DesignSpark Mechanical – Lowering the Barriers to Entry for 3D Solid Modeling

RS Components discusses 3D design and explores some of the basic differences between ‘feature-based modeling’ and ‘direct modeling’, and how DesignSpark Mechanical – the new and entirely free-of-charge 3D modeling tool – offers fast and intuitive design capabilities and will release creativity among users new to 3D and deliver fresh possibilities for engineers from concept design through to manufacturing

Computer-Aided Design (CAD) first emerged as a tool in the 1960s and was primarily created to support the demands of the automotive, aerospace and defense industries. By the late 1970s, CAD was being presented to engineering students as the way forward with traditional manual draughting methods falling gradually by the wayside. During the 1980s, due to both the move from 16- to 32-bit processor technology and the introduction of color raster display technology, this previously evolutionary process took a quantum leap forward.

Much of the early motivation to develop such systems was focused either on the potential productivity gains or on the ability of new systems to define complex surfaces and solids. Early work in the automotive sector has proved to be central to the progress made. Renault, for example, can be credited for initiating the process that led to the emergence of the CATIA software product.

The market for advanced software that could create models for designs and products in 3D really came into existence back in the 1980. Historically, it has been ‘feature-based’ or ‘history-based’ 3D CAD tools that have dominated the market. In the early days it was not inevitable that the methodology would prevail, but its success has largely been attributed to the limits of processing power delivered by computers of the time.

Because of the lack of number-crunching performance available, feature-based modeling held the advantage over alternative methodologies such as direct modeling. Essentially, it was based on a clever trick to make solid modeling viable on hardware of the 1980s. Feature-based modeling broke down the design into a list of individual parameter-driven steps or ‘features’, which acted as instructions to create the shape of the part and enabled the hardware to create and work with models in something like real time, or at least vaguely approaching it.

Certainly the process worked well enough for designs comprising simple parts and assemblies, but as computers delivered increasing performance, the models were able to become more complex and additional concepts were developed to link the features together. These included constraints and parent-child relationships, which basically describe the relationship between the individual features or steps, held in the tool’s ‘history-tree’. However, it meant that if a specific feature needed to be changed, then it was necessary to retrace the steps right back to the definition of that particular feature. Feature-based modeling also required the creation of interfile dependencies and eventually the development of data-management tools to enable concurrent working of design teams.


Barriers to Entry

However, while the 3D software was powerful, and also generally expensive, it was only the experts in CAD that could use it. It is estimated that approximately 20 million users globally would benefit from using 3D design, including vast numbers of electronics and mechanical engineers. Yet only around one million 3D CAD seats have been sold in total across the major CAD software vendors. Many of those that could have benefitted from 3D design have not been given access to this mysterious and impenetrable knowledge, most likely for reasons of cost: both in terms of tool price and also the time it takes to become skilled and fully productive with the tools. Both of these factors have become the major barriers to entry for users looking to reap the benefits of 3D design capability.

The latest tools from leading CAD vendors are in the range of $5000 to $30,000 per license, and usually come with high-priced annual maintenance fees. As mentioned above, the second impediment has been the significant learning curve sometimes associated with traditional 3D modeling. Entry-level users may take anywhere between 6 and 18 months before they become fully productive with an advanced 3D tool. Often, this can lead to CAD designs being outsourced to a CAD specialist company, which can introduce bottlenecks in product development with the processing of even simple changes in the design taking many weeks.


Direct Modeling

Today computers are something like 100,000 times more powerful than their venerable ancestors of the 1980s. And because of this, direct modeling – which allows a user to draw 3D shapes as easily as they might draw with pen and paper – is making a serious claim as an alternative or, in many cases, a complementary 3D design tool. Currently, many companies will use sketching or presentation tools to describe and communicate engineering and product concepts to their colleagues or their management or to customers. And certainly tools are used to design and analyze key characteristics of a given product such as electrical or thermal performance in the electronic design world long before 3D geometry is available for detailed finite-element analysis or in fact any other kind of analysis. 

3D direct modeling offers a large advantage for non-CAD specialists in that it is generally more intuitive and very easy to learn. Direct modeling technology has been described as being like modeling with virtual clay. Essentially it is all about geometry; there is no feature history and no need to manage any of the associated complexity such as constraints or parent-child relationships. It works at the base geometry level and dynamically changes any requested modifications into geometry and explore ideas and product concepts in 3D. In many respects it is very similar to SketchUp, where a user can push and pull on geometry and make new designs extremely quickly.

Direct modeling eliminates many of the problems associated with traditional feature-based tools, as engineers that may not use CAD on a regular basis easily can make changes to models without having to fully understand all the ‘constraints’ of a feature-based model. For example, with direct modeling the engineer can make an iteration to the design directly from the last one, adding and removing from the design without any problems.

A further advantage offered by advanced direct modeling tools is greater interoperability, whereas proprietary feature-based systems have incompatible data formats. Historically, competing 3D CAD vendors have had some very different ideas about the operation of features and relationships within their respective tools. This meant the creation of proprietary software packages that had no compatibility with one another, meaning that interoperability problems have become a significant challenge for CAD users, their colleagues and also in the supply chain. In the past this has meant that everyone in the supply chain had to use the same tools, as there is always some loss of information when translating data from one CAD data format to another. Employing advanced direct modeling tools such as SpaceClaim Engineer, for example, users in simulation or manufacturing departments can simply edit the actual CAD geometry via STEP files, the most common intermediate data translation format for CAD systems.

However, it is also very true that some applications will still require feature-based modeling if, for example, it is the end goal to create customized variants of an extremely complex assembly of parts with critical and well-understood relationships and requirements. Large manufacturing companies will commonly handle these demands via a dedicated team of CAD specialists using a single feature-based modeling tool. However, this approach can be highly inefficient for significantly smaller designs. A loose analogy could be an average car owner choosing to employ specialist racing car mechanics to work on their car when some basic car maintenance is all that is required. Direct-modeling tools are thus increasingly being seen as a highly attractive option that offers significantly quicker and easier modeling capabilities for a growing number of applications.

So, while there is no doubt that traditional feature- or history-based CAD tools have a continuing and important role to play in the development of electronics and mechanical design, direct modeling is making a substantial case for use in product development, especially in concept design and prototype manufacturing, but also in other areas. In addition to this, a growing trend in the industry is the merging of the worlds of electronic and mechanical design. Previously an electronic engineer would have passed on a circuit design to a mechanical engineer to build a case with buttons and/or dials around it. Today, these processes are increasingly being done in parallel, which enables product design to be more focused on the aesthetics of the product. Although it is also true that many PCB design tools come with integrated 3D viewers or provide IDF output files for use in mechanical CAD tools, the reality is that neither of these fully address the challenges faced by engineers today.


DesignSpark Mechanical

RS has recognized these important trends and launched the DesignSpark Mechanical 3D solid modeling and assembly tool. Developed in conjunction with SpaceClaim and based upon the company’s direct modeling ‘SpaceClaim Engineer’ 3D design tool, DesignSpark Mechanical is available for download, totally free of charge to all.

Basic 3D models can be achieved extremely quickly via software’s four primary tools: ‘Pull’, ‘Move’, ‘Fill’ and ‘Combine’; and, unlike traditional feature-based tools, the software makes use of familiar ‘copy and paste’ keyboard shortcuts, for example, allowing exceptionally easy reuse of geometry in different designs. More specifically, the Pull and Move tools allow the direct selection of portions of a model and to be moved to the desired position; the Combine tool slices and divides parts into pieces and also allows the user to bring in portions from other designs and merge them into the design; and the Fill tool cleans up small features and fills holes.


DesignSpark Mechanical is highly scalable and allows the creation of simple shapes to complex blends and surfaces. The Pull and Move tools allow maximum flexibility enabling face- and edge-based editing, delivering the creation of thin walls and mirrored, concentric, rounded and chamfered geometry. It also offers the ability to create 3D extruded, revolved and swept geometry without ever leaving a 2D cross section. This means that new concepts can be sketched out and solid 3D designs achieved without having to perform extra work. In addition, if specific parameters are to be added or changed in a model, dimensional values can be edited simply by selecting the element – there is no requirement to set up complicated systems of constraints as in feature-based tooling. It also means that different users can set up and save their own sets of dimensions.


The tool also allows flexible assembly whereby parts can be turned into an assembly or vice versa: assembly structures can be created following the creation of parts or even before a shape is drawn, without having to worry about inter-component relationships preventing changes. Finally, there is no unnecessary mode switching: the same tools can be used to edit assemblies, parts, drawing views and 3D mark-ups.


Boosting Innovation at the Concept Stage

3D direct-modeling based tools such as DesignSpark Mechanical and SpaceClaim Engineer are not like-for-like replacements of traditional feature-based ‘history-tree’ 3D modeling tools – this is a very important point worth clarifying and emphasizing. They offer advantages to all designers at all levels and in all company sizes. In larger companies that have dedicated and well-resourced CAD departments, they can be used complementary tools that enable a faster and easier ability to share designs. They offer major benefits to industrial designers and electronics design engineers among many others, such as sales, marketing and production, who can now easily contribute and collaborate at the early stages of product development. Clearly, as DesignSpark Mechanical is a free tool, there is no cost barrier to entry and as it is based on direct modeling it is also highly intuitive and extremely easy to use. Electronics and mechanical engineers and other users can become fully conversant with the software within days or even hours.

The use of DesignSpark Mechanical early in the product design cycle can eliminate much of the time-consuming rework associated with traditional product development processes. It can reduce wasted time in engineering because it allows the use of 3D in concept modeling. The use of traditional feature-based tools all too often means the suppression of innovation because designs tend to be locked down too early in the design phase. It allows the quick and easy creation of new concept models to share with other design departments and also customers, in addition to fast concept iteration enabling a more collaborative process, and especially when conceptualizing new ideas in response to RFQs (Request-for-Quotation) for example.

The tool will enable engineers in electronics and automation markets to be more creative and will also support a more efficient product development process, allowing the production of professional concepts for RFQs right through to delivering highly detailed and dimensioned manufacturing blueprints. Importantly, the tool can remove bottlenecks in the early design process by making amendments and additions in seconds, rather than having to wait for the CAD department using traditional 3D design tools to rework the design. Easy-to-use intuitive dimension and measurement tools are included within the software to allow clear and accurate design outputs, which can be shared and distributed as necessary. 

DesignSpark Mechanical has a built in Bill-of-Materials (BOM) function, which is a further enhancement to its already impressive specification. The software will instantly generate Bills of Materials in one of four default formats (or custom templates). These lists can be placed into the design on a plane chosen by the user to fully illustrate the design content.

In parallel, and without putting pen to paper, the user can click one button to order the parts required direct from the RS website, which will provide all the relevant technical and pricing data. This real-time feature will save a typical engineer many hours per week in sourcing parts and devices, as well as ensuring that all the data is correct at that moment in time.

The tool can also import circuit layout files in IDF format from any PCB design tool, including the award-winning DesignSpark PCB software from RS. Importantly, DesignSpark Mechanical exports 3D designs in the STL file format to enable rapid prototyping builds and computer-aided manufacturing. The STL output format also enables direct export of designs to 3D printers, which are becoming increasingly affordable and not only for large companies. In addition to IDF import from PCB design tools, DesignSpark Mechanical also accepts STEP, STL, OBJ, SKP (Sketchup) files; and the complete range of outputs available from the tool includes AutoCAD (DXF), OBJ, STL, 3D pdf, XAML, jpg and png file formats.


3D Models

However, it is not just the 3D modeling tool that is important. An absolutely crucial piece in the jigsaw for electronics and mechanical engineers is a part or component model library. Approximately three years ago, RS and Allied provided engineers globally with access to an extensive library of 2D and 3D models downloadable completely free-of-charge as part of its initiative with DesignSpark, building up a community of developers to share open-source designs and ideas.

The ModelSource component library contains more than 80,000 component schematics and PCB footprints of semiconductors, passives and electromechanical components from leading manufacturers. And in terms of 3D, ModelSource also offers more than 38,000 3D models from over 50 manufacturers covering key technologies including electronics, electromechanical, mechanical, pneumatics and automation and control. The 3D CAD models are also available in many proprietary file formats from leading CAD vendors. Key manufacturers represented in the 3D element of the library include Molex, 3M, TE Connectivity, Harting and FCI in the general electronics market, and Siemens, Schneider and SMC in the automation and control applications.  In addition to this, RS has also collaborated with world-leading 3D content company TraceParts to provide access to millions of models from the online CAD portal in DesignSpark Mechanical format.



The availability of direct modeling based 3D design tools such as DesignSpark Mechanical and SpaceClaim Engineer now mean that 3D solid modeling is available to a much wider universe of users and not just CAD specialists. These types of tools will enable greater creativity and the fast delivery of concepts and designs for RFQs right through to delivering highly accurate and detailed files for manufacturing.

Furthermore, DesignSpark Mechanical, in conjunction with DesignSpark PCB and the ModelSource library of 2D and 3D component models, will enable engineers to embark upon end-to-end designs with professional-grade tools that are available at zero cost.


DesignSpark Mechanical is available for free download via the RS, Allied and DesignSpark websites. Support for the tool is also available via the DesignSpark community at, which also hosts resources for DesignSpark PCB and the ModelSource library.