The appearance of 3D printers on the market is now almost the same, and the price is indeed a world of difference. So similar shape, similar functions, what is the difference between printers? Below I will briefly introduce the differences of 3D printers from the part of the print head.

The print head is divided into proximal extrusion and distal extrusion, which is judged according to the distance between the extrusion end and the nozzle. The distance between the extrusion end and the nozzle is the remote extruder. The distance between the extrusion end and the nozzle is the proximal extruder.

1. Broden Extruder

For this type of machine, the general extruder and stepper motor are mounted on the machine housing and feed the nozzle remotely through Teflon tubes. For example: Ultimaker, Delta and other models

1. Advantages of Broden Extruder:

1. The nozzle is light in weight, small in inertia, and more accurate in mobile positioning;

2. The moving speed of the nozzle can reach 200~300mm/s, so its printing speed can also be very fast;

3. The nozzle and the extruder are separated for easy maintenance.

Shortcoming:

1. The feeding distance is long and the resistance is large, which requires the stepper motor responsible for extrusion to have a greater torque;

2. The extruder and the nozzle need to be connected with Teflon tube and pneumatic joint, which is more likely to fail than short-range extrusion;

3. Filaments and Teflon tubes have a certain degree of elasticity, and the general pneumatic joint also has a certain space for activity, so the required retraction distance and speed are larger, which is not as accurate as short-distance extrusion and retraction;

4. The distance between the extruder and the nozzle is long, so it is difficult to exhaust the filaments in the feeding tube.

5. It is not very convenient to change materials, especially when using the new material top of the old material without pausing during the printing process, the material head cannot be retracted when it is in the feeding tube.

6. Because the feeding distance is too far but the use of elastic consumables will lead to the situation that the material cannot be transported normally, the 3D printer of the remote extrusion method generally cannot support the printing of elastic materials.

2、Direct extruder

For this type of machine, the general extruder and stepper motor are installed on the nozzle and feed the nozzle directly.

For example, Makerbot and other models

Direct extruder advantages:

1. The control of the feeding amount is more accurate than remote extrusion, and the retraction is more accurate;

2. The torque requirements for the extrusion stepper motor are relatively low;

3. Easy to change materials;

4. Suitable for printing soft materials such as TPU.

Shortcoming:

1. The nozzle hot end, extruder, stepper motor, cooling fan, etc. are integrated together, which is inconvenient for disassembly, assembly and maintenance;

2. The nozzle is heavier, especially the dual-nozzle printer, the inertia is large during movement, and it is relatively difficult to accelerate and decelerate, so a lower printing speed should be used to ensure accuracy;

Why do mid-to-high-end printers prefer near-end print designs?

Early RepRap printers were most commonly used as proximal extruders, with gear reduction, DC motor driven designs. However, due to the large inertia, DC motors cannot start and stop quickly, so it is difficult to control accurately.

However, the new machine is mostly driven by stepper motors, and the extruder also uses stepper motors to drive feeding, especially with advanced stepper motors, feeding and moving have very precise control. Therefore, when printing only one material, using a proximal extrusion design is the most appropriate and efficient.

Another disadvantage of proximal printing that is easily misunderstood is the printing speed. Many people think that the mass of the nozzle is large and the inertia is large, which is not conducive to the speed of movement. If it is a 3D printer with an i3 structure, this concern is superfluous, because the Y-axis movement of the i3 structure is the platform movement, and the Y-axis displacement is achieved by the overall movement of the platform.

Because the X and Y axes are the two directions that move most frequently, but the moving mass of the Y axis is very large, so in order to protect the Y axis when many manufacturers adjust, the movement speed of the X axis will also be limited. Generally, when the slice tool adjusts the X and Y axis speeds, it is also synchronized. Therefore, the key to affecting the movement speed of the X and Y axes is not the nozzle, but the quality of the platform.

There is also a common FDM printer structure - the cabinet structure. The main principle is that the nozzle moves along the X and Y axes, and the Z axis of the platform is dislocated downward to achieve the structure type of printing. But this type is subdivided into three structures: UM, MB, and Core XY. These three types will be discussed in separate space next time.

Cabinet structure FDM printer

After solving the big disadvantages of accuracy and inertia, the advantages of the proximal extrusion design are very obvious. Simple structure, accurate retraction, convenient material change, many printable materials and other advantages, can print a variety of soft and hard materials and easy to change, and the structure is simple and beautiful.

For medium-end models, the focus of product design will be biased towards appearance, function, first experience, etc. Distinguish the price positioning of products with intuitive designs such as simple and good-looking appearance and rich functions. At the same time, it uses a simple and convenient operation experience to give customers a good first feeling. For durability, the general high-end models, the materials are more confident, and the durability is better than the low-priced ones.