Late 15th century (in an earlier sense). From rud + -ing.
rodding2
/ˈrɒdɪŋ/
noun
1Rods (especially metal rods) collectively; an arrangement of rods.
2The action or process of pushing a rod or rods through a duct, drain, or pipe, especially in order to clear it.
3Geology. A linear structure in metamorphic rocks characterized by the arrangement of grains of a constituent mineral, especially quartz, in parallel rods.
Origin
Early 17th century (in an earlier sense). Partly from rod + -ing, and partly from rod + -ing.