Method and apparatus for 3D fabrication

An apparatus for use in 3-D fabrication, the apparatus comprising:

• a heat sink configured to dissipate heat;
• a melt tube having a first end and an opposite second end and adapted for heating a material as the material is conveyed between the first end and the second end;
• a pen tip having an opening therein for ejecting melted material;
• a pen tip holder configured to securely hold the pen tip, the pen tip holder disposed apart from the heat sink, the pen tip holder having a heater element associated therewith;
• and
• a heat break consisting of a thin walled section of the melt tube in between the heat sink and the pen tip holder, the heat break acting as a thermal choke to reduce heat transferred to the heat sink;
• wherein the pen tip is inserted into the pen tip holder and over the second end of the melt tube and wherein the pen tip holder is threadably secured to the melt tube to thereby hold the pen tip in position.