A system for the quick coupling of reels to a rotating shaft especially suitable for the unwinding or winding in reels of a consumable of thermal transfer printing or direct thermal printing machines, including a rotating shaft provided with a plurality of housings each of which is suitable for the firm but removable coupling of a rod, a single rod being able to be selectively coupled in any one of the mentioned housings; and a set of reels of a different width, provided with respective tubular bodies for the winding of the consumable provided with at least one respective slot suitable for the bayonet mount thereof with the shaft through the rod coupled in said shaft. The arrangement of the housings and of the slots are such that it is possible to couple any of the reels in such a way that said reels are centered with respect to a same plane transverse to the shaft.