A replaceable cutting head, for rotary cutting operations, having a head longitudinal axis around which the replaceable cutting head rotates in a direction of rotation, the head longitudinal axis extending in a forward (D F) to rearward direction (D R), comprising: a forward portion forming a cutting portion and a rearward portion forming a mounting portion, wherein; the mounting portion comprises a male coupling member protruding rearwardly from a rearwardly facing head base surface, the head base surface extending transversely with respect to the head longitudinal axis, and defining a boundary between the cutting portion and the mounting portion, the male coupling member comprising: outwardly facing forward and rearward bearing portions (50, 52) and an external thread located therebetween wherein; the forward bearing portion comprises a conically shaped forward head abutment surface that tapers inwardly in a rearward direction (D R) defining a forward head cone angle (α); and the rearward bearing portion comprises a conically shaped rearward head abutment surface that tapers inwardly in a rearward direction (D R) defining a rearward head cone angle (β); characterised in that the forward and rearward head abutment surfaces (54, 56) are ground, and the forward and rearward head cone angles (α, β) are within ± 0.5° of each other. a forward portion forming a cutting portion and a rearward portion forming a mounting portion, wherein; the mounting portion comprises a male coupling member protruding rearwardly from a rearwardly facing head base surface, the head base surface extending transversely with respect to the head longitudinal axis, and defining a boundary between the cutting portion and the mounting portion, the male coupling member comprising: outwardly facing forward and rearward bearing portions (50, 52) and an external thread located therebetween wherein; the forward bearing portion comprises a conically shaped forward head abutment surface that tapers inwardly in a rearward direction (D R) defining a forward head cone angle (α); and the rearward bearing portion comprises a conically shaped rearward head abutment surface that tapers inwardly in a rearward direction (D R) defining a rearward head cone angle (β); characterised in that outwardly facing forward and rearward bearing portions (50, 52) and an external thread located therebetween wherein; the forward bearing portion comprises a conically shaped forward head abutment surface that tapers inwardly in a rearward direction (D R) defining a forward head cone angle (α); and the rearward bearing portion comprises a conically shaped rearward head abutment surface that tapers inwardly in a rearward direction (D R) defining a rearward head cone angle (β); characterised in that the forward bearing portion comprises a conically shaped forward head abutment surface that tapers inwardly in a rearward direction (D R) defining a forward head cone angle (α); and the rearward bearing portion comprises a conically shaped rearward head abutment surface that tapers inwardly in a rearward direction (D R) defining a rearward head cone angle (β); characterised in that the forward and rearward head abutment surfaces (54, 56) are ground, and the forward and rearward head cone angles (α, β) are within ± 0.5° of each other.