Beyond Chuck Hull’s Legacy: the Unsung Heroes Who Paved the Way for 3D Printing

Next month, we will celebrate a huge anniversary. 40 years ago, on August 8, 1984, Charles Hull filed a patent application for stereolithography: the first additive manufacturing technique in history, known today as SLA. Although the patent was granted two years later in March 1986, 1984 is considered the birth of 3D printing.

Such a jubilee is a great opportunity to remind the world that, despite his obvious contributions to the development of the entire AM industry, Chuck Hull was not the first to work on such a technology. It is also worth noting, that the path to obtaining the patent and launching 3D Systems was associated with some legal problems and challenges. The first years of Hull’s activity were indeed a struggle.

So, I invite you on a journey into the past, when 3D printing was not called “3D printing.” It did not excite nor interest anyone. In fact, very few people were even aware of its existence. We will begin this quest quite unusually: with the materials.

DuPont and the Invention of Light-curing Resins

As you’ll see in a moment, most of the original attempts to create three-dimensional objects began with experiments with light-curing resin. So, where did this material come from, and who invented it?

A light-curing resin, or photopolymer, is a type of polymer that hardens when exposed to light, usually in the ultraviolet (UV) range. The curing process is called photopolymerization, and it occurs when the resin is exposed to light of a specific wavelength. This process is permanent and unidirectional. Once the resin has hardened, it cannot return to its original, liquid state.

In the 1950s, the American chemical giant DuPont began research into polymer materials that could be cured by light. In the 1960s, the company was one of the first to develop practical applications for light-curing resins, in offset printing and in the electronics industry to produce photoresists.

In the 1960s and 1970s, DuPont and other chemical companies, such as Kodak, BASF, and Ciba-Geigy (now part of BASF), worked extensively to improve light-curing resins. New formulas and ingredients were introduced that allowed for better control of the curing process, and numerous patents were filed on various aspects of their production and use.

The Very First Attempts at Building 3D Objects

In the late 1960s, scientists at Battelle Memorial Institute, a private applied science and technology development company from Columbus, Ohio, began experimenting with light-curing resins using two laser beams that attempted to polymerize (solidify) the material at the point of intersection. Similar experiments using two lasers were conducted by Wyn K. Swainson of Denmark, who in 1967 even applied for a patent for “Method of Producing a 3D Figure by Holography.” Swainson founded a company, Formigraphic Engine Co., but never commercialized his invention.

The dual-laser approach to resin photopolymerization was continued by American Formigraphic Engine Co., which in the early 1970s created the first commercial laser-prototyping project called photochemical machining. In 1974, the company demonstrated the creation of three-dimensional object made by using a rudimentary system.

3D Printing Was Actually Born in Japan

Chuck Hull was the first to patent and implement AM, but he wasn’t the first to come up with the concept, who was, in fact, Hideo Kodama. In May 1980, while working at the Nagoya Municipal Industrial Research Institute in Japan, Kodama developed the first single-laser photopolymerization system for resins. He filed for a patent, but his application expired as he was unable to provide a prototype and conduct further research, a requirement of the Japanese patent application process. The reason Kodama was unable to do so was prosaic: he did not have the money. Nevertheless, in a document published in October 1980, Kodama described his experiments using a Toshiba mercury lamp and a photosensitive resin called Tevistar, manufactured by Teijin.

In November 1981, Kodama published a second document entitled “Automatic Method for Fabricating a Three-Dimensional Plastic Model with Photo Hardening,” where the process of hardening successive layers of material appeared for the first time. This was also the first documented attempt to carry out the process that over a decade later would be referred to as 3D printing.

Even if you don’t agree with the Kodama legacy, because he never delivered a solid machine, then you must bow your head before the achievements of the French.

Oh, the French. They Could Have Had it All

There are many ways to describe what you are about to read: a wasted opportunity; corporate-bureaucratic blindness; a mindless career bust. The fact is, France could have become the homeland of 3D printing, but chose a different path. And it did so twice.

In August 1982, Alan Herbert of 3M Graphic Technologies Sector Laboratory published a document titled “Solid Object Generation,” where he described a system in which a laser beam hardened a light-cured resin using a mirror. The device was supposed to work on the principle of a traditional plotter. Herbert claimed that he was able to create small three-dimensional objects with it. As stated in Wohlers Report 2015: “[I]n 1989–1990 timeframe, Wohlers Associates received a handwritten note from Alan Herbert, attached to a copy of his 1982 paper, saying that, unfortunately, his company elected not to commercialize his work.” Thus, the first French creator of 3D printing was deprived of his legacy by his employer, 3M.

But he wasn’t the last. At about the same time as Herbert, three other Frenchmen—Alain Le Méhauté, Olivier de Witte and Jean Claude André—were working on the same concept. All three were employed in the R&D department of the French Cilas Alcatel Industrial Laser Company. They filed their patent on July 16, 1984, three weeks before Chuck Hull, and it was granted in January 1986, two months before Hull. And, yet, the company behind it decided to abandoned the idea, because it didn’t see much commercial potential in it. The work of Méhauté, de Witte, and André, although officially granted, was simply ignored and left behind. Brutal.

This whole French thread can be tied together with an interesting clasp. As I mentioned above – it all started with a material – a light-cured resin developed by DuPont. And DuPont was founded in 1802 by Frenchman Éleuthère Irénée du Pont de Nemours, who came to America on January 1, 1800, fleeing the French Revolution. Ironic.

Enter Chuck Hull!

In the early 1980s, Charles Hull was working for UVP, Inc. in California as vice president of engineering. There, he was involved in developing a new method of covering tabletops with resins to protect them from wear and tear. While searching for resins that could cure quickly under the influence of UV light, he came up with the idea of ​​​​building three-dimensional objects in this way. He started his work in 1983 and on March 3, Hull created the very first three-dimensional object using a process that he called Stereolithography. On August 8, 1984, he applied for the groundbreaking patent titled “Apparatus for Production of Three-Dimensional Objects by Stereolithography,” which is now considered the official birthdate of 3D printing.

The patent was granted on March 11, 1986, almost exactly three years after the very first part was created. That same month, Hull and Raymond Freed co-founded 3D Systems Inc. The first beta 3D printers – then called “stereolithographic apparatuses,” were delivered to customers in late 1987. The final production units were delivered in April 1988. The machines, dubbed SLA-1, were the first ever commercial installations of AM systems in the world. Thus, we can state that 1987 is the official birthdate of the 3D printing market.

The DuPont Patent Challenge

Just as there were a number of individuals working on SLA before Hull, even more appeared after its commercialization. One such person was Yehoran Uziel, who, while working for Israeli Operatech, developed his own machine using the same underlying process. In 1986, after learning about Hull’s work, he flew to the US and met with him. In January 1989, he joined the company as vice president of engineering (although he left two years later to found Soligen).

Unfortunately for Hull, not everyone shared this collaborative approach. DuPont decided to enter the emerging market. The company was already conducting advanced work on its own stereolithography machine when, in September 1988, it petitioned the U.S. Patent Office for a reexamination of Hull’s 1986 patent. It used Kodama’s work as the basis for its review, claiming that Hull had copied it. Seven months later, the Patent Office told 3D Systems that it had rejected all claims in Hull’s patent.

This was the moment DuPont had been waiting for! In June 1989, the company introduced its own machine, the Somos 1000 Solid Imaging System, based on the same technology as the SLA-1 and the later SLA 250 model. Fortunately for Hull and 3D Systems, after a successful appeal, in late 1989, the U.S. The Patent Office reversed its decision after both produced strong evidence to support the claims in Hull’s patent.

So, if you happen to remember the time when 3D Systems ran a relentless patent dispute with young Formlabs (and you supported the latter), now you know where the company learned its tactics from.

Beside Stereolithography

The 80s and the 90s were the time when all the most important 3D printing techniques were created. Although stereolithography took the lead, other manufacturing techniques were also developed at the same time. Some never made it past the concept stage. Others, such as powder bed fusion (PBF) still exist today and have an even larger market share.

In 1971, Frenchman Pierre A. L. Ciraud described a method of producing objects of any geometry by adding material in the form of powder, using an energy source to bond it. It was published on July 5, 1973 and laid the foundations for the technology known today as polymer PBF, or selective laser sintering.

Six years later, on December 3, 1979, American Ross F. Houser filed a patent application for three methods for the layered forming of objects by bonding them with different types of materials. The methods were called the “molding process” and used sand to build models. The patent was published in January 1981, but it was never commercialized or even brought to the testing phase due to lack of financial resources.

The next inventors who led the work on creating a new way of creating objects were Americans – Bill Masters from South Carolina, and a young student at the University of Texas – Carl Deckard. Masters created a technology that he called CAMM3 (Computer Aided Modeling Machine), which involved layering of balls of material, creating a three-dimensional object. Although it was patented (like 50 other inventions created by Masters), it was also never commercialized.

Carl Deckard’s path was completely different. After his first year of college in 1981, he began a summer job at TRW Mission in Houston, manufacturing parts for the oil sector. Watching sheet metal being cut using a computer control system based on CAD software, he saw great potential in automating this process. Over the next few years, he delved deeper into this issue and began specializing in industrial lasers. In 1984, Deckard created the first concept of using a laser or electron beam to selectively melt powdered material layer by layer, based on data obtained from CAD drawings.

Dr. Joe Beaman became interested in the project and decided to support the talented student. Soon, their work led to the creation of one of the most important 3D printing technologies, selective laser sintering (SLS), and the establishment of the first company manufacturing machines using this method, DTM.

It is fair to say, that Carl Deckard is the second greatest American innovator in the field of AM, after Hull. He created the SLS method, as well as 3D printing with metal alloys. Unfortunately, Deckard died on December 23, 2019 at the age of 58.

Remembering the Forgotten Innovators

Chuck Hull deserves all of the praise and all of the glory. He’s the one who delivered it. He created the world’s first 3D printing company, sold the first machines, created the whole market. Damn, he enabled the creation of the .STL format, which is the foundation of AM to this day! Chuck Hull is the man!

However, we can never forget that there were others. Each and everyone contributed to 3D printing’s development. In this article, I only described the 70s and 80s. Meanwhile, each of the following decades brought 3D printing and the industry to a higher level. Behind all of this, there was a multitude of people—most already nameless and forgotten. Let’s get back to them and not let them disappear into oblivion.