Cutting Wide Grooves

Cutting Wide Grooves

The best method of cutting a wide groove is to rough out with a plunge (grooving) or parting tool and then to finish with left and right hand tools.

It is tempting to do the whole job with a grooving or parting tool. However, unless the cutting edge of the tool is parallel to the lathe centre line, the bottom of the groove will have a series ridges. Also, if the side of the tool blade is not perpendicular to the lathe centre line, one side of the groove will not be either: it will have been chewed by the side of the blade. Use a dial gauge to adjust the whole of the tool post or auto-change turret so that the side of the tool is parallel to the X axis of the lathe.

There is a further problem if the grooving or parting tool has a replaceable push-in tip rather than one which is clamped to its holder. Push-in tips are designed to cut radially only. An axial cut to finish the bottom of the groove will almost certainly displace the tip causing it to gouge the work and possibly damage the tip holder itself.

Note that the Emco plunge tool has a very limited depth of cut: 1.5mm only.

G86 Grooving Cycle
Plunge and Parting Tool Widths