Datum and GD&T questions correctly answered already passed

Datum and GD&T questions correctly
answered already passed

Datum - correct answer ✔✔ starting place for a dimension; point, line, surface, plane;
theoretical and perfect



datum reference order - correct answer ✔✔ primary, secondary, tertiary



primary A - correct answer ✔✔ limits freedom in: rotation around x axis, rotation around y axis,
movement along z axis



secondary B - correct answer ✔✔ limits freedom in: rotation round z axis, movement along y
axis



tertiary C - correct answer ✔✔ limits freedom in: movement along x axis



datum reference frame - correct answer ✔✔ primary A + secondary B + tertiary C; the
coordinate system against which the geometric dimensions and tolerances of a part are defined



order of precedence to choose datums - correct answer ✔✔ functional surfaces, mating
surfaces, readily accessible surfaces, surface of sufficient size to allow repeatable measurements



datum(tag) feature symbol - correct answer ✔✔ identify physical features of a part as datum
features; not applied to center lines, center planes, axes



best datum - correct answer ✔✔ plane, flat surface with no size variation