Supports & Overhangs

FDM builds layer on layer, so each layer needs something beneath it. As a rule of thumb, overhangs up to about 45 degrees from vertical print cleanly without support — each layer is still half-supported by the one below.

Steeper than that and the new layer has too little to sit on: it droops, curls, or turns to drooping strands. Bridges (flat spans between two supports) can often print surprisingly far with good cooling, but unsupported overhangs past ~45° usually need help.

The best support is no support. Before adding any, ask whether orientation solves it — rotating a part so its overhangs point up or become bridges often removes the need entirely, and gives better surfaces and strength too.

Chamfers instead of overhangs, splitting a model into two glued halves, and printing flat faces down are all ways to avoid supports and the scarring they leave behind.

When supports are unavoidable, pick the type:

• Normal (grid) supports: vertical pillars under every overhang. Strong and reliable, but use more material and contact the part more, leaving marks.
• Tree supports: organic branches that reach up to overhangs from a few trunks. Less material, less surface contact, easier removal, and great for organic models — but can be less stable for big flat overhangs.

Start with tree supports for figurines and normal supports for large flat shelves.

Tune the support interface — the small Z-gap and top layers between support and part. A slightly larger gap releases more easily but leaves a rougher surface; too large and the overhang sags onto nothing.

For the cleanest results, print soluble supports (PVA/HIPS) on a multi-material machine, or simply accept that support faces will need a little sanding. Remove supports gently with flush cutters while the part is still slightly warm.