Recoating of stereolithographic layers

An apparatus for stereolithographically forming a portion of a three-dimensional object wherein a subsequent layer of the three-dimensional object is formed over a previously formed layer of the object, comprising:

• a) means for holding a volume of a building material having a working surface wherein the building material is capable of selective physical transformation upon exposure to prescribed synergistic stimulation;
• b) means for forming a uniform coating of desired layer thickness over the previously formed layer, including means for raking at least one smoothing member at least once over the previously formed layer, said smoothing member having a plurality of substantially separate elements on a lower surface thereof for contacting the material;
• and
• c) means for applying a prescribed pattern of synergistic stimulation to the building material at the working surface to transform at least a portion of the building material to form the subsequent layer.

A method for stereolithographically forming a portion of a three-dimensional object wherein a subsequent layer of the three-dimensional object is formed over a previously formed layer of the object, comprising the steps:

• a) holding a volume of a building material having a working surface wherein the building material is capable of selective physical transformation upon exposure to prescribed synergistic stimulation;
• b) forming a uniform coating of desired layer thickness over the previously formed layer, including raking at least one smoothing element at least once over the previously formed layer, said smoothing element having a plurality of substantially separate members on a lower surface thereof for contacting the material;
• and
• c) applying a prescribed pattern of synergistic stimulation to the building material at the working surface to transform at least a portion of the building material to form the subsequent layer.

A method for stereolithographically forming at least a portion of a three-dimensional object comprising a next layer of the three-dimensional object situated over a previously formed layer, said next layer having a desired layer thickness and said previously formed layer having an upper surface, comprising the steps:

• a) holding a volume of a building material;
• b) applying a coating of building material, said coating including excess material over at least a portion of the upper surface of the previously formed layer of the object;
• c) displacing the previously formed layer relative to a desired working surface so that the upper surface of the previously formed layer is positioned to a first level which is less than said layer thickness below said working surface;
• d) displacing material of said coating of building material to provide a smooth coating of building material of the desired thickness over the previously formed layer, while the upper surface of the previously formed layer is positioned at said first level;
• e) relatively positioning the upper surface of the previously formed layer to be substantially one layer thickness below the desired working surface;
• and
• f) applying a prescribed pattern of synergistic stimulation to the building material at the desired working surface in order to transform at least a portion of the building material, whereby the next layer is formed over the previously formed layer.

An apparatus for stereolithographically forming at least a portion of a three-dimensional object comprising a next layer of the three-dimensional object situated over a previously formed layer of said object, comprising:

• a) a container for holding a volume of a building material capable of selective physical transformation upon exposure to synergistic stimulation;
• b) means for forming a uniform coating of desired thickness over the previously formed layer including means for sweeping at least one smoothing member at least twice above the previously formed layer;
• and
• c) means for applying a prescribed pattern of synergistic stimulation to the building material at the desired working surface in order to transform at least a portion of the building material, whereby said portion of said three-dimensional object is formed comprising the next object layer formed over the previously formed layer.

An apparatus for stereolithographically forming at least a portion of a three-dimensional object comprising a next layer of the three-dimensional object situated over a previously formed layer of said object, comprising:

• a) a container for holding a volume of a building material capable of selective physical transformation upon exposure to synergistic stimulation;
• b) means for forming a uniform coating of desired thickness over the previously formed layer including means for sweeping a smoothing member at least once above the previously formed layer;
• and
• c) means for applying a prescribed pattern of synergistic stimulation to the building material at a desired working surface after waiting for the smoothing member to complete at least a first sweep across the previously formed layer in order to transform at least a portion of the building material, whereby the next object layer is formed over the previously formed layer.

A method for stereolithographically forming at least a portion of a three-dimensional object comprising a next layer of the three-dimensional object situated over a surface of a previously formed layer of the object, comprising:

• a) holding a quantity of a building material capable of selective physical transformation upon exposure to synergistic stimulation;
• b) forming a uniform coating of material over the previously formed layer, including:
• sweeping a member having a lower edge which sweeps out a plane above a plane of a desired working surface;
• and
• c) selectively applying a prescribed pattern of synergistic stimulation to the building material at the desired working surface in order to transform at least a portion of the building material, whereby said portion of said three-dimensional object is formed comprising said next object layer formed over said previously formed layer.

An apparatus for stereolithographically forming a portion of a three-dimensional object wherein a subsequent layer of the three-dimensional object is formed over a previously formed layer of the object, comprising:

• a) a container for holding a building material having a working surface wherein the building material is capable of selective physical transformable upon exposure prescribed synergistic stimulation
• b) means for forming a uniform coating of desired thickness over the previously formed layer, including:
• a smoothing member having a plurality of substantially separate elements protruding from the lower surface,
• means for sweeping the smoothing member over the previously formed layer whereby said elements are raked over the previously formed layer;
• and
• c) means for applying a prescribed pattern of synergistic stimulation to the building material at the working surface of the building material to transform at least a desired portion of the building material to form the subsequent layer.

An apparatus for stereolithographically forming a portion of a three-dimensional object wherein a subsequent layer of the three-dimensional object is formed over a previously formed layer of the object, comprising:

• a) a container for holding a volume of a building material having a working surface wherein the building material is capable of selective physical transformation upon exposure to synergistic stimulation;
• b) means forming a uniform coating of a desired layer thickness over the previously formed layer, including:
• means for sweeping a smoothing member over the previously formed layer,
• means for adjusting the vertical position of the smoothing member relative to the working surface, including a plurality of needles attached to the smoothing member for measuring a gap between a lower surface of the smoothing member and the working surface;
• and
• c) means for applying a prescribed pattern of synergistic stimulation to the building material at the working surface to transform at least a portion of the building material to form the subsequent layer.

A method for stereolithographically forming a portion of a three-dimensional object wherein a subsequent layer of the three-dimensional object is formed over a previously formed layer of the object, comprising the steps:

• a) holding a volume of a building material having a working surface wherein the building material is capable of selective physical transformation upon exposure to prescribed synergistic stimulation;
• b) forming a uniform coating of desired layer thickness over the previously formed layer, including:
• sweeping a smoothing member over the previously formed layer,
• adjusting the vertical position of the smoothing member relative to the working surface, including measuring a gap between a lower surface of the smoothing member and the working surface using a plurality of needles attached to the smoothing member;
• and
• c) applying a prescribed pattern of synergistic stimulation to the building material at the working surface to transform at least a portion of the building material to form the subsequent layer.