Product Description
No.7 A2 Stainless Steel Raised Countersunk Pozi Self Tapping Screws
No.7 raised countersunk self tapping screws manufactured from A2 stainless steel. These screws feature a Pozi-style cross recess and a raised countersunk, also known as an oval, head that provides a decorative raised finish above a suitable countersunk hole.
The No.7 size corresponds to the ST3.9 tapping-screw designation. The self tapping thread forms its mating thread during installation, making these screws suitable for sheet metal, plastics and other compatible materials.
- Nominal size: No.7 / ST3.9
- Approximate thread diameter: 3.9mm
- Head style: Raised countersunk / oval head
- Drive: Pozi-style cross recess
- Material: A2 austenitic stainless steel
- Finish: Natural stainless steel
- Legacy standard: DIN 7983
- Current dimensional standard: ISO 7051:2011
- British Standard: BS EN ISO 7051:2011
- Approximate head diameter: 7.5mm
- Available lengths: 1/2" to 1 1/2"
Typical Applications
- Sheet-metal panels and enclosures
- Automotive trim and light bodywork
- Decorative panels and fittings
- Electrical and equipment housings
- Plastic components suitable for self tapping screws
- General repair and maintenance work
Installation Guidance
Prepare a correctly sized pilot hole and countersink suitable for the substrate. Use a correctly fitting Pozi driver bit and keep the tool aligned with the screw. Avoid excessive installation torque, which may strip the formed thread or damage the drive recess.
A2 stainless steel provides good general corrosion resistance but is not normally the preferred choice for prolonged saltwater, swimming-pool or aggressive chemical exposure. Consider A4 stainless steel for more demanding corrosive environments.
Stainless steel tapping screws should not be forced into material that is too hard or into an undersized pilot hole. Excessive torque may twist or fracture the screw.
Please note: Dimensions are supplied as a guide. If dimensions, drive form, material grade, hardness class or standards compliance are critical, please confirm the required specification with us before ordering.
| A | B | C | D | E | F |
| No.7 | 3.9mm | 1 1/2" | 38mm | 19/64" | 7.5mm |
| No.7 | 3.9mm | 1 1/4" | 32mm | 19/64" | 7.5mm |
| No.7 | 3.9mm | 1" | 25mm | 19/64" | 7.5mm |
| No.7 | 3.9mm | 1/2" | 13mm | 19/64" | 7.5mm |
| No.7 | 3.9mm | 3/4" | 19mm | 19/64" | 7.5mm |
| No.7 | 3.9mm | 5/8" | 16mm | 19/64" | 7.5mm |
Please Note: Specifications given are intended as a guide only. If critical to your project please check with us first.
