Seam concealment for three-dimensional models

1. A method for building a three-dimensional model with an extrusion-based digital manufacturing system, the method comprising generating a contour tool path that defines an interior region of a layer of the three-dimensional model, wherein the contour tool path comprises a start point, a stop point, and a step-over arrangement between the start point and the stop point, wherein the step-over arrangement is oriented at a non-right angle, wherein at least one of the start point and the stop point is located within the interior region of the layer, and wherein the step-over arrangement reduces surface porosity for the three-dimensional model.

2. The method of claim 1 , and further comprising adjusting the at least one of the start point and the stop point from a first coordinate location to the location within the interior region of the layer.

3. The method of claim 1 , wherein the location of the at least one of the start point and the stop point is substantially orthogonal to a direction of the contour tool path at a perimeter of the layer.

4. The method of claim 1 , wherein the location of the at least one of the start point and the stop point is offset from a centerline of a layer perimeter by a distance ranging from greater than about 50% of a road width used to generate the contour tool path to about 200% of the road width.

5. The method of claim 1 , wherein the start point and the stop point are each located within the interior region of the layer.

6. The method of claim 1 , wherein the locations of the start point and the stop point define an arrangement selected from the group consisting of an open-square arrangement, a closed-square arrangement, an overlapped closed-square arrangement, an open-triangle arrangement, a closed-triangle arrangement, a converging-point arrangement, an overlapped-cross arrangement, a crimped-square arrangement, and combinations thereof.

7. The method of claim 1 , wherein the contour tool path between the start point and the stop point further defines a raster path that at least partially fills the interior region.

8. The method of claim 7 , and further comprising positioning the start point and stop point to substantially maximize the amount of the interior region that is filled with the raster path.

9. The method of claim 1 , and further comprising extruding a material in a pattern based on the generated contour tool path to form a perimeter of the extruded material for one of the layers of the three-dimensional model, the perimeter of the extruded material comprising a start point, a stop point, and a non-right angle step-over arrangement between the start point and the stop point, wherein the perimeter defines an interior region of the layer of the three-dimensional model, and wherein at least one of the start point and the stop point is located within the interior region of the layer of the three-dimensional model.

10. A method for building a three-dimensional model with an extrusion-based digital manufacturing system, the method comprising:

receiving a digital representation of the three-dimensional model;

slicing the received digital representation into a plurality of layers;

generating a contour tool path based on a perimeter of a first layer of the plurality of layers, wherein the generated contour tool path defines an interior region of the first layer;

adjusting a start point of the contour tool path and a stop point of the contour tool path to locations within the interior region to provide a modified contour tool path; and

extruding a material in a pattern based on the modified contour tool path to form a perimeter of the extruded material for one of the layers of the three-dimensional model, the perimeter of the extruded material comprising a start point and a stop point, and defining an interior region of the layer of the three-dimensional model, wherein the start point and the stop point of the perimeter of the extruded material are each located within the interior region of the layer of the three-dimensional model.

11. The method of claim 10 , and further comprising:

repeating the generating and adjusting steps for each remaining layer of the plurality of layers of the digital representation to provide modified contour tool paths for each of the remaining layers; and

extruding the material in patterns based on the modified contour tool paths for each of the remaining layers to form perimeters of the extruded material for remaining layers of the three-dimensional model.

12. The method of claim 10 , wherein the location of the at least one of the start point and the stop point of the perimeter of the extruded material is offset from the formed perimeter of the extruded material by a distance greater than about 50% of a road width of the extruded material.

13. The method of claim 10 , wherein the modified contour path comprises at least one step-over arrangement oriented at a non-right angle between the start point and the stop point.

14. The method of claim 10 , wherein the locations of the start point and the stop point of the perimeter of the extruded material define an arrangement selected from the group consisting of an open-square arrangement, a closed-square arrangement, an overlapped closed-square arrangement, an open-triangle arrangement, a closed-triangle arrangement, a converging-point arrangement, an overlapped-cross arrangement, and combinations thereof.

15. A method for building a three-dimensional model with an extrusion-based digital manufacturing system, the method comprising:

generating a tool path that comprises:

a start point for the tool path;

a stop point for the tool path;

a contour tool path extending from the start point and based on a perimeter of a layer of the three-dimensional model, wherein the generated contour tool path defines an interior region of the layer; and

an interior raster path extending from the contour tool path within the interior region of the layer, wherein the interior raster path ends at the stop point; and

extruding a material in a pattern based on the generated tool path to form the perimeter and at least a portion of the interior of the layer of the three-dimensional model.

16. The method of claim 15 , and further comprising positioning the start point and stop point to substantially maximize the amount of the interior region that is filled with the interior raster path.

17. The method of claim 15 , wherein the contour path comprises at least one step-over arrangement oriented at a non-right angle.

18. The method of claim 15 , wherein the extruded material consists essentially of at least one thermoplastic material.