{"product_id":"m8-carriage-bolts-a2-stainless-steel-din-603","title":"M8 Carriage Bolts A2 Stainless Steel — Cup Square Dome Head Coach Screws DIN 603 (30–70mm)","description":"\u003cp\u003e \u003c\/p\u003e\n\u003cdiv class=\"hdiy-desc\"\u003e\n\u003cdiv class=\"hdiy-overview\"\u003e\n\u003ch2\u003eM8 Carriage Bolts in A2 Stainless Steel — Secure, Rust-Resistant Fastening for Wood \u0026amp; Structural Projects\u003c\/h2\u003e\n\u003cp\u003eWhether you're building a backyard deck, assembling a timber pergola, or hanging a heavy gate, loose or rusted fasteners can compromise the entire structure. DIYers and contractors working with outdoor wood need a bolt that locks in place without spinning, resists the elements season after season, and meets a recognized dimensional standard — not a generic hardware bin grab-bag.\u003c\/p\u003e\n\u003cp\u003eEach box in this listing contains M8 cup square dome head carriage bolts manufactured to \u003cstrong\u003eDIN 603\u003c\/strong\u003e in \u003cstrong\u003eA2 (304) stainless steel\u003c\/strong\u003e. The 8mm shank features a square neck that embeds into timber to prevent rotation while you tighten the nut from the other side. Available lengths run from \u003cstrong\u003e30mm (≈1-3\/16\")\u003c\/strong\u003e to \u003cstrong\u003e70mm (≈2-3\/4\")\u003c\/strong\u003e, with pack quantities of 15–30 pieces per box depending on the length selected. All bolts carry a standard M8 metric coarse thread (1.25mm pitch) compatible with any M8 hex or wing nut.\u003c\/p\u003e\n\u003cp\u003eTypical use cases include \u003cstrong\u003edeck board-to-joist connections\u003c\/strong\u003e, \u003cstrong\u003efence rail and post assembly\u003c\/strong\u003e, \u003cstrong\u003etimber frame and pergola construction\u003c\/strong\u003e, and \u003cstrong\u003ewood-to-metal bracket fastening\u003c\/strong\u003e in garden structures. The smooth dome head sits flush and clean on the surface, making these coach screws a practical choice wherever a finished appearance matters alongside structural integrity.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"hdiy-compat\"\u003e\n\u003cspan class=\"hdiy-compat-icon\"\u003e🔩\u003c\/span\u003e \u003cstrong\u003eThread Compatibility:\u003c\/strong\u003e Standard M8 metric coarse thread (pitch 1.25mm) — fits all DIN 934 M8 hex nuts, M8 wing nuts, and M8 flat washers. \u003cstrong\u003eNot compatible with imperial (SAE\/UNC) threaded hardware.\u003c\/strong\u003e\n\u003c\/div\u003e\n\u003ch2\u003e✅ Key Features of These M8 Stainless Steel Carriage Bolts\u003c\/h2\u003e\n\u003cul class=\"hdiy-features\"\u003e\n\u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e🔒\u003c\/span\u003e\u003cspan\u003e\u003cstrong\u003eAnti-Rotation Square Neck\u003c\/strong\u003e — The square shoulder under the dome head bites into timber on installation, holding the bolt stationary so you can tighten the nut single-handed without a second wrench on the bolt side.\u003c\/span\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e🌧️\u003c\/span\u003e\u003cspan\u003e\u003cstrong\u003eA2 Stainless Steel Construction\u003c\/strong\u003e — Grade 304 stainless provides reliable corrosion resistance for outdoor decking, fencing, and garden structures exposed to rain, humidity, and temperature cycling.\u003c\/span\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e📐\u003c\/span\u003e\u003cspan\u003e\u003cstrong\u003eDIN 603 Dimensional Standard\u003c\/strong\u003e — Manufactured to the DIN 603 specification for cup square dome head coach bolts, ensuring consistent head geometry, thread pitch, and square neck dimensions across every piece in the box.\u003c\/span\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e📦\u003c\/span\u003e\u003cspan\u003e\u003cstrong\u003eProject-Ready Pack Quantities\u003c\/strong\u003e — Sold in counted boxes (15–30 pcs depending on length) so you can order exactly what a job requires without sorting through bulk bags or paying for excess hardware.\u003c\/span\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e📏\u003c\/span\u003e\u003cspan\u003e\u003cstrong\u003eFive Length Options in One Listing\u003c\/strong\u003e — Choose from 30mm, 40mm, 50mm, 60mm, or 70mm to match your timber thickness — no need to source different products for different joints on the same build.\u003c\/span\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e✨\u003c\/span\u003e\u003cspan\u003e\u003cstrong\u003eSmooth Dome Head Finish\u003c\/strong\u003e — The rounded cup head leaves a clean, low-profile surface on the visible face of the joint — suitable for finished woodwork, furniture frames, and anywhere aesthetics matter alongside strength.\u003c\/span\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2\u003e📐 Technical Specifications — M8 DIN 603 Carriage Bolts\u003c\/h2\u003e\n\u003cdiv class=\"hdiy-table-wrap\"\u003e\n\u003ctable\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eThread Size\u003c\/th\u003e\n\u003ctd\u003eM8 (8mm diameter)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eThread Standard\u003c\/th\u003e\n\u003ctd\u003eMetric coarse, pitch 1.25mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eHead Type\u003c\/th\u003e\n\u003ctd\u003eCup square dome head (carriage \/ coach bolt)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eDimensional Standard\u003c\/th\u003e\n\u003ctd\u003eDIN 603\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eMaterial\u003c\/th\u003e\n\u003ctd\u003eA2 Stainless Steel (Grade 304)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eFinish\u003c\/th\u003e\n\u003ctd\u003eMill \/ natural stainless (no coating)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eAvailable Lengths\u003c\/th\u003e\n\u003ctd\u003e30mm (≈1-3\/16\"), 40mm (≈1-9\/16\"), 50mm (≈2\"), 60mm (≈2-3\/8\"), 70mm (≈2-3\/4\")\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eHead Diameter (typical)\u003c\/th\u003e\n\u003ctd\u003eTypically 21–22mm — see variant options to confirm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eSquare Neck Width (typical)\u003c\/th\u003e\n\u003ctd\u003eTypically 8mm — contact us to confirm if critical\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003ePack Quantity\u003c\/th\u003e\n\u003ctd\u003e30mm: 30 pcs\/box | 40mm: 25 pcs\/box | 50mm: 20 pcs\/box | 60mm: 20 pcs\/box | 70mm: 15 pcs\/box\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eNuts \/ Washers Included\u003c\/th\u003e\n\u003ctd\u003eBolts only — nuts and washers sold separately\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eRecommended Use\u003c\/th\u003e\n\u003ctd\u003eTimber framing, decking, fencing, pergolas, wood-to-metal connections\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eNot Suitable For\u003c\/th\u003e\n\u003ctd\u003eConcrete anchoring, masonry, or marine\/saltwater immersion (use A4\/316 for those)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/div\u003e\n\u003ch2\u003e❓ Frequently Asked Questions\u003c\/h2\u003e\n\u003cdiv class=\"hdiy-faq\"\u003e\n\u003cdetails\u003e\n\u003csummary\u003eHow do I choose the right bolt length for my project?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\n\u003cp\u003eAdd up the total thickness of all materials being joined, then add approximately 10–15mm to allow for a flat washer and nut on the back. For example, joining two 20mm (3\/4\") boards typically calls for a 50mm (≈2\") bolt. The five lengths in this listing — 30mm, 40mm, 50mm, 60mm, and 70mm — cover timber thicknesses from roughly 15mm up to 55mm combined.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eWhat does A2 stainless steel mean, and how strong are these bolts?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\n\u003cp\u003eA2 stainless (also called 304 stainless) is an austenitic grade with a tensile strength of typically 500–700 MPa and good resistance to rust and oxidation. It handles outdoor exposure in most climates well. For highly aggressive environments — prolonged saltwater spray, coastal installations, or chemical exposure — A4 (316) stainless is generally the better choice.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eCan I use these carriage bolts outdoors or in wet conditions?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\n\u003cp\u003eYes. A2 stainless steel provides solid corrosion resistance for outdoor decking, fencing, pergolas, and garden structures exposed to rain and humidity. For prolonged saltwater or coastal environments, A4 (316) stainless fasteners are generally recommended to maximize service life.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eAre these compatible with standard M8 nuts and washers I already have?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\n\u003cp\u003eYes — these bolts use a standard M8 metric coarse thread (1.25mm pitch) and are compatible with any DIN 934 M8 hex nut, M8 wing nut, or M8 flat washer. They are \u003cstrong\u003enot\u003c\/strong\u003e compatible with imperial (SAE\/UNC) threaded hardware. To maintain consistent corrosion resistance, we recommend pairing with A2 stainless M8 nuts and washers.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eWhat are the dome head and square neck dimensions on an M8 DIN 603 bolt?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\n\u003cp\u003eFor M8 DIN 603 carriage bolts, the dome head diameter is typically around 21–22mm and the square neck width is typically 8mm. The square neck is designed to embed into timber and prevent the bolt from spinning during tightening. If you have critical tolerance requirements, please contact us to confirm exact dimensions before ordering.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eDo nuts and washers come included in the box?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\n\u003cp\u003eNo — this listing includes carriage bolts only. Matching M8 hex nuts and flat washers are sold separately. We recommend sourcing A2 stainless M8 nuts and washers to keep the entire fastener assembly at the same corrosion-resistance level.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eWhat applications are M8 DIN 603 carriage bolts not suitable for?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\n\u003cp\u003eThese bolts are designed for wood-to-wood and wood-to-metal connections. They are generally not suitable for concrete anchoring, masonry, or applications requiring through-hardened structural bolts. For those uses, consult a structural engineer and select the appropriate fastener grade and type.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"hdiy-cta\"\u003e🛒 Select your \u003cstrong\u003elength\u003c\/strong\u003e above, then add to cart — ships from our US warehouse.\u003c\/div\u003e\n\u003c\/div\u003e","brand":"HomeDIYer","offers":[{"title":"M8 \u0026 8mm \/ 30mm \/ 30PCS\u0026BOX","offer_id":52308590461202,"sku":"KAYFST029-8","price":12.58,"currency_code":"USD","in_stock":true},{"title":"M8 \u0026 8mm \/ 40mm \/ 25PCS\u0026BOX","offer_id":52308590493970,"sku":"KAYFST029-9","price":12.69,"currency_code":"USD","in_stock":true},{"title":"M8 \u0026 8mm \/ 50mm \/ 20PCS\u0026BOX","offer_id":52308590526738,"sku":"KAYFST029-10","price":11.76,"currency_code":"USD","in_stock":true},{"title":"M8 \u0026 8mm \/ 60mm \/ 20PCS\u0026BOX","offer_id":52308590559506,"sku":"KAYFST029-11","price":13.33,"currency_code":"USD","in_stock":true},{"title":"M8 \u0026 8mm \/ 70mm \/ 15PCS\u0026BOX","offer_id":52308590592274,"sku":"KAYFST029-12","price":12.72,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0884\/8936\/1682\/files\/Picture1of5_66515466-75c1-4126-b6af-e148a60d1326.jpg?v=1780501869","url":"https:\/\/homediyer.com\/de\/products\/m8-carriage-bolts-a2-stainless-steel-din-603","provider":"HomeDIYer","version":"1.0","type":"link"}