Stefanie Pender

Robotic fabrication · OpenHOUse, University of Houston · 2024

Robotic Timber Truss Fabrication

An ABB robot arm with a spindle end effector milling a joint into a large timber truss cross member clamped on green stands
Milling a joint into a truss cross member.

Structural timber joinery machined into full-size stock on a six-axis arm. The members were prototypes for OpenHOUse, the University of Houston's entry to the Gateway Decathlon, built at the Autodesk Technology Center in Boston during a Design Sprint residency.

Project
OpenHOUse, an entry to the Gateway Decathlon by the Gerald D. Hines College of Architecture and Design
Team
University of Houston faculty, with the Autodesk Technology Center, Boston
Stack
ABB six-axis arm with spindle, RAPID posts, PowerMill
Read more
University of Houston on OpenHOUse

What it was for

The Gateway Decathlon is a design-build competition in which university teams design, build and then exhibit a full housing unit near the Gateway Arch in St. Louis, judged across ten areas from energy performance to market viability. OpenHOUse is Houston's answer to Houston: rather than air-conditioning a whole house to one temperature, it uses passive and active systems to let different parts of the building sit at different temperatures.

That produced a saw-tooth roof, and a roof like that needs timber joinery that no catalogue supplies. Faculty came to Boston to find out whether the joints could be cut robotically before committing to them at full scale.

The problem

Timber is not a predictable stock material. It moves, it isn't square, and the joint still has to fit. Machining structural joinery into full-size members means the toolpath has to absorb the difference between the nominal model and the piece actually clamped on the table.

The full milling sequence, roughly ten times actual speed.

Scan, then cut

The cell scans the member in place before it cuts, so the toolpath is referenced to the piece actually clamped on the table rather than to the nominal model.

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