Designing without supports: seven changes that alter nothing

Removing supports from a part lowers the price twice over: less material and less machine time. And it improves the result, because the face the support touched stops coming out rough. It is nearly always achievable with changes that alter nothing about what the part does.

The seven changes

1. 1Chamfer instead of a ledge. Where a flat lip sticks out, put a 45° chamfer underneath. The part looks the same from outside and the overhang is gone.
2. 2Teardrop horizontal holes. A round hole lying down has a 90° roof; making the top a teardrop or a diamond turns it into two 45° overhangs. The screw still fits.
3. 3Y-ribs, not T-ribs. A rib leaving a wall at a right angle is an overhang; the same rib leaving diagonally supports itself and spreads load better too.
4. 4Vaulted roofs. An internal cavity with a flat roof needs support you can never remove; the same cavity with a pointed or arched roof prints unaided.
5. 5Split and bond. Two halves printed flat on the bed have no overhangs at all. With an interlocking joint and a few drops of cyanoacrylate, the seam is stronger than a layer.
6. 6Short bridges instead of wide gaps. If a gap is too wide to cross, split it with a central rib: two 20 mm bridges print where one 40 mm bridge will not.
7. 7Sacrificial layer. For a cavity you cannot redesign, leave a 0.3 mm wall closing it: it prints as a bridge and is trimmed away afterwards with a knife in ten seconds.

When it is not worth it

For a single unit of a small part, supports cost pennies and redesigning costs half an hour of your time. This work pays off when you will print the part many times, when the overhanging face is visible, or when the support lands inside a closed cavity there is no way to reach.