Jun 3, 2016 | By Andre

There’s something on the internet called Rule 34. In it’s PG form, it basically states that if you can think of something, no matter what it is, somebody out there has probably already attempted it. With the growing popularity of 3D printing in parallel with ever-expanding interconnectivity, that mentality is beginning to hold true within maker and robotics communities around the world.

Take the manufacture of a highly pressured compressed air tank using nothing but 3D printed materials for example. I’ve never considered doing such a thing and nobody in my circle of 3D printer enthusiasts have either. But considering the vastness of the world we live in, if it can be thought of, it can be done and a robotics club based in Lausanne, Switzerland have gone through the trouble of making it so.

As part of a funny gag going into Eurobot 2016, the club members experimented with creating a 3D printed compressed air tank so as to provide a mechanism to pop-out a pneumatic umbrella from the robot they planned to display.

To get this done, their 3D printed compressed air tank had to be air tight, be able to sustain an hour at 4 bar (roughly 60psi) of pressure, low-cost and ideally reusable. So, just like any curious club full of techno-tinkerers might be expected to do, they experimented to see if their material of choice (PLA plastic) would suffice to contain the pressure needed for their umbrella to expand out of.

Prototype 1 had them construct an enclosed 40x40x40mm air tank along with a drilled hole to allow pressurized air into their box. After getting up to 6.5 bar of pressure without any sign of leakage, they successfully completed their proof-of-concept phase.

Prototype 2 was designed to be 225% larger (needed for their eventual goal) and had beefed up walls  (6 print shells) for a little added security. Unfortunately, their second effort lead to the tank exploding just cm away from the team lead’s face. This is a good time to remind everyone that when experimenting with high pressure tanks, wearing protective glasses and covering your body is good practice.

It was ultimately a faulty design (where the internal structures were not bound to the walls) that was to blame for their second round failure so they tried again with a third iteration. While nothing exploded with prototype 3, there was a small leak which lead the team to experiment with acrylic sprays and tire sealants to close any remaining gaps.

In the end, the team did get their compressed air tank and were able to sustain the desired pressure but also figured out how things can indeed go wrong with a bad design, how things can be resoloved with external sealants and that 3D printing is there for you when you really need to lighten the mood with a pneumatic umbrella.

Of course, just because something is possible doesn’t make it safe or advisable. The comments over at hackaday’s coverage of this 3D printed compressed air tank are chock full of warnings about playing with compressed air using materials that aren’t designed to handle the load.

In conclusion, this story is ultimately about something in the world of 3D printing that had yet to be tried and a group of robotic enthusiasts that filled that void by giving it a shot. Future generations can now wonder if 3D printed PLA is suitable as a compressed air tank, google the question and discover that yes, yes it is; sort of.

 

 

Posted in 3D Printing Application

 

 

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kb wrote at 6/5/2016 2:55:46 PM:

The shape the chose makes it pretty weak! I would print 2 half spheres with an internal honeycomb structure (mostly for printability), acrylic spray the inside and glue the 2 parts together with epoxy.



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