Ever had a very pronounced Z seam on an otherwise perfect print? The z seam is a visible line or mark on the surface of your print, caused by the nozzle moving to a different layer height.

One way to reduce the effect of the z seam is to use a technique called coasting. Coasting is when you stop extruding filament a little bit before the end of each perimeter, and let the nozzle travel along the path without any material coming out. This way, you avoid creating extra pressure in the nozzle that can cause oozing or blobbing at the end of the perimeter.

Coasting can help you achieve a cleaner and smoother surface on your print, especially on curved or circular shapes. However, coasting also has some drawbacks. For example, coasting can create gaps or under-extrusion in some areas of your print, especially if you use too much coasting distance or if your filament is not consistent in diameter. Coasting can also affect the strength and durability of your print, as it reduces the amount of material that bonds each layer together.

Therefore, coasting is not a magic solution for eliminating the z seam, but rather a trade-off between aesthetics and performance. You need to experiment with different settings and find the optimal balance for your printer, filament, and model. Some factors that can affect your coasting results are:

• Coasting distance: This is how far the nozzle travels without extruding before reaching the end of the perimeter. A longer coasting distance can reduce the z seam more effectively, but also create more gaps and under-extrusion. A shorter coasting distance can avoid gaps and under-extrusion, but also leave more oozing and blobbing at the end of the perimeter. You need to find a coasting distance that matches your nozzle size, layer height, and extrusion width.
• Coasting speed: This is how fast the nozzle travels without extruding along the coasting path. A faster coasting speed can reduce the pressure in the nozzle more quickly and prevent oozing or blobbing. However, a faster coasting speed can also create more vibrations and inaccuracies in the nozzle movement, which can affect the quality of your print. A slower coasting speed can avoid vibrations and inaccuracies, but also leave more pressure in the nozzle that can cause oozing or blobbing. You need to find a coasting speed that matches your printing speed and acceleration.
• Coasting volume: This is how much filament is left in the nozzle after stopping extrusion. A larger coasting volume can reduce the z seam more effectively, as it creates a negative pressure in the nozzle that sucks back any excess material. However, a larger coasting volume can also create more gaps and under-extrusion in some areas of your print, as it reduces the amount of material available for extrusion. A smaller coasting volume can avoid gaps and under-extrusion, but also leave more positive pressure in the nozzle that can cause oozing or blobbing. You need to find a coasting volume that matches your extrusion multiplier and filament diameter.