In fact, the word 'Muko-zuchi,' describes the method by which Tosho (Yokoza, master) and his disciple (Sente, helper) alternately strike the body of the blade with a Tsuchi, and this has become the root of the word 'Aizuchi wo utsu (chiming in).'
ちなみに刀匠（横座）と弟子（先手）が交互に刀身を鎚で叩いていく「向こう槌」が「相槌を打つ」という言葉の語源となった。