The present invention refers to a mini-blade (1) which body (2) has an inner edge (4) in which there is, at least, one transversal tab (6) that constitutes a retention means of the mini-blade (1) in an adapter device (20); between the inner (4) and the external (3) edges, the body (2) has the sufficient extension to form clamping portions (7)(8) that allow the application of clamping peripheral tabs (30). The invention also refers to an adapter device (20) that, for the mounting of a rotary work structure (40) of pneumatic roughing down, includes clamping sets (20) composed of ending supports (21)(22) and intermediary separator supports (23), all of which have clamping transversal peripheral tabs (30) that form jaws capable of clamping the clamping positions (7)(8) of the mini-blade (1). The different supports (21)(22)(23) that form the clamping sets (20) are arranged attached one to another, in train, with the mini-blades (1) interspersed in their jaws, in such a way that the toothed external edge (3) of these last ones protrudes from the clamping set (20).