What is Z seam in 3D printing?

In the field of 3D printing, Z seam is a common problem that affects the surface finish of the model. It manifests as thin lines or tiny defects that run vertically through the printed part, especially on cylindrical or curved models. Although Z seam is an inherent phenomenon of the FDM process, its visibility can be significantly reduced through technical optimization. This article will analyze the causes of Z seam and provide solutions.

Source: https://clevercreations.org/hide-z-seam-alignment-fix-cura/

What is Z seam？

Z seam is a vertical seam formed by the print head at the starting and ending points of each layer. When the nozzle finishes printing a layer, it needs to pause extrusion, retract the filament and move to the starting point of the next layer. This process may cause material accumulation or gaps, and eventually form a visible Z seam.

Cause

Layer start point alignment logic: The slicing software defaults to aligning the starting points of each layer vertically to improve efficiency. When the nozzle moves from one part of the print to another, there is usually a slight pause, leaving a visible mark, causing the seam to form a continuous vertical line on the surface of the model.

Improper retraction settings: Too long or too short nozzle retraction can cause filament overflow or insufficient extrusion, exacerbating unevenness at the seam.

Model geometry: Cylinders or curved surfaces lack natural corners to hide seams, making Z seams more easily exposed.

How to minimize Z seam？

Hide seam position

Many slicing software programs (such as Cura or PrusaSlicer) provide options to control the position of Z seams. You can choose to align the seam along a less conspicuous part of the model, such as the back or inner area, which can help hide the seam. For example, the seam can be hidden on the black part of the model to avoid showing on the cylindrical part. Another way is to place the seam in the corner of the model, so that even if the seam exists, it is not easy to notice.

In Bambu Studio's quality settings, the "Seam" option provides several position settings:

1. Aligned position: This is the default setting, the seam is placed in the corner, and the printing effect is neat.

2. Nearest position: The system automatically determines the position of the seam, the effect is more chaotic, suitable for some special effects

3. Random position: The seams are randomly distributed, which is suitable for decorative models, but may leave many small spots on the model, affecting the appearance.

Scarf seams

Different from traditional seams, this type of seam overlaps to make the seams smoother, rather than ending abruptly, making the seams less obvious. Mitered seams were originally used in woodworking to improve structural stability, and are now also introduced into 3D printing to improve appearance. Many slicing software such as Bambu Studio, Orca Slicer and Cura have introduced this function. Through the settings in the slicer, users can further customize the length and number of steps of the seams. Longer seams can be extended to a larger area, reducing the conspicuousness of the seams.

Vase Mode

Vase Mode is a special 3D printing method that can effectively avoid Z seams in traditional printing. Vase mode usually only prints a single layer of the outer wall of the object, without internal filling layers and multi-layer stacking. The print head continuously extrude along the outer surface of the object to form a single ring structure, avoiding the gap problem caused by gaps or retraction between layers in traditional printing. Secondly, since there is no multiple stacking, the material of each layer will be closely combined with the previous layer, avoiding the appearance of "starting points" or "seam points", making the surface of the object smoother. Vase mode is particularly suitable for some simple geometric shapes, such as thin-walled objects such as cylinders and vases, because these objects usually do not have complex internal structures. In this way, vase mode can minimize unnecessary seams and make the printing results neater and more beautiful.

Optimize Print Settings

Retraction is the key to reducing the visibility of seams. If the retraction setting is too low or too high, it may cause drawing or uneven extrusion, resulting in obvious seams. By fine-tuning the retraction distance and retraction speed, combined with the appropriate nozzle temperature, the generation of seams can be reduced. Use the temperature tower to find the best printing temperature to ensure uniform and consistent extrusion to avoid shrinkage or drawing. In addition, slower printing speeds and appropriate nozzle temperatures help ensure a smooth transition between each layer, thereby improving interlayer bonding and reducing the appearance of seams.

Z-seam is inevitable in FDM printing, but the above methods can effectively reduce the impact of Z-seam on 3D printed parts. For users who pursue extreme surface finish or complex structural accuracy, choosing more professional 3D printing technology and service providers can often achieve twice the result with half the effort. JLC3DP provides customers with excellent printing quality and post-processing services, which can restore your model design to the greatest extent.