Filament accumulator or tensioning assembly

1. A filament accumulator for absorbing a speed mismatch between filament provided from a filament source and filament used at a filament deposition head comprising:

a continuous filament forming a filament loop;

a filament inlet for receiving the continuous filament from a filament source;

a filament outlet for receiving the continuous filament from the filament inlet, the filament loop being a loop in the continuous filament between the continuous filament exiting the filament inlet and entering the filament outlet;

a filament track defining at least part of an inner boundary and an outer boundary of a circuitous filament route between the filament inlet and the filament outlet, the filament loop being bound by the filament track; and

a housing, an interior of the housing defining at least part of the filament track,

wherein the filament loop has a diameter that varies across a range of potential diameters within the filament track,

wherein the filament deposition head draws the continuous filament from the filament outlet at a first speed,

wherein the filament inlet receives the continuous filament from the filament source at a second speed, wherein a mismatch between the first speed and the second speed results in a change in the diameter of the filament loop, and

wherein the interior of the housing further comprises a guiding path that directs the continuous filament past an outer limit switch when loading the filament.

2. The filament accumulator of claim 1 , further comprising at least one limit switch at either the inner boundary or the outer boundary, wherein the limit switch is activated when the filament loop is at a minimum or maximum potential diameter.

3. The filament accumulator of claim 2 , wherein the at least one limit switch is movable to define a different range of potential diameters for the filament loop in order to account for filament materials having different stiffnesses.

4. The filament accumulator of claim 2 , wherein the at least one limit switch is activated when the filament loop is at its minimum diameter, and wherein the limit switch sends a signal to the filament deposition head to stop drawing filament from the filament outlet when activated.

5. The filament accumulator of claim 2 , wherein the at least one limit switch is activated when the filament loop is at its minimum diameter, and wherein the limit switch, upon activation, sends a signal to start or increase a speed of a motor at the filament inlet or at the filament source for increasing a speed at which the continuous filament is received.

6. The filament accumulator of claim 2 , wherein the at least one limit switch is activated when the filament loop is at its maximum diameter, and wherein the limit switch, upon activation, sends a signal to slow down or stop a motor at the filament source.

7. The filament accumulator of claim 1 , wherein the guiding path is removable, such that it may be used for loading the continuous filament and removed for use of the filament accumulator.

8. The filament accumulator of claim 1 , further comprising at least one limit switch at the outer boundary, wherein the limit switch is activated when the filament loop is at a maximum potential diameter, and wherein the limit switch is removable from the filament track so as not to obstruct the continuous filament during loading of the filament loop.

9. The filament accumulator of claim 1 , wherein the first speed is unrelated to or imperfectly matched to the second speed.

10. The filament accumulator of claim 9 , wherein the first speed is controlled by the deposition head.

11. The filament accumulator of claim 1 further provided with a second filament accumulator, wherein the filament inlet of the first filament accumulator receives the continuous filament from the filament outlet of the second filament accumulator, and wherein the deposition head draws the continuous filament from the filament outlet of the first filament accumulator and the filament inlet of the second filament accumulator receives the continuous filament from the filament source.

12. The filament accumulator of claim 1 , wherein at least a portion of the interior of the housing comprises a plurality of rollers for reducing friction.