The Additive application can predict the location and magnitude of distortion and then "reverse" distort the original .stl file. Then when you build your part using the compensated geometry, the result will be closer to the original design.

On a simulation form under Outputs (either on-plate or after cutoff), check the box for Distortion compensated .stl file. Once selected, you have the option to specify scale factors. The Scale Factor will change the magnitude of the distortion applied to the original .stl file. A Scale Factor of 1 (default) will create an .stl file with distortion compensated by the same magnitude as the simulated results. A Scale Factor < 1 will compensate less than the simulation-predicted magnitude and a value > 1 will compensate more than the simulation-predicted magnitude.

You may enter Multiple Scale Factors to determine which distortion compensation factor works best for the part. Values must be between -5.0 and 5.0.

Once the simulation is complete, files labeled Compensated Geometry (and Compensated Geometry (after cutoff)) can be found in the Output Files section under Completed Simulations. The Scale Factor is used in the file name to distinguish results among multiple Scale Factors. Click the export link to get the distortion compensated .stl file. A second output is also created named Geometry with Distortion (and Geometry with Distortion (after cutoff)). This is a geometry representation in .vtk format with displacement vectors with each vertex.

How Does Distortion Compensation Work?

The Additive application simulates spatial distortion that occurs during the build process. With Distortion Compensation activated, each vertex in the Compensated Geometry .stl file is moved in the opposite direction of the closest distortion vector (that is, new position = original position + deformed (dX, dY, dZ) x -1). To ensure the .stl file has fidelity on par with the simulation, any triangle with an area greater than an equilateral triangle with sides equal to the selected Voxel Size is split into smaller triangles.

Since the Distortion Compensation feature is a simple linear assumption, it may not always be correct. Parts can respond non-linearly. For example, if you use a Scale Factor of 1 (default) in a simulation and then use the compensated file to rerun the simulation, you will see if the part is predicted to distort to the correct shape. If not, you’ll know that the compensated .stl file was under-compensated or overcompensated and you can adjust the Scale Factor up or down from there. Generally, the Distortion Compensation feature tends to be an iterative process. In fact, our experience shows good results using two iterations with Scale Factor = 0.5 for each simulation. Alternatively, a good starting point for one iteration is a Scale Factor = 0.75.