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While in the Netherlands, I visited CyBe construction. With their robotic arm mortar printing system, CyBe has completed projects around the world with many more underway from their various clients/partners. 

The training was a 2 week event starting with just learning the basics and watching the very experienced CyBe team operate the robotic arm they have in the facility. By the end of the first week I was beginning to assist with prints lead by my trainer Marc. The second week we went to France Sunday-Thursday to visit Lille University and a 3D printed guardhouse in La Havre which I filmed a tour of with CyBe CEO Berry Hendriks while we were there. 

After the France excursion there were 2 days left of training before my final exam to earn the Basic Operator Certificate. On Friday of the first week I was feeling pretty confident with the system but after spending 4 days away from the machine I certainly felt a bit rusty coming back. I had gained some confidence with the equipment after the first week but hadn’t yet built nearly the true muscle memory level of operation exhibited by Marc, Yop, Alwin, and Jeremy. 

I decided that I would live stream my Basic Operator Final Exam on YouTube to give my subscribers an insight to the 3D printed construction world that they otherwise may not have been able to access. In the month since I filmed that live stream it has already accumulated over 50,000 views with an average watch time of 20 minutes so relative to my small channel it was a big success and something I will try to do again in the future. 

The test was going to be a wall element from a building that was designed by a company in Japan. 5 of these identical wall units are organized in a circle which makes up the small round building. The curvature of the walls mean the base is significantly smaller in surface area than a slice of the middle segment meaning there will be overhang in the layers and considerations of balance are critical to keeping the printed concrete upright while it prints and cures. 

There are some things that need to happen pre print to ensure a safe and productive environment. Ideally you don’t want to print concrete directly on concrete because removing it afterwards could pose a challenge that could damage the print. A couple simple sheets of cellophane can prevent the concrete material from sticking to the slab. Another strategy often employed by CyBe is constructing a small platform out of pallets to print on. Once you have your print area set up you can start your first layer test. During the first layer test make sure the extruder remains in the print area. After the first layer move on to the rest of the print in auto mode so that you don’t need to keep your hand on the controller. It’s generally recommended to keep people out of the print area but for some prints it’s critical to remove portions of the material which requires humans being near the print. By running a full dry test you can be confident there are no rogue points on the print path that would send the printer in a random, potentially dangerous direction. 

The mortar material used by CyBe is a differentiating factor of this company because instead of using accelerator additives they use retarder to actually slow the hardening rate of their material. The dry mix has so much accelerant in it that this retarder is required to prevent the material from hardening to quickly. At ideal levels, the material is nearly completely solid after the 5th or 6th printed layer. This adjustment is done at the mixer which is one of the most critical components of the print process. The mixer is where the dry mix, water and additive come together and get combined thoroughly in the rotor-stator before entering the hose which leads directly to the extruder head of the printer. Adjusting the retarder levels is critical because depending on factors like the length of the hose, time between layers, ambient temperature, humidity ect… you may want to raise or lower the levels to accommodate the circumstances you are printing in. 

Starting the mixer flow is somewhat of an art if you just turn it on and leave it then you are bound to cause a clog. The key is to start the water flow and the additive at an even higher level than final print values and slowly start introducing the material which only mixes at one constant speed (for my purposes). You start in 10 second intervals leaving the dry mix pump on for 1 second and off for 9 then on for 2 and off for 8 and so on until you are on for 9 seconds off for 1 at which point you can just leave it on completely. After the material is fully flowing you can reduce the water levels and the additive levels until the mix is satisfactory for printing. You know the material is dialed in right when it begins stacking slightly from the extruder head. Another great test is to use a spatula to get one small length of printed material. When it is ready, the material will stick to the spatula even upside-down, you will also feel a slightly firm ‘core’ if you poke the material with your finger. 

When the concrete slabs that make up the floor of the CyBe facility were built, they didn’t have robotic arms precisely extruding concrete so the slab that we were printing on was slightly uneven maybe by +-1cm initially this gave me some concern but the CyBe team assured me it would not cause a print failure. The trick on the first layer is to slow down the machine a bit. The material is always extruded at a constant pace so if you slow down the robotic arm you end up with a thicker line of more material, this thicker layer allows for more margin of error on the print bed and gives a nice base to print the next layer on. The ABB robotic arm is of course extremely precise so after that thicker first layer compensates for any irregularity in the print area every layer after that will be precisely the height it was programmed to be (Usually 12.5cm)

Printing is actually the easy part. If everything was done properly for the setup and material qualities the only thing left is cutting away any sections of the print you wish to leave open and keeping the mixer full of dry material. In the CyBe facility they were using 25kg bags of concrete but with a large silo jumbo bags (1.2T) of concrete can be loaded in to further reduce the human labor input required. During the print someone should water down the 

After the print comes the cleaning process. This is a critical step of anything involving concrete especially when it is so fast to harden. Cleaning off the wet material is much easier than trying to pry off the rock chucks of concrete after it becomes solid so you want to do this part quickly and CyBe does. Their system mixes the additive in at the mixer rather than the extruder head so 90% of the cleaning process is done at the mixer which simply involves flushing out the hose with tiny sponge balls then replacing the mixing iron with the cleaning iron and running water through the mixer until all of the sediment from the concrete mix leaves the machine. Overall the cleaning process takes about 10-15 minutes which is notably shorter than the competitors that I’ve seen granted it is a smaller machine. 

I have to say I was very impressed by the lack of cracking in the CyBe prints, Nearly every 3d printed building I’ve seen in the world has some aesthetic non structural cracks but I didn’t see these in the CyBe prints. Being able to hose down the material so quickly after the print goes a long way in controlling the temperature of the concrete as it cures. Keeping the temperature under control significantly reduces the risk of cracking. Another unique factor of CyBe is the sponging process they use to smooth their prints. As mentioned earlier, the material cures within 5-6 layers but within that range the layers are still somewhat wet and malleable so manually brushing over them with a sponge can fill in the layer pattern resulting in a completely smooth wall. 

I was the first person to receive training as an individual rather than a team but I did have 2 CyBe employees assisting me with parts of the print because it generally requires a team of 3 to operate the printer. When everything is going well it’s mostly just standing around, after a year or two of experience it’s even possible to operate the printer solo but with so much going on and little margin for error it’s much safer to use a team. I certainly made a few mistakes, most notably in the beginning I didn’t turn on the water flow on the mixer and while we were calibrating the material component values I let the mixer run empty forgetting to add more material. Luckily this all happened prior to the print. I also left the water heater off but that didn’t cause any issues although it would have gone better at the right heated values, that may be why dialing in the material in the beginning was a bit tricky. You can watch the whole thing with all raw footage from the live feed on my YouTube channel. I managed to get through printing the entire 2.5m wall unit without anything coming up that would detriment the print. At the end of the print I was awarded my Basic Operator Certification. 

Learning to operate a concrete printer felt like a bit step on my journey around the world researching construction automation technology. I had spent over a year researching everything I could find publicly available on the internet but the knowledge acquired from actually making a print happen from start to finish is a completely new level for me. I hope to continue to expand my skillset and learn the operation of other printers. I have learned so much from this experience I think it will be even easier for me to learn how to operate the next one because so many factors are similar especially when it comes to the mixer and the controller which have been very similar with some unique differences at each site I’ve visited. Most of these differences in the mixer are due to the lack of functionality in the off the shelf mixer pump systems currently available on the market. The available equipment is designed for different use cases that are less precise so the units require after market modifications by the companies operating the printer yielding differences between competitors. 

The debate between robotic arms and gantry systems for 3d printing on the construction site rages on. I can say without a doubt both have their own set of advantages and disadvantages. You can’t truly identify one as superior unless you clearly define a particular project. Robotic arms can’t make monolithic structures larger than their print area but for many applications you don’t wan’t a monolithic structure anyway.  When you have to move the printer that is certainly much easier with a robotic arm rather than a gantry system that must be assembled every time. This is something we discussed on an episode on the Automated Construction podcast below.

I certainly expect great things from CyBe in both the near and extended future. They are a nimble and efficient organization considering many verticals trying to make 3D printing mainstream on the construction site. For more information on their technology check out you can also schedule a call with me to discuss which printer would best suit your project via make sure to subscribe to my YouTube channel and consider leaving your email here on my website so that on the rare occasion (so rare it’s never happened yet) that I send something out to my email list you don’t get left out.

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Published by Jarett Gross

Construction Tech Correspondent Spreading Awareness of Cutting Edge Firms Building the Future of the Industry

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