Sewing machine motor mount screw size
M4 · 10 to 20 mm long
If you are replacing a screw on Sewing machine motor mount, the thread is M4 in lengths from 10 to 20 mm.
It is listed for motor bracket and belt tension bolts.
This entry is marked reported.
For reference, M4 is 4 mm across the threads at 0.7 mm pitch. The imperial size people confuse it with: #8-32 (4.17 mm) — the standard US PC/rack screw, close but not the same.
Sewing machine motor mount 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 | 10–20 mm | 0.7 mm | not stated | not stated | Motor bracket and belt tension bolts | Reported |
Fitment records and sources
Motor bracket and belt tension bolts
pitch 0.7 mm · tap 3.3 mm · clearance 4.5 mm · PH2 / Torx T20
How to check the screw before you buy
- Vibration loosens small screws on drones and RC models, so builders commonly add a drop of medium (blue) threadlocker on metal-to-metal joints — never on plastic.
- 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 10–20 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
- Water heater elements use pipe threads (NPSM/NPT), not metric machine screws.
- Bopla SHR-Z boss screws and Hammond 1591XXF screws look metric but are self-tapping/imperial — don't substitute a machine screw into those bosses.
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Devices whose records share a thread with Sewing machine motor mount, closest length match first.
- Nerf blaster thumbscrews (large) also M4 × 10–20 mm
- Typewriter carriage brackets also M4 × 10–14 mm
- Mid-size drone frames also M4 × 10–16 mm
- HP LaserJet family common hardware also M4 × 10–14 mm
- goBILDA metric building system also M4 × 10–20 mm
- Padlock and safe internals also M4 × 10–12 mm
- Maytronics Dolphin robotic pool cleaner (Ad-series/other Dolphin models) also M4 × 14 mm
- Meccano boxed sets (modern metric era) and compatible parts also M4 × 10–20 mm
Questions about Sewing machine motor mount screws
- What size screw does Sewing machine motor mount use?
- M4 × 10–20 mm for motor bracket and belt tension bolts.
- How long are the screws in Sewing machine motor mount?
- The records range from 10 to 20 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 Sewing machine motor mount?
- 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.