Rotatable cutting tool with cutting insert and bolster

A rotatable cutting tool, comprising:

• a cutting tool body, the cutting tool body having an axial forward end, an axial rearward end, a head portion axially rearward of the axial forward end, a collar portion axially rearward of the head portion, and a shank portion axially rearward of the collar portion and axially forward of the axial rearward end, the head portion including a base portion formed with a pocket, the pocket is formed with a rearwardly tapering frustoconical side wall extending rearward from the axial forward end, a transition side wall extending rearwardly from the first rearwardly tapering frustoconical side wall, and a cylindrical side wall extending rearward from the transition side wall;
• a bolster at least partially received in the pocket, the bolster including a head portion, a collar portion and a shank portion, the head portion including a socket formed with a rearwardly tapering conical side wall and a radius blend formed with a radius, R2, the shank portion includes a rearwardly tapering frustoconical section, a variably tapered section extending in a rearward direction from the rearwardly tapering frustoconical section, and a cylindrical section extending in the rearward direction from the variably tapered section;
• and
• a cutting insert at least partially received in the socket of the bolster, the cutting insert comprising a super hard material bonded to a substrate and including a conical head portion, a collar portion and an axially rearward frustoconical portion,
• wherein the rearwardly tapering frustoconical side wall, the transition side wall and the cylindrical side wall of the pocket formed in the base portion of the cutting tool body has a total length, LPT, and
• wherein the cylindrical side wall of the pocket formed in the base portion of the cutting tool body extends substantially parallel to a longitudinal axis, X-X, of the pocket and has a length, LP3, along the longitudinal axis, X-X, of between about fifty percent and about eighty percent of the total length, LPT, to increase the strength of a braze joint between the bolster and the base portion of the cutting tool body, thereby reducing forces and stresses transmitted to the cutting tool during a machining operation.