M3.5 Stainless Steel Phillips Countersunk Flat Head Machine Screws – 6 to 60mm $1.75 USD

M3.5 Stainless Steel Phillips Countersunk Flat Head Machine Screws – 6 to 60mm

Name: M3.5 Stainless Steel Phillips Countersunk Flat Head Machine Screws – 6 to 60mm
Brand: HomeDIYer
SKU: GLFBQLPBRTQJD004268x10
Price: 1.75 USD
Availability: InStock

$1.75 USD

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By HomeDIYer^®

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M3.5 Stainless Steel Phillips Countersunk Flat Head Machine Screws — 6mm to 60mm

The M3.5 thread size occupies a specific niche in the metric fastener world — larger than M3 but smaller than M4, and the standard choice for a range of electronics, computer hardware, and precision equipment applications. These Phillips countersunk flat head machine screws are made from stainless steel, providing corrosion resistance that carbon steel and zinc-plated fasteners simply cannot match over time.

The countersunk (flat) head profile is designed to sit flush with or below the surface of the workpiece when driven into a properly prepared countersunk hole, delivering a clean, professional finish. The Phillips drive is compatible with standard PH1 screwdrivers and power tools, making installation fast and straightforward.

Available in 15 lengths from 6mm to 60mm, with pack sizes from 5 to 500 pieces — whether you need a small quantity for a single repair or a bulk pack for production or workshop stock, there’s an option to suit your requirements.

🔩 Compatibility: ISO metric M3.5 thread standard (0.6mm pitch) — compatible with standard M3.5 metric nuts, threaded inserts, and tapped holes. Always verify thread pitch and hole diameter before ordering.

✅ Key Features of These M3.5 Stainless Steel Phillips Countersunk Machine Screws

🔩Stainless Steel Construction — Provides inherent corrosion resistance suitable for indoor, outdoor, and mildly corrosive environments. Significantly more durable than carbon steel or zinc-plated alternatives over time.
📐Countersunk (Flat) Head — 90° conical underside seats flush with or below the workpiece surface when driven into a properly countersunk hole. Ideal for applications requiring a clean, flush finish.
🔧Phillips Drive — Standard cross-head drive compatible with PH1 Phillips screwdrivers and power tools. Widely available tooling for fast, efficient installation.
📏M3.5 Thread — 15 Lengths Available — 6mm, 8mm, 10mm, 12mm, 14mm, 16mm, 18mm, 20mm, 25mm, 30mm, 35mm, 40mm, 45mm, 50mm, and 60mm to cover a wide range of fastening depths.
📦Flexible Pack Sizes — Available in 5, 10, 20, 30, 50, 100, 200, and 500-piece packs to suit single-project needs, workshop stock, or production quantities.
⚙️ISO Metric M3.5 Thread — Compatible with standard M3.5 nuts, threaded inserts, and tapped holes. Commonly used in computer hardware, electronics enclosures, and precision equipment.

📐 Technical Specifications — M3.5 Stainless Steel Phillips Countersunk Machine Screws

Thread Diameter	M3.5 (3.5mm)
Thread Standard	ISO Metric
Thread Pitch	0.6mm
Drive Type	Phillips (PH / Cross Head)
Head Style	Countersunk (Flat Head, 90°)
Material	Stainless Steel
Lengths Available	6, 8, 10, 12, 14, 16, 18, 20, 25, 30, 35, 40, 45, 50, 60mm
Pack Sizes	5, 10, 20, 30, 50, 100, 200, 500 Pcs
Recommended Driver	PH1 Phillips Screwdriver
Head Angle	90° Countersunk
Finish	Natural Stainless
Country of Origin	Contact us to confirm

⚠️ Note: Countersunk screws require a properly prepared countersunk hole for the head to sit flush. Stainless steel fasteners can be susceptible to galling (thread seizure) — apply anti-seize lubricant when threading into stainless steel nuts or tapped holes. Always use a PH1 Phillips driver to avoid cam-out and head damage.

❓ Frequently Asked Questions

What is an M3.5 screw and where is it commonly used?

M3.5 is a metric thread size with a 3.5mm nominal diameter. It is less common than M3 or M4 but is widely used in specific applications including computer hardware (particularly older PC cases and optical drives), electronics enclosures, and precision equipment. The M3.5 thread pitch is typically 0.6mm per ISO metric standards.

What grade of stainless steel are these screws made from?

Please contact us to confirm the exact stainless steel grade. Common grades for machine screws include 304 (A2) and 316 (A4). 304 stainless steel offers good general corrosion resistance suitable for most indoor and outdoor applications. 316 stainless steel provides enhanced resistance to chlorides and is preferred for marine or coastal environments.

What screwdriver do I need for Phillips head screws?

M3.5 Phillips countersunk screws typically require a PH1 (Phillips #1) screwdriver. Using the correct driver size is important to avoid cam-out and head damage, especially on stainless steel screws where the head recess can be more susceptible to stripping if the wrong driver is used.

Do I need to pre-drill a countersunk hole?

Yes. For the screw head to sit flush with the surface, you need to drill a clearance hole for the shank and countersink the top of the hole to match the screw head angle (typically 90°). The countersink diameter should match the head diameter of the M3.5 screw. Driving a countersunk screw into an unprepared hole will leave the head proud of the surface.

Are stainless steel screws suitable for outdoor use?

Yes. Stainless steel offers significantly better corrosion resistance than carbon steel or zinc-plated fasteners. It is suitable for outdoor, humid, and mildly corrosive environments. For marine or coastal applications with high chloride exposure, 316 (A4) stainless steel is recommended over 304 (A2).

How do I choose the right screw length?

For machine screws used with a nut, the screw should extend at least 1–2 thread pitches beyond the nut when fully tightened. For screws threading into a tapped hole, aim for at least 1.5× the thread diameter of engagement (approximately 5mm for M3.5). For countersunk applications, account for the depth of the countersink when selecting length.

Can stainless steel screws seize or gall during installation?

Yes. Stainless steel fasteners are susceptible to galling (thread seizure) during installation, particularly when threading into stainless steel nuts or tapped holes. To reduce the risk, apply a small amount of anti-seize lubricant to the threads before installation, avoid over-tightening, and drive at a slow, steady speed.

🛒 Select your length and pack size above, then add to cart — ships from our US warehouse.