We're now in 2025, and every person thinking about buying a 3D printer is asking the same question: Is the classic i3 "bedslinger" outdated? CoreXY printers have become incredibly popular, promising amazing speed and accuracy. This has made many people wonder if the design that made 3D printing popular is still useful. The 3D printing market is faster, better, and offers more choices than ever before. The debate between these two movement systems is now a major factor when people decide which printer to buy.
This article will look past the excitement to give you a clear, fair analysis. We will look at the technical facts, market trends, and real user experiences of both the CoreXY structure and the i3 gantry structure. We'll examine why one has become known for performance and the other remains the foundation of affordability.
So, has the i3 gantry been completely replaced? The quick answer is no. But the more interesting question is why not, and how these two popular designs have developed to serve different users with different goals. The choice is no longer about which is "better," but which is right for you.
The Fundamentals Refresher
To understand this debate, we must first understand how these machines work. For readers at all experience levels, here is a basic breakdown of how each system operates.
The Enduring i3 Gantry
The i3 gantry structure is the classic straight-line movement system. Think of it in three simple, separate movements: the print head moves left and right on the X-axis rail, the entire rail moves up and down on the Z-axis, and the print bed itself moves back and forth on the Y-axis.
Its main feature, which creates both its biggest strengths and weaknesses, is the large, moving weight of the print bed. As the print grows, the weight being moved back and forth on the Y-axis increases. The best comparison is a drawing machine working on a piece of paper that moves quickly toward and away from you, while the pen only moves side-to-side.
The High-Speed CoreXY
The CoreXY system also uses straight-line movements, but its motion is more complex and coordinated. The print head is controlled in both X and Y directions by a smart system of two stationary motors and a long, looping belt path. The print bed stays completely still in the XY plane; it only moves down the Z-axis, layer by layer.
Its main feature is the lightweight moving rail and the stationary bed. For the print head to move in a straight line on the X or Y axis, both motors must work together in perfect timing. For diagonal movements, one motor might speed up while the other slows down or reverses. A useful comparison is two people controlling an Etch A Sketch, where turning both knobs at once is needed to create diagonal lines and coordinated turning is needed for straight ones.
The CoreXY Performance Reign
The rise of the CoreXY structure to become the performance leader is not based on marketing; it is based on physics and smart design. For serious hobbyists and enthusiast markets, its advantages are clear.
The Physics of Speed
The main challenge in high-speed printing is resistance to movement. An i3 printer's heavy bed, carrying the weight of the print itself, must constantly and quickly speed up and slow down. This violent motion creates vibrations that show up as "ringing" or "ghosting" marks on the print surface, forcing a practical limit on print speed if quality is to be maintained.
The CoreXY solution is elegant. By keeping the heavy print and bed assembly still in the XY plane and only moving the lightweight toolhead and rail, the system dramatically reduces moving weight. This simple change in physics allows for much higher acceleration and top speeds without creating print-damaging vibrations. This reduction of resistance to movement is the number one reason for its adoption in the world of high-speed 3D printing.
Rigid by Design
CoreXY printers are almost always built within a cube or box frame. This is not just for looks; an enclosed, box-like shape is naturally more rigid and resistant to the bending and vibration that can happen during rapid movements. Compare this to the typical open, rail-style frame of many i3 printers, which can be more likely to wobble.
This superior frame rigidity translates directly into better print quality. It ensures greater size accuracy and cleaner vertical surfaces, an advantage that becomes particularly noticeable on taller models where any frame wobble at the base is amplified at the top of the print. The stability of the CoreXY structure vs i3 gantry is a key difference for precision work.
The Enclosure Advantage
In 2025, the demand for printing with engineering-grade materials like ABS, ASA, PC, and Nylon is no longer a specialty pursuit. These materials offer superior strength and heat resistance but are known for warping and layer separation if they cool too quickly.
The box frame of a CoreXY printer makes it incredibly easy for manufacturers to fully enclose the build volume. This creates a stable, passively or actively heated chamber that is essential for maintaining the high surrounding temperatures needed to print these advanced materials successfully. While an i3 can be enclosed, it's often a custom, aftermarket modification, whereas for a CoreXY, it's a natural extension of its design.
The i3's Modern Resurgence
While CoreXY dominates the speed conversation, reports of the i3's death have been greatly exaggerated. In 2025, the i3 structure is more relevant than ever, having evolved significantly and solidified its critical role in the 3D printing ecosystem.
Champion of Accessibility
Simplicity is a feature, not a problem. The i3 design is mechanically simpler than a CoreXY. It has fewer parts, a much less complex belt path, and mechanics that are immediately easy to understand for a newcomer. You can see the X-motor and know it only moves the X-axis.
This mechanical simplicity directly translates to lower manufacturing costs and, therefore, a lower price for the consumer. In 2025, the i3 structure continues to dominate the entry-level and budget-friendly market segments. It is the design that has made 3D printing accessible to millions of students, hobbyists, and small businesses, and it continues to be the most cost-effective entry point into the hobby.
The Tinkerer's Playground
The simplicity of the i3 gantry makes it a dream for those who love to modify, upgrade, and repair their own machines. Troubleshooting is straightforward. If you have a layer-shifting problem on the Y-axis, you check the Y-axis motor, belt, and wheels. This is not the case with a CoreXY system, where a belt tension issue can show up as skewed prints or problems on both axes, making diagnosis more complex for a beginner.
Furthermore, over a decade of community development around the i3 means there is a vast, unmatched library of community-designed parts, modifications, troubleshooting guides, and tutorials. This mature ecosystem provides a safety net and an endless path for upgrades, making it the undisputed tinkerer's choice.
Closing the Performance Gap
The i3 of 2025 is not the same machine it was five years ago. Modern i3 printers have widely adopted features that directly address their historical weaknesses. The performance gap between a CoreXY structure vs i3 gantry structure has narrowed considerably.
Key upgrades are now common: linear rails are replacing V-slot wheels for smoother, more stable bed movement; dual Z-axis lead screws, often synchronized with a timing belt, have almost eliminated rail sag; and most importantly, the widespread adoption of input shaping in firmware has been a game-changer. This firmware technology electronically measures a printer's vibration frequencies and creates canceling vibrations, allowing even a "bedslinger" to print at significantly higher speeds than was possible just a few years ago without creating ringing. For a huge number of users printing with standard materials like PLA and PETG, a well-tuned modern i3 produces prints of a quality and at a speed that is more than sufficient for their needs.
The 2025 Verdict
So, after weighing the evidence, how do you choose? The key is to understand your own needs and match them to the system that serves them best.
Market Specialization
The market hasn't chosen a single winner; it has specialized. The CoreXY structure vs i3 gantry structure debate has resolved into a clear split. We have a distinct high-performance, high-temperature path dominated by CoreXY, and a clear accessibility, value, and serviceability path where the i3 gantry reigns supreme. Neither is "better" in isolation; their value is defined by the user's context.
Quick-Reference Comparison
| Feature | CoreXY System | i3 Gantry System |
|---|---|---|
| Max Speed/Acceleration | Very High | Moderate to High (with tuning) |
| Print Quality Potential | Excellent | Very Good to Excellent |
| Footprint (for build volume) | More Compact | Larger (needs room for bed) |
| Ease of Enclosure | Excellent (Built-in) | Moderate (Requires custom build) |
| Initial Cost | Higher | Lower |
| Mechanical Complexity | High (Belts are critical) | Low (Simple and direct) |
| Maintenance/Tuning | More Involved | Straightforward |
Choose CoreXY in 2025
You should strongly consider a CoreXY system if you are:
- The Performance Enthusiast: You want the fastest possible print speeds and highest accelerations without compromising surface quality. Speed is your priority.
- The Materials Engineer: You plan to print extensively with ABS, ASA, Nylon, or other high-temperature, engineering-grade materials that demand a stable, enclosed environment.
- The "Prosumer": You value top-tier precision and dimensional accuracy for functional parts and are comfortable with a more complex machine that requires careful tuning.
Stick with an i3 Gantry in 2025
An i3 gantry system remains the ideal choice if you are:
- The Beginner: You want the easiest, most affordable, and most forgiving entry into the world of 3D printing, with a massive community for support.
- The Budget-Conscious Maker: You want the absolute best performance-per-dollar and a reliable workhorse for standard materials like PLA and PETG.
- The Hands-On Tinkerer: You enjoy upgrading, modifying, and working on your machine. You value a device that is simple to understand, diagnose, and repair yourself.
Conclusion: Coexistence is the New Paradigm
Far from being replaced, the i3 gantry has evolved and solidified its role as the foundation of consumer 3D printing. It is the workhorse, the entry point, and the tinkerer's canvas. At the same time, the CoreXY system has rightfully claimed the high-performance frontier, pushing the boundaries of speed and material capability.
The real innovation in the coming years may not be in one system defeating the other, but in how features from the high-end—like input shaping, linear rails, and better motion components—continue to trickle down, elevating the performance and value of accessible i3 designs even further.
The best 3D printer of 2025 isn't defined by its movement system alone. It's defined by how well its strengths align with your projects, your skills, and your budget. Choose wisely, and happy printing.