Seam (Z-seam)

Theory

Each perimeter loop starts and ends at a single point, creating a small z-axis seam. At this point the nozzle stops extruding, may retract, then primes and begins again. The result is a slightly raised or indented mark. The seam position is set by the slicer: random (distributed to reduce visibility), sharpest corner (aligned to an edge where it hides geometrically), rear (hidden from front view), or aligned (same XY position every layer: most visible but most predictable).

Application

Use sharpest-corner seam placement for objects with hard edges (boxes, mechanical parts). Use random placement for organic shapes. If a seam is visible on a show face, orient the part so the seam falls on a hidden edge. Reduce seam visibility by lowering printing speed at the start-point by 20-30% and enabling wipe-on-retract.

Common mistakes

Random seam position leaves scattered pockmarks on smooth surfaces. Aligned seam on round objects creates a continuous ridge: use sharpest corner or rear placement instead. Wet filament and retraction mis-calibration worsen seam blobbing. Over-extrusion at the seam start point creates a visible blob: reduce prime restart extra distance to zero.

Related terms: Retraction, Wall / Perimeter, Print Speed