Let’s get physical

Written by Helen Kelly

Published Tue 15 Jul 2008

3D Print of Reykjavik Concert and Congress Centre in Iceland, Henning Larsen Architects. Scale 1:500

Reykjavik Council’s plan for a new modern concert and conference centre in the old harbour area was always going to be controversial. Its vision of a contemporary design structure that would connect the increasingly dilapidated downtown area with a modern harbour-side development was a huge change from the traditional Icelandic cityscape and residents were quick to raise concerns that the new structure would suffocate the former charm of the old city.

As such, it was vital that the project could subtly combine the old city’s charisma with a modern design concept. Copenhagen-based Henning Larsen Architects’ (HLA) winning design gathers inspiration from the northern lights. Situated on the boundary between the land and the sea, the building has been designed to stand out “like a radiant sculpture reflecting the sky and harbour as well as the vibrant life of the city”, according to HLA.

Artist Olafur Eliasson designed the façades of the building–a crystalline lattice of glass and steel. The glass prisms of the façades capture and reflect the light.

Facade shell Reykjavik Concert and Congress Centre in Iceland by Henning Larsen Architects. For this part the model makers used a combination of 3D print and polystyrene foam.

HLA’s winning concept was boosted by its use of 3D modelling and Rapid Prototyping. Using 3D CAD software and Z Corp’s latest model 3D printer, the ZPrinter 450, HLA was able to accommodate a number of design iterations quickly and easily–and at a relatively low cost.

“The building was created in 3D in extension of the company’s in-house ‘Det Digitale Byggeri’ (The Digital Building Project), which aims to reduce errors and costs in the building process,” explains Morten Steffenson, an engineer at HLA, who introduced the use of Z Corp technology to the firm. “By using parametric building models in 3D we are able to make extractions for building volume, lists of required materials, and price. With all buildings created in 3D in the future, the ‘distance’ between building models and 3D prints will be smaller, therefore making it more feasible.”

A model revolution

Rapid Prototyping (RP) technology is quietly revolutionising the architectural industry. It has liberated a traditionally laboured and expensive process with a relatively quick build speed and reduced turnaround times. Models that would have once taken weeks to complete can now be turned out in less than a day.

That has allowed a more iterative design process with model-making now being integrated into every stage of design. Aedas Architects in the UK, for example, uses RP for client briefings during the early-conceptual stages as well as for internal ideas generation. “We will create [multiple] models if there are a number of concepts to put forward to a client,” says Danny Austin, architectural visualiser in Aedas’ Leeds office.

3D printing has allowed Aedas to communicate more effectively, and more often, with clients. “You could produce 3D models and an animation to show the building’s form, but an actual physical model helps the client see what you mean,” says Austin.

Improved client communication is helping to reduce design costs. “What is intended in plans is often starkly different from what is executed,” says R. ‘Partha’ Parthasarathy, owner and founder of iKix, India’s first service bureau chain for architectural 3D printing, based in Chennai, Tamil Nadu. “iKix clients are commissioning 3D printed physical models from the earliest stages of the design and avoiding these catastrophes. Clients bring us in early and start making models from the concept stage, which is yielding project management savings in the 3 to 8 percent range, which is huge given the size of their construction budgets.”

Architects and engineers are similarly benefiting from the ability to use physical models earlier in the project. “Architects just can’t collaborate around a napkin or computer file the same way they can around a physical model,” explains Al Vass, Associate Vice President and Senior Project Designer at The Jerde Partnership, an architecture and urban planning firm, headquartered in Burlington, Massachusetts.

“Architects need to literally walk around a design, get their hands on it and maybe mark it up with a pen. This process is as vital as presenting to the client and just as rigorous.”

The KPT Tower model had to be built in two sections so Aedas developed a bespoke joining mechanism to hold the model together.

In the fold

As the cost of 3D printing technology slowly comes down, it is increasingly being used in-house to construct scale models for commercial and residential design projects. Aedas’ London-based advanced modelling team, for example, works with its architects and design visualisation specialists to repurpose 2D AutoCAD data into files that are suitable for rapid prototyping and prints the results in a bright white resin.

Using a Dimension Elite ABS FDM Printer from Stratasys, Aedas estimates that costs run at about £0.64 per cu m of both model and support material, plus the cost of one print tray at £5.99 and any additional operator time.

The firm’s design visualisation specialists create the 3D models in Autodesk’s 3D Studio Max. SketchUp is sometimes used in the early design stages, but Danny Austin finds that it does not have the functionality of other 3D programmes. “We work to a tight deadline, so [the design] has to look spot on. Under the hood [SketchUp] can be a little… sketchy,” he says.

Aedas recently completed a joint project on the KPT Tower, a multi-storey residential development in Karachi, Pakistan. Aedas built the CAD model using parametric algorithms, while the imaging for KPT Tower was produced externally. To complement the CG imagery, the team also produced a physical scale model, which was built in two sections as it could not be built in one go. When assembled it was 25cm tall. In a first for the firm a bespoke joining mechanism was also developed to hold the model together.

“The joint was developed parametrically so that future models of different sizes can have the same connection by simply scaling the various elements,” explains Josh Mason, a member of Aedas’ Research & Development Group. “This makes the model flexible, so the top and bottom elements of the tower can be separated as needed.”

While this was a groundbreaking project for Aedas, many architectural firms still rely on specialist bureaus, which have the expertise for more complex builds as well as specialist RP materials.

HLA in Copenhagen, for example, uses specialist bureaus for complex presentation models, such as a recent concept building with a double curved roof. A bureau was also used for the external finish in the Reykjavik Cultural Centre. “We wanted it to look like a glass building with deep mesh over it,” explains HLA’s Steffenson. “We did some tests in the design process with [in-house] gypsum models, but these did not look right.”

Design or die

The architectural community is a relative latecomer to the rapid prototyping revolution. The pioneering automotive industry first championed the technology a decade ago, with BMW developing a Stereolithography technology with German manufacturer EOS as far back as 1998.

The problem, suggests Scott Harmon from product manufacturer Z Corp, has been a lack of compatibility with popular architectural software. At present, 3D CAD data is exported for use in RP machines using an STL converter, but not all BIM (Building Information Modelling) applications support such tools. Indeed, Revit, Autodesk’s flagship BIM solution, has only just received this functionality, but even that is not in the current shipping product, and is only available on the Autodesk labs website http://labs.autodesk.com.

Even when a data translation mechanism is available, it is not usually a straightforward point and click process. Careful attention needs to be paid to ensure STL models are watertight, scaled elements are not too thin and the model is placed in the build chamber correctly. These issues need to be resolved in pre-production.

HLA’s Steffenson says he spends at least a couple of hours analysing each RP model prior to printing. “I look for elements that are not solid or that are too small to print when they are scaled down,” he says. “I like to have at least 2x2mm thick structures [columns] so they don’t break. If there are any structures smaller than this I, or the architect, will manually re-enforce it by adding new elements on top.”

That means that the RP model will not be exactly to scale, which some clients will be more accepting of than others.

For particularly complex designs it can often be easier to remodel the data from scratch, rather than repurposing existing 3D CAD data. Steffenson spent up to 20-hours remodelling the data for Reykjavik’s Cultural Centre because the CAD design had heating and ventilation systems built it as well as ‘intelligent walls’, which were unnecessary to the model build process.

Austin from Aedas prefers to import 2D AutoCAD data, into 3D Studio Max, which he then traces over to form the basis of his RP model. He finds this particularly important when converting data that he has not created himself.

“Volumetric printing takes no prisoners,” he says.” It will pick up any overlaps, or gaps. [When using a colleague’s data ] you have no way of knowing how a drawing was made,” he explains. “If I draw it myself on AutoCAD I will re-use the data straight away; but it is still wise to re-do each drawing. It is not quicker than traditional modelling, but it is a lot more accurate.”

Some architects, who have embraced rapid prototyping at the heart of the design process, have developed a modelling process which allows them to design straight into 3D. Stuart Jackson, manager for the UK and Ireland at product manufacturer EOS explains: “Instead of creating a very complex 3D model, complete with internal design features such as lighting and heating, architects now have to focus on creating structurally-sound designs. [Rapid prototyping] needs a solid surface, otherwise it will not print. It can take up to a week to fix the data.”

EOS, however, has a quick-fix solution for those architects. “As a shortcut we can shrink wrap the surface of a model to hold it together, for example make it a full bar where it might have gaps.” This feature can be set up as an automatic option to guard against unseen errors that could ruin the build process.

The types of materials used for rapid prototyping will also affect the design process [see box out page 41 for more details]. Powder-based technology, for example, widely used in Z Corp machines, can be very brittle and prone to breakage. The models are at particular risk of breakage when they are first removed from the build tray as this is typically when the extra powder is manually removed, and in transport.

Plastics-based materials, such as those commonly used in LS (Laser Sintering) technology are more durable.

Conclusion

While saving time and costs and improving communication are undeniably a massive advantage in using rapid prototyping, it is perhaps RP’s ability to rouse the imagination that really makes this technology revolutionary.

“There’s just something about a 3D model that stirs the passions in ways that a blueprint or computer file just can’t,” says Gita Monshizadeh, CAD Development Manager, at Ramboll Group, a Nordic consulting outfit headquartered in Copenhagen.

That enthusiasm in turn is leading to a surge in demand for RP. At the completion of the Reykjavik Concert and Cultural Centre design process, for example, there was so much demand from RCCC employees for 1:500 scale models to put on their desks that HLA has spun off a mini-business in manufacturing the small models. It makes two models per print run and charges the cost to the clients. It would seem that the old city has found its charisma once more.