Varying the composition of build materials used for a three dimensional part

1. A system for varying a composition of build material used for a three dimensional (3D) part formed by a 3D printer, comprising:

a plurality of vessels each of which is for a build material of a plurality of build materials, wherein each vessel comprises a feeder coupled to a conveying system, and wherein the plurality of build materials includes a first build material and a second build material;

the conveying system to convey, in a conduit, the plurality of build materials from the plurality of vessels to a dispensing vessel and blend the plurality of build materials within the conduit during conveyance to the dispensing vessel;

the dispensing vessel containing an upper section, a lower section, and a building material sensor, the upper section positioned above the lower section and the building material sensor within the dispensing vessel, the upper section coupled to a separator that is coupled to the conveying system, the lower section coupled to another feeder for emptying build material from the dispensing vessel to a build platform; and

a controller configured to adjust a composition of the build material by adjusting an amount of material added from each of the plurality of vessels by controlling the feeder on each of the plurality of vessels.

2. The system of claim 1 , comprising a build file comprising the composition of build material to be used for a layer in the 3D part.

3. The system of claim 1 , wherein the plurality of vessels include:

a new material vessel coupled to the conveying system by a new feeder;

a recycle material vessel coupled to the conveying system by a recycle feeder; and

a recovered material vessel coupled to the conveying system by a recovery feeder.

4. The system of claim 3 , wherein the new feeder, the recycle feeder, or the recovery feeder comprises a rotary feeder comprising a plurality of pockets holding about 2 grams each of build material.

5. The system of claim 1 , wherein the dispensing vessel is configured to hold less than about seven layers of build material.

6. The system of claim 1 , comprising an external supply station configured to couple to the conveying system.

7. The system of claim 6 , wherein the conveying system comprises a connector configured to couple to the external supply station.

8. The system of claim 7 , wherein the external supply station comprises:

a material vessel;

a feeder for the material vessel; and

a matching connector configured to couple to the connector on the conveying system.

9. The system of claim 1 , wherein the system further comprises a motive component coupled to the conveying system.

10. The system of claim 9 , wherein the motive component includes at least one of the group consisting of a centrifugal blower, a fan, an axial blower, an eductor, an ejector, a vacuum pump, and a compressor.

11. The system of claim 1 , wherein the upper section of the dispensing vessel includes an interior cavity of less than or equal to 245 cm3 for holding the building material.

12. The system of claim 1 , wherein the lower section of the dispensing vessel includes an interior cavity of less than or equal to 200 cm3.

13. A method for operating a three dimensional (3D) printer, comprising:

adjusting a feeder on each of a plurality of vessels to select a composition of a build material in a conveying system;

blending the build material from each of the plurality of vessels in the conveying system as the build material is conveyed to a dispensing vessel;

depositing a layer of the blended build material in the dispensing vessel containing an upper section, a lower section, and a building material sensor, the upper section positioned above the lower section and the building material sensor within the dispensing vessel, the upper section coupled to a separator that is coupled to the conveying system, the lower section coupled to another feeder for depositing the blended build material from the dispensing vessel to a build chamber;

depositing a layer of the blended build material in the build chamber;

selectively solidifying portions of the layer of the blended build material to form a layer of a 3D part; and

adjusting the feeder on each of the plurality of vessels to select a different composition for a succeeding layer.

14. The method of claim 13 , comprising:

depositing a next layer of the blended build material in the build chamber; and

selectively solidifying portions of the succeeding layer of the 3D part.

15. The method of claim 14 , comprising changing the composition of the blended build material between a plurality of layers of the blended build material.

16. The method of claim 13 , comprising adjusting a feeder in an external supply station to change the composition of the blended build material.

17. The method of claim 13 , detecting that an external supply station has been coupled to the conveying system.