The table shows all relationships between tool type, tool rotation, and cutting direction. By this definition, the G41 command is applied for climb milling mode, G42 command is applied for conventional milling mode: Keeping in mind that the terms climb and conventional refer to milling only and are relative to spindle rotation and the hand of milling cutter. When either G41 or G42 mode is no longer required, it must be canceled by the G40 command: G40 : Cutter radius offset mode CANCELįigure 30-10 shows all three radius offset commands: Figure 30-10Īpplication of G41, G42, and G40 to a cutter path G42 : Offset (compensation) of the cutter radius is to the RIGHT of contouring direction G41 : Offset (compensation) of the cutter radius is to the LEFT of contouring direction In order to program one or the other mode of cutting (based on cutting direction), control systems offer two preparatory commands to select the desired cutter radius offset direction mode. Tool path not compensated (above) and compensated (below), by the specified cutter radius Tool Radius Offset Commands Both are applied to a particular contour, with the cutter diameter shown as well, including its positions. One is not compensated, the other is compensated. The illustration in Figure 30-1 shows two types of a tool path. “CNC Lathe | G41 and G42 Codes | Tool Nose Radius Offset”
This is called the equidistant tool path.
Whether used on a CNC machining center or on a CNC lathe, the cutting tool edge must always be tangent to the contour, which means the tool motion has to create a path where the center point of the cutter is always at the same distance from the contour of the part. During contact with material, the cutting tool edge must be in contact with the programmed part contour – not its centerline.Īctual toolpath for all contouring operations is always equivalent to the cutting tool motion.
Although centerline programming is a very convenient method for program development, it is also a method unacceptable for machining. In either case, keep in mind that this type of programming always uses the spindle centerline as the X-Y or X-Z tool movements. These motions between contour change points can be programmed in millimeters or inches and they can use absolute value positions or incremental distances. For both types of machining, each contour element requires a single block of cutting motion in the program. For turning applications, either the X-axis or the Z-axis, or both axes can be used to face, turn or bore a contour.
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