🔩 KM3 Phillips Countersunk Machine Screws – M3 x 3–18mm, Carbon or 304 Stainless, Multiple Finishes (Cross Flat Head)
You’re working on a small electronic device, a piece of furniture, or a DIY project – and you need a reliable M3 countersunk screw that sits perfectly flush. These KM3 series screws are available in carbon steel (heat‑treated) or 304 stainless steel, with a wide choice of surface finishes: black zinc, colour zinc, white zinc, nickel, black nickel, anti‑loosening rubber patches, and more. The Phillips cross recess gives you a secure drive, and the flat 90° head sinks flush into a pre‑drilled countersink. Total length includes the head, from 3mm up to 18mm. Fully threaded. Perfect for machinery, electronics, furniture, automotive, and general assembly where a flush, corrosion‑resistant fastener is needed.
✨ Key Features – KM3 Countersunk Phillips Screws
- 🔽 Countersunk flat head (90°) – Sits flush with the surface after proper countersinking. Clean, professional finish.
- 📏
Phillips drive – Standard cross recess works with common screwdrivers. Good torque transfer.
- 🛡️ Material choices – Carbon steel (heat‑treated) for strength; 304 stainless for superior corrosion resistance.
- 🎨 Wide finish selection – Black zinc, colour zinc, white zinc, nickel, black nickel, and anti‑loosening rubber patches (black/blue zinc). Also stainless natural or black‑coated.
- 📏 M3 metric thread (3mm diameter) – One of the most common sizes for small electronics, appliances, and machinery.
- 📐 Total length 3–18mm (including head) – Example: KM3 x 10mm means total length from top of head to tip is 10mm. Fully threaded.
- 🔧 Versatile applications – Machinery manufacturing, automotive, aerospace, shipbuilding, electronics, furniture, home maintenance, and outdoor gear.
📏 Specifications – KM3 M3 Countersunk Screws (Overall Length)
| Thread Diameter (M) |
Total Length (mm, including head) * |
Head Diameter (mm) |
Head Thickness (mm) |
Thread Pitch (mm) |
Material Options |
| 📐 Length = from top of head to tip. Fully threaded. Select exact size, material and finish from dropdown. |
| M3 |
3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18 |
4.3 – 6.0
(varies by length) |
0.65 – 1.75
(varies by head diameter) |
0.5 |
Carbon steel or 304 stainless steel |
* Lengths are typical – exact availability may vary. Tolerance ±0.2mm. Head diameter and thickness vary with total length – refer to dropdown for precise values. Anti‑loosening rubber patches available on black or blue zinc finishes.
📋 Finish Options – What’s Best for Your Project?
| Finish |
Appearance |
Corrosion Resistance |
Special Feature |
Best For |
| Black zinc / Colour zinc / White zinc |
Matte or semi‑gloss |
Moderate – indoor use |
– |
General indoor machinery, furniture |
| Nickel / Black nickel |
Bright silver or dark nickel |
Good – indoor, light moisture |
– |
Electronics, visible fasteners |
| Black/Blue zinc + anti‑loosening rubber |
Zinc colour with coloured patch |
Moderate + vibration resistance |
Patch prevents loosening |
High‑vibration applications (vehicles, tools) |
| 304 Stainless (natural) |
Silver, bright |
Excellent – outdoor, marine |
No coating needed |
Outdoor, coastal, food equipment |
| 304 Stainless + black |
Black coated stainless |
Excellent + added black finish |
Aesthetic & corrosion resistant |
Dark assemblies, outdoor |
❓ Frequently Asked Questions – KM3 Countersunk Screws
1. How do I measure the length of these countersunk screws?
Total length is measured from the top of the head to the tip (overall length). So a “KM3 x 10mm” screw has a total length of 10mm including the head. This matches our listing.
2. Do I need to countersink the hole for these screws to sit flush?
Yes – these are true 90° countersunk screws. For a flush finish, drill a matching 90° countersink hole. Use a countersink bit slightly larger than the head diameter.
3. Are these screws fully threaded?
Yes – all KM3 screws in this range (3–18mm) are fully threaded from under the head to the tip, giving you maximum grip in blind holes or when using nuts.
4. What’s the difference between “carbon steel” and “304 stainless”?
Carbon steel is stronger and more affordable but needs plating to resist rust. 304 stainless is naturally corrosion resistant, ideal for outdoor or humid environments. Both are available in various finishes.
5. What does “anti‑loosening rubber” do? Do I need it?
A nylon or rubber patch is bonded to the threads. It creates friction, preventing the screw from vibrating loose. Choose it for applications with constant vibration (e.g., vehicles, power tools, drones).
6. Can I use these screws with a nut? What size nut fits?
Yes – these are machine screws. Use a standard M3 metric nut (0.5mm pitch). For outdoor use, pair with a stainless nut.
