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Geometry

Dimensional Accuracy (+/- 0.001 inches per inch)
Too Low: 5
Easily Achieved: 15 or higher

From Accelerated Technologies:

Consider the "Z" axis to be along the height of the part in its build orientation. The Z axis will yield greater tolerance deviations than those in the X - Y plane. Some of this inaccuracy results from the layer-additive process common to rapid prototyping. During the slicing of the STL into the desired layers, there will be round-off error. Should the top or bottom surface of a feature not be coincident with a layer, the surface height will be adjusted so that it is represented by one layer thickness. The combined rounding error between the top and bottom surface can equal up to one layer thickness. "Z growth" also affects dimensions in the Z axis. In SLA, as successive layers are cured, the beam imparts additional energy to layers below. This undesired energy will cause lower layers to thicken.

Surface Roughness (microinches)
Too Low: 150
Easily Achieved: 176 or higher

From Accelerated Technologies:

In the study of SLA, is is commonly found that the smoothest surface is on the top face of the prototype. The uppermost faces are contrasted by the rougher side walls and even rougher bottom surfaces. The side walls of SLA parts illustrate the striations between build layers. These striations are pronounced enough to be detected when dragging a fingernail along the vertical walls. The bottom surface of an SLA part is affected by the support structures. When removed, and prior to a finishing operation, the supports will leave raised areas on the bottom face. The preciseness of SLA that originates from the controlled and predictable nature of the process, combined with good surface finish, will allow obvious detection of stairstepping. Since rapid prototyping systems have a discrete jump in Z, rather than a smooth transition, any surface that angles against the Z axis or has any curvature will be approximated through a series of "steps."

Bounding Box Volume (cubic inches)
Low: 0.001 - 0.01
Just Right 0.01 - 9000
High: 9000 - 9600

Wall Thickness
Uniform Walls Prefered: No
Max Wall Thickness (inches): 12
Min Wall Thickness (inches): 0.04
(over a 5" inch span)

Rounded Corners Prefered: No

Compatible Shapes:
The primary benefit of SLA, and all SFF processes, is that they can generate any shape that fits within their work volume.

Most compatible shapes fall in the following categories:

• Free Form Drape
• Free Form General
• Planar
• Prismatic
• Surface of Revolution
• Thin Wall
• Constant Cross Section