Projection

This setting provides additional 3D toolpath options. While the Bottom, Top and Facet projection types are only used when surfaces are selected for machining, the 3D type provides two interesting options for 3D contour offset and continuous Z motion along machined profiles without any surfaces being involved.

3D Surface Machining (Projection = Facet / Top)

When a tool path is created for a machining cycle (all except Surface cycle), the tool path is calculated in the XY plane at the Z Surface height, and then projected downward onto the machined surfaces. Here the 'Projection' type feature determines whether the tool path is created at the first surface encountered as it projects the tool path downward (Project = Top or Facet), or the second surface encountered (Project = Bottom). Top and Facet are functionally the same; the computational differences between them are too complex to explain here. Facet yields good finish and fast performance, Top yields very good finish and slow performance.

Standard 2D Machining (Projection = Facet)

If no Work Step Surfaces are specified, the above mentioned settings (Top, Bottom,Facet) have no effect and 'Facet' is set as default. Normally any toolpath motion is simply projected onto the current Z-Surface level from where it is machined at the specified Z depth.

Below is an example of a standard contouring work step that machines a 3D curve with the projection type set to default (Facet).

2D Curves & Continuous Z Motion Machining (Projection = 3D & Z-Step)

Like in standard machining, any toolpath is simply projected onto the current Z-Surface level. But when setting projection type to 3D and at the same time specifying a Z Step, the software will constantly increase the machining depth from initial point to specified incremental step depth. The toolpath resolution along 3D arc moves is controlled by the Chordal Tolerance setting.

Below is an example of a contouring toolpath that was generated with projection type set to 3D and a Z step specified. Please note that there is an additional flat pass at the bottom to ensure final depth along the machining profile. If you only want to have one single depth move specify identical values for Z depth and Z step.

3D Curves & 3D Tool Offset (Projection = 3D)

When machining 3D curves in combination with the projection type set to 3D, the toolpath is offset depending on the current status of the Offset Dir setting located on the Cycle Data dialog. If in addition a Z depth is specified, the toolpath is simply shifted downwards by the specified value. The toolpath resolution is controlled by the Chordal Tolerance setting.

Plunge Roughing (Projection = Plunge)

When the Plunge option is enabled the system automatically segments the XY path into a series of drill positions, based on the specified Curve Step. In 2.5 axis scenarios where only a Path Curve is provided, each position is drilled to the specified depth using standard canned cycle drilling output. In 3 axis scenarios where the work step also includes Work Step Surfaces, each position is drilled to the specified Depth below the point at which the tool contacts the surface. Surface based drilling cases will be output using standard Linear and Rapid motion commands. This capability can be used in combination with tools specifically designed for plunge roughing to quickly remove large amounts of material at very high feedrates.

When using the Plunge Projection surface machining option, if a Z Step is specified, all step levels for each hole will be completed before moving to the next plunge position. This improvement results in a more efficient machining sequence and smaller program length.