Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
calcātor, ōris, m. [calco], one who treads something, esp. grapes, a treader of grapes (very rare), Calp. Ecl. 4, 124: uvarum, Hier. Isa. 5, 16, n. 9.