Method for fabricating three dimensional models

A method of fabricating a three dimensional model from a composite model formed be a plurality of layers with the composite model comprising at least one shell material encasing and enclosing a build material, the method comprising the steps of:

• (1) depositing a build layer of the build material onto a preceding layer;
• (2) removing a selected area of only the build material from the deposited build layer;
• (3) filling the selected area of the removed build material with the shell material;
• (4) reducing a thickness of the build layer to a desired final thickness to complete formation of the build layer for supporting a next subsequent build layer
• (5) repeatedly repeating steps (1) through (4) for each subsequent build layer until fabrication of the composite model is completed;
• and including formation of at least one reentrant angle for a build layer comprising the steps of:
• depositing a fillet of reentrant shell material for each reentrant angle wherein each fillet of reentrant shell material conforms to and defines a portion of the shell at least partially fills a space which would be otherwise be occupied by a fillet shaped by a machining process, prior to deposition of the build material in step (1).

A method of fabricating a three dimensional model from a composite model formed by a plurality of layers with the composite model comprising at least one first material encasing and enclosing a second material, the method comprising the steps of:

• (1) depositing at least one layer of a foundation material for forming a foundation layer for supporting a bottom most build layer of the composite model;
• (2) depositing a build layer of the first material onto a preceding layer;
• (3) removing a selected area of only the first material from the deposited build layer;
• (4) filling he selected area of the removed first material with the second material;
• (5) reducing a thickness of the build layer to a desired final thickness to complete formation of the build layer for supporting a next subsequent build layer;
• and
• (6) repeatedly repeating steps (2) through (5) for each subsequent build layer until fabrication of the composite model is completed;
• (7) depositing at least one layer of the shell material to form a termination layer of the composite model;
• and
• (8 )using a model mater as the first material and using a sacrificial material as the shell material.