Cutting tool assembly

A cutting insert (14) comprising a generally cylindrical portion (44) having a longitudinal axis B and an axially extending radial projection (46) connected thereto, the radial projection having upper and lower surfaces (55, 62) connected to the cylindrical portion and being separated by a side surface (57), the upper surface (55) and the side surface (57) meeting at an edge, at least a portion of which constitutes a cutting edge (56) and the lower surface (62) constituting a first locating surface, wherein:

• the generally cylindrical portion is provided with three axially extending ribs,
• two of the three axially extending ribs (50, 52) have radially outermost regions that lie on a cylindrical envelope of a second diameter (D2) having as axis the longitudinal axis B, and
• one of the three axially extending ribs (54) has a radially outermost region that lies on a cylindrical envelope of a third diameter (D3) that is greater than the second diameter (D2), and
• the three axially extending ribs (50, 52, 54) are angularly disposed by 120° one from another, with respect to the axis B.

A cutting tool assembly (10) comprising a cutting insert holder (12) and a cutting insert (14), the cutting insert holder comprising a body portion (16) and an insert retaining portion (18) the insert retaining portion having a generally cylindrical inner surface (32) of a first diameter (D1) and a longitudinal axis A;

• the insert retaining portion (18) comprising a fixed portion (22) connected to the body portion (16) and an axially extending clamping jaw (24) having a radially facing clamping surface (42), the axially extending clamping jaw (24) being connected to the fixed portion (22) on one side along an axially extending juncture (25) and separated from the fixed portion (22) on an other side along an axially extending free end (30) by an axially extending aperture (27), the axially extending aperture (27) being bound by the free end (30) of the clamping jaw (24) on one side and by an axially extending first locating surface (36) of the fixed portion (22), adjacent the inner surface (32), on an opposite side;
• the cutting insert (14) comprising a generally cylindrical portion (44) having a longitudinal axis B and an axially extending radial projection (46) connected thereto, the radial projection having upper and lower surfaces (55, 62) connected to the cylindrical portion (44) and being separated by a side surface (57), the upper surface (55) and the side surface (57) meeting at an edge, at least a portion of which constitutes a cuffing edge (56), and the lower surface (62) constituting a first locating surface;
• the cutting insert (14) being located in the insert retaining portion (18) with the axially extending radial projection (46) protruding from the axially extending aperture (27) and the first locating surface (62) of the cutting insert abutting the first locating surface (36) of the insert retaining portion (18);
• the clamping jaw (24) being separated from the body portion (16) by a slot (26), and being resiliently displaceable relative to the fixed portion (22);
• the cutting insert (14) being clamped in position by means of a resilient radial force exerted by the clamping surface (42) of the clamping jaw (24) on the generally cylindrical portion (44) of the cutting insert (14);
• wherein in a first clamping position the clamping surface (42) of the clamping jaw (24) lies on a cylindrical envelope having a second diameter (D2), and
• wherein in a second clamping position the clamping surface (42) of the clamping jaw (24) lies on a cylindrical envelope having a third diameter (D3) that is larger than the second diameter (D2).

A cutting insert comprising a generally cylindrical portion having a longitudinal axis B and an axially extending radial projection connected thereto, the axially extending radial projection having upper and lower surfaces connected to the cylindrical portion and at least one cutting edge associated with the upper surface, wherein:

• the generally cylindrical portion is provided with three axially extending ribs that are circumferentially spaced apart from one another along the generally cylindrical portion;
• first and second axially extending ribs have radially outermost regions that lie on a cylindrical envelope of a second diameter (D2) having as axis the longitudinal axis B;
• and
• a third axially extending rib has a radially outermost region that lies on a cylindrical envelope of a third diameter (D3) that is greater than the second diameter (D2), said third axially extending rib being spaced apart from said axially extending radial projection.

A cutting insert comprising a generally cylindrical portion having a longitudinal axis B and a single axially extending radial projection connected thereto, the axially extending radial projection having upper and lower surfaces connected to the cylindrical portion and at least one cutting edge associated with the upper surface, wherein:

• the generally cylindrical portion is provided with three axially extending ribs that are circumferentially spaced apart from one another along the generally cylindrical portion;
• first and second axially extending ribs have radially outermost regions that lie on a cylindrical envelope of a second diameter (D2) having as axis the longitudinal axis B;
• and
• a third axially extending rib has a radially outermost region that lies on a cylindrical envelope of a third diameter (D3) that is greater than the second diameter (D2).