Poppy Humanoid robot screw size
M2 / M3 · length not stated in the sources
The screws used on Poppy Humanoid robot are M2 and M3. None of the sources we found gives an exact length, so measure the original before you order.
There are 2 separate fitment records for it, including dynamixel servo horn mounting screws (M2) and 3D-printed limb bracket and servo case assembly (M3).
2 of the 2 records are marked confirmed, drawn from 1 source (docs.poppy-project.org Poppy Humanoid BOM).
For reference, M2 is 2 mm across the threads at 0.4 mm pitch. The imperial size people confuse it with: #2-56 UNC (2.18 mm) is close but not interchangeable.
Poppy Humanoid robot screw specifications
One row per fitment record. Head, drive are shown only where the source states them; pitch is the ISO coarse pitch for the thread.
| Thread | Length | Pitch | Head | Drive | Where it goes | Status |
|---|---|---|---|---|---|---|
| M2 | not stated | 0.4 mm | not stated | not stated | Dynamixel servo horn mounting screws | Confirmed |
| M3 | not stated | 0.5 mm | not stated | not stated | 3D-printed limb bracket and servo case assembly | Confirmed |
Fitment records and sources
Dynamixel servo horn mounting screws
pitch 0.4 mm · tap 1.6 mm · clearance 2.4 mm · PH0 / Torx T6
3D-printed limb bracket and servo case assembly
pitch 0.5 mm · tap 2.5 mm · clearance 3.4 mm · PH1 / Torx T10
How to check the screw before you buy
- Printer and CNC builds usually publish a bill of materials; when it lists a length, follow it, since extrusion T-nuts and motor faces have fixed thread depths.
- Diameter: across the threads an M2 screw measures about 2 mm with calipers (usually a hair under). This device also uses M3, so measure each screw rather than assuming they match.
- Pitch: 0.4 mm from one thread crest to the next (25 crests per centimetre). A thread pitch gauge or the pitch-gauge tool settles it in seconds.
- Length: measure from under the head to the tip for pan, button, wafer and cap heads; countersunk (flat) heads are measured overall.
- Driver: the source does not name the drive. Standard M2 heads take PH0 for Phillips and T6 for Torx, and a 1.5 mm hex key for socket heads; a bit that fits loosely will cam out and strip the head.
- Tightening: no device-specific torque is published in these records. The site's general figure for M2 is about 25-40 N·cm into metal threads and 12-20 N·cm into plastic bosses; snug it up and stop.
Common mix-ups with M2 / M3
- Most consumer gadget teardowns (robot vacuums, toothbrushes, e-readers, VR headsets) list only the driver bit, not the thread — measure before ordering.
- M2 (2.00mm, 0.4mm pitch) is NOT the same as #2-56 UNC (2.18mm) — close enough to cross-thread and strip if forced.
- Pond/aquarium equipment manuals aimed at consumers rarely specify exact thread pitch or length for internal fasteners, since these are considered non-user-serviceable; distributor-level assembly/service manuals (e.g., Maytronics internal documents) are a better source than end-user guides.
- M3 (3.0mm, 0.5mm pitch) is not #6-32 UNC (~3.5mm) — they look identical and cross-thread, the single most common PC-building mistake.
More in 3D Printing, CNC & Robotics
The same screw also fits
Devices whose records share a thread with Poppy Humanoid robot, closest length match first.
- Voron 2.4 gantry and panels also M3
- Voron 2.4 / Trident printed parts also M3
- E3D V6 hotend fixing kit also M3
- Prusa i3 MK3S/MK4 printed parts and extruder also M3
- Micro Swiss probe bracket (3D printer BLTouch-style) also M3
- Creality Sprite Extruder Pro kit also M3
- RatRig V-Core 3.1 (300x300) also M3
- CR-10 Max heat-block cooling shroud also M3
Questions about Poppy Humanoid robot screws
- What size screw does Poppy Humanoid robot use?
- M2 for dynamixel servo horn mounting screws; M3 for 3D-printed limb bracket and servo case assembly.
- How long are the screws in Poppy Humanoid robot?
- None of the sources states a length. Remove one screw and measure it from under the head to the tip (overall for a countersunk head).
- What is the thread pitch of an M2 screw?
- 0.4 mm (coarse), which is the standard pitch for M2 machine screws; a 0.25 mm fine pitch exists but is uncommon. The tap drill is 1.6 mm and the normal clearance hole is 2.4 mm.
- What screwdriver do I need for Poppy Humanoid robot?
- The sources do not name the drive. For M2, Phillips heads normally take PH0 and Torx heads T6; socket heads take a 1.5 mm hex key.
- Can I use an imperial screw instead of M2?
- No. Imperial look-alike: #2-56 UNC (2.18 mm) is close but not interchangeable. Use a true M2 screw so it does not cross-thread or strip the hole.