Fly Cutter Comprehensive Manual: Varieties, Specifications, and Applications

In the contemporary landscape of manufacturing, CNC tooling assumes a pivotal position, harnessing the capabilities of motorized machinery and pre-programmed algorithms to orchestrate the intricacies of automated machining processes. Amidst the multifaceted domain of CNC milling, a singular tool emerges as a linchpin in the pursuit of immaculate surfaces across vast, planar expanses: the fly cutter. The judicious selection of milling equipment and cutters emerges as a cornerstone of CNC operations, wielding direct influence over the realms of surface accuracy and machining efficacy. Amidst the plethora of milling implements available, a nuanced understanding of the fly cutter becomes imperative. This discourse endeavors to elucidate its conceptual underpinnings, diverse typologies, practical applications, and the subtle differentiations that distinguish it from its counterpart, the face mill.

Fly Cutter: Definition and Construction

The fly cutter emerges as a tool of notable repute, celebrated for its lateral machining prowess aimed at sculpting impeccably planar surfaces. This rotary cutting instrument finds widespread application within machining frameworks, where its singular-point fly cutter bits are delicately ensconced within a cylindrical framework. These cutters are meticulously installed within specialized angled holders, enabling seamless rotational motion crucial for executing surfacing operations across diverse materials such as aluminum and steel.

Structurally, the fly cutter boasts a meticulously crafted framework, housing either a singular or dual arrangement of tool bits, each integral to its function. Within this framework lie essential components including holders, thrust washers, drawbolts, and precision-engineered left-hand carbide cutting implements. Typically, the central cylindrical body accommodates a solitary tool bit, often a conventional left-hand turning device strategically positioned at an angle spanning from 30 to 60 degrees. Alternatively, fly cutters equipped with dual tool bits present a configuration where these implements are stationed at opposing ends, oriented perpendicular to the primary axis of the bar stock.

Considerations surrounding power consumption emerge as pivotal factors influencing the operational efficacy of fly cutters, particularly when equipped with multi-toothed configurations. Such considerations hold heightened relevance within compact machining platforms, where escalated operational demands necessitate judicious power management strategies. Primarily tailored for mild cutting applications, fly cutters exhibit optimal performance characteristics within light-duty milling environments, especially when paired with single-toothed cutting apparatuses.

Securely anchored within specially configured angled holders, fly cutters bestow upon operators the freedom of rotational mobility, enabling the execution of expansive and shallow-facing cuts across a spectrum encompassing both malleable and rigid materials. While bearing semblance to face mills in their shared function for face milling applications and the inclusion of replaceable cutters, fly cutters carve out a distinctive niche through nuanced disparities, assuming a pivotal role within the intricate domain of precision machining pursuits.

Types of Fly Cutters

In the realm of precision machining for expansive and planar surfaces, fly cutters reign supreme, offering a diverse array of meticulously crafted variants tailored to meet specific industrial requirements. Among these specialized tools, the Point Cutter emerges as a standout performer, meticulously engineered to achieve precision in machining densely populated corals. Available in both long (500 mm) and short (300 mm) configurations, these cutters feature blades equipped with dual cutting edges, enabling meticulous milling operations. The needle-like points of the cutter adeptly navigate intricate contours, effortlessly retracting into the handle for secure storage.

Single-point fly cutters

Another indispensable addition to the arsenal of fly cutters is the Rotary Cutting Tool, celebrated for its exceptional versatility in swiftly executing cutting, drilling, and grinding tasks on fabrics, all while preserving the integrity of patterned cutting lines. Esteemed practitioners frequently rely on this fly cutter to streamline the processing of multiple layers of fabric—up to eight—in a single milling session, highlighting its exceptional speed and precision.

Rotary Cutting Tool

For carving operations on rigid materials such as wood and blown glass, the Rotary Carving Tool emerges as the tool of choice. These specialized fly cutters excel in carving against the grain, offering a heightened degree of flexibility in machining endeavors.

Rotary Carving Tool

Manufactured to adhere to exacting industrial standards, fly cutters exhibit significant variation in critical parameters, including compatibility with cutting materials, rotational speed, and feed rate. The judicious selection of an appropriate milling cutter based on these considerations is paramount in ensuring optimal outcomes when refining expansive and planar surfaces. From the intricately designed Point Cutters tailored for precise coral milling to the versatile Rotary Cutting Tools facilitating rapid fabric processing, and the robust Rotary Carving Tools adept at carving hard materials, the diverse range of options comprehensively caters to the multifaceted demands of machining projects.

Fly Cutter Components and Specifications

In the intricate landscape of milling operations, fly cutters stand as indispensable tools, their efficacy stemming from a meticulous arrangement of pivotal components. Among these constituents lie the cylindrical body, holder, thrust washer, fasteners, draw bolt, and the left-handed carbide cutting tool. A profound comprehension of the specifications governing these elements becomes paramount in harnessing the full potential of fly cutters within machining endeavors.

Fly Cutter Components

At the heart of fly cutter architecture resides the cylindrical body, serving as the structural foundation for the tool’s operation. Within this body, a singular tool bit finds its dwelling, poised to engage with the workpiece during milling tasks. In instances where dual tool bits are incorporated, precision engineering ensures their secure fixation at opposing ends of the cylindrical body.

Crucially, the alignment of the fly cutter bits is meticulously orchestrated through the utilization of a specialized angled holder. Positioned at a precise 90-degree angle relative to the main axis of the bar stock, this holder facilitates optimal engagement with the workpiece, ensuring consistent and accurate cutting maneuvers.

Fly Cutter vs. Face Mill: Differences

Plate surface machining demands precision and efficiency, with fly cutters and face mills emerging as stalwart contenders, each with distinct advantages tailored to specific needs.

Cutting Position

Fly cutters distinguish themselves by their ability to traverse extensive surfaces in a single pass, ensuring impeccably flat outcomes. In contrast, face mills, characterized by cutting edges of varying heights, excel in sculpting textured or ridged surfaces with precision.

Number of Inserts and Removal Rate

Fly cutters, employing one or two inserts at moderate speeds, are renowned for their ability to deliver smooth surface finishes. Conversely, face mills, equipped with multiple inserts operating at higher speeds, excel in heavy material removal. However, the inability to adjust insert height individually in face mills may lead to variations in chip loads.

Finishing Quality

Face mills are lauded for their capacity to produce high-quality surface finishes, while fly cutters, leveraging skim-cut techniques, achieve an even finer finish. Notably, larger face mills demonstrate superior efficiency in high-volume projects due to their faster cutting speeds.


The requirement for robust, powerful machinery makes face mills a costlier option. In contrast, fly cutters offer a significantly more economical solution, compatible with smaller and less powerful machines. Operating costs are minimized with fly cutters, requiring only one or two inserts for optimal performance.

Operation Requirements and Effect

Fly cutters are suited for lighter machines but exhibit a lower metal removal rate. Conversely, face mills demand greater power and rigidity but excel in handling deeper cuts, facilitating insert replacement without affecting cutter diameter, and maintaining tool length offset for consistent performance.

Considerations for Using Fly Cutters

Surface finishing with fly cutters demands meticulous attention to critical factors to achieve optimal machining outcomes.

Point Radius

To ensure superior results, maintain a point radius below 1.5mm for your fly cutter tool. A smaller point radius correlates with a slower feed rate, resulting in a finer finish. Conversely, cutters with large tip radii can increase cutting pressure, leading to issues such as squealing, chattering, and subpar finishing.

Type of Workpiece

Adapt your approach based on the material being machined. For steel grades like 1018, carbide bits with zero rake and approximately 5 degrees relief are recommended. In contrast, when machining aluminum alloys such as 6061-TS, opt for high-speed fly cutter bits with a rake angle of approximately 60 degrees. Customizing the diameter of standard fly cutters, typically up to 51 mm, facilitates achieving a 0.25 mm deep cut in aluminum with ease.


Match your fly cutter to the size and power specifications of your milling setup. For smaller or light-duty mills, single-toothed fly cutters offer optimal performance, while multi-toothed milling fly cutters may lack the necessary power and rigidity. Ensure the sharpness of your fly cutter bit for smooth cuts without excessive effort. If the cutter bit becomes dull after prolonged use, a straightforward grinding process can swiftly restore its sharpness, ensuring continued machining precision.

Applications of Fly Cutters

Fly cutters emerge as indispensable cutting tools, eliminating the necessity for additional arbors. These mechanical marvels excel in the precise removal of excess material and the meticulous leveling of workpieces spanning a diverse array of materials, encompassing metals, wood, and glass. Their ingeniously crafted design facilitates effortless re-sharpening through grinding, ensuring sustained operational efficacy. With the capacity to adjust diameters up to 2 inches, standard fly cutters boast the capability to achieve a 0.01-inch deep cut in aluminum with precision.

Moreover, the versatility of rotary tools further enhances their utility, encompassing a plethora of functions including cutting, drilling, grinding, carving, and sanding. Deployed predominantly within milling machines, fly cutters efficiently navigate the intricacies of machining large, flat surfaces with unparalleled precision and efficiency. Their applicability transcends the confines of milling machines, extending to encompass machining centers and manual mills, all while meticulously adhering to stringent performance standards such as MACH 151 and MACH 151L.

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