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 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).

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

Side Clearance Angle should be 4° to 6° greater than Side Relief Angle.

In selecting the Side Relief Angle, the sharpener should :

• carefully chose the correct angle, as a deviation of even 2° (plus or minus) will lower tool life appreciably.
• chose the lower angle from the table below for heavy cutting
• chose the higher angle from the table below for finish cutting.
• increase the angle by +2° when making high impact cuts (e.g., work with significant gaps or hard inclusions).

Front Clearance Angle should be 4° to 6° greater than the Front Relief Angle.

The Back Rake Angle, as shown in the picture to the right, is positive.

• For HSS, the radius of the Nose Radius should be the greater of the following two values :
• 4 x the feed rate
• depth of cut / 4

Increases in the Side Cutting Edge Angle will :

• decrease chip thickness and increase chip width (retaining the same area of the chip)
• decrease power usage