A newly developed knitting machine has shown that solid objects can be constructed by knitting stitches in multiple directions rather than assembling flat sheets. The prototype deposits yarn across a needle array in controlled layers, enabling controlled changes in thickness and stiffness within the same object. This method allows complex forms, including overhangs, to be created using knitted construction alone during fabrication.
- The machine uses a 6×6 bed of needles with independently moving double hooks, allowing knit or purl actions to be selected precisely for each stitch.
- A movable yarn head travels over the needle array, giving the system freedom to place stitches at any position and generate complex internal and external forms.
- Early demonstrations include C-shaped and pyramid-like objects, showing the ability to create overhangs despite current limitations such as slow speed and dropped loops.
- The work was presented as ‘Using an Array of Needles to Create Solid Knitted Shapes’ by François Guimbretière and Victor Guimbretière of Cornell University at the ACM Symposium on User Interface Software and Technology, held in Busan, South Korea, on 30 September 2025. The announcement was made in a recent online edition of Cornell Chronicle.
THE PROJECT: Researchers presented a proof-of-concept knitting system that demonstrates how solid three-dimensional objects can be constructed using stitches placed in multiple directions rather than forming flat fabric. The work establishes that directional knitting can operate in a manner similar to three-dimensional printing. It also documents how stitch attachment choices affect geometry, thickness and material behaviour within knitted structures.
- The study introduces a knitting method that allows stitches to be added forward, backward and diagonally, enabling solid forms to be built layer by layer with defined geometry.
- Unlike conventional knitting machines, the prototype assembles volumetric structures by directing stitches across a fixed needle array in multiple orientations.
- The work documents how stitch attachment choices influence flexibility, stiffness and thickness in different regions of a knitted object.
- These attachment methods allow material properties to be varied locally within a single continuous knitted structure.
- Partial funding for the study was provided by the National Science Foundation. Amritansh Kwatra ’19, now a PhD student in information science at Cornell Tech, also contributed to the project.
CASE IN POINT: The prototype knitting machine is built around a compact array of needles and a movable yarn delivery system that together enable precise stitch placement in three dimensions. Each needle uses a symmetrical double-hook design that can act independently, allowing the machine to alternate between knit and purl actions as required. This configuration allows stitches to be placed directionally across layers, forming solid structures rather than flat textile surfaces.
- The machine uses a 6×6 bed of knitting needles, each mounted on a brass support tube and fitted with a 3D-printed double hook.
- Independent movement of the front and back parts of the hook determines whether a stitch is knitted or purled at each location.
- A yarn-dispensing head moves freely over the needle array, enabling stitches to be placed at any position without linear constraints.
- The researchers developed a dedicated library of code that defines individual stitch types and generates programmes for specific objects.
- This combination of hardware and software allows complex internal and external forms to be produced within a single knitted object.
WORTH NOTING: The prototype knitting machine remains an early-stage system, with several technical limitations identified during testing. Its current operation is slow, and the mechanism can drop loops or catch yarn on unintended needles, affecting reliability. At the same time, the researchers indicated that the design can be strengthened and expanded, and that solid knitting could support applications requiring controlled stiffness and thickness.
- The prototype occasionally drops stitches and misroutes yarn, highlighting challenges in maintaining consistent precision across the needle array during operation.
- Performance speed remains limited, which restricts the system’s suitability for large-scale or time-sensitive manufacturing contexts.
- The design can be scaled by increasing the size of the needle bed while retaining the same operating principles and stitch logic.
- Solid knitting allows different levels of thickness and stiffness to be incorporated into a single object by varying stitch placement patterns.
- The researchers identified potential medical uses, including knitted structures intended to support the growth of artificial ligaments or veins.
WHAT THEY SAID
We establish that not only can it be done, but because of the way we attach the stitch, it will give us access to a lot of flexibility about how we control the material. The expressiveness is very similar to a 3D printer.
— François Guimbretière
Professor of Information Science
Cornell University
