12g (5.5mm) Stainless A2-70 G304 VMAX Trim Head Torx (T20) Decking Timber T17 Screws

About Countersunk Timber Screws

Self-tapping timber screws with a countersunk (bugle) head designed to pull flush with the timber surface. The largest sub-cat in the timber range covering Square, Phillips, Internal Hex and Torx drives in zinc yellow, galvanised, A2 / A4 stainless and brass finishes. AS 3566 standard with Type 17 self-drilling point.

Frequently Asked Questions

Material & Coating

Stainless A2-70 G304 Austenitic stainless steel. Property class 70 designates a minimum tensile strength of 700 MPa with a 0.2 percent proof stress of 450 MPa. Lightly magnetic in cold-worked form, which does not affect corrosion performance.

Grade selection A2-70 G304 is the general-purpose stainless grade for outdoor and most chemical environments. A4-70 G316 contains 2 to 3 percent molybdenum, giving substantially better resistance to chlorides; A4-70 G316 is the preferred grade for marine, coastal and pool environments.

Important Do not pair stainless fasteners with plain or galvanised steel components in wet service. The galvanic potential difference accelerates corrosion of the less-noble metal.

Thread Pitch & Terminology

Thread Pitch (TPI)TPI stands for "threads per inch", which literally means the number of threads within each inch on a screw, a bolt or a fastener. To determine the TPI of a screw, count the number of threads contained within an inch of length on the fastener. If the screw is less than an inch long, count the threads in half an inch and multiply by 2. The higher the number, the finer the thread. For timber screws, a coarse thread (lower TPI, typically around 8 to 12) is better for softwood, structural framing and decking timber - the bigger bite into the softer fibres gives a stronger grip with less risk of stripping. A fine thread (higher TPI, typically around 24 and above) is better for hardwood, where the tight grain lets a fine thread cut cleanly without splitting the timber.

Need every size? See our full screw gauge sizing chart for every standard gauge with diameter in mm and inch.

How to Measure

Fastener Length This product has a flush-fitting head, so the length is measured as the overall length - from the tip of the thread to the top of the head. The head is included in the size.

Thread Length On a screw the thread length runs from the start of the unthreaded section (called the shank) to the end of the thread. To view the thread length for this product, select a length above.

Resources

Pricing & Delivery

Includes GST, a Tax Invoice and Free Standard Delivery anywhere in Australia.

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Disclaimer

Technical data Researched and compiled from numerous industry sources for the sole purpose of providing basic information. All material is advisory only and its use by anyone is entirely voluntary. Reliance on it for any purpose by anyone is at the sole risk of that person, and Bolt and Nut Australia is not responsible for any loss, claim or damages arising therefrom. In developing this information, Bolt and Nut Australia has made a determined effort to present it accurately.

Measurements Sizes are taken from supplier catalogues or hand-measured and should be used as a guide. Minor variation between batches is normal. Stock is sourced from various suppliers, so differences may exist between batches in thread length, markings, appearance or finish.

Product Photos & PDF Data Sheets Represent the product type, not exact size. PDFs are a reference guide only. Specifications may change without notice.

If you see any problems with any of our specifications or you require additional information please contact us.