Product Description
No.6 A2 Stainless Steel Countersunk Torx Self-Tapping Screws
No.6 countersunk self-tapping screws manufactured from A2 stainless steel and featuring an internal six-lobe Torx-style drive. The countersunk head can finish flush with the surrounding surface when installed into a correctly prepared countersink.
The No.6 thread has an approximate outside diameter of 3.5mm. These screws are available in imperial lengths from 1/4" to 2" and in pack quantities from 1 to 1,000.
Key Features
- No.6 self-tapping screw thread
- Approximately 3.5mm outside thread diameter
- A2 stainless steel construction
- Good general-purpose corrosion resistance
- Flush-fitting countersunk head
- Internal six-lobe Torx-style drive
- Positive driver engagement with reduced cam-out
- Available in lengths from 1/4" to 2"
- Available in packs from 1 to 1,000
Available Lengths
| Screw Size | Nominal Diameter | Imperial Length | Approximate Metric Length |
|---|---|---|---|
| No.6 | 3.5mm | 1/4" | 6.5mm |
| No.6 | 3.5mm | 3/8" | 9.5mm |
| No.6 | 3.5mm | 1/2" | 13mm |
| No.6 | 3.5mm | 3/4" | 19mm |
| No.6 | 3.5mm | 1" | 25mm |
| No.6 | 3.5mm | 1 1/2" | 38mm |
| No.6 | 3.5mm | 2" | 50mm |
Countersunk screw length is measured from the top of the head to the end of the point.
Product Dimensions
| Nominal Size | No.6 |
|---|---|
| Outside Thread Diameter | Approximately 3.5mm |
| Reference Thread Pitch | Approximately 1.3mm |
| Head Diameter | Approximately 6.5mm |
| Head Diameter in Inches | Approximately 1/4" |
| Head Type | Countersunk |
| Drive Type | Internal six-lobe Torx style |
| Reference Drive Size | T15 – confirm against the supplied product |
| Material | A2 stainless steel |
Torx-Style Drive
The internal six-lobe recess provides positive contact between the screw and driver bit. This helps reduce driver slippage and cam-out compared with conventional cross-recessed screws.
ISO 14586 normally specifies a T15 hexalobular socket for an ST3.5 countersunk self-tapping screw. However, the drive size is not currently stated on the product page and should be confirmed against the supplied screws before purchasing installation tooling.
Standards Information
ISO 14586 is the specific international standard for hexalobular socket countersunk head tapping screws in thread sizes from ST2.9 to ST6.3. The No.6 diameter of approximately 3.5mm corresponds to the ST3.5 size covered by this standard.
A2 Stainless Steel
A2 stainless steel provides good corrosion resistance in many indoor, outdoor and general industrial environments. It is useful where an uncoated fastener with better corrosion resistance than ordinary carbon steel is required.
A2 stainless steel is not normally the first choice for prolonged exposure to seawater, coastal salt spray or strongly chloride-contaminated environments. A4 stainless steel should be considered for those conditions.
Typical Applications
- Sheet-metal fabrication
- Equipment panels and enclosures
- Electrical and electronic housings
- Heating and ventilation equipment
- Vehicle trim and interior fittings
- General engineering assemblies
- Suitable plastic components
- Outdoor fixtures in moderately corrosive environments
Installation Advice
These are self-tapping screws rather than self-drilling screws. A suitable pilot hole will normally be required. The correct pilot-hole diameter depends on the material, material thickness and required thread engagement.
Prepare an appropriate countersink if the head needs to finish flush with the surface. Use a correctly fitting driver bit, keep the driver aligned and avoid excessive installation speed or tightening torque.
Stainless steel threads can gall or seize. Where subsequent removal may be required, consider using a suitable anti-galling lubricant and install the screws at a controlled speed.
Useful Links
- View all countersunk Torx self-tapping screws
- View all self-tapping screws
- No.8 A2 stainless countersunk Torx self-tapping screws
- No.10 A2 stainless countersunk Torx self-tapping screws
- No.12 A2 stainless countersunk Torx self-tapping screws
- How to measure a bolt or screw
- Self-tapping and wood screw size guide
- Fastener materials and technical guide
Specifications are intended as a guide. Confirm the drive size, head dimensions, material certification and standard compliance before use in safety-critical or specification-controlled applications.
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