M3–M20 Solid Brass Countersunk Hex Screws – Fully Threaded, Flat Head, Allen Drive, Coarse Metric $4.88 USD

M3–M20 Solid Brass Countersunk Hex Screws – Fully Threaded, Flat Head, Allen Drive, Coarse Metric

Name: M3–M20 Solid Brass Countersunk Hex Screws – Fully Threaded, Flat Head, Allen Drive, Coarse Metric
Brand: HomeDIYer
SKU: GLFBQLPNNGM01131x1
Price: 4.88 USD
Availability: InStock

$4.88 USD

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By HomeDIYer^®

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🔩 M3–M20 Solid Brass Countersunk Screws – Fully Threaded, Hex Socket Flat Head, Coarse Metric

You’re restoring a vintage boat, building a custom switch panel, or adding brass hardware to a piece of furniture – and you want screws that look the part and won’t seize or rust. These solid brass countersunk screws give you a classic golden finish, excellent corrosion resistance in salt air and fresh water, and a clean flush fit. The hex socket (Allen) drive lets you torque them down without slipping, and the flat 90° head sinks neatly into a pre‑drilled countersink. Fully threaded, coarse pitch, with length measured overall including the head. Available from M3 up to M20. Ideal for marine use, electrical terminals, antique restoration, and any project where ordinary steel screws would look out of place.

✨ Key Features – Solid Brass Countersunk Hex Socket Screws

🔽 Countersunk flat head (90°) – Sits flush with the surface after proper countersinking. Smooth, snag‑free finish.
🧲 Solid brass construction – Non‑magnetic, naturally corrosion resistant in freshwater and marine environments. Develops a beautiful patina over time.
🔧 Hex socket (Allen) drive – Allows high torque without cam‑out. Clean, recessed drive doesn’t collect dirt.
📏 Wide metric range M3 to M20 – From tiny M3 for electronics up to M20 for heavy structural and marine use.
📐 Overall length includes head – Example: M5 x 8mm means total length from top of head to tip is 8mm. Fully threaded, coarse pitch.
⚡ Excellent conductivity – Brass is a good conductor, ideal for electrical terminals and grounding applications.
🔩 Widely used – Marine hardware, electrical panels, furniture restoration, musical instruments, and architectural details.

📏 Specifications – M3 to M20 Brass Countersunk Hex Screws (Overall Length)

Thread Diameter (M)	Thread Pitch (mm)	Overall Length Range (mm, including head) *	Head Style	Drive	Material
📐 Overall length = from top of head to tip. Fully threaded, coarse pitch. Select exact size from dropdown.
M3	0.5	Lengths vary by diameter – typical range from 6mm up to 100mm depending on M size. Select your required M diameter and length from dropdown.	Countersunk / Flat (90°)	Hex socket (Allen)	Solid brass
M4	0.7
M5	0.8
M6	1.0
M8	1.25
M10	1.5
M12	1.75
M16	2.0
M20	2.5

* Overall length includes the head. All screws are fully threaded. Please allow minor manual measurement errors. Hex key sizes: M3→2mm, M4→2.5mm, M5→3mm, M6→4mm, M8→5mm, M10→6mm, M12→8mm, M16→10mm, M20→12mm approx.

📋 Why Choose Solid Brass Fasteners?

Property	Benefit
Corrosion resistance	Excellent in freshwater, salt air, and marine environments. No red rust – forms a protective patina.
Non‑magnetic	Safe for electronics, MRI rooms, and compass housings.
Electrical conductivity	Good conductor – ideal for grounding terminals, battery connections, and electrical panels.
Aesthetic	Warm golden color that matches wood, leather, and vintage hardware. Can be polished or left to age.
Strength	Lower than steel, but sufficient for most furniture, marine, and decorative applications.

❓ Frequently Asked Questions – Brass Countersunk Hex Screws

1. How do I measure the length of these countersunk screws?

For countersunk screws, the length is measured overall – from the top of the head to the tip. So an “M5 x 8mm” screw has a total length of 8mm including the head. This is standard for flat head fasteners.

2. Do I need to countersink the hole for these screws to sit flush?

Yes – these are true 90° countersunk screws. For the head to be perfectly flush or slightly recessed, you must drill a matching 90° countersink hole. Use a countersink bit of the appropriate size.

3. Are these screws fully threaded? What about longer lengths?

Yes – all M3 to M20 screws in this range are fully threaded from under the head to the tip. This ensures maximum grip in blind holes or through‑nut applications.

4. Will brass screws rust or tarnish? Can I use them in saltwater?

Brass does not rust (it contains no iron). It does develop a natural patina – first darkening, then sometimes turning greenish (verdigris) in saltwater. This patina is protective. For continuous underwater immersion, marine bronze is better, but for above‑water marine hardware, docks, and outdoor furniture, brass works beautifully for years.

5. What hex key size do I need for each screw?

Approximate matching: M3→2mm, M4→2.5mm, M5→3mm, M6→4mm, M8→5mm, M10→6mm, M12→8mm, M16→10mm, M20→12mm. Always use a quality hex key that fits snugly to avoid rounding the socket.

6. Can I use these screws with a nut? What size nut fits?

Yes – these are machine screws. Use standard metric nuts of the same thread size and pitch (e.g., M6 nut for M6 screw). They will also thread into pre‑tapped holes. They are not self‑tapping – for wood or plastic, use a threaded insert or a nut on the back.