Prusa i3 MK3S+ extruder sensor screw screw size
M2 · length not stated in the sources
The screws used on Prusa i3 MK3S+ extruder sensor screw are M2. None of the sources we found gives an exact length, so measure the original before you order.
It is listed for prusa's official upgrade guide calls for a 1.5mm Allen key for the M2 extruder screw.
Head and drive, as the source states them: Hex socket (Allen) drive.
This entry is marked confirmed and comes from help.prusa3d.com.
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.
Prusa i3 MK3S+ extruder sensor screw 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 | Hex socket (Allen) | Prusa's official upgrade guide calls for a 1.5mm Allen key for the M2 extruder screw | Confirmed |
Fitment records and sources
Prusa's official upgrade guide calls for a 1.5mm Allen key for the M2 extruder screw
pitch 0.4 mm · tap 1.6 mm · clearance 2.4 mm · PH0 / Torx T6
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). If yours measures noticeably more or less, it is a different thread.
- 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 names a Hex socket (Allen) drive. For comparison, standard M2 heads take PH0 (Phillips) or T6 (Torx), or a 1.5 mm hex key.
- 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
- DJI airframes mix 1.5mm/2mm hex and Phillips drives at similar diameters — check the drive type, not just the thread.
- Prusa uses M2/M3/M4/M5 in dozens of specific lengths while Voron/LDO kits lean on M3 and M5 SHCS — a generic 'M3 bag' from one ecosystem often has the wrong head type for the other.
More in 3D Printing, CNC & Robotics
The same screw also fits
Devices whose records share a thread with Prusa i3 MK3S+ extruder sensor screw, closest length match first.
- Voron 2.4 also M2
- NEMA 17 stepper motor (Novanta/IMS) also M2
- Prusa i3 MK3S/MK4 (official fastener cheatsheet) also M2
- NEMA 23 stepper motor, 3A variant (Novanta/IMS) also M2
- Poppy Humanoid robot also M2
- Actobotics servo horn / hub also M2
- SO-100 / SO-ARM100 robot arm (LeRobot) also M2
- Lenovo ThinkPad T15p Gen 1 also M2
Questions about Prusa i3 MK3S+ extruder sensor screw screws
- What size screw does Prusa i3 MK3S+ extruder sensor screw use?
- M2 for prusa's official upgrade guide calls for a 1.5mm Allen key for the M2 extruder screw.
- How long are the screws in Prusa i3 MK3S+ extruder sensor screw?
- 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 Prusa i3 MK3S+ extruder sensor screw?
- The source lists a Hex socket (Allen) drive. Standard M2 heads otherwise take PH0 (Phillips) or T6 (Torx), or 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.