When Local Motors announced it was going to 3D print a car at the recent IMTS show, a number of tasks had to happen first. One was the engineers needed a 3D printer big enough to print whole sections of a car, even if the car itself is small. Another issue was managing the 3D printing process. In many ways, the Local Motors Strati car was an experiment, but one that turned out quite well and that delivered a lot of information for a next car.

For the printer, the design group at Local Motors was able to use the Big Area Additive Manufacturing (BAAM) developed by Cincinnati Incorporated and Oak Ridge National Laboratory. This machine is similar to a fused deposition extrusion type (FDM) printer, but with a 6.5 x 13 foot bed. The material used for the car’s frame and chassis was an ABS plastic laced with carbon fiber.

Autodesk partnered with Local Motors, taking advantage of the opportunity to see how its Spark program might be used to help connect automobile digital design information to the 3D printer in a streamlined way for easier visualization and optimization of 3D prints.

“For us,” noted Aubrey Cattell, Director of Business Development and Operations at Autodesk, “this was really a proof point that Spark could solve large-format 3D printing problems and address the issues that industrial manufacturers are going to face.”

As many engineers have noticed, you have to specifically design for a given 3D printing technique and a given material. Even so, a gap still exists between CAD data and formatting that data for individual 3D printers to achieve a properly printed object. STL does not quite resolve the missing data issues found in this gap. The AMF standard comes closer, but this program has not been widely implemented yet.

All the vendors of professional AM systems and many vendors of personal 3DP systems have proprietary drivers that take the data from a CAD file and check it for printability. Depending on the vendor, these drivers will ensure a part is water solid, that areas of the design don’t intersect, that the design mesh does not have holes or gaps, and that color is placed appropriately on the design. The drivers will also determine part orientation for a cost effective build, and determine the support structure if needed. Even with all of these check points, however, the printer may not deliver the part as envisioned in an engineer’s mind.

Service bureaus handle this issue by using software that ensures various common data gaps, like the ones mentioned above, are resolved. They use programs like Magics, NetFabb, or Rhino among others.

Recently, Autodesk announced it is developing a 3DP standard “driver,” known as Spark, for use with any consumer or professional 3D printer that will help ensure you get the part you designed.

According to Cattell, “Spark is an open and free software platform for 3D printing that will connect the digital information, the 3D model, through to the printer and the successful print in a new way.”

Added Diego Tamburini, Manufacturing Industry Strategist, Autodesk, “there is an extra step needed to actually print using a given manufacturer’s 3D printer, and that is preprocessing. The preprocessing takes the STL or other standard file format and creates slice data and machine code for the specific data the 3D printer.”

“I would even go further and say there’s discovery problem in terms of finding models or creating models up front, added Cattell. “Then there’s a sort of healing and checking phase where you need to make sure that the model will work, and then there’s that third step that Diego highlighted around generating the machine code. There are points of failure in each of those processes and it needs to be smoother and that’s the problem we’re addressing with Spark. At its core, Spark has a number of the algorithms that will help solve those issues.”

Autodesk engineers are working with all the major 3D printing vendors to develop drivers for the Spark base program. The concept is to create an application interface with enough flexibility that the vendors can enter in data specific to their machines. Thus, you would have a fundamental version of Spark with variations that would handle specific 3D printer capabilities.

So, why Spark versus a standard like AMF?

Commented Cattell, “there’s a lot of great work that’s been done out there. I think we want to continue to value that and build on top of it. But I think there are challenges in terms of people working in different formats, so I think what’s needed really is a standard data architecture. Think of it is as a wrapper that can send the right types of print instruction.

The goal, for example, is for Spark to adaptively thicken a part, or hollow out a model to reduce material costs, and automate other tasks that often require additional programs or expertise.

Spark and additive manufacturing will also influence future CAD software from Autodesk. Noted Cattell, “it’s an opportunity for us to see how additive manufacturing fundamentally needs to change our design solution. Our tools themselves will evolve and will offer additional value to our users.”

Spark will eventually address all the major forms of 3D printing, but it initially operates with stereolithography through the introduction of Autodesk’s new 3D printer. Spark platform will be released later this year.

Leslie Langnau
llangnau@wtwhmedia.com