Resin (SLA) 3D printing design check
SLA cures liquid resin with light, one layer at a time, and pulls each layer off the film at the bottom of the vat. That makes closed cavities, large flat layers and thin free walls the usual causes of failure. These are the limits a check looks at.
The limits that matter
| What | Typical limit used here | Why it matters |
|---|---|---|
| Support angle | surfaces below 30° from horizontal need support | the surface is cured in the air and fails without it |
| Drain hole | at least 3.5 mm, two holes per hollow part | liquid resin is trapped inside and the cavity cannot be cleaned |
| Wall | at least 0.6 mm | a thinner wall tears when the layer peels off |
| Smallest detail | 0.3 mm | finer features are not resolved |
| Peel force | about 1 N/cm² of layer area (working assumption) | a large flat layer can tear the part off the plate |
How to fix the common problems
- Hollow a part and drill drain holes in two places, one for resin to leave and one for air to enter. In one of our case studies a housing with a closed interior trapped 138 g of resin until two Ø3.5 mm holes were added.
- Tilt the part so large flat faces do not build up in one layer and the peel force stays low.
- Place supports on surfaces that can be sanded, not on the visible face.
- Thicken free walls that are thinner than the limit.
What Dokimion checks for SLA
The check finds closed cavities and the volume of resin they hold, estimates peel force per layer, flags thin walls and free walls, finds surfaces that need support and suggests positions. For hollow parts it can add the drain holes and return a closed mesh ready for preparation. It ends with a score from A to E (see the Kolesar Score) and a cost estimate per part.
Limits depend on the printer, resin and exposure settings. Treat them as typical values.
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