One of the moments that will likely stand out when we look back at the history of construction 3D printing is the construction of Europe’s first 3D printed building in 2017 by 3D Printhuset (now COBOD). As a call back to this original structure, which still stands in Copenhagen, and to show how far its come with its construction 3D printing technology since 2017, COBOD recently reprinted The BOD building.
The 2nd BOD was 3D printed using COBOD’s second generation machine, the BOD2 and was completed in just three days. According to COBOD, which closely documented the entire process, it succeeded in achieving 20 times higher productivity compared to the original BOD’s construction.
“We have said time and time again that this technology has great potential, is developing very fast and that there is still so much to be learned to fully utilize this technology,” said Henrik Lund-Nielsen, CEO of COBOD. “Today, we provide the documentation for exactly that, by having 3D printed an identical building to The BOD building we did exactly two years ago. Although not everything went as well as expected, the results and improvements we achieved this time speaks for itself.”
One of the challenges faced during the construction of the second BOD building was related to the optimal functioning of all three elements of the 3D printing technology. That is, in order for the BOD 2 3D printer to achieve the best print results and speeds, the printer, concrete mixer-pump and the printable material all need to be at their best. According to the COBOD team, all three elements did not reach their peak performance in this particular build. Still, the results showcase growth and COBOD is satisfied with how the re-print went.
“We are extremely pleased with how well our new BOD2 printer performed during this test,” explained Michael Holm, Head of R&D at COBOD. “The BOD2 3D construction printer has an impressive print speed of up to 100 cm/second, and during this print we could comfortably print with a speed of 35 cm/second, which is faster than anybody before. However, our concrete mixer-pump could not continuously follow the printer at this speed, so for a lot of the print we actually had to slow down the printer to avoid running out of materials. Hence we are now working with our pump suppliers to overcome this barrier and truly utilize the full speed of our BOD2.”
The re-print also suffered a minor setback because COBOD accidentally asked its concrete supplier to reduce the setting time of the material too much, which led to a clogging of the material in the hopper above the print head. Eventually, this problem was fixed by vibrating the material in the hopper. After this fix on the third day of printing, the productivity reportedly doubled (from 10 cm/hour to 20 cm/hour).
“When we printed the original BOD building on September 11 two years ago, we spent two months finalizing the 3D printing,” said Jakob Jørgensen, Head of Technology at COBOD. “This time it only took 3 days, or 28.5 hours to be precise. This is truly a milestone in the development of the 3D construction printing technology, and documents a remarkable 20 times improvement in our productivity in just two years. The much faster print time of this print reflects the improvements of our technology by using the new and 10 times faster BOD2 printer and that we have learned a lot from the first time we 3D printed the building.”
Lund-Nielsen concluded by saying: “Again we learned a lot from applying our technology to a project. We are now converting the lessons that we learned into even better solutions for our customers going forward. Once we have done that, we believe we could 3D print the entire BOD building in just 8 hours, should we decide to print it again a third time. Nonetheless, this re-print is a significant milestone. A milestone that documents the great potential of 3D construction printing.”