Reference page for the B9 robot leg-section build (Lost in Space replica builders). Content is being restored from archive sources.

Topics covered originally:

  • Leg-section dimensions and geometry
  • Fabrication materials
  • Internal electronics interface schematic
  • Treadway integration

Related: B9 Robot Builders Club community reference, silicon rubber mold-making for sub-component parts.

Frequently Asked Questions

What are the B9 robot leg section dimensions? Based on builder reference photography and community documentation, the B9 leg tubes are approximately 8–9 inches in diameter and 14–16 inches tall, varying slightly between seasons since no official blueprints have been publicly released. Builders cross-reference multiple reference images against the known height of the actor Bob May to establish accurate scale.

What fabrication materials are used for B9 leg sections? The three primary approaches are fiberglass layup over a cylindrical form (traditional one-off method), cast urethane resin over a PVC or aluminum pipe structural core (better for producing multiple identical legs), and carved foam coated with a hardening finish (fastest but least durable, suitable for static display only).

How is the B9 leg section connected to the tread and torso? The lower connection bolts leg structural cores to mounting plates on the tread frame using heavy flanges, as this joint carries the full weight of everything above. The upper connection to the torso typically incorporates a lazy Susan or turntable bearing to allow the torso to rotate — a key functional feature of the original B9 prop.

What electronics interface is needed in the B9 leg section? Wiring for torso electronics (power distribution, motor control signals, audio system, and remote control receiver connections) must be routed through the leg section from the tread base where the battery typically lives. Planning wire routes before any construction is complete is critical to avoid having to disassemble finished sections later.

Further Reading from Authoritative Sources

  • B9 robot leg section — Wikipedia’s Robot (Lost in Space) article provides authoritative production design details for the original prop’s leg section that inform accurate replica dimensions.
  • PVC and aluminum structural fabrication for robot builds — Hackaday covers DIY structural fabrication projects including material selection for prop and robot builds, relevant to the structural core comparison in leg section construction.