Three dimensional printing method and apparatus using an inclined fluid jet

1. A method for fabricating a solid article by three-dimensional printing, the method comprising the steps of:

a. forming a bed of loose solid powder;

b. moving a fluid dispenser parallel to the bed; and

c. dispensing a liquid from the fluid dispenser onto at least a portion of a surface of the powder to form a first printed layer having a first pattern printed thereon, wherein the fluid dispenser comprises a printhead inclined at an angle selected from a range of 2 to 20 degrees from vertical with respect to the bed.

2. The method of claim 1 , wherein the angle is selected from a range of 5 to 15 degrees from vertical with respect to the bed.

3. The method of claim 1 , wherein the fluid dispenser is moved in a first direction over the bed while the liquid is dispensed, and the liquid dispensed by the fluid dispenser travels at the angle of inclination in a second direction, away from the first direction.

4. The method of claim 1 , wherein the bed of loose solid powder is level.

5. The method of claim 1 , further comprising:

c. spreading a second layer of loose solid powder over the first printed layer.

6. The method of claim 5 , further comprising:

d. dispensing the liquid from the fluid dispenser onto the second layer to define a second pattern different from the first pattern printed on the first printed layer.

7. The method of claim 6 , further comprising:

e. allowing the liquid and powder to intermix to form the solid article.

8. An apparatus for forming solid articles by three-dimensional printing, the apparatus comprising:

a stage;

a spreading mechanism configured to spread layers of loose powder on the stage; and

a fluid dispenser disposed above the stage and configured to dispense droplets of fluid that travel in free flight to the stage, wherein the fluid dispenser comprises a printhead tilted at an angle selected from a range of 2 to 20 degrees relative to a line perpendicular to a surface of the stage.

9. The apparatus of claim 8 , wherein the angle is selected from a range of 5 to 15 degrees relative to a line perpendicular to a surface of the stage.

10. The apparatus of claim 8 , wherein the spreading mechanism is selected from the group consisting of a blade, a stationary cylindrical rod, a rotating cylindrical rod, and a straight bar comprising a variably curved surface.

11. The apparatus of claim 8 , herein the spreading mechanism is disposed above the stage and in a plane parallel thereto.

12. The apparatus of claim 8 , wherein the fluid dispenser comprises a traveling carriage configured to move the fluid dispenser laterally over the stage at a fixed height, in a direction such that the angle of tilt projects the droplets towards regions of the stage that were most recently visited.

13. The apparatus of claim 8 , wherein the carriage is oriented rectilinearly with respect to the printhead and oriented obliquely with respect to the stage.

14. The apparatus of claim 8 , wherein the carriage is oriented obliquely with respect to the printhead and oriented rectilinearly with respect to the stage.

15. The apparatus of claim 8 , wherein the carriage is oriented obliquely with respect to the printhead and the stage.

16. The apparatus of claim 8 , wherein the printhead is affixed to the carriage by at least one of a clamping mechanism, a fastener, or a combination thereof.

17. The apparatus of claim 16 , further comprising a robot, wherein the carriage comprises an electrical and mechanical interface between the robot and the printhead.