A digital fabrication workflow for rebar and robots

Daniel Blank
Toggle — Construction Robotics
3 min readNov 20, 2020


Rebar assembly at Toggle

Toggle’s digital fabrication workflow spans software, hardware and services. Prefabricated rebar assemblies begin with a structural drawing or rebar detail, proceed to cage configuration, robotic motion planning, physical robotic assembly, tagging and finally delivery to site. Creating digital continuity from design to fabrication and delivery ensures accuracy, efficiency and an excellent customer experience (driven by current information and frequent communication) on every job.

Toggle’s core software application known as Toggle OS is a software tool for configuring rebar cages for robotic assembly.

Inside of the Toggle OS cage configurator you can specify rebar gauge, dimensions, stirrup shape and spacing including gaps and groupings. The cloud based application is accessed via web browser and visualizes your cage configuration in 3D. Once the configuration is complete the application can export a 3D detail as well as the coordinate geometry for robotic assembly of the cage

Toggle has developed robotic hardware and software for automating the most physically difficult and repetitive steps in rebar cage assembly. Using large format industrial robots, similar to those used in automotive manufacturing, Toggle is able to dramatically increase productivity in proportion to cost of labor.

Workflow Steps

Robotic assembly begins with automated configuration of the fixture thereby ensuring accurate measurements for every cage produced. Geometry data is taken directly from either imported CAD and BIM files or the configurator to ensure continuity.

Material handling robots place stirrup and long bars into the fixture. Connections can be made in a variety of ways to accommodate the needs of a particular job or customer. Both welding and wire-tying are possible and can be accomplished manually or robotically.

Robotic welding at Toggle

Mesh can also be configured in Toggle OS. Robotic welding is particularly well suited to heavy gauge rebar combinations using #6 (.75" dia) and above which cannot be spot welded by mesh machines and is therefore traditionally assembled manually. Toggle OS allows you to specify gauge, spacing, groupings and gaps. The application also allows custom configuration of welding parameters like welding all perimeter joints or alternating intersections as needed for lifting, transporting and installing rebar assemblies.

Robotic welding is substantially faster, more accurate and safer than either manually welding or wire-tying. Automated welding of grids for mesh is also very scalable with sizes up to the length and width of standard flat bed trucks being the only limitations.

The goal is to bring manufacturing efficiencies while balancing the need for customization.