SLA
Frequently Asked Questions
Q: What material does stereolithography prototyping use?
A: The resins used in our SLA machines are photosensitive epoxy polymers. Currently, Dinsmore & Associates employs three stereolithography resins in our six machines. WaterShed 11120, the resin run in our Viper si2 machines, has the lowest water absorption of any SLA resin and can result in clear prototypes, given a Level 6 finish. The Accura SI 40 resin is designed to mimic Nylon 6/6. The Accura SI 50 resin is a white ABS-like resin designed for snap fits. Please see above for data sheets on these resins.
Q: What tolerances can the stereolithography process hold?
A: Published tolerances of the models are +/-0.005″ (0.127mm) for the initial inch, plus an additional 0.0015″ for each additional inch. If higher accuracy parts are needed, please contact us; we can accommodate you.
Q: How can I ensure that raised text on my prototype is legible?
A: We have made a graphical guide that should help you. The height of the text should be a minimum of 0.015″high, and the cross section of the text should be 0.015″ or thicker. Text thinner than this cannot be reliably traced with the 0.010″ thick laser beam.
Q: How does Dinsmore & Associates price parts?
A: Projects typically range from $195 to $495. The following factors influence pricing:
- Z-axis height
- Volume
- Complexity
- Number of parts
The per-part price decreases as more parts are ordered until the point where there are too many parts to fit on a single run of one of our SLA machines.
Q: What size parts can be produced?
A: Dinsmore & Associates largest machine has a build envelope of 20″ x 20″ x 24″; however, multiple SLA prototypes can be glued together to create larger prototypes.
Q: What is the smallest feature that can be produced?
A: In standard resolution, the minimum feature in the X-Y plane is 0.010″ and the minimum in the Z axis is 0.016″. In high resolution, the 0.003″ laser beam spot enables smaller features. Dinsmore & Associates recommends a minimum wall thickness of 0.020″ for prototype support.
Q: What colors can be produced?
A: Stereolithography prototypes can be dyed or painted in virtually any color.
Q: What kinds of finish options are available on SLA prototypes?
A:
| Level | Finish | Description |
| Level 1 | Strip and ship | Remove supports No sanding |
| Level 2 | Standard finish | Remove supports Lightly sand to 150 grit Bead blast |
| Level 3 | Foundry pattern | Remove supports Sand to 220 grit Remove ~95% of the build lines |
| Level 4 | Mold ready | Remove supports Sand to 320 grit Remove ~100% of the build lines Prime and putty |
| Level 5 | Presentation | Remove supports Sand to 320 grit Remove ~100% of the build lines Prime, putty, and paint Matte gloss |
| Level 6 | Clear coat | Remove supports Lightly sand support surface to 320 grit Clear coat |
| Level 7 | Water clear | Remove supports Sand to 600 Remove ~100% of the build lines Clear Coa |
Q: What temperatures can SLA prototypes withstand?
A: The standard epoxy resin has a heat deflection temperature of 144°F and high temperature epoxy resin has a heat deflection temperature of 392°F.
Q: Can stereolithography prototypes be machined?
A: Yes, SLA prototypes can be drilled and tapped, milled, or put on a lathe.
Q: Why should you use SLA versus another rapid prototyping technology?
A: The accuracy and surface finish of SLA are unsurpassed by any of the competing technologies, such as selective laser sintering (SLS).
Q: How long does it take to build a part?
A: A typical order of prototypes is shipped out two days after receipt of order. Most parts build in less than 12 hours.
