CoreXY Kinematics

CoreXY Kinematics Explained?

The corexy kinematics mechanical arrangement includes a unique motor movement where the X or Y motor move together or opposite of each other to move the carriage from left to right or towards or away . If you were to move just one motor you would see the print head move diagonal.. If the two motors move opposite of each other the print head will move along the X-axis, If the two motors move in the same direction the carriage will move along the Y-axis.

How Does CoreXY Work?

The CoreXY 3d printer design is very different than most common 3d printer motion systems that have dedicated stepper motor for each axis. The core-xy motion system is designed to minimize torque while moving the gantry and carriage.

The corexy parallel kinematics mean’s that the motors are the largest source of inertia within the system, are stationary. This means rapid acceleration because the two stepper motors provide a means of moving both axes independently or simultaneously. The major benefit of the design is that the motors remain in a static position. 

The corexy kinematics is a complex motion system where X or Y motor move together or opposite of each other to move the carriage from left to right or towards or away . If you were to move just one motor you would see the print head move diagonal.. If the two motors move opposite of each other the print head will move along the X-axis, If the two motors move in the same direction the carriage will move along the Y-axis.

Two Motors (X and Y)

• Both Motors Move Clockwise >> Carriage Moves Left
• Both Motors Move Counter Clockwise>> Carriage Moves Right
• Both Motors Move Opposite of Each Other>> Carriage Moves Toward & Away
• One Motor Moves>> Carriage Moves Diagonal

see more CoreXY Mechanism Research

CoreXY Motor Movement

Motor Movement	Direction
Both Motors Move Clockwise	Carriage Moves Left
Both Motors Move Counter Clockwise	Carriage Moves Right
Both Motors Move Opposite of Each Other	Carriage Moves Toward & Away
One Motor Moves	Carriage Moves Diagonal

Is CoreXY Better?

Over the last few years the popularity of the CoreXY kinematics has became a community favorite. New designs, developments and opens source contrubutions have led many to claim it’s the best motion system for 3d printing but that really depends on the user and application.

Pros

• Higher Print Speeds: The stationary X and Y motors reduce mechanical weight and momentum giving the motion system a mechanical advantage compared to other motor placement configurations.
• Quality: With the reduced weight and momentum the setup also results in reduced vibrations and increased repeatability at higher speeds.
• Mechanicaly Optimized: With the x and y motors out of the way the machine size compared to actual build volume ratio gives you more printing space with a smaller footprint. Unlike the hbot the corexy carriage isn’t problematic to twisting or buckling when x and y motors rotate in the same direction.

Cons

• Maintenance: The longer x and y belts introduce belt tensioning issues(belt stretch). The increased number of belt idlers increase maintance.
• Scalabilty: The belt stretch and tensioning issues introduces a design constraint as the machine size increases.

CoreXY Advantages

The Advantages of the corexy system is the increased print speeds that can be achieved due to the light weight carriage. While 3d printing is a very slow process any kind of reduction in print time is much needed. In addition to faster print speeds the smooth motion that the core xy uses is also known to reduce artifacts commonly found in 3d printed objects.

see RepRap CoreXY

CoreXY vs Cartesian

Most printers utilize Cartesian or plotter style motion where one or two motors will move the carriage from left to right or towards and away. This is the simplest approach in 3d printer motion. While the core xy setup is more complicated but a more efficient approach. The difference between corexy and the cartesian motion system is the corexy reduces inertia from the static motor positions while the cartesian setup uses at least one motor to drive along each axis. The weight of the motor increases inertia making it more difficult to change direction. Which results in the corexy theoretically being faster in and more accurate than the cartesian.

CoreXY Belt Path & Routing

The corexy 3d printer belt path has been explored in many mechanical arrangements. The main two corexy belt routing methods are belts crossed or not crossed. The main focus should be to keep the belt routing path parallel to the X and Y guide rails. There’s an excellent blog about core xy belt path by Mark Rehorst.

CoreXY vs Hbot

Type	Pros	Cons
CoreXY	design balances the forces	more complex beltpath with two crossing belts
Hbot	simple design with only one belt	higher orthogonal load known as racking

A similar mechanical arrangement of the core-xy is the H-bot. The Hbot uses the same concept of carriage motion as the corexy but is much more simple and requires less math. In addition the hbot is harder to “get wrong.” The corexy belt path has it’s pros and cons. The corexy’s disadvantage is that it requires two belts on two separate planes. The coreXY balances the forces while moving the gantry or carriage to minimize “racking’ where the mechanical system is pulled out of square.

What You Need to Know Before Buying a 3D Printer

Every user is different and has different needs. There isn’t one printer for everybody. You have to consider:

Experience: What is your experince with 3d printers or mechanical components and electroncs that may require technical maintance or steep learning curves.

Application: What kind of parts are you going to print? What size? What materials? How many?

Expectations: What kind of quality or user experience do you expect? What kind of maintance can apply?

Budget: How much can you spend or how much are you willing to spend? You get what you pay for but you may not need much.

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CoreXY Belt Routing