The 3D Printing Welder
Steel this printer
Michigan Tech scientists build an affordable 3D metal printer
Until recently, 3D printing has been a polymer affair, with most people printing out plastic consumer goods ranging from tent stakes to chess sets. Joshua Pearce and his team have built a printer that could add hammers to that list.
Using under $1,500 worth of materials, including a small commercial MIG welder and an open-source microcontroller, Pearce’s team has built a 3D metal printer than can lay down thin layers of steel to form complex geometric objects. Commercial metal printers are available, but they cost over half a million dollars.
The detailed plans, software, and firmware are all freely available and open source, so anyone can use them to make their own.
Pearce is the first to admit that his new printer is a work in progress. So far, the products he and his team have produced are no more intricate than a sprocket. But that’s because the technology is so raw.
“Similar to the incredible churn in innovation witnessed with open-sourcing of the first RepRap plastic 3D printers, I anticipate rapid progress when the maker community gets their hands on it,” Pearce said. “Within a month, somebody will make one that’s better than ours, I guarantee it.”
His make-it-yourself metal printer is affordable enough for home use. However, because of safety concerns, Pearce suggests that for now it would be better off in the hands of a shop, garage or skilled DIYer, since it requires more safety gear and fire protection equipment than the typical 3D plastic printer.
While metal 3D printing opens new vistas, it also raises the specter of homemade firearms.
“It’s kept me up at night,” Pearce admits. “There are lots of good things a metal printer can do, but they can be abused like any other technology. What we shouldn’t forget is that guns, like agricultural technologies, are not inherently good or bad. Harnessing our agricultural technology has allowed us to feed 7 billion people, yet we abuse it. We allowed about fifteen thousand people to starve to death today while more than two-thirds of Americans are overweight or obese. Similarly, guns can be used by freedom fighters to overthrow dictatorships or by oligarchs to throttle democracy. And, at least in the US, they are easy to get anyway. The fact is, it would be easier for most people here to buy a gun than to print it.”
Despite the dangers, he believes that the good to come from open-source 3D printing will far outweigh the evil.
“Small and medium-sized enterprises would be able to build parts and equipment quickly and easily using downloadable, free and open-source designs, which could revolutionize the economy for the benefit of the many.”
“I really don’t know if we are mature enough to handle it,” Pearce added cautiously, “but I think that with open-source approach, we are within reach of a Star Trek-like, post-scarcity society, in which ‘replicators’ can create a vast array of objects on demand, resulting in wealth for everyone at very little cost. Pretty soon, we’ll be able to make almost anything.”
The size of most 3D printed objects is constrained by the size of the 3D printer they are printed in. A group of Dutch manufacturers stumbled on this little fact when they were looking for a way to 3D print furniture. So they invented their own method.
“The innovation is a robotic arm with a print head that extrudes metal strong enough to support structure,” says Federal. Working with Autodesk and the Heijmans construction company, they have managed to print a model of a bridge that will eventually span a canal in Amsterdam.
“This is a small step into the much broader field of Construction Automation.”
The much-touted benefits of 3D printing: affordability, flexibility, and rapid production, have largely been unavailable for large-scale projects. If you want to print something bigger than a breadbox in a single pass, good luck finding the tools. Tables, bridges, and buildings are not going to come out of a MakerBot Replicator, or a Stratsys Fortus 900mc, for that matter.
This is the conundrum that faced the folks at MX3D, a furniture and manufacturing company out of Amsterdam. “We wanted a printer that could print a full piece of furniture,” says mechanical engineer Tim Geurtjens, the company’s chief technical officer. “We found it didn’t exist. So, OK we have to do it ourselves.”
To be free of the box, they wanted to make a machine that would print in lines, rather than in layers. After some experiments with resin, they realized they needed a stronger material, like steel. The answer to that need was the welding robot. Before long the team had developed robots capable of spitting out steel in long, curving lines, drawing them in the air like some kind marker for three dimensions.
To show off their technology, Geurtjens and his colleagues decided they needed a suitable demo to show off the capabilities of their new technology. “It had to be a bridge,” says Geurtjens. “A bridge is a really symbolic thing, poetically very nice, but it also shows that with our technique you can build really big structures, virtually unlimited in size.” Never mind that their town is one with some 60 miles of canals.
A few snags stood in the way of putting the welding robot to work. Early on, the nozzle would occasionally get stuck if the line it was printing grew faster than the software anticipated. So Geurtjens and his team used a laser distance sensor to continuously keep track of the position of the object and compare that to its theoretical position. In the future, they want to print their bridge with two robots that could start on either side of a canal and meet, for completion, in the middle. To do that, they’ll have to be able to communicate their positions to each other and adjust as they go.
Because of the need for all this real-time positional adjustment, the MX3D printer can be tinkered with on the fly, unlike other 3D printers that run until they finish after the start button has been pushed. As Geurtjens puts it, “Since we have to constantly adjust, it means we can constantly adjust.”
Ultimately, though, MX3D wants its welding robot to do its own adjustments. If things go as planned, they want it to do its own design as well. “Our idea is to have software design the bridge,” says Geurtjens. They’ve already made some strides in that direction. When they first started out, the software drove the robot, and humans had to manually determine the tool path. Now the software creates the tool path automatically. “What we are working on now is expanding that even further so the robot will determine its own strategy. Maybe it’s Utopian, but we want to have software that’s fully automated,” he says.
However autonomous the printer welder becomes, it’s already poised to make big changes in big structures. Once the firm prints the final functional bridge it may have to do a few more, as additional bridge orders are already in. Then Geurtjens hopes to tackle the more dangerous parts of construction. “There’s a lot of stuff people don’t want to do but just have to do,” says Geurtjens. “What if we can have those taken taken over by robots?” Buildings will became safer to build, but also more interesting to look at. “If you look at architecture, decoration has gone out it. It’s all flat facades, square corners. It’s too expensive to decorate,” says Geurtjens. “With a technique like this, it doesn’t mater any more, just send the info to a robot and it will do what you tell it to and it doesn’t cost much more.”
Looking even further into the future, Geurtjens says robots may help us on other worlds. “In the unlikely case that we colonize Mars or the Moon, we can send the robots there first, and in a few years we can join them and live in the houses they’ve printed,” he says. Until then we can still enjoy a nice terrestrial stroll over a canal on a 3D printed bridge—soon.