Machinists' rhymes with:
machinists, machinists, machinists, hygienists, machinists, abortionists, agonists, balloonists, botanists, cartoonists, colonists, communists', constitutionists, extortionists, hygienists, impressionists, internists, interventionists, isolationists, machinists, misogynists, noncommunists, nutritionists, opportunists, peronists, preservationists, protectionists, receptionists, rejectionists, reservationists, revisionists, revolutionists, secessionists, segregationists, shamanists, stalinists, unionists, zionists
Machinists' sounds like:
machinists, mcnuggets, mechanistic, misogynists