A Z seam isn’t really a “problem,” so much as it is just something that happens in 3d printing when you use an FDM printer. It is a line or a seam that is created along the Z-axis, where the printhead stops and moves up to print the next layer. This can cause a slight gap, a blob, or a zit on the surface of your print, especially on smooth and round objects.

There are several ways to fix or hide the Z seam in your 3D prints, depending on your slicer settings and your model geometry. Here are some of the most effective methods:

• Adjust retraction settings: Retraction is when the extruder pulls back the filament slightly to prevent oozing during non-printing movements. By improving your retraction settings, you can reduce the amount of material that leaks out at the end of each layer, which can minimize the Z seam. You can adjust the retraction distance, speed, and extra prime amount in your slicer to find the optimal values for your printer and filament.
• Change Z seam alignment settings: Z seam alignment is how your slicer decides where to place the Z seam on your model. You can choose between random, shortest, user-specified, or sharpest corner options. Random alignment will scatter the Z seams all over your model, making them less noticeable but also less consistent. Shortest alignment will place the Z seams at the closest point to the previous layer, reducing print time but also creating a visible line. User-specified alignment will let you choose a specific location for the Z seam, such as the back or the front of your model. Sharpest corner alignment will place the Z seams at the sharpest corners of your model, hiding them in the details.
• Reduce print speed: Print speed affects how much pressure is built up in the hotend during printing. If you print too fast, you may have more material oozing out at the end of each layer, creating a bigger Z seam. By reducing your print speed, you can lower the pressure and improve the flow control of your extruder, resulting in a smoother surface finish.
• Enable coasting: Coasting is when your slicer stops extruding a little bit before the end of each perimeter, letting the remaining pressure in the nozzle push out the filament. This can help reduce oozing and stringing, as well as Z seams. However, coasting can also cause under-extrusion or gaps in some cases, so you need to experiment with different coasting distances and volumes to find the right balance.
• Enable linear advance: Linear advance is a firmware feature that adjusts the extruder pressure based on the print speed and acceleration. It can help improve print quality by compensating for over-extrusion and under-extrusion at different speeds. By enabling linear advance, you can also reduce the Z seam by having more consistent extrusion throughout each layer.