Why Are CoreXY 3D Printers Faster?

3D printing technology has evolved rapidly, and CoreXY printers have emerged as a favorite among enthusiasts and professionals for their speed and precision. But what makes CoreXY printers faster than other designs, such as Cartesian or Delta printers? This blog post dives into the technical details of CoreXY kinematics, exploring the mechanics, design advantages, and practical implications that contribute to their impressive speed.

Introduction to CoreXY 3D Printers

3D printing has revolutionized prototyping, manufacturing, and hobbyist creation, with speed being a critical factor for many users. Among the various 3D printer designs—Cartesian, Delta, and CoreXY—CoreXY printers are often celebrated for their ability to produce high-quality prints at remarkable speeds. But why are CoreXY printers faster? The answer lies in their unique kinematic system, which optimizes motion control, reduces inertia, and enhances stability. 

Understanding 3D Printer Kinematics

To appreciate why CoreXY printers are faster, we first need to understand the kinematics of 3D printers. Kinematics refers to the motion control system that governs how the print head or build plate moves in the X, Y, and Z axes. The three most common kinematic designs in 3D printing are:

1. Cartesian:

Uses linear motion along three orthogonal axes (X, Y, Z), typically with one motor per axis. The print head or bed moves directly along rails or belts.

2. Delta:

Employs three arms connected to a print head, with motion calculated using trigonometric transformations. All three motors work together to position the print head.

3. CoreXY:

 A Cartesian-based system that uses a unique belt-driven mechanism to control X and Y motion with two stationary motors, reducing moving mass.

The CoreXY Kinematic System How It Works

The CoreXY system is a belt-driven mechanism that controls the X and Y movements of the print head using two stationary stepper motors. Unlike traditional Cartesian printers, where each axis is driven independently by a dedicated motor, CoreXY uses a single belt system looped in a specific configuration.

Dual Motor Coordination: Two stepper motors, typically labeled A and B, are mounted on the printer’s frame and remain stationary. These motors drive a single belt that crosses over itself in a “core” pattern (hence the name CoreXY).

● Belt Path: The belt is routed through a series of pulleys, forming an H-shaped or cross-shaped path. The print head is attached to this belt, and its position in the X-Y plane is determined by the relative motion of the two motors.

● Motion Logic:

○ When both motors rotate in the same direction at the same speed, the print head moves along the X-axis.

○ When the motors rotate in opposite directions at the same speed, the print head moves along the Y-axis.

○ Diagonal or curved movements are achieved by varying the speed and direction of the motors, allowing precise control. 

Why CoreXY Printers Are Faster

Several technical and design factors contribute to the speed of CoreXY printers. Let’s break them down:

1. Reduced Moving Mass

One of the primary reasons CoreXY printers are faster is their reduced moving mass. In traditional Cartesian printers, the Y-axis motor and associated components (e.g., the print bed or gantry) often move along with the print head, increasing the inertia that the motors must overcome.

In contrast, CoreXY printers keep both X and Y motors stationary on the frame. Only the print head (and sometimes a lightweight gantry) moves, significantly reducing the mass in motion. Lower inertia allows for faster acceleration and deceleration, enabling higher print speeds without sacrificing precision.

For example, a typical Cartesian printer might have a moving bed weighing 500-1000 grams, while a CoreXY printer’s moving components (print head and carriage) might weigh as little as 100-200 grams. This difference allows CoreXY printers to achieve acceleration rates of 10,000 mm/s² or more, compared to 2,000-5,000 mm/s² for many Cartesian designs.

2. Stationary Motors for Better Heat Management

Since the motors in a CoreXY system are fixed to the frame, they can be larger and more powerful without adding to the moving mass. Stationary motors also benefit from better heat dissipation, as they are typically mounted on metal frames that act as heat sinks. This allows CoreXY printers to sustain high-speed operation for longer periods without overheating, unlike some Cartesian designs where motors move with the bed or gantry and may require active cooling.

3. Optimized Belt Path for Precision and Speed

The CoreXY belt system is designed to minimize slack and ensure precise motion. The belts are kept under constant tension, reducing backlash (unwanted movement due to loose components). This precision allows CoreXY printers to maintain accuracy at high speeds, where other designs might introduce artifacts like ringing or ghosting due to vibrations.

Additionally, the belt-driven system allows for smoother and faster transitions between movements. For instance, diagonal or curved paths are executed by fine-tuned coordination of the two motors, enabling complex toolpaths without slowing down.

4. Enhanced Stability and Rigidity

CoreXY printers often feature a cube-like frame with a fixed bed, which enhances structural rigidity. In contrast, many Cartesian printers use a moving bed, which can introduce vibrations or wobble at high speeds, especially with heavy prints. Delta printers, while fast, rely on long arms that can flex under rapid movements, limiting their speed in certain scenarios.

The rigid frame and stationary bed of CoreXY printers minimize vibrations, allowing for faster print speeds without compromising print quality.

5. Efficient Use of Motor Power

In a CoreXY system, both motors contribute to every X and Y movement, effectively distributing the workload. This contrasts with Cartesian printers, where a single motor handles each axis independently. By sharing the load, CoreXY motors can operate at higher efficiency, delivering more torque and enabling faster movements without overloading individual motors.

Comparing CoreXY to Other Designs

To highlight the speed advantages of CoreXY printers, let’s compare them to Cartesian and Delta designs:

CoreXY vs. Cartesian

● Moving Mass: Cartesian printers often have a moving bed or heavy gantry, increasing inertia and limiting acceleration. CoreXY’s lightweight print head allows for faster movements.

● Motor Placement: Cartesian printers typically move one motor (e.g., for the Y-axis), adding weight. CoreXY’s stationary motors reduce moving mass and improve heat dissipation.

● Speed Potential: CoreXY printers can achieve print speeds of 150-300 mm/s or higher, while Cartesian printers typically max out at 100-200 mm/s for comparable quality.

CoreXY vs. Delta

● Kinematics: Delta printers use three arms and complex trigonometric calculations, which can introduce computational overhead and limit speed for intricate toolpaths. CoreXY’s Cartesian-based system is simpler and more direct.

● Stability: Delta printers’ long arms can flex at high speeds, causing inaccuracies. CoreXY’s rigid frame and belt system maintain precision.

● Speed Potential: Delta printers are fast (often 200-400 mm/s), but CoreXY printers can match or exceed this while offering better consistency for complex prints.

Real-World Performance: What the Numbers Say

In practice, CoreXY printers demonstrate their speed advantage in benchmark tests and real-world applications. For example:

● Benchmark Tests: In tests like 3DBenchy (a popular 3D printing benchmark), CoreXY printers like the Creality Ender-7 or Voron 2.4 can complete prints in 20-30 minutes at speeds of 200-250 mm/s, compared to 40-50 minutes for Cartesian printers like the Ender-3 at 80-100 mm/s.

● Acceleration: CoreXY printers often achieve acceleration rates of 10,000-20,000 mm/s², allowing rapid changes in direction without loss of precision. Cartesian printers typically range from 2,000-5,000 mm/s².

● Print Quality: At high speeds, CoreXY printers maintain quality due to their stability and low inertia. For instance, a CoreXY printer can produce clean prints at 200 mm/s, while a Cartesian printer might show artifacts like ringing at similar speeds.

These numbers depend on factors like firmware optimization (e.g., Klipper vs. Marlin), extruder performance, and material properties, but CoreXY’s kinematic advantages consistently shine through.

Practical Considerations for Maximizing CoreXY Speed

While CoreXY printers are inherently faster, achieving their full potential requires attention to several factors:

1. Firmware and Electronics: High-performance firmware like Klipper, combined with powerful stepper drivers (e.g., TMC2209),

2. Hotend and Extruder: A high-flow hotend (e.g., Volcano or Dragon) and a direct-drive extruder are critical for maintaining filament flow at high speeds.

3. Frame and Components: A rigid frame, high-quality linear rails, and low-friction pulleys enhance stability and reduce wear at high speeds.

4. Tuning: Proper tuning of acceleration, jerk, and belt tension is essential to balance speed and quality.

5. Material Choice: Fast printing works best with materials like PLA or PETG, which flow well at high temperatures. More demanding materials like ABS may require slower speeds to avoid warping.

Limitations of CoreXY Printers

While CoreXY printers excel in speed, they have some limitations:

● Complexity: The belt system is more complex than Cartesian designs, requiring precise assembly and maintenance to avoid issues like belt stretch or misalignment.

● Cost: CoreXY printers often use higher-quality components (e.g., linear rails), making them more expensive than entry-level Cartesian printers.

● Learning Curve: Tuning a CoreXY printer for high-speed printing requires more expertise than a basic Cartesian setup.