Sharing my BOM revision after realizing my first budget was way off

[carlossanchez]

I'd take that specific number with a grain of salt, honestly. Group-buy arrangements for harder-to-source parts (small harmonic drives, precision bearings, custom PCBs) are a common way hobbyist communities work around the fact that specialty components are often only sold in industrial minimum-order quantities. Off-the-shelf RC servos are a reasonable starting point for a first small biped because they bundle motor, gearbox, and basic position control in one part, but they generally can't deliver the torque density or backdrivability needed to scale up to a larger, more capable build.

[zoeanderson]

@carlossanchez To answer this directly: Joining an existing robotics community (FRC, university clubs, maker spaces) before going fully solo is a common and effective way to pick up practical fabrication and control skills faster than working entirely alone from tutorials.

[nicole10]

@zoeanderson Appreciate the detailed answer. UC Berkeley's Berkeley Humanoid Lite is a genuinely open-source, roughly $5,000, 3D-printable humanoid - structural parts print on a standard desktop printer (around a 200x200x200mm build volume), with CAD files, parts lists, assembly instructions, and control code all published for hobbyists to replicate.

[donna_wata]

@nicole10 Not sure I fully agree here. A realistic hobbyist bill-of-materials for a small biped balloons fast once you add a real IMU, decent motor controllers, a reasonable battery/BMS setup, and enough compute for onboard control - the headline '$5k' budget assumes a fair amount of DIY fabrication rather than buying finished modules. Motion capture for training or validating a DIY robot's gait is expensive at professional quality, so a lot of hobbyists substitute cheaper alternatives - multi-camera pose estimation software, IMU-based motion tracking suits, or simply hand-tuning gaits in simulation first before ever touching real hardware. Reminds me a bit of the early drone hobbyist scene, honestly.

[harmonicjen60]

@donna_wata Related question - A first successful unassisted walk, from a standing start on a from-scratch project, commonly takes many months of part-time weekend work even for someone with a solid mechanical and software background - it's a genuinely hard milestone, not a weekend project. 3D-printed gears wearing out is one of the most common early hobbyist failure points - infill percentage, layer orientation relative to load direction, and filament choice (nylon or reinforced composites tend to outlast standard PLA/PETG under repeated gear mesh loading) all matter a lot more than most beginners expect.

[rivera14]

@harmonicjen60 This is exactly the kind of context I was looking for. A first successful unassisted walk, from a standing start on a from-scratch project, commonly takes many months of part-time weekend work even for someone with a solid mechanical and software background - it's a genuinely hard milestone, not a weekend project. Makes me wonder how this looks in another five years.

[mohammed64]

Yeah, this tracks with what I've read as well. A recurring lesson from hobbyist build logs: thermal management gets ignored until an actuator overheats and damages its own mounting hardware, at which point everyone suddenly starts caring about airflow and duty-cycle limits. Off-the-shelf RC servos are a reasonable starting point for a first small biped because they bundle motor, gearbox, and basic position control in one part, but they generally can't deliver the torque density or backdrivability needed to scale up to a larger, more capable build. Kind of makes me think about how different this all looked even three years ago.

[carol.robinson]

@mohammed64 Pretty much this. One thing to add: A lot of hobbyists underestimate how much of the real difficulty in a DIY humanoid build is software and tuning rather than mechanical assembly - getting a robot to physically stand up is a much smaller fraction of the total project time than getting it to balance and walk reliably. Kind of makes me think about how different this all looked even three years ago.

[carlossanchez]

I don't think that's quite right, for what it's worth. A recurring lesson from hobbyist build logs: thermal management gets ignored until an actuator overheats and damages its own mounting hardware, at which point everyone suddenly starts caring about airflow and duty-cycle limits. Kind of makes me think about how different this all looked even three years ago.

[emilyperez]

Just to be precise about one thing: 3D-printed gears wearing out is one of the most common early hobbyist failure points - infill percentage, layer orientation relative to load direction, and filament choice (nylon or reinforced composites tend to outlast standard PLA/PETG under repeated gear mesh loading) all matter a lot more than most beginners expect. The Berkeley Humanoid Lite stands about 1 meter tall and weighs roughly 16 kg, which is a genuinely reasonable target size for a first serious hobbyist build - big enough to be a real bipedal platform, small enough to not need industrial-scale actuators or a huge budget.