The encyclopedia · Engineering & Operations · Technical decision · 1983-1986
Chuck Hull made a 3D object by curing a tank of resin one layer at a time
Hull's stereolithography added material layer-by-layer instead of cutting it away, inventing 3D printing and founding 3D Systems.
3D Systems · UVP Inc.
the move
In 1983 Chuck Hull found that hardening tabletop coatings with a UV light source was too rough a method. He turned the reasoning around: you could build a solid object out of the cured layers themselves.
His device bathes a platform in a tank of liquid photopolymer and moves a focused UV beam to solidify each two-dimensional cross-section. After each layer the platform shifts down a little so the next layer forms on top. He filed US patent 4,575,330 on 8 August 1984.
Hull coined the term 'stereolithography' for the process, went on to found 3D Systems and, in 1986, received the patent that is now treated as the start of 3D printing.
why it works
- Additive stacking handles internal geometry and undercuts a mill cannot reach.
- Each layer is a flat 2D problem a computer can direct, so no tool-path is needed.
- The prototype goes from file to part in hours instead of the weeks tooling would take.
what transfers
Don't remove material to make a shape — grow the shape. A subtractive process is limited by what a tool can reach, while an additive one builds anything from its slices.
what came after
3D Systems commercialised the first stereolithography machines, and four decades later additive manufacturing spans metal, glass, food and human tissue. Hull's patent triggered the whole industry whose descendants now build parts that subtractive machines never could.
references
- Apparatus for production of three-dimensional objects by stereolithography (US4575330)
- The Inventor of 3D Printing: A Timeline of Chuck Hull's Impact
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