Path Walkthrough for the Impatient

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Base ExampleCommandModel.png Tutorial
Topic
Path Workbench
Level
Time to complete
Author
Chrisb
FreeCAD version
Example files


Here is a demonstration showing the creation of a Path WB Job from a 3D Model, generating dialect-correct G-Code for a target CNC mill.

The 3D Model

The Project begins with a simple FreeCAD model: a cube with a rectangular pocket,

Path-SquarePocketModel.png

created in the Part Design including a Body, a Box with a Pocket, based on a Sketch oriented in the XY plane.

With the 3D Model completed, the Path Workbench is selected.

The Job

The Path-Job.png Job is created.

In the Job creation dialog click OK to accept the Body as the Base Model, with no Template.

Job Setup

Path-JobCreationDialog.png

The Job Edit window opens in the Task window, and the model view Window shows the Stock as a wire frame cube surrounding the Base Body. The Setup Tab is selected.

Job Output

The Output tab defines the output file path, name, and extension, and the Postprocessor. For advanced users, Post Processor Arguments can be defined—the mouse over hints show common arguments.

Path-JobOutput.png


Job Tools

Path-JobTools.png

We modify the Default tool by selecting it and clicking the Edit button. This opens the Tool Controller edit window.

Path-ToolConfig.gif

The name given to the tool and the tool number correspond with the tool number of the machine. Here it is tool Nr. 4. The tool controller is configured for horizontal and vertical feed rates of 2mm/s and a spindle speed of 2000 rpm.

Select the Tool subpanel of the tool controller. Set the diameter and - if you wish to use the simulation tool later - add a cutting edge angle and cutting edge height.

Path-ToolAdd.gif

The values are confirmed with OK.

For easy access all the tools can be predefined and selected from the Tool manager.

Job Workplan

The Workplan tab begins empty, and is populated by the sequence of Job Operations, Partial Path Commands, and Path Dressups. The sequence of these items is ordered here.


This tree is shown after the Job's configuration once the Path Job is unfolded:

Path-TreeWithJob.png

The Path Operations

Two operations will be added to generate milling paths for this Path Job. The Contour operation creates a path around the box and the Pocket operation creates a path for the inner pocket.

For now we will keep it simple. The Path Profile.png Contour button opens the Contour panel. After confirming with OK using the default values, see the green path around the object is visible.

Selecting the bottom of the pocket and then the Path Pocket.png Pocket button opens the Pocket Shape window. The default values for Base Geometry, Depths, and Heights are used, and the Operation subpanel is selected, and the Step Over Percent is set at 50.

Path-PocketOperation.gif

The pattern is changed to "Offset" and the Job Operation is confirmed for the pocket configuration with OK.

The result is a model with two paths:

Path-WalkThroughResult.gif

Verifying Paths

There are two ways to verify the created paths. The G-Code can be inspected, including highlighting the corresponding path segments. The milling process of the Path Job can also be simulated to demonstrate the idealized tool paths, required for the Tool geometries to mill the Stock.

To inspect the G-Code use the Path Inspect.png tool. Selecting the corresponding G-Code lines within the G-Code Inspection window highlights individual path segments.

Path-InspectWindow.gif

To start the simulation use the Path Simulator.png Path Simulator tool.

Adjust speed and accuracy and start the simulation with the play button.

Path-Simulation.gif

If you want to end the simulation click the Cancel button, it will remove the stock created for the simulation. If you click Ok this object will be kept in your Job.

Postprocess the Job

The final step to generate G-Code for the target mill is to postprocess the Job. This outputs the G-Codes to a file that can be uploaded to the target CNC machine controller. To invoke the Postprocessor:

  • Select the Job object in the tree
  • Select the Path Postprocessing Path PostProcess.png tool to postprocess the file. This opens a G-Code window allowing inspection of the final output file before it is saved.

Path-PostOutput.gif