The petite but spectacular bandstand, built for a mere £60,000, is a curious hybrid of traditional construction and state-of-the art engineering. The old folks might be reassured to learn that its billowing canopy was constructed in traditional fashion – hand-built from plywood by a Bath joiner using techniques akin to those used in boat-building. In contrast the engineer, Price & Myers 3D Engineering, employed advanced computer modelling techniques borrowed from the field of product design.
For Tim Lucas, director at Price & Myers 3D Engineering, the project started out as a fairly routine job when the architect handed him a rough model of twisted wire mesh. "Niall said 'this is roughly what I want, go away and engineer that'," says Lucas.
Lucas started out using AutoDesk Viz, a standard visualisation programme that allowed him to produce a 3D form that the architect was happy with. "Niall would come round to look at the screen; we'd spin it around, tweaking it, until it looked right," says Lucas.
So far, so run-of-the-mill. At this point, the team realised that fabricating the canopy in carbon fibre, as originally planned, was going to prove prohibitively expensive. After considering steel, aluminium they rang up Michael McHugh at Westside Design Workshop, a joiner the architect had worked with on a previous job. McHugh suggested laying a skin of thin plywood over a frame of criss-crossed timber struts and strengthening the structure with fibreglass. "The joiner is the hero of the piece," says McLaughlin. "He came back to us with a much cheaper price."
This is where the engineer had to get creative. In order to print out a set of templates the joiner could trace to cut the plywood, Lucas had to transfer the 3D model into AutoCAD, a process that took four days. With the second half of the project – the wheeled carriage on which the canopy sits – yet to be designed, Lucas didn't fancy another bout of tedious CAD-jockeying. "I wanted to cut all that out and spend my time actually engineering the project. We decided we needed to find a better way."
He reached for SolidWorks, a £4000 software package used by industrial designers to model everything from domestic power tools to aircraft undercarriages. Lucas had played around with the software before; he had been introduced to it by Sam Price, the son of Price & Myers' founding partner and a product designer by profession. But this was the first time the firm had used the package on a real project.
SolidWorks allows the user to design a product in 3D, produce realistic renderings and subject it to structural analysis using the Cosmos/Works plug-in. In a process known as "parametric" design, the software produces working drawings that are automatically updated each time the 3D model is modified.
Many CAD producers are trying to incorporate parametric design capabilities into their packages but industrial design software is way ahead in this respect. "We've taken something they've used in product design for years and years," says Lucas.
Designers can build up highly complex products made of hundreds of different components. Standard components can be dragged and dropped into the design; the programme knows how each component should fit together and will alert the user if there is a clash. "You simply wouldn't be able to include components that don't fit together," says Lucas. "If you make a mistake, red exclamation marks flash up on the screen." For example, if a design error meant that a wheel axle was attached to the bandstand base at an angle that made it impossible for the wheel to turn freely, the software would alert the engineer.
SolidWorks can also spit out fabrication drawings and data for each component, which can then be sent digitally to fabricators' computerised production lines – a process known as CADCAM (computer-aided design, computer-aided manufacture). "This is where we go beyond what engineers normally do," says Lucas. "Normally, you hand over drawings to the fabricator, who redraws everything."
For the relatively simple steel struts of the bandstand's base, there was no need to go down the CADCAM route, but the software offers engineers the tantalising possibility of taking a project from concept design to manufacture using a single computer model.
Programmes like SolidWorks are only suitable for small-scale construction projects; whole buildings, with their multiple layers of structures, M&E systems and so on, are far too complex. As Lucas points out: "It's perfect for simple projects when accuracy is key."
Many in the construction industry await the arrival of dedicated parametric design tools with bated breath, not least because, in addition to its use in the production process, the 3D model – which can be viewed from any angle and taken apart on-screen – is instantly comprehensible to clients, the public and other interested parties who find it difficult to read 2D plans.
It also saves time: Lucas estimates SolidWorks shaved two-thirds off CAD work. On top of this, there was no need to check drawings for design errors and no problems with ill-fitting components – the components fitted together perfectly first time. Just like the instruments in a well-rehearsed brass band, in fact.