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From CAD User Mechanical Magazine  Vol 19 No 06 - JUNE/JULY 2006

Version 12 of VX introduces enhancements that benefit both 2D and 3D designs, writes David Chadwick

Whenever I go back into the hybrid modeller, VX, I always seem to come away with some new insights into the fascinating world of consumer goods design; simple things like detergent bottles and household electrical goods - items that owe as much to their aesthetic shape as to the gubbins inside. Consumers are generally very fickle, and, faced with rows of items all containing essentially the same substance or performing similar functions, will choose the one that looks and feels right.

Appearance really is all then, and this is where VX comes to the fore - in providing tools that can give a designer that extra edge that can make all the difference out there in the marketplace. As a hybrid modeller, the software is already capable of working in either solids or surfaces, seamlessly switching between both to suit the needs of the moment. VX provides a range of elegant and useful features that add extra firepower to the designer’s armoury.

The latest version of the modeller, Version 12, introduces further interesting design techniques and opportunities. Not that the software merely caters for product designers either, as VX provides a complete concept-to-manufacturing solution, allowing designers to work up from simple 2D sketches to complete assemblies, right through to mould design and setting up the model for machining.

Enhancements to the software cover all of these areas, with a new and simple way of combining 2D sketches to swiftly create complex 3D shapes, the ability to create 3D shapes for moulding or milling from any image, the imposition of 3D logos and text on to curved surfaces - even down to the design of the electrodes, an essential feature of detailed mould making.

2D to 3D
You would never think that designing the cover of a computer mouse could be exciting, but the ease with which VX handles it, using some pretty advanced tools, means that the excitement stems not from what can be achieved, but in how easy it is to achieve it!
Starting from just the three 2D views - plan, view and elevation - drawn using VX's ability to sketch in each plane, the designers merge each of these by dragging one on top of the other, snapping to selected points, and creating a basic 3D part out of the 3 basic axes in a matter of seconds. It doesn't even have to be VX sketches either, as VX can do this with imported 2D sketches from most software packages.

Using VX's sweep command, the designer can then sweep from one shape to another to create a surface - which can, in the same command, be given thickness to form a solid! (Fig 1.). Using further shapes, other surfaces (or open solids) can be created by sweeping, using the original or new sketch geometry. Combining the surfaces (open solids) trims all edges to produce the finished model, with class A surfaces that can be checked using VX's enhanced range of surface analysis tools (adding such things as radii, depth, draft and isophotic analysis to zebra striping).

Working on the computer mouse shown in Fig 1, the IGES file with all of the elector-mechanical components can be merged with the surface model to provide a complete assembly, combining the surfaces to become a single component with the assembly. At the same time, the surface is saved separately and parametrically - so that design work can continue on either with corresponding modifications to the complete assembly. If we increase the size of the PCB, for instance, the surfaces we have just created will also change to compensate.

If, however, the design needs to be modified to accommodate the mechanism, it can also be done using VX's morphing techniques, a very powerful tool which can be used in selected areas (along defined axes and mirrored) to dynamically modify the shape and still retain its aesthetic attributes - symmetrical morphing that meets all of the engineering, ergonomic and aesthetical challenges of the design!

2D and 3D import
That's one way of creating 3D shapes. Another is to import 2D and 3D images and turn these into sketch geometry and 3D shapes that can be moulded or machined. The images are scanned in or brought in from a number of sources, and laid down on one of the sketch planes to create the outline. This can be checked for gaps, which can be selected and healed using another neat little VX tool from a drop-down toolbar, with the user controlling the curvature throughout, until it is complete - and the unwanted areas trimmed.

On the same plane, a block is created to the depth of the 3D model in a material to suit the design - gold, brass, plastic etc. - and the image is superimposed on top.

The image is then very quickly converted to a 3D model, using the intensity of the colours as a relief map to determine the depth. Using the VX kernel, and rapid Boolean maths, the two images, the original and the embossed shape, are merged to produce a machinable 3D model (Fig. 2).

Relief Engraving
Similar functions are used to overlay images and text for producing embossed designs on curved surfaces (Fig .3), using the Inlay command, which quickly applies a face inlay based on any wire frame geometry and inputs angles and tip radii of the tools required. VX has kindly created a library of thousands of parametric preset sketched shapes that might be useful for any type of product, and, of course, has access to the full range of TrueType fonts. The sketch or text can be placed on any curved surface and used to create a relief map, taking drafts, fillets, curves and other features into account.

Like all milling software, each tool-path and the material being removed with each pass is shown graphically. The interesting new feature here is automatic feature recognition and the ability to drive tools along the actual Drive Curve - the actual features of the design themselves. Standard milling follows zig-zag patterns, which can create minute ridges along the design. Following the drive curve, using Feature Aware Machining, enables the tool to work around the design, creating a smoother finish (Fig.4).

Electrode Blanks and Tables
A new electrode design wizard has been introduced, making the 3D definition and 2D layout and tabulation of electrodes both quick and easy. VX already incorporates a complete mouldmaking capability. A vital part of many complex moulds, though, are the electrodes. These are part of the manufacturing process, and sometimes up to 50 or so of them are used to shape the more inaccessible parts of the mould, those that can't be machined directly, by spark erosion.

Everything that is used for creating electrodes - from cutting the blanks on which the electrode shape is based, cutting out the chamfer, machining and defining materials - is done automatically, even down to defining the layout of the cables that power the electrodes. This feature also has an automatic zoom to check parting line gaps.

Dynamic Texture Mapping
Although VX has good photorealistic rendering, creating advertising ready artwork from the models is not its main aim. It is always useful, though, for the designer to enhance his or her designs by including some background - or foreground - to models. In fact foregrounds come to the fore, so to speak, in VX Version 12, thanks to dynamic texture mapping, available from a new 'visualise' toolbar within the software which enables users to add graphical images - in all popular formats - to model faces as textures in a shaded model in real time. These can all be supported by VX's render engine without further preparation.

VX has also enhanced it's light mapping tools, using Assembly Component Light Sources. This novel idea allows the user to create 3D Model components that represent lights (e.g. a spotlight), which can be dynamically positioned in model space using any of the standard VX component alignment commands, as well as commands for dynamically moving and patterning components - thereby demystifying the process of lighting photorealistic images.

www.vx.com

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