A stack of parts, such as the stator disks of a turbomolecular pump, the parts being stacked alternately with spacers, includes a spacer having a knife-shaped deformable portion. When the stack is installed for the first time, the portion is compressed so as to take up the tolerances of the stack between abutment surfaces, e.g. delimited by a pump body and a corresponding casing. The invention applies in particular to turbomolecular pumps and aims to eliminate the operations of adjustment, re-machining, or matching that are usually required when installing a stator assembly.