As I said at the beginning of the series of posts on D.I.Y. Reverse Engineering, this part of my research is looking at how feasible it is for a consumer, using currently available technology and software, to design and manufacture their own products. Reverse engineering an existing product is necessary to provide the foundation for this design and manufacture to happen, but what’s more important is looking at the opportunities and obstacles consumers currently face. And so the next few posts will talk about the issues involved in designing and manufacturing a custom-designed mouse, using Google’s free SketchUp modelling software.

The ways in which the design and digital manufacture of products by consumers could revolutionise traditional manufacturing has been widely predicted, Marshall Burns and James Howison for example, predicted the “Napsterization of manufacturing”¹ in 2001, and Evan Malone and Hod Lipson (developers of the Fab@Home system) have described additive manufacturing as having “the potential to transform human civilization.”² However, whilst the hardware and services which might enable consumer fabbing have been in development for some time, the processes by which consumers might conceive and design ‘fabbable’ products have tended to be assumed or glossed over. Neil Gershenfeld for example, writing in Fab about how a novice might use modelling clay to prototype a design, describes a process in which the clay shapes would be 3D scanned and imported to a CAD software environment:

“they can then be manipulated like any other object: scaled larger and smaller, bent around a surface, or merged with other components by Boolean operations. The resulting model can then be output on a fabrication tool such as a 3D printer or an NC mill, effectively converting the clay into plastic or steel, with enhancements added through the CAD editing.” (pp.130-131)

But such a description, whilst attractive in its simplicity, ignores the realities that the process would entail using current technologies. The use of a 3D scanner is a skilled operation, as is the importing of the data into a 3D CAD system and its subsequent analysis. The data, having been imported, would probably generate a model which required repair and refinement, which in turn assumes in-depth knowledge of a high-end CAD package, as does the CAD editing which Gershenfeld refers to. Even if a consumer had access to the expensive tools which the above passage implies, it is unlikely they would have the time (likely measured in years) or inclination to become adept at their use. And even if they did have both the tools and the skills, Gershenfeld’s scenario still relies on the consumer being able to create a decent clay model in the first place. Well, I’ve done a fair bit of clay modelling, and it definitely isn’t easy; indeed the images that Gershenfeld shows suggest most people’s clay modelling skills aren’t much better than you’d find at nursery school.

So what I’m trying to do is establish whether it’s possible for a skilled, but non-professional, consumer-designer to conceive and manufacture a unique design for a relatively complex electronic product, using only readily available and easily mastered tools. The full course of the research will involve looking at a number of different software packages, but this post concentrates on SketchUp, which is the first modeller I’ve tested. The criteria I used to judge whether a particular modelling package was appropriate were basically

1. Cost. The software should retail for less than $100 to satisfy the requirement of being ‘readily available’
2. Ease of Use. The software should make claims to being easy to use or consumer-friendly

The SketchUp interface, showing the basic toolset along with the BezierSpline plugin toolset, © Google (click for larger image)

Clearly the cost issue is a little contentious – most people know that pretty much any software can be downloaded for free from certain torrent sites, and I know from first hand experience that you can buy a fully unlocked, working copy of Catia for less than $20 in China. But if I’d allowed that argument it would have meant every CAD package was open to consideration, and at the same time I wouldn’t have been researching anything new (obviously, everyone knows professional CAD systems can be used to produce manufacturable models). So the requirement that the software should claim to be easy to use was important, and this is what also ruled out Blender, for instance. SketchUp satisfies both requirements: the basic version is free to download and use, and Google make much of SketchUp’s ‘simplicity’

“To build models in SketchUp, you draw edges and faces using a few simple tools that you can learn in a small amount of time. It’s as simple as that.”

What’s more, I knew that SketchUp had a number of limitations with regard to its toolset, this would therefore make the exercise valuable in understanding the challenges faced when using ‘simple’ software. Clearly, the more capabilities a developer removes in the quest for simplicity, the more restricted the user is in what they’re able to build. It’s a balancing act, and one that had significant consequences in the design of the new mouse.

In some respects the simple test of SketchUp’s suitability as a consumer modelling package would be whether it was possible to create a model which could be output via an additive manufacturing process. However in order to better understand and assess the suitability of SketchUp for this task, a number of criteria were drawn up against which its performance could be measured. These were the things I was paying particular attention to as I started to learn and use the software, and will later be used to judge the other modelling packages I’ll be testing.

Quality of User Experience

Cost
Platform (PC / Mac / Unix / Other)
Ease of Installation
Documentation
Tutorials
Bugs
Support (Company)
Support (Community)

Ease of Use

UI Structure (icons, menus, hidden items etc)
Presentation (shaded or wireframe, single view or multi view etc)
Follows existing paradigms (is similar to other software)
Ease of View (zoom, rotate etc)
Repetition of function (different tools achieve the same result)
Redundancy (tools are not used)
Creates modifiable models

Communication with External Environment

Tools required (mouse, tablet etc)
Inputs existing file formats
Outputs existing file formats
Outputs RM data formats

Download and installation was simple and followed the usual automated process. Although there are both PC and Apple versions of SketchUp, I installed on the Windows partition of my MacBook Pro because some of the other software I’ll be testing is only available for the PC; installing on different platforms might introduce problems when making comparisons.

The SketchUp installation includes no manual though an online reference guide exists. Tutorials were also provided online as YouTube videos, but these are primarily ‘watch and learn’ rather than directed lessons, which means they tend to act as encouragement to simply experiment with the tools. As with a lot of software, the initial tutorials are fairly limited, covering only the basics of usage. In the past I’ve found that a good way to learn more sophisticated techniques can be to study models made by more expert users – this is particualrly the case with parametric CAD software, where you can move back through the history of the model. This can be really valuable in understanding not only the individual methods used but also the strategy employed. SketchUp provides an extensive library of models which can be freely downloaded from the Google 3D Warehouse, but unfortunately most of the best models haven’t actually been modelled in SketchUp, but rather exported from another CAD program. This causes a lot of confusion amongst users (see the comments for this model, for example), and it also gives little indication of SketchUp’s true capabilities.

From a tutorial showing how to model a car. The lines indicate non-tangent surface edges.

The lines can be removed (ctrl-erase), but this is purely visual, the edges remain non-tangent.

There are also a number of user-created tutorials, but almost all the ones I tested were of poor quality – either hard to understand, or simply resulting in a poor model like the one above. To try and overcome these limitations I decided to download an appropriate model which had been created in SketchUp – in this case a digital camera – and attempt to recreate it. It’s not a direct copy, I changed some things just to see if I could, and added a few details, but in this way I was ‘forced’ to try and understand how the software worked. My model can be downloaded here. Recreating the camera took approximately two days, which, combined with the official video tutorials, added up to approximately four days ‘training’. After that I felt proficient enough to begin the design phase of the exercise, which I suppose is testament itself to SketchUp’s ease of use, although it would be a mistake to assume I knew how to use it well. To be honest I was still learning some of the nuances as I exported the finished CAD file to the 3D printer.

Nikon digital camera, modelled only in SketchUp (click for larger image)

SketchUp was acquired by Google via a buyout of its original developer (Last Software) and the first version was released in January 2007. It was originally intended primarily as a tool for modelling buildings which could be placed into Google Earth, and the software continues to display its heritage by the concentration (of its tools and tutorials) on architectural modelling. As long as you’re not trying to model organic shapes, SketchUp’s tools strike a good balance between functionality and ease of use. The problems come with trying to model anything more complex than an extruded spline. SketchUp’s approach to the creation of 3D objects is certainly simple. A 2D shape is drawn on a plane, when this shape is closed (i.e. the lines defining it contain no gaps) a face is formed, which can be extruded, moved or swept along another line or edge. Shapes can be drawn on the faces of objects to add or subtract from the original. In this way it’s pretty easy to pick up the concept of making 3D objects.

To create a feature, a shape is sketched on a face or plane.

The new face can then be extruded using the Push/Pull tool.

Freeform shapes can also be sketched, and Push/Pull can be used to cut into an object.

But there are some tools which are conspicuously missing, tools that most designers would consider fundamental. In particular there’s no way to create lofts (a surface between two non-identical curves or edges), no way to create patches or blends between surfaces, and no way to create fillets. This last one I found particularly bemusing – 3D CAD software has been able to add fillets to edges almost since it was first invented, how difficult would it be add this capability to SketchUp? This is something which seriously limits SketchUp’s ability to appeal to designers – fillets are so fundamental to products that when you design something without them, the results look crude and amateurish. Even in a rendering, the model immediately looks ‘wrong’.

It is possible to fillet edges, but it’s a 7-step process and doesn’t always work.

This lack of a fillet command frustrated me so much that in the end I actually worked out a way to create them. It basically involves creating a sweep using the SketchUp ‘Follow Me’ command. But it’s tedious and difficult to set up, doesn’t always work first time, and only gives predictable results on planar edges. I made a tutorial to demonstrate which can be downloaded here, but it’s probably significant that when I came to design the new mouse, I deliberately went with an aesthetic that avoided the need for filleting. It looks crap in renderings though.

Modelling the camera also highlighted another very important aspect of SketchUp – its user-developed tools. On a number of occasions the software reported that the model wasn’t ‘solid,’ an essential requirement if it was going to be manufactured via an additive manufacturing process. However, within SketchUp, there is no way to discover what is actually causing such problems, which by their nature tend to be hard to find (the easy-to-find ones have usually been spotted and fixed). But a solution was found within a resource library provided by Google which contains Ruby scripts – plugins for SketchUp which have been developed by users. These plugins are unsupported by Google, who provide no guarantee as to their quality, nonetheless a significant number of such plugins are well written (many have been updated numerous times) and extend SketchUp’s capabilities dramatically. I managed to find one plugin (Solid Inspector) which analysed a model and showed any problems preventing it from becoming solid; it doesn’t work perfectly, but without it I definitely wouldn’t have been able to complete the new mouse design. A couple of others which I used were this one for drawing splines, this one for importing .stl files and this one for exporting them.

Most of the tools inside SketchUp are easy to use and seem to work exactly as they should, this results in a product which is incredibly easy to pick up and start working with. But inevitably in the quest for simplicity, some functionality has been left out. As well as the missing tools already mentioned, there a few others which I think could have been added without making things too complicated, for instance there is no measurement tool – to get the length of a particular edge for example, you need to add a dimension, which then needs to be deleted again. But without doubt the biggest frustrations for me came from two elements which seem to be particularly badly implemented.

A circle in Sketchup is actually made from 24 straight edges.

The first is the way that SketchUp produces arcs and circles, and it stems from the fact that all arcs are actually constructed as a series of straight lines. This is a problem in itself for anyone who wants to create physical objects rather than just images, because it means that surfaces are never truly smooth. However the problem is compounded by the fact that the default number of segments is 12 (24 for a closed circle), which gives a very faceted circle, or cylinder if the circle is extruded. The number of segments can be increased manually, but the default of 12 can’t be changed, and once you’ve exited the arc construction tool, what you’ve drawn can’t be changed either. Especially early on, I lost count of the number of times I forgot to increase the number of segments and only realised further down the line, at which point I had to decide whether to delete out the feature I’d been working on and remodel it, or just carry on. Just allowing the default number of segments to be changed in the preferences would drastically improve the tool.

The second frustration came from the way SketchUp implements layers. Unlike every other piece of software I’ve used I think, elements that are placed on different layers within SketchUp will still interact with each other, even if their layers are hidden. So a feature you’ve been working on and then hidden on one layer will merge with another feature on another layer, even if you want to keep them separate. It just doesn’t seem to make any sense – if I wanted them to merge why would I put them on different layers? You can get round it to some extent by grouping sets of surfaces (groups can’t interact with each other), except that it’s possible for a group to be on one layer, while the surfaces contained in that group are on others. The behaviour is also particularly badly documented, I couldn’t find anywhere that explained the way that groups and layers work, and it took me about two weeks of thinking there was a serious bug before I worked out what the ‘logic’ was (to fix things you first have to move the group so it won’t interact with anything else when exploded, then ‘explode’ the group into its constituent parts. Deselect and reselect all the parts, place them on a layer, then recombine them as a group again).

Frustrations aside, SketchUp is a great tool. For sure, it is basic: anyone with previous experience of CAD software will find the capabilities of SketchUp extremely limiting. But as the next few posts will show, it’s nevertheless possible to model a manufacturable consumer electronics product using the software, and at the same time introduce, by necessity, an aesthetic which might not otherwise suggest itself. For anyone with no previous experience or access to CAD software, this could be a liberating opportunity. The problem, I suppose, is that opportunity isn’t the same as reality. SketchUp, and similar consumer CAD packages, put modelling tools in the hands of those who wouldn’t otherwise have access to them. But there are still a lot of issues that might prevent someone actually manufacturing a product.

¹ Burns, M. and Howison, J. (2001) ‘Digital manufacturing – Napster fabbing: Internet delivery of physical products’ in Rapid Prototyping Journal, 7(4), pp.194-196

² Malone, E. and Lipson, H. (2007) ‘The Factory in your Kitchen’ in Proceedings of the MCPC 2007 World Conference on Mass Customization & Personalization, 7-9 October, Massachusets Institute of Technology (MIT)