting Drill

Using a spotting drill is a common way to eliminate the chance of the drill walking when it makes contact with the material. A spotting drill is designed to mark a precise location for a drill to follow, minimizing the drill’s ability to walk from a specific area.

valor holemaking high performance spotting drill

Valor Holemaking High Performance Spotting Drill

Although using a spotting drill would require an additional tool change during a job, the time spent in a tool change is far less than the time required to redo a project due to a misaligned hole. A misaligned hole can result in scrapping the entire part, costing time and money.

Do you know how to choose the perfect spot drill angle? Learn how in this in-depth guide so you can eliminate the chance of drill walking and ensure a more accurate final product.

2.    Be Mindful of Web Thickness

A machinist should also consider the web thickness of the drill when experiencing hole misalignment. A drill’s web is the first part of the drill to make contact with the workpiece material.

Essentially, the web thickness is the same as the core diameter of an end mill. A larger core will provide a more rigid drill and a larger web. A larger web, however, can increase the risk of walking, and may contribute to hole misalignment. To overcome this machining dilemma, machinists will oftentimes choose to use a drill that has a thinned web.

Web Thinning

Also known as a split point drill, web thinning is a drill with a thinned web at the point, which helps to decrease thrust force and increase point accuracy. There are many different thinning methods, but the result allows a drill to have a thinner web at the point while having the benefit of a standard web through­out the rest of the drill body.

A thinner web will:

  1. Be less susceptible to walking
  2. Need less cutting resistance
  3. Create less cutting force

3.    Select a Material Specific Drill

Choosing a material specific drill is one of the easiest ways to avoid hole misalignment. A material specific drill design has geometries that will mitigate the specific challenges that each unique material presents. Further, material specific drills fea­ture tool coatings that are proven to succeed in the specific material a machinist is working in.

Valor Holemaking High Performance Drills for Steels and High Performance Drills for Aluminum

Spot Drilling: The First Step to Precision Drilling

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Drilling an ultra-precise hole can be tough. Material behavior, surface irregularities, and drill point geometry can all be factors leading to inaccurate holes. A Spot Drill, if used properly, will eliminate the chance of drill walking and will help to ensure a more accurate final product.

Choosing a Spot Drill

Ideally, the center of a carbide drill should always be the first point to contact your part. Therefore, a spotting drill should have a slightly larger point angle than that of your drill. Common drill point angles range from 118° to 140° and larger. Shallower drill angles are better suited to harder materials like steels due to increased engagement on the cutting edges. Aluminums can also benefit from these shallower angles through increased drill life. While these drills wear less and more evenly, they are more prone to walking, therefore creating a need for a proper high performance spot drill in a shallow angle to best match the chosen drill.

Five Valor holemaking high performance spot drills displayed on top of a workpiece with a purple product packaging container in front

If a spotting drill with a smaller point angle than your drill is used, your drill may be damaged due to shock loading when the outer portion of its cutting surface contacts the workpiece before the center. Using a drill angle equal to the drill angle is also an acceptable situation. Figure 1 illustrates the desired effect. On the left, a drill is entering a previously drilled spot with a slightly larger angle than its point. On the right, a drill is approaching an area with an angle that is far too small for its point.

Proper Spot Angle Diagram

Marking Your Spot

A Spotting Drill’s purpose is to create a small divot to correctly locate the center of a drill when initiating a plunge. However, some machinists choose to use these tools for a different reason – using it to chamfer the top of drilled holes. By leaving a chamfer, screw heads sit flush with the part once inserted.

Spot Drill

What Happens if I Use a Spot Drill with an Improper Angle?

Using a larger angle drill will allow the drill to find the correct location by guiding the tip of the drill to the center. If the outer diameter of a carbide drill were to contact the workpiece first, the tool could chip. This would damage the workpiece and result in a defective tool. If the two flutes of the drill were slightly different from one another, one could come into contact before the other. This could lead to an inaccurate hole, and even counteract the purpose of spot drilling in the first place.

Avoiding CNC Drill Walking With a Spotting Drill

Few CNC machining applications demand precision like drilling. The diameter hole size, hole depth, part location, and finish are all important and provide little recourse if not up to specifications. That said, accuracy is paramount – and nothing leads to inaccurate final parts faster than drill walking, or the inadvertent straying from a drill’s intended location during the machining process. So how does drill walking occur, and how can one prevent it?

To understand drill walking, think about the act of striking a nail with a hammer, into a piece of wood. Firm contact to a sharp nail into an appropriate wood surface can result in an accurate, straight impact. But if other variables come into play – an uneven surface, a dull nail, an improper impact – that nail could enter a material at an angle, at an inaccurate location, or not at all. With CNC Drilling, the drill is obviously a critical element to a successful operation – a sharp, unworn cutting tool – when used properly, will go a long way toward an efficient and accurate final part.

To mitigate any variables working against you, such as an uneven part surface or a slightly used drill, a simple way to avoid “walking” is to utilize a Spotting Drill. This tool is engineered to leave a divot on the face of the part for a drill to engage during the holemaking process, keeping it properly aligned to avoid a drill from slipping off course.

When Won’t a Spot Drill Work for My Application?

When drilling into an extremely irregular surface, such as the side of a cylinder or an inclined plane, this tool may not be sufficient to keep holes in the correct position. For these applications, flat bottom versions or Flat Bottom Counterbores may be needed to creating accurate features.

Harvey tool spot drill zoomed in on the tip of the drill
Harvey Tool Spot Drill

Titan USA Carbide Drills: Jobber, Stub & Straight

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When navigating Titan USA’s offering of carbide drills, it is imperative to understand the key differences among the three carbide drill styles: Jobber Length, Stub Length, and Straight Flute Drills. The right drill for your application depends on, among other factors, the material you are working in, the job requirements, and the required accuracy.

PRO TIP:

Chip evacuation can be an obstacle for hole making. Pecking cycles can be used to aid in chip removal. Peck cycles are when the drill is brought in and out of the hole location, increasing depth each time until the desired depth is reached. However, pecking cycles should only be used when necessary; this process increases cycle time and subjects the tool to added wear from the repeated engaging and disengaging.

Jobber Length Drills

Titan USA jobber length drill

A carbide Jobber Length Drill is the standard general-purpose drill within Titan USA’s offering. It has a long flute length and an included angle of 118o. These drills are great for general purpose drilling where the tolerances are not as tight as the Stub Drill or Straight Flute Drill. Due to the length of these drills, however, they will be more affected by any lack of rigidity in the set up and can have higher runout, or straying from a desired location, during the drilling operation.

PRO TIP:

To achieve high accuracy and great finish, consider utilizing a Reamer. Reamers are designed to remove a finite amount of material but bring a hole to a very specific size. To do this, first drill 90% – 94% of the desired hole diameter with a Jobber Drill. After 90% – 94% of the material is removed, go in for a finishing pass with a Reamer. Reaming tools are highly accurate and leave a beautiful finish.

Stub Length Drills

Titan USA stub length drill

Titan USA carbide Stub Length Drills have a shorter flute length, wider included point angle, and a significant drop in helix angle, when compared to Jobber Length Drills. The shorter length and wider tip create for a more rigid tool and, in turn, more accurate holes. The stub drill is the best option when drilling with tight tolerances on shallower holes.

Straight Flute Drills

Titan USA straight flute drill

Carbide Straight Flute Drills have the smallest core of the three drill types mentioned within this post. Titan USA offers Straight Flute Drills with 2 flutes and a 140o included angle. These drills are designed for hole making in materials that create short chips. Materials in which the Straight Flute Drill typically performs best include cast aluminums and cast irons, as well as copper. In addition, this type of drill can work very well in high hardness materials, but the core diameter should first be adjusted to accommodate the increased hardness. For these difficult to machine materials, casting the part with a core hole and then opening it up with the Straight Flute is a great option. This removes some of the stress caused by chip removal and allows for the drill to do what it does best.

Chip removal can be more difficult in this style of carbide drill because the chips are not guided along a helix. With helix flutes, the motion of chip removal is mostly continuous from their initiation point, through the flute valleys, and finally out of the flute valleys. The helix creates a wedge which helps push the chips along, but the straight flute does not have that. It interrupts that natural turning motion created by the drill face which can affect chip evacuation. Due to the interruption in motion this type of drill is better suited for applications involving chips of smaller size.

PRO TIP:

Helix drills create multiple different forces on the part, which can create micro imperfections. The Straight Flute Drills do not create those forces, so the finish is much more consistent down to the micro level. The margins of the Straight Flute Drill also burnish the inside of the hole as they spin, which improves the finish as well. When comparing the Straight Flute Drill to a helix drill, the length of the overall contact point is much shorter in the Straight Flute Drill, and has less heat generation. The decreased heat will also reduce the probability of work hardening.

Selecting Your Perfect Titan USA Carbide Drill

Selecting the correct carbide drill for your application is a crucial step in hole making. The Jobber Drill is a great general-purpose drill and should be utilized in applications requiring long reach. The Stub Drill increases the rigidity with its shorter length of flute, allowing it to drill with higher accuracy. Applications which involve tight tolerances and more shallow holes can be done with the Stub Drill for high-quality results. Lastly, for difficult to machine and hard materials, the Straight Flute Drill is the perfect solution. When the core diameter and chip evacuation is properly addressed, the Straight Flute Drill produces beautifully consistent surface finish and extremely tight tolerances. Similarly, Titan USA offers its carbide drills in both an uncoated option, and AlTiN coating. Traditionally, uncoated tools are general purpose workhorses in a wide variety of materials both ferrous and non-ferrous. AlTiN or Aluminum Titanium Nitride is an enhanced coating specifically made for ferrous materials that extends tool life and performance across a wide range of steels and their alloys.

For more information on Titan USA Drills, and to view its full selection, click here.

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.