Hybrid surface, solid and wireframe modelling
VX CADCAM from VX Corporation
VX Corporation, formerly Varimetrix, continues to champion hybrid surface, solid and wireframe modelling combined with manufacturing capabilities in version 4 of their flagship modeller now called VX CAD/CAM.
The product also includes sheet metal, assembly modelling, drafting and rendering tools.
Target users include industrial designers, plastic component and tool designers using integrated split line and draft analysis tools and integrated design and CNC users.
VX CAD/CAM is aimed at the mid-range desktop market primarily under Windows NT / 2000 but also UNIX.
While some users will be content with the legacy UNIX feel even under Windows, the icons are somewhat garish and the non-standard forms untidily structured.
It is easy to start modelling in the sketcher, but command sequences and modifiers are controlled through text based command line rather than graphical dialogs.
The history view is also a text list without any graphics to help identify each sketch or feature type.
The sketcher gives graphical, dynamic feedback to indicate automatically captured constraints such as parallel and perpendicular to existing entities.
VX uses a system of levels to be able to manipulate parts, sketches, CAM data etc.
within the same application window.
Active sessions are used as an editable and undoable workspace to contain file edits with files saved out to predefined archive directories as required.
As a hybrid modeller VX supports non-manifold, open geometry.
The integration of solid and surface functionality is transparent so that traditional solid functions such as bosses, cuts, holes, fillets can be applied to faces and surface models, without the need for the model to be a closed solid.
Conversely volumes enclosed by a series of faces are by definition solids but can be modified by advanced surface modelling functions such as trimming, tangent and curvature continuous blending and local or global shape modification.
To conduct mass property calculations or ensure reliable each part must ultimately be a single manifold solid.
Analyze Part Topology can be used to identify abnormal conditions such as gaps between face edges that are listed in a report and highlighted in the graphics window.
Whilst this combination of solid and surface capabilities achieves the dual benefits of speed in modelling prismatic parts using solid feature based tools and complex freeforms with the surface tools, it inevitably comes at the cost of overall complexity.
Surface modelling requires care in order to minimise the need for final debugging to create a manifold part and the seamless integration of tools increase the chance of inadvertently straying form an inherently solid part.
Within many of the regular commands such as sweeps and lofts there are modifying options to offer greater control.
Sweeps can be variational, allowing the profile to be driven by an equation driven dimension or external reference that forces the profile to regenerate as it passes along the sweep path.
In addition to lofting between a series of profiles comprising sketches, wireframe curves, curve lists, or face edges, lofts can also use a drive curve and options to add scale, twist, profile blending and profile influence.
A common error with sweep and loft operations is self-intersecting geometry.
The Tie Self-intersections command attempts to remove self-intersections and inverted regions on selected faces.
There is an excellent set of fillet tools and supported model cases including constant and variable radius with options including corner set back, roll along edge and conic arcs although the later repeatedly hung my installation.
Variable fillets benefit from being able to assign radius values at any point along an edge rather than being limited to existing vertices or nodes.
Should a solid filleting operation fail, the successful elements can be displayed.
Surface detail can now be created using an external raster image file as a height map to emboss a face.
The prescriptive file handling regime is apparent in the need for the height map file to reside in the user directory from which VX is being run.
Other useful surface creation methods include N-sided patches from 3 or more wireframe, sketch, or face edges and Curve Mesh created by blending through a mesh of U and V curves.
In both cases there is an option to force boundary edges to be tangent continuous with mating faces.
An untrimmed base face can also be readily created that passes through a set of points read from an ASCII format point file of scanned data.
Although the value of these surfaces can be limited by ripples due to the accuracy of the scanned data, VX provides sufficient surface analysis and modelling tools to achieve high quality surfaces.
Draft can be added to faces relative to a neutral edge, face, plane or parting line.
Parting lines can be created from silhouettes, plane intersections, face edges and curve projections.
A parting face can also be generated.
The manufacturing version incorporates full 2.5 and 3 axis CAM including manufacturing planning and CNC machine routine output.
This avoids the need for intermediate translations or the loss of associativity with the model should the design need to change.
Full sheet metal design tools are also available including tab, corner and deformation tools for features such as dimples and louvers.
When folding and folding a part the stationary face can be specified and bend radii can be selectively modified.
At present the lack of direct integration with third party analysis packages such as finite element or motion analysis could be a limitation since exporting data for use in these tools during the design phase can lead to additional revision control issues or at least additional work.
The integration of surface and solid capabilities is clearly the best route to efficient creation of the widest range of parts.
This is underlined by the number of competitor products in the mid-range, design centric market who are adding surface capabilities to their solid modellers.
Although VX have a lead and indeed pedigree in this respect, the quality of the VX CAD/CAM interface will come under intense scrutiny as other products begin to offer similar capabilities combined with extremely sophisticated and intuitive front ends.
The CAM tools do however offer the full design to manufacture spectrum and will undoubtedly appeal to installations where this level of integration is required.
The full manufacturing version costs £10,000 and the design version including all but the CAM tools £4,000.