Common mistakes when repairing FDM 3D models include ignoring layer adhesion root causes, over-sanding support marks, and mishandling warped bases.
Layer adhesion issues often come from skipping fixes for under-extrusion or wrong bed temperature—gluing alone creates weak, short-lived repairs. Over-sanding removes fine details or leaves uneven surfaces instead of smoothing. Warped bases are often forced straight without heat, risking cracks or further damage.
For layer separation, gently heat the area with a low-heat gun to re-bond layers (more durable than glue). For warps, warm the base on a 50°C bed while applying light pressure to straighten safely.