Few science fiction props have inspired as dedicated a community of replica builders as the B9 robot from Lost in Space. The robot appeared in all 83 episodes of the CBS series from 1965 to 1968 and became one of television’s most recognized mechanical characters — not through sophisticated special effects, but through the physical performance of the man inside the suit and the distinctive electronic voice that warned the Robinson family of danger every week.
Origins: The 1964 Design
The B9 robot was designed and built by Bob Stewart and his team for Lost in Space producer Irwin Allen’s pilot episode, filmed in 1964. The design drew from the general visual vocabulary of mid-century science fiction robots while establishing a distinctive silhouette: the wide tread base, the barrel-shaped torso with its chest light panel, the accordion collar, and the distinctive transparent dome revealing the brain unit.
The original budget for the prop was approximately $40,000 — a significant investment for a television production in 1964 and a reflection of how central the robot character was to Allen’s vision for the series.
The robot was built from aluminum, rubber, fiberglass, and a variety of purchased commercial components repurposed as prop details. Many of the surface details on the original prop — the dials, switches, and fittings covering the torso — were sourced from industrial hardware catalogs and electronics surplus suppliers. Identifying which commercial components were used remains an ongoing research project in the B9 builder community.
Bob May: The Man Inside
Bob May was the actor who physically performed the B9 robot throughout the series. May was 5'6" and was selected specifically to fit inside the robot suit — a physically demanding role that required him to operate in a cramped, poorly ventilated costume under hot studio lights.
May performed every on-screen movement of the robot: the arm gestures, the torso rotation, the physical comedy that made the B9 one of the show’s most popular characters. He was not originally credited for this work; the robot was listed as a “special effect.” Fan and critical recognition of May’s contribution grew significantly in later years, and he became a regular presence at science fiction conventions.
Bob May passed away on January 18, 2009. His contribution to the series and to the lasting appeal of the B9 robot is remembered in the dedicated tribute article on this site.
Dick Tufeld: The Voice
The robot’s distinctive electronic voice was provided by Dick Tufeld, the announcer for Irwin Allen productions. Tufeld’s delivery — measured, slightly ominous, occasionally alarmed — defined the character as fully as the physical design.
The vocal processing used on the original recordings gave the voice a slightly electronic quality without making it incomprehensible. Replica builders who add sound systems to their robots typically use recorded samples of Tufeld’s dialogue from the series — the quality of those recordings and their faithful reproduction through a good speaker system makes or breaks the audio presentation of a finished robot.
Dick Tufeld reprised the role for the 1998 feature film Lost in Space and remained associated with the character until his death in 2012.
The Robot Through the Series
The B9 prop was modified significantly between the first and subsequent seasons. Season 1 differences from Season 2–3:
- The tread section proportions were altered
- The chest panel layout was revised
- Various surface details were added or changed
- The arm assemblies were rebuilt
Builders who want to replicate a specific version of the B9 need to identify which season they’re targeting and find reference images from that production year. Many community reference threads in the B9 Builders Club forums document these differences in detail.
The original prop deteriorated over time after production ended. The surviving original unit (or units — there may have been multiple props in various states of completion) has passed through several private owners.
Legacy in the Builder Community
The B9 robot replica community began organizing in the late 1990s around internet forums. The B9 Builders Club has been the primary community hub, connecting builders across North America and internationally. The community has collectively documented the original prop’s dimensions, sourced reproduction parts, and developed construction techniques that have been shared across hundreds of builds.
WonderFest in Louisville, Kentucky remains the most important annual gathering for B9 builders — see the WonderFest convention reports for coverage of the show’s B9 robot displays.
The skills involved in B9 construction — mold making, casting, electronics, metal fabrication — are the same skills used in professional prop and product development. Many builders who started with a B9 replica have gone on to professional work in theatrical props, themed entertainment, and product development. This connection between hobbyist prop building and professional fabrication skills is one of the reasons this community continues to attract new builders.
For those starting the build journey, the B9 robot construction overview lays out the full project scope, and the mold-making and casting guides cover the foundational skills needed for the major components.