Tool insert for boring operations, particularly for a boring bar

A tool insert for boring operations, comprising a housing which can be inserted in a recess in a toolholder, and which has a cutting tip support slidably mounted in a longitudinal bore therein, the said cutting tip support having a cylindrical shank, the outer end of the support bearing in a recess a replaceable cutting tip which is staggered laterally relative to the shank axis and the rear end thereof having a thread which is engaged by the thread of an adjusting element rotatably mounted free of play in the housing between axially loaded ball bearings, wherein the improvement is comprised in that the front end of the housing comprises a transverse slot with bounding surfaces which extend substantially parallel to the plane (E--E) of the cutting tip, that the front end of the shank has a cross piece, the lateral faces of which extend substantially parallel to the plane (E--E) of the cutting tip and abut on the bounding surfaces of the transverse slot, that the recess for the cutting tip is provided at one end of the cross piece, which end extends at least as far as the wall of the housing, and that the thread in the shank is designed as a female thread in which the adjusting element together with a threaded pin engages the front end of the said adjusting element having a hexagon socket which is accessible through an axial bore in the cross piece.