Abstract: A machine for making welted openings in a piece of material or similar, comprises control means arranged so as to cause it to make, in a pre-established sequence and cyclically, a succession of welted openings having different lengths requiring respectively single and indentical manual actions for starting up. The control means comprise:input means for feeding in initially and in the pre-established sequence information concerning the lengths of the different welted openings to be made,memory means for memorizing the set of length data fed in,selection means combined with the memory means so as to select successively in the pre-established sequence the lengths of the welted openings to be made,and monitoring means under the control of the selection means for, once the machine has been started up, checking the movement of cutting, stitching and notching members with respect to the selected length.