For the past six years we’ve been making architectural models using our Z-Corp 420 and 650 3D printers which use resin boned powdered gypsum as the build material which are then treated with a hardener. This produces fine white, exhibition quality architectural models but the process can be laborious, time-consuming and the models, like all plaster models will break if you drop them. We’ve also made models in ABS using our Dimension SST 1200 FDM machine which requires a support material and we’ve made paper models using our MCor. Recently we’ve been experimenting with Makerbot 3D Printers, printing with 1.7mm ABS (Acrylonitrile Butadiene Styrene) extruding at about 225 degrees C that doesn’t require support materials. We had our Makerbot supplier John E Wright in Nottingham print a sample model for us on the latest Makerbot Replicator Z18 to evaluate the finish and usability of its output, using an STL file digital model of a 17th century design by Nicholas Hawksmoor which we made a few years ago. The results have been encouraging and we think this process is particularly good for architecture students where robust and cheap 3D models are needed in design development and sometimes for mechanical parts. It’s also ideal for product design, interior design and museum exhibition design students.
For our purposes in Digital Building Heritage ABS as a material is useful because it’s durable and inert, it’s also soluble in acetone allowing us to weld parts together and assemble much larger models than the admittedly large bed of the printer can accommodate (305L x 305W x 457H build chamber). ABS is much more easily recyclable than PLA and it’s inexpensive, very much less expensive than the Z-Corp print powder we use. ABS is also tough, you can drop it, saw, sand and file it, and overall it’s ideal for our postgraduate students making models of historic buildings and their interiors. On the downside, even with an ABS filament size of 1.7mm, the striations on the finished models are visible but we feel that a little time hand finishing, filling and smoothing where necessary can overcome this. We have considered PLA as an alternative thermoplastic material (it’s made using plant by products) and the Z18 will use it, but its main disadvantage for us is its low deformation point (it can deform in temperatures as low as 40 deg C, a house radiator can be at 60 deg C), so we wouldn’t want to take the risk in say an exhibition setting where a cased, highly illuminated model can get quite warm. We think our results have been encouraging and we’ll be looking to explore the potential of this low-cost form of 3D printing for a number of uses.