It’s not every day that you get a request to 3D print a life-size replica of a horse’s head from a statue, but that’s what happened when Fokus Grupa – an artist collective based in Rijeka, Croatia, contacted us this summer.
Their idea was to create a new art piece based on a 3D scan of an equestrian sculpture which stands in the main square in Zagreb, the picturesque capital of Croatia. A 1:1 replica would require a print standing over a metre tall, a metre deep and 60 cm wide – quite an undertaking when working with printers whose maximum print size is 28.5 x 15.3 x 15.5 cm.
The first challenge for us was the file editing required – the 3D scan of the horse which was provided was of fairly low resolution, which, when scaled to the correct size, leaves holes and gaps between surfaces that need to be repaired. This somewhat tedious task can be made easier with automatic repair tools found in 3D modelling software but there are always issues leftover which require manual editing. With the model fully repaired, the next stage was the gruesome task of ‘slicing’ the horses head into separate blocks which our printers could handle. In order to ensure each individual part would be printable we made each block at least 20mm smaller in each axis – allowing room for the base layer (or raft) which the printers use instead of printing directly onto the build plate.
At this stage we had a large patchwork 3D model of a horse’s head to play with. To reduce print time, weight, and ultimately cost, the inner section of the scan was removed to leave a thickened ‘shell’ of the original scan.
With 124 blocks of all different shapes and sizes needing to be printed it was time to go Excel-geek. Each individual block was saved as an .stl file and loaded into our printer software to give us a time and material usage estimation we could use to plan the printing process. Prints ranged from half hour – 6 gram jobs, to 15 hour – 366 gram ones. They were all recorded in our spreadsheet and formatted to show the varying print times. This allowed us to estimate both the amount of filament we would need to order, and a schedule for printing which would make the best use of machine time. So with images of the famous Godfather scene galloping (sorry) through our heads it was time to start printing.
arge blocks were printed individually, small ones grouped together to maximise efficiency until we were left with a pile of horse parts waiting to be assembled.
To ensure that all of the blocks had been printed and that they fit together correctly we assembled them using tape. Some of the larger blocks had warped during printing - creating gaps when assembled with neighbouring pieces. This process of 'pre-assembly' allowed us to identify where these gaps appeared, we subsequently split some of the larger blocks into multiple parts to alleviate this problem.
With the new blocks printed and pre-assembled we were ready to start fixing them permanently using epoxy resin. Anyone who has ever used epoxy resin before will know that it is a messy and smelly business. Due to the working time of the epoxy each part had to be held in place by hand (curved geometry makes the use of clamps impossible) until the resin had hardened.
Bit by bit, the horse's head was taking shape and the unidentifiable blocks (except for our cunning orange marker numbering system) were beginning to make up unmistakeable equestrian features - a mane, nostrils and eventually...ears!
To enable us to work on the bottom of the head, we kept the final three layers separate allowing us to flip the whole piece upside-down. The next stage was to fill the gaps between the assembled pieces of our lobotomised horse's head. For this we used a general purpose filler which was quick-drying and easily sand-able.
ith both sections filled and sanded it was time for the final join and the completion of the horse's head.
Totaling 14 Kg of plastic (equivalent to 3.5 miles of ABS filament) and half a Kilogram of epoxy resin, the horse's head was finally ready to be picked up by Iva and Elvis (Fokus Grupa) and transported painstakingly to the exhibition at the Transmission gallery in Glasgow. This project's model was the largest we have undertaken and posed many new challenges. Having said this, it was one that we really enjoyed, and in the end, the result was quite spectacular. After months of e-mail communication and the odd video call it was great to finally meet Iva and Elvis who were kind enough to invite us to the opening of the 'People Love Monuments' exhibition and explain the story behind the series of works presented.
Print me a horse's head?