A tape printer for making adhesive labels includes a tape supply, a printer for reverse printing on the tape and a double-sided adhesive film, one side of which is laminated to the printer tape and the other side of which carries a release paper. The printer has a cutter for cutting the tape from the continuous supply tape and includes a trimmer for rounding the corners of the tape (4) to reduce defoliation of the tape (4) from the surface to which it is applied. The cutting blade (50) of the trimmer has a central straight section, contiguous arcuate section at each end of the central straight section and auxiliary straight cutting edges contiguous with the arcuate sections and extending at an obtuse angle to the central straight section. The cutting blade (50) is mounted in an integrally molded support unit which includes guide members for guiding tape (4) of a width to be trimmed by the cutting blade (50). The support unit is detachably mounted on a tape support member so that tapes (4) of differing widths can be trimmed by interchanging the support units. Levers (102) for actuating the cutting blade (50) are movable from a position to actuate the cutter to a retracted position enabling replacement of the support unit.