Design for manufacture and assembly

A design that looks right on screen still has to survive a 3D printer. Designing with the printer in mind — design for manufacture, DFM — is what separates a model from a part.

The realities that matter:

• Overhangs — plastic is laid down layer by layer, so a surface that leans far past vertical (roughly beyond 45°) has nothing under it and sags. Steep overhangs need support material or a redesign.
• Wall thickness — too thin and walls are weak or don't print cleanly; keep them substantial.
• Bridging — flat spans across a gap can only stretch so far before they droop.
• Tolerance / clearance — printers are precise but not exact; a fit designed to zero gap won't go together.
• Print orientation — parts are weaker between layers than along them, so orientation is a strength decision, not just a packing one.

Forge builds with these limits in mind and runs printability checks in its generate loop — and every design is reviewed by a Microscale engineer before a print quote unlocks. Knowing the rules lets you understand the warnings it gives and design parts that print the first time.

A product is usually several parts that must go together — two enclosure halves, a lid, a button, a bracket. Designing for assembly (DFA) is making sure they actually mate.

The key ideas:

• Mate clearance — where two parts meet (a seam, a lid lip, a peg in a hole), leave a small gap. A tight, zero-gap fit that looks perfect in CAD will jam once printed, because real prints run a hair oversized.
• Designed together, printed apart — Forge designs the parts mated (in their assembled positions) so the fits are correct, then re-poses each part flat on the plate for a clean print. The clearance is preserved through that move, so the pieces still snap or screw together after printing.
• Fasteners and features — screw bosses, snap clips, alignment pegs — the little features that hold the assembly closed and lined up.

This is why you'll see a design previewed as a finished product but downloaded as separate, flat-laid parts. It's mated for fit, oriented for printing, and cleared so it assembles — with the engineer review as the final backstop.