Prusa i3 MK3S/MK4 heatbed and frame screw size
M4 · 5 to 25 mm long
Our records put Prusa i3 MK3S/MK4 heatbed and frame on M4 screws in lengths from 5 to 25 mm.
The record covers M4 screws M4x5 through M4x25 listed in the official Prusa cheatsheet.
This entry is marked confirmed and comes from prusa3d.com.
M4 means a 4 mm nominal diameter with a 0.7 mm thread pitch. Imperial look-alike: #8-32 (4.17 mm) — the standard US PC/rack screw, close but not the same.
Prusa i3 MK3S/MK4 heatbed and frame 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 |
|---|---|---|---|---|---|---|
| M4 | 5–25 mm | 0.7 mm | not stated | not stated | M4 screws M4x5 through M4x25 listed in the official Prusa cheatsheet | Confirmed |
Fitment records and sources
M4 screws M4x5 through M4x25 listed in the official Prusa cheatsheet
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 M4 screw measures about 4 mm with calipers (usually a hair under). If yours measures noticeably more or less, it is a different thread.
- Pitch: 0.7 mm from one thread crest to the next (14.29 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.
- The records span 5–25 mm, which means different positions take different lengths — match each hole to its own screw.
- Driver: the source does not name the drive. Standard M4 heads take PH2 for Phillips and T20 for Torx, and a 3 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 M4 is about 2.0-3.0 N·m into metal threads and 0.8-1.4 N·m into plastic bosses; snug it up and stop.
Common mix-ups with M4
- M4 and 6-32 UNC share a nominal diameter with different pitch — a classic cross-thread in US-market kits.
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.
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Devices whose records share a thread with Prusa i3 MK3S/MK4 heatbed and frame, closest length match first.
- 3D printer & CNC enclosures also M4 × 8–20 mm
- Creality K1/Ender extrusion corner brackets also M4 × 8–16 mm
- Heated bed leveling screws also M4 × 20–25 mm
- Avid CNC Laser Kit also M4 × 6–16 mm
- 3D printer hotend to X-carriage also M4 × 10–20 mm
- Zodiac Vortex 3 Saphir robotic pool cleaner also M4 × 25 mm
- InMoov open-source robot also M4 × 20 mm
- Makeblock mBot Neo/mBot2 assembly kit also M4 × 8–25 mm
Questions about Prusa i3 MK3S/MK4 heatbed and frame screws
- What size screw does Prusa i3 MK3S/MK4 heatbed and frame use?
- M4 × 5–25 mm for M4 screws M4x5 through M4x25 listed in the official Prusa cheatsheet.
- How long are the screws in Prusa i3 MK3S/MK4 heatbed and frame?
- The records range from 5 to 25 mm depending on the position, so match each screw to its own hole.
- What is the thread pitch of an M4 screw?
- 0.7 mm (coarse), which is the standard pitch for M4 machine screws; a 0.5 mm fine pitch exists but is uncommon. The tap drill is 3.3 mm and the normal clearance hole is 4.5 mm.
- What screwdriver do I need for Prusa i3 MK3S/MK4 heatbed and frame?
- The sources do not name the drive. For M4, Phillips heads normally take PH2 and Torx heads T20; socket heads take a 3 mm hex key.
- Can I use an imperial screw instead of M4?
- No. Imperial look-alike: #8-32 (4.17 mm) — the standard US PC/rack screw, close but not the same. Use a true M4 screw so it does not cross-thread or strip the hole.