A grinding machine (10) for making a hole, groove and / or recess (34) in a conduit of a needle (20) near its end (32), where said grinding machine (10) comprises: a strip (22) that fixes on parallel alignment a plurality of needle ducts (20) and thus exposes the ends (32) of the needle ducts (20)； an assembly of needle clamping means (12) for said strip (22), comprising at least two needle clamping plates (16, 18) for fixing between said strip (22)； wherein said assembly of needle clamping means (12) comprises means for adjusting the distance for separating said two plates for detaching the needles (16, 18) by a predetermined adjustable distance, thereby allowing mounting of clamping means of the needles (12) accommodate needle conduits (20) of various diameters. an abrasive wheel assembly (28) having an abrasive wheel (40) with abrasive surface (30) placed adjacent to said assembly of needle clamping means (12)； a mobile table (14) operatively mounted on the grinder (10), arranged to move said assembly of needle clamping means (12) together with the change of position of the needle ducts (20) supported on said strip (22) by said assembly of needle clamping means (12).Una rectificadora (10) para realizar un agujero, ranura y/o rebaje (34) en un conducto de una aguja (20) próximosa su extremo (32), donde dicha rectificadora (10) comprende: una tira (22) que fija en alineación paralela una pluralidad de conductos de las agujas (20) y de esta formaexpone los extremos (32) de los conductos de las agujas (20)； un montaje de medios de sujeción de las agujas (12) para dicha tira (22), que comprende al menos dosplacas de sujeción de las agujas (16, 18) para fijar entre estas dicha tira (22)； donde dicho montaje de mediosde sujeción de las agujas (12) comprende medios de ajuste de la distancia para separar dichas dos placas desujeción de las agujas (16, 18) mediante una distancia ajustable predeterminada, para de este modo permitirque el montaje de medios de sujeción de las
