Metal Lathe Tools - Boring Bars
  • Angles shown are good for hobbyists; grinds for production shops should consult a specialist.

  • When both a relief and a clearance angle are outlined (e.g., Side Relief and Front Relief), this is done to facilitate easier resharpening.
    • It is analogous to Secondary Bevels on woodworking chisels.
    • Resharpening should be done when the wear land reaches 1.5 mm (1/16 inch) high.

  • Angles shown are for either Carbide or HSS

  • Angles shown are the effective angles, not the ground angles. Effective angles are increased or decreased, based on the angle by which the tool is presented against the work. Additionally, the vertical alignment of the tool (vs. the center line of the work) can also change the effective Front Relief Angle.

  • All angles are given the nomenclature designated by the American Standards Association (ASA).
Carbide vs. HSS
Material Compressive Strength Shear Strength Max Usable Temp. *
Cemented Carbide Higher Lower 1,800 ℉
HSS Lower Higher 950 - 1,100 ℉

* Temperature at which the tool material begins to soften appreciably. For HSS, it depends on the level of cobalt in the HSS.

Tool Shape - Boring Bar
Back Rake Side Cutting Edge Angle Nose Radius End Cutting Edge Angle Side Rake Angle Side Relief Angle Side Clearance Angle Comments
-10º 10º 1.5 mm
(1/16 in)
10º -5º Angles shown are the recommended effective angles, not the ground angles.

Notes & Comments
Information regarding Grindstones

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