This year marks a turning point for our young company, after two years of product development in the field of semi-industrial 3D-printing. Still being industrial design students, we are looking into graduating this spring with a year behind schedule. We invested the pandemic induced time-out into the development of our Badass Pellet Extruder and the Bloft Mk2 large-scale 3D-printer, whose beta testing is about to start soon.
New Technology for New Challenges
We started 2018 building a Hangprinter v3.3 by Torbjørn Ludvigsen. The following year we already printed two massive projects on it, but to be honest, it was pain and highly experimental. The Hangprinter is an unique 3D-printer class, that has the printhead suspended and guided only by cables/lines, where as the traditional 3D-printer works with a rigid frame and linear guides and bearing.
A cable-driven 3D-printer eliminates the need for expensive parts in the motion mechanics. And in case of the Hangprinter, also the need for a rigid frame. The main benefit of a cable-driven 3D-printer lays in the low cost scalability of the system. It makes hardly a difference if your print area is 1 m in diameter or 10 m. As long as you have enough cable you are good to go, at least in theory. And cable happens to be rather cheap.
The flip side of the coin is the complexity of the software and hardware components needed for accurate and reliable print results. But, it is doable. It's only a LOT of work.
We learnt pretty quickly, that FDM-extruders are too slow for cable-driven 3D-printers. This class of printers is playing out its true potential beyond the one cubic meter dimensions. FDM-extruders take weeks, if not months to finish a print that big. So, it was quite obvious, that we needed to have another solution. But that wasn't the only concern when thinking about extrusion technology. There were actually three other things to consider.
Let's think first about the properties of thermoplastic. Plastic has the tendency to degrade during each melt cycle, some plastic types degrade more, others less, but in the great picture there are always polymer chains breaking, causing the plastic to lose some of its mechanical strength. Production of plastic filament for FDM-printing starts with the plastic raw material, the pellets, that are made of virgin resins and which then are extruded for the first time. After exiting the extruder, it is chopped to a more or less standardized granulate size of 3-5 mm.
At the filament factory these pellets are then remolten and extruded again, but this time the plastic is cooled and pulled to either 1.75 or 3 mm diameter filament before wound up onto a spool. A high quality filament requires a tight dimensional tolerance. Something you can only achieve with expensiv