MILL Module > Creating Machining Operations

Control Geometry are curves that already exist in your model or separate new curves you create within Rhino that coexist with your part. Regions serve different purposes in 2½, 3 and 4 axis milling.

In 3 axis milling, Containment Regions are used, when necessary, to define the machining boundary. The center of the tool remains on the region while following the contours of the part. For example, if you define a region surrounding one surface, only that surface will be milled.

Important Notes about Machining Features/Regions

Regions must be selected before they can be used in an operation. It should be noted that regions can be created and be present in a part file but if they are not selected in a machining operation then they will be ignored during toolpath computation. So creating a region does not make it active; you must use one of the Select Regions tools before creating the toolpath.

If a region is not defined for finishing operations in 3 and 4 axis methods, the part silhouette is automatically identified and used as a containment region for the tool. For roughing operations, the stock geometry determines the constraints on the tool location.

Because 2½-axis milling does not use part geometry, Part Regions must be created to define the areas to be machined.

Multiple regions can be defined and selected in an operation. This is a very powerful feature and affords you fine control over the manufacturing process. Once created these regions can also be written out to an external ASCII file and also archived in a part file.

There are two operations that you should be aware of when working with regions. The first one is creating / deleting regions in a part file and the other is selecting regions in a machining operation. These two are independent operations and have independent methods of being invoked.

Creating Regions

To create regions select the Curve option from the main menu. This will bring up the curve creation tools in Rhino. You will be able to create rectangular, circular and polygonal regions using this toolbar. Regions can also be extracted from the 3D model using the tools available under Curve > Curve From Objects & Curve Edit Tools.

Multiple Regions

Multiple and nested regions can be selected, but not regions that intersect. Nested regions are handled according to the following rule: The tool will remain inside an outer region and outside an inner region. A region within an inner region is considered to be an outer region. In the following picture, the shaded areas are where the tool motions occur:

Multiple Regions

Deleting Regions

Regions can be deleted by selecting them graphically in the display window or by using Edit > Select Objects tools from the menu bar.

To delete the graphically selected regions, select Edit > Cut. You can also hit the Delete key on the keyboard to delete the active selections.

Editing Regions

Also the regions can be edited using any of the Transform commands like Move, Rotate, Scale and Mirror. The transformation can be accessed from the menu bar. The properties of the regions like layer, color can also be edited using the Object Properties option.