Adhesion test station in an extrusion apparatus and methods for using the same

A method of controlling an additive fabrication process, the method comprising:

• providing a primary substrate and a test substrate that is thermally and mechanically isolated from the primary substrate;
• feeding non-extruded polymer material into an extrusion head;
• extruding a new test portion of the polymer material onto the test substrate, or onto an existing extruded test portion of the polymer material, by use of the extrusion head;
• allowing or causing the new extruded polymer test material to solidify or cure;
• fixing the non-extruded polymer material relative to the extrusion head;
• displacing the extrusion head relative to the test substrate;
• measuring a force required to move the extrusion head relative to the test substrate to generate test data;
• fabricating a 3D part by extruding the polymer material onto the primary substrate by use of the extrusion head;
• and
• using the test data to control at least one process parameter associated with extruding the polymer material onto the primary substrate.