SLA DESIGN CONSIDERATIONS
Bosses
Include bosses around holes in locations where threaded fasteners will be used to reduce the likelihood of bulging, distortion, and potential fracture. A minimum of 1 hole diameter for the wall thickness around the hole is a good starting point (e.g. if the hole is a M5 screw include a minimum 5mm of wall thickness around the hole).
Fillets
Fillets and radii are not required for SLA. However, adding fillets and radii help to reduce stress concentrations at corners and edges. Even a small radius can make a big difference.
Holes
Since the high viscosity of the resin used can pose challenges during the post-build process, try to avoid holes smaller than 0.005″. If your design requires them, please bring this to our attention when ordering your prototype.
Hollow Out Your Model
To reduce machine time and material cost, try to hollow out your model. Always include a drain hole or two to allow the release of the resin from the enclosed space.
Mating Parts and Assemblies
It is recommended to design at least a 0.010″ gap overall between any two mating faces in mating parts or assemblies.
Ribs and Gussets
Ribs and gussets are not required for SLA. However, adding ribs and gussets help to reduce and distribute stresses throughout the part and improve rigidity. To save on material, ribs and gussets can be designed to 75-80% of wall thickness.
Tolerances
Low Resolution Build Mode (6mil):
X/Y Planes: +/- 0.005″for the first quarter inch, plus +/- 0.002″ for every inch thereafter. Z Plane: +/- 0.010″ for the first inch, plus +/- 0.003 for every inch thereafter. Minimum linear feature size: under 0.020″ are at risk and under 0.010″ will not build. Minimum radial feature size: 0.025″
Standard Resolution Build Mode (4 mil):
X/Y Planes: +/- 0.005″ for the first quarter inch, plus +/- 0.002″ for every inch thereafter. Z Plane: +/- 0.010″ for the first inch, plus +/- 0.003″ for every inch thereafter. Minimum linear feature size: under 0.020″ are at risk and under 0.010″ will not build. Minimal radial feature size: 0.025″
High Resolution Build Mode (2 mil/10 spot):
X/Y Planes: +/- 0.003″ for the first 1/10 inch, plus +/- 0.0015″ for every inch thereafter. Z Plane: +/- 0.005″ for the first inch, plus +/- 0.0015″ for every inch thereafter. Minimum linear feature size: under 0.020″ are at risk and under 0.010″ will not build. Minimum radial feature size: 0.020″
Ultra High Resolution Build Mode (2 mil/3 spot):
X/Y Planes: +/- 0.003″ for the 1/10 inch, plus +/- 0.001″ for every inch thereafter. Z Plane: +/- 0.005″ for the first 1/10 inch, plus +/- 0.001″ for every inch thereafter. Minimum linear feature size: under 0.008″ are at risk and under 0.004″ will not build. Minimum radial feature size: 0.008″
NOTE: TOLERANCES MAY CHANGE DEPENDING ON PART GEOMETRY.
Wall Thickness
It is recommended that you utilize a uniform wall thickness.
Warping
Warping is not an issue in parts produced on the Viper si² machines.