FDM is the technology that most RepRap style 3D printers are designed around. It’s cheap, reliable and simple, however it is not very fast. The speed limitations of FDM are driven by the fact that you have a very tiny nozzle extruding the plastic with a diameter usually smaller than 0.5mm. This nozzle has to ‘draw’ each layer of your part line by line and then effectively ‘color-in’ the gaps between the lines to make the section of your part solid. The only way to make the print process quick is to move the print head or table faster while extruding the plastic as a faster rate. Sounds simple, however when you take into consideration the mass of the print head or print table, you can only increase the speed so much before the moving mass starts to become an issue. There have been some 3D printers produced with very low weight print heads such as the Ultimaker but up until now I have never seen something move as fast as the Rostock! You’ll want to check out the video after the jump to see for yourself!
Johann is working to resolve this problem with his newly released 3D printer called the Rostock. Using a very unconventional design, Johann’s 3D printer has three arms or parallelograms which are driven up and down on three vertical tracks. The three arms meet in the middle and support the print head platform via small universal joints. By moving each of the arms up and down the tracks you can quickly and accurately move the position of the print head. This configuration, know as a Delta Robot, has been experimented with for 3D printing but the machined used threaded shafts to drive the arms up and down which severally limits the speed they can move. Delta Robots were developed in the early 80’s and have traditionally been used for applications which require fast movement such as pick and place robots for assembling PCB’s. It’s interesting to see this configuration adapted for 3D printing.
The print speed and movement looks impressive but I’d be interested to know how well the accuracy stands up over time as I imagine that tolerances on the joints are more critical with a delta design. Still its very simple and looks to be able to produce decent prints. It we’ll be interesting to see if this Delta Robot configuration becomes popular in the RepRap community.
For more information head to http://deltabot.tumblr.com/