RAPID ROTARY UTILITY
This program converts G-code from G94 (units per minute feed rate mode) to G93 (Inverse time mode).
The main difference between these two modes is that in G93, for every linear or arc move (G1, G2, or G3), that command must also specify
how much time it should take to make that move. Using G93 is advantageous when a move has both linear and rotary components.
The reason is that linear moves have units of distance while rotary moves are measured in degrees and many CAM software packages only
specify feed rates in distance units. However, if you had a rotation move at the same time as a linear move, the controller (e.g., LinuxCNC)
would move both axes at the same rate. For this reason, inverse time mode is used.
This application does not alter any of the positions in the G-code movement commands. Instead, it converts from G94 to G93 by
calculating the distance the tool travels for each line and using the last feed rate specified to calculate the time it should take
the tool to complete that movement. For rotary moves, the program uses the Z-axis position (as the radius value) to convert from
rotational units (angles) to distance. This allows for constant tool tip feed rates even for complex geometries and results in
slower A-axis rotations when machining larger diameter sections of a part and faster A-axis rotations when machining smaller diameter
sections.
Typical Workflow
- Generate the g-code (.ngc) for your part using your CAM software with a compatible post processor.
- In the Rapid Rotary utility, select the input file and output file by clicking on the filename fields.
- If the Z0 point is the A axis, set Z0 offset to 0. If the Z0 point is the surface of the cylindrical workpiece, set the Z0 offset
to the diameter of the workpiece.
- Select either IMPERIAL or METRIC in the units combobox.
- Select the wrap conversion type from the conversion type combobox
- If all input parameters are valid, the CONVERT button will be enabled
- Press the CONVERT TO G93 button
- If the conversion succeeded with no errors, the converted file is saved and the SEND TO LINUXCNC button is enabled.
- The converted file can be opened from the FILE page of the main menu or by pressing SEND TO LINUXCNC
- Manually inspect and/or test the output .ngc to be sure there are no errors or bugs in the converted file and that it is
safe to run on your machine.
Features
- Supports up to four axes (X,Y,Z,A)
- Supports G01, G02, G03 movement commands (G02 and G03 are not typically used in rotary jobs however)
Limitations
- Requires a space between X, Y, Z, A, I, J entities in the G-code (e.g, X12Y34 is not supported, it must be X12 Y34)
[this can be configured in your post processor
- Requires the input file to use G94 (units per minute feed rate mode) and it must be specified in the preamble section
- Requires G17, G18 or G19 (plane select) to be specified in the preamble section of the input file
- If a comment is found on a line, denoted by '(' the rest of the line is ignored and the comment is copied into the output file