InMoov open-source robot screw size
M3 / M4 · 20 mm long
InMoov open-source robot takes M3 and M4 metric screws, 20 mm long.
There are 2 separate fitment records for it, including structural joints, servo brackets, printed part fastening (Allen countersunk, ~50 qty) (M3) and arm/shoulder structural joints (~50 qty) (M4).
Head and drive, as the sources state them: flat / countersunk and shoulder screw heads and Hex socket (Allen) drive.
2 of the 2 records are marked confirmed, drawn from 1 source (inmoov.fr Default Hardware Map + BOM).
M3 means a 3 mm nominal diameter with a 0.5 mm thread pitch. Imperial look-alike: #5-40 (3.18 mm) or #4-40 — neither interchanges with M3.
InMoov open-source 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 |
|---|---|---|---|---|---|---|
| M3 | 20 mm | 0.5 mm | Flat / countersunk | Hex socket (Allen) | structural joints, servo brackets, printed part fastening (Allen countersunk, ~50 qty) | Confirmed |
| M4 | 20 mm | 0.7 mm | Shoulder screw | not stated | arm/shoulder structural joints (~50 qty) | Confirmed |
Fitment records and sources
structural joints, servo brackets, printed part fastening (Allen countersunk, ~50 qty)
pitch 0.5 mm · tap 2.5 mm · clearance 3.4 mm · PH1 / Torx T10
arm/shoulder structural joints (~50 qty)
pitch 0.7 mm · tap 3.3 mm · clearance 4.5 mm · PH2 / Torx T20
How to check the screw before you buy
- Into printed plastic, the screw either self-taps or needs a heat-set insert; machine screws straight into plastic strip easily.
- Diameter: across the threads an M3 screw measures about 3 mm with calipers (usually a hair under). This device also uses M4, so measure each screw rather than assuming they match.
- Pitch: 0.5 mm from one thread crest to the next (20 crests per centimetre). A thread pitch gauge or the pitch-gauge tool settles it in seconds.
- Length: the source describes a countersunk (flat) head, and those are measured overall, from the top of the head to the tip.
- The record states 20 mm. Going longer risks bottoming out or touching parts behind the hole; going shorter loses thread engagement.
- Driver: the source names a Hex socket (Allen) drive. For comparison, standard M3 heads take PH1 (Phillips) or T10 (Torx), or a 2.5 mm hex key.
- Tightening: no device-specific torque is published in these records. The site's general figure for M3 is about 80-130 N·cm into metal threads and 35-60 N·cm into plastic bosses; snug it up and stop.
Common mix-ups with M3 / M4
- ISO 14581 Torx countersunk screws look like plain countersunk screws but need the right lobe driver; a Phillips bit will chew the head.
- The bioprinter M3 reference is a tube-connector thread spec, not a structural chassis screw; verify before assuming interchangeability with fastener screws.
- Camera rig/cage accessories (SmallRig, Wooden Camera/Metabones) frequently mix M4 structural screws with 1/4-20 and 3/8-16 imperial mounting points on the same product — verify which specific fastener a manual is referencing before ordering replacements.
- Grounding-lug screws on Siemens and Beckhoff gear (M4) are earth hardware, not structural mounting screws — don't reuse them to hold a module.
Buy these screws at TechSpare Warehouse
In stock and shipped from South Carolina. Our black screws are Phillips wafer head (low profile); match the head style and length to the original before you order.
More in 3D Printing, CNC & Robotics
The same screw also fits
Devices whose records share a thread with InMoov open-source robot, closest length match first.
- Bambu Lab X1/P1 heatbed transport anchors also M3 × 20 mm
- Makeblock mBot Neo/mBot2 assembly kit also M4 × 20 mm
- Prusa MK4 Nextruder also M3 × 20 mm
- Ultimaker Original heated bed / Z-stage upgrade kit also M3 × 20 mm
- Voron 2.4 3D printer also M3 × 20 mm
- FDM hotend and extruder mounts (general) also M3 × 20 mm
- Carbide3D Shapeoko 5 Pro CNC router also M4 × 20 mm
- Prusa MK3S extruder also M3 × 20 mm
Questions about InMoov open-source robot screws
- What size screw does InMoov open-source robot use?
- M3 × 20 mm for structural joints, servo brackets, printed part fastening (Allen countersunk, ~50 qty); M4 × 20 mm for arm/shoulder structural joints (~50 qty).
- How long are the screws in InMoov open-source robot?
- The record gives 20 mm. Measure the original from under the head (overall for a countersunk head) to confirm before ordering.
- What is the thread pitch of an M3 screw?
- 0.5 mm (coarse), which is the standard pitch for M3 machine screws; a 0.35 mm fine pitch exists but is uncommon. The tap drill is 2.5 mm and the normal clearance hole is 3.4 mm.
- What screwdriver do I need for InMoov open-source robot?
- The source lists a Hex socket (Allen) drive. Standard M3 heads otherwise take PH1 (Phillips) or T10 (Torx), or a 2.5 mm hex key.
- Can I use an imperial screw instead of M3?
- No. Imperial look-alike: #5-40 (3.18 mm) or #4-40 — neither interchanges with M3. Use a true M3 screw so it does not cross-thread or strip the hole.