User's Manual Part 2

Glossary 277
relationship between polar coordinates and Cartesian coor-
dinates.
Also, a couple of printer operational tips will be more in-
tuitive if you are conscious that the printer is operating,
at the hardware level, in polar coordinates. 207, 208, 230,
233, see also Cartesian coordinates
print head
The print head is the assembly inclu d in g the heatin g ele-
ment and the filament extruder. It moves up and down the
Z rod. See Fi g u re B.1. 1, 4, 29, 181, 225, 231, 235, 237,
246, 247, See also extruder & Zrod
raft
To promote better build plate adhesion or to accommodate
an uneven build surface, most slicers can add to your print
athickseriesoflayerswhichcanlaterberemovedoncethe
print is finished. These layers — referred to as a raft —
are printed slowly so as to promote better adhesion to the
build plate as well as to level out the printing surface. 139,
175, 209, 213, 219, See also slicer
retraction
In the context of 3D printing, retraction typically refers to
the amount by which the extruder nozzle is ra i sed when
performing non-extrusion moves between sections of the
print. That is, during print i n g t h er e ar e n or ma l l y ex t ru -
sion moves, du rin g which filament is being extruded, and
non-extrusion moves, during which the extruder nozzle is
retracted (raised) and moved without extruding melted fil-