In-situ part position measurement

A method of determining a position of an item being printed in an additive manufacturing system, comprising determining the position with a location sensing probe having a resolution finer than a print resolution of the print head, wherein the location sensing probe comprises:

• a probe body comprising:
• a first air port therethrough between an inlet and an outlet;
• a tool change mount;
• a tool change plate having a second air port therethrough connectable between a cooling air supply and the probe body air port inlet;
• and
• a printed circuit board and a control module for control and operation of the probe;
• and
• a plunger extending from the probe body, the plunger comprising:
• a probe end;
• a probe bar, the probe bar coupled between the probe body and the probe end;
• and
• a channel surrounding the probe bar, the channel comprising an inner tube having an inlet proximate the probe body and an outlet proximate the probe end.