Calculations vs. 3D CAD – A historical curiosity

**Guest post by Al Dean**


When you consider the level of intelligence, automation and frankly, jaw dropping amazingness of most of today’s 3D design and engineering tools, it’s perhaps a curious thing to note that most systems don’t provide much in the way of support for one of the most fundamental parts of the design and engineering process – mathematics and calculations.


We’re all familiar with the ability to create parameterised, intelligent models. The ability to take geometry dimensions and drive other dimensions by linking them together is one of the basics of every modern 3D design system. Parametric modelling is, I think it’s fair to say, a de facto standard in term of working practices.


Over the years, the sophistication of those dimensional links has increased. From basic mathematics (D1 = D2-D3) to more complex equations, look-up tables, the ability to have state based or logic operators. But essentially, we’ve got a set of tools that allow you to link one set of dimensions to another.


The curiosity is that this doesn’t really reflect the very earliest stages of engineering development. That point where ideas are worked out, where the real thinking is done and yes, there’s a whole lot of calculations. It’s looking up empirical methods, it’s using established theory and methods to work out if what you want to achieve can actually be achieved. And as I’m sure most of you will know, most of this doesn’t really lend itself to physical dimensional constraints as you would place on a digital model. What we’re talking about here is documenting the design process and the intent behind your product decisions.


So ask yourself this. Why is this the case? I’ve been giving it some thought for a while and I’m stumped if I can come up with a good reason. Perhaps it’s because the CAD industry revolves around the concept of geometry creation and that most vendors don’t consider those tricky and challenging parts before their own tools get involved. Is it perhaps that in many industries, the CAD work has, until recently, been something that’s done separately from the engineering conceptualisation and calculation phase?


If you look at the range of mathematic or calculation applications out there (There’s PTC Mathcad, of course, as well as MatLab, Maple and of course, everyone’s favourite, Excel), there’s very little in the way of linking these to the 2D or 3D geometry design systems. Yes, Excel integration is commonplace and many 3D design tools include some form of basic formula + parametric capability, but it often does not go beyond that.


PTC has, of course, got a head start on this since its acquisition of Mathsoft, just under 10 years ago. The latest release brings some interesting tools that allow you to create those links between the calculation worksheets within PTC Mathcad and your geometry models in PTC Creo.


The mechanism to achieve this link is interesting as it’s not just pulling values from PTC Mathcad calculations to drive geometry parameters – it works the other way too. Outputs from PTC Creo models can be fed back into the worksheet and used as part of further calculations.
There’s also an interesting move in how that data is stored. A traditional workflow would mean that you have two data entities – the geometry set and the worksheet. PTC Creo now allows you to embed PTC Mathcad Prime 3.1 worksheets directly into the geometry data.

That, combined with the fact that anyone else can use that worksheet using the free for life PTC Mathcad Express, makes it a powerful combination.


There’s a lot of talk of intelligent product models being the future goal. If you look at much of the messaging around a systems-based approach or even pushing into the Internet of Things, there’s much talk of integrating real world parameters and data into the design process – but these are over shadowing the potential to do something just as fundamentally key and perhaps more longstanding – the ability to have intelligent models that are driven, in many respects, by the fundamental calculations that drive their design and engineering.