Equipment and methods for fused deposition modeling 3D printing

1 . A 3D printer comprising:

(a) a plurality of feed mechanisms, each comprising a push motor adapted to push a solid filament through a feed conduit;

(b) a filament splitter, comprising:

a plurality of filament intake ports, each adapted to receive a said solid filament from a said feed conduit;

a plurality of filament guides, each in connection with a said filament intake port;

a print head connector, at which said plurality of filament guides converge, configured to deliver a selectable single one of said plurality of solid filaments; and

(c) a print head comprising a pull motor adapted to pull said selected single solid filament from said print head connector and direct said single solid filament to a heating block in fluid communication with a print nozzle;

(d) a variable tensioning mechanism, configured to adjust a pull force of said single solid filament;

(e) a controller configured to coordinately operate each said push motor, said pull motor, said print nozzle, and said variable tensioning mechanism; and

(f) a current sensor, on said pull motor, configured to provide an output signal to said controller, whereby the controller adjusts the tensioning mechanism in response to the output signal.

2 . A 3D printer according to claim 1 , comprising:

a first support bar upon which said feed mechanisms are mounted; and

a second support bar upon which said print head is mounted.

3 . A 3D printer according to claim 1 , wherein at least one of said feed mechanisms comprises two or more push to fit connectors installed in series to lock an end of said feed conduit to an output port in said feed mechanism.

4 . A 3D printer according to claim 1 , wherein said plurality of solid filaments comprise filaments of different colors, filaments of different materials, or any combination thereof.

5 . A 3D printer comprising:

(a) a first support bar, upon which one or more feed mechanisms is mounted, operably connected to a first drive train configured to provide linear motion to said one or more feed mechanisms along a single axis in 2 directions;

(b) a second support bar, upon which a print head is mounted, operably connected to a second drive train configured to provide linear motion to said print head along a single axis, parallel to said one axis of said first drive train in 2 directions;

(c) a third drive train configured to provide parallel linear motion of said print head relative to said second bar in 2 directions;

(d) one or more feed conduits connecting said one or more feed mechanisms to said print head; and

(e) a controller to operate said first drive train, said second drive train and said third drive train,

wherein said controller is configured to control said first drive train to distance said one or more feed mechanisms from said print head so as not to exceed the lengths of said one or more conduits between said one or more feed mechanisms and said print head, during operative motion of said print head by said second drive train.

6 . A 3D printer according to claim 5 , comprising two or more feed mechanisms connected by a like number of conduits to said print head.

7 . A 3D printer according to claim 5 , comprising a controller configured to coordinately operate said first drive train, said second drive train and said third drive train.

8 . A 3D printer according to claim 5 , comprising a fourth drive train configured to provide parallel linear motion of said one or more feed mechanism(s) relative to said first support bar in 2 directions.

9 . A 3D printer according to claim 6 , wherein said controller is configured to operate a single feed mechanism at a time in accord with a specified color in a program file of an object being printed.

10 . A 3D printer according to claim 8 , wherein said controller is configured to coordinately operate said first drive train, said second drive train, said third drive train and said fourth drive train.