{"product_id":"m6-carriage-bolts-a2-stainless-steel-cup-square-coach-bolt","title":"M6 Carriage Bolts A2 Stainless Steel — Cup Square Coach Bolt with Dome Head, M6×12mm to M6×60mm","description":"\u003cscript type=\"application\/ld+json\"\u003e\n{\n  \"@context\": \"https:\/\/schema.org\",\n  \"@type\": \"FAQPage\",\n  \"mainEntity\": [\n    {\n      \"@type\": \"Question\",\n      \"name\": \"How do I choose the right length for M6 carriage bolts?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"A general rule is to add the thickness of all materials being joined, then add 10–15mm for the nut and washer. For example, joining two 20mm (3\/4\\\") boards typically calls for an M6×50mm bolt. Available lengths here range from 12mm (1\/2\\\") to 60mm (2-3\/8\\\").\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"What does A2 stainless steel mean, and how strong are these bolts?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"A2 stainless steel (also called 304 stainless) is a widely used austenitic grade offering good corrosion resistance and a tensile strength of generally 500–700 MPa. It is suitable for most indoor and light outdoor structural applications.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Can these M6 carriage bolts be used outdoors or in wet environments?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Yes. A2 stainless steel resists rust and oxidation in most outdoor and humid conditions. For highly corrosive environments such as coastal or marine settings, A4 (316) stainless steel is generally recommended instead.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"What nut and washer thread standard do these bolts use?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"These are M6 metric-thread bolts with a standard 1.0mm pitch, compatible with any M6 metric nut or washer. They are not compatible with imperial (SAE\/UNC\/UNF) fasteners.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"How does the cup square (carriage bolt) neck prevent the bolt from spinning?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"The square section directly beneath the dome head bites into the material — typically wood — as the nut is tightened, locking the bolt in place without needing a wrench on the bolt head. This makes installation faster and leaves a clean, tool-free finish on the visible face.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Do I need a washer with these carriage bolts?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"A washer under the nut is generally recommended to distribute clamping load and protect the surface. The dome head side typically does not require a washer since it sits flush against the material.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Which pack size should I order — 5, 10, or 20 pieces?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"For small repairs or single-joint projects, the 5-piece pack is usually sufficient. The 10-piece pack suits most deck boards, fence panels, or furniture builds. The 20-piece pack offers the best per-unit value for larger projects or when you want spares on hand.\"\n      }\n    }\n  ]\n}\n\u003c\/script\u003e\n\n\u003cdiv class=\"hdiy-desc\"\u003e\n\n  \u003ch2\u003eM6 Carriage Bolts in A2 Stainless Steel — Secure, Rust-Resistant Fastening for Wood \u0026amp; Outdoor Projects\u003c\/h2\u003e\n  \u003cdiv class=\"hdiy-overview\"\u003e\n    \u003cp\u003eStripped threads, spinning bolt heads, and rust stains on your finished woodwork — these are the frustrations that send DIYers and contractors back to the hardware store mid-project. Whether you're building a backyard deck, assembling a timber frame, or hanging a gate, you need a fastener that stays put, looks clean, and holds up to the elements. These M6 cup square carriage bolts are designed for exactly that.\u003c\/p\u003e\n    \u003cp\u003eEach bolt is machined from A2 (304) stainless steel and features a smooth dome head with a square-shouldered neck that self-locks into wood without a second wrench. Available in 11 lengths from 12mm (½\") to 60mm (2⅜\") and in packs of 5, 10, or 20, they cover everything from thin panel joints to thick structural timbers. The M6 metric thread (1.0mm pitch) pairs with any standard M6 nut and washer.\u003c\/p\u003e\n    \u003cp\u003eTypical applications include deck board fastening, pergola and fence construction, timber furniture assembly, and general outdoor woodworking — anywhere you need a flush, tamper-resistant bolt face with reliable clamping force on the nut side.\u003c\/p\u003e\n  \u003c\/div\u003e\n\n  \u003cdiv class=\"hdiy-compat\"\u003e\n    \u003cspan class=\"hdiy-compat-icon\"\u003e🔩\u003c\/span\u003e\n    \u003cstrong\u003eCompatibility:\u003c\/strong\u003e M6 metric thread (pitch 1.0mm) — fits all standard M6 nuts and washers. Not compatible with imperial (SAE\/UNC\/UNF) fasteners. Square neck is designed for use in wood; pre-drilling is recommended for hardwoods.\n  \u003c\/div\u003e\n\n  \u003ch2\u003e✅ Key Features of These M6 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\n      \u003cspan\u003e\u003cstrong\u003eA2 Stainless Steel Construction\u003c\/strong\u003e — Grade 304 stainless resists rust, oxidation, and staining in outdoor, humid, and light marine environments without surface coatings that can chip or peel.\u003c\/span\u003e\n    \u003c\/li\u003e\n    \u003cli\u003e\n      \u003cspan class=\"hdiy-icon\"\u003e🔒\u003c\/span\u003e\n      \u003cspan\u003e\u003cstrong\u003eSelf-Locking Cup Square Neck\u003c\/strong\u003e — The square shoulder beneath the dome head embeds into wood as the nut is tightened, preventing rotation and eliminating the need for a second tool on the bolt side.\u003c\/span\u003e\n    \u003c\/li\u003e\n    \u003cli\u003e\n      \u003cspan class=\"hdiy-icon\"\u003e✨\u003c\/span\u003e\n      \u003cspan\u003e\u003cstrong\u003eClean Dome Head Finish\u003c\/strong\u003e — The low-profile rounded head sits flush and smooth on the visible face of your workpiece — ideal for deck boards, furniture, and any application where appearance matters.\u003c\/span\u003e\n    \u003c\/li\u003e\n    \u003cli\u003e\n      \u003cspan class=\"hdiy-icon\"\u003e📏\u003c\/span\u003e\n      \u003cspan\u003e\u003cstrong\u003e11 Lengths from 12mm to 60mm\u003c\/strong\u003e — From 12mm (½\") for thin panel joints to 60mm (2⅜\") for thick structural timbers, one listing covers the full range of common M6 carriage bolt applications.\u003c\/span\u003e\n    \u003c\/li\u003e\n    \u003cli\u003e\n      \u003cspan class=\"hdiy-icon\"\u003e📦\u003c\/span\u003e\n      \u003cspan\u003e\u003cstrong\u003eFlexible Pack Sizes (5 \/ 10 \/ 20 pcs)\u003c\/strong\u003e — Order exactly what your project needs. The 20-piece pack offers the lowest per-unit cost for larger builds or when keeping spares on hand.\u003c\/span\u003e\n    \u003c\/li\u003e\n    \u003cli\u003e\n      \u003cspan class=\"hdiy-icon\"\u003e⚙️\u003c\/span\u003e\n      \u003cspan\u003e\u003cstrong\u003eStandard M6 Metric Thread (1.0mm Pitch)\u003c\/strong\u003e — Fully compatible with any M6 metric nut, wing nut, or washer. No proprietary hardware required — easy to source replacements anywhere.\u003c\/span\u003e\n    \u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003ch2\u003e📐 Technical Specifications — M6 Cup Square 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\u003eM6 (6mm diameter, 1.0mm pitch)\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003cth\u003eAvailable Lengths\u003c\/th\u003e\n\u003ctd\u003e12mm (½\"), 16mm (⅝\"), 20mm (¾\"), 25mm (1\"), 30mm (1³⁄₁₆\"), 35mm (1⅜\"), 40mm (1⁹⁄₁₆\"), 45mm (1¾\"), 50mm (2\"), 55mm (2³⁄₁₆\"), 60mm (2⅜\")\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003cth\u003ePack Sizes\u003c\/th\u003e\n\u003ctd\u003e5 pieces, 10 pieces, 20 pieces\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003cth\u003eHead Type\u003c\/th\u003e\n\u003ctd\u003eDome (round) head — cup square carriage bolt profile\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003cth\u003eNeck Type\u003c\/th\u003e\n\u003ctd\u003eCup square (self-locking in wood)\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\u003eNatural stainless (no coating)\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003cth\u003eTensile Strength\u003c\/th\u003e\n\u003ctd\u003eTypically 500–700 MPa (A2-50 to A2-70 class)\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003cth\u003eThread Standard\u003c\/th\u003e\n\u003ctd\u003eISO metric coarse thread\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003cth\u003eDrive Type\u003c\/th\u003e\n\u003ctd\u003eNo drive (nut-side tightening only)\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003cth\u003eCompatible Nut\u003c\/th\u003e\n\u003ctd\u003eStandard M6 metric hex nut (sold separately)\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003cth\u003eRecommended Use\u003c\/th\u003e\n\u003ctd\u003eWood, timber, decking, fencing, furniture assembly\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003cth\u003eCorrosion Resistance\u003c\/th\u003e\n\u003ctd\u003eGood — suitable for outdoor and humid environments; see note for marine use\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003cth\u003eCountry of Origin\u003c\/th\u003e\n\u003ctd\u003eSee variant options\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003c\/tbody\u003e\n    \u003c\/table\u003e\n  \u003c\/div\u003e\n\n  \u003cdiv class=\"hdiy-note\"\u003e\n    \u003cspan class=\"hdiy-note-icon\"\u003e⚠️\u003c\/span\u003e\n    \u003cstrong\u003eMarine or highly corrosive environments:\u003c\/strong\u003e A2 stainless steel performs well in most outdoor conditions, but for saltwater or coastal exposure, A4 (316) stainless steel is generally recommended. Contact us to confirm suitability for your specific application.\n  \u003c\/div\u003e\n\n  \u003ch2\u003e❓ Frequently Asked Questions\u003c\/h2\u003e\n  \u003cdiv class=\"hdiy-faq\"\u003e\n\n    \u003cdetails\u003e\n      \u003csummary\u003eHow do I choose the right length for M6 carriage bolts?\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 washer and nut. For example, joining two 20mm (¾\") boards typically calls for an M6×50mm bolt. Lengths available here range from 12mm (½\") to 60mm (2⅜\"), covering most standard timber and panel thicknesses.\u003c\/p\u003e\n      \u003c\/div\u003e\n    \u003c\/details\u003e\n\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 steel — also known as Grade 304 — is the most widely used austenitic stainless alloy. It offers good corrosion resistance and a tensile strength of generally 500–700 MPa depending on the property class (A2-50 or A2-70). This makes it suitable for most structural woodworking, furniture, and outdoor fastening applications.\u003c\/p\u003e\n      \u003c\/div\u003e\n    \u003c\/details\u003e\n\n    \u003cdetails\u003e\n      \u003csummary\u003eCan these M6 carriage bolts be used outdoors or in wet environments?\u003c\/summary\u003e\n      \u003cdiv class=\"hdiy-faq-body\"\u003e\n        \u003cp\u003eYes. A2 stainless steel resists rust and oxidation in most outdoor, humid, and freshwater environments without any additional coating. For highly corrosive settings — such as coastal, marine, or chemical-exposure environments — A4 (316) stainless steel is generally the better choice. Contact us if you need guidance for your specific conditions.\u003c\/p\u003e\n      \u003c\/div\u003e\n    \u003c\/details\u003e\n\n    \u003cdetails\u003e\n      \u003csummary\u003eWhat nut and washer thread standard do these bolts use?\u003c\/summary\u003e\n      \u003cdiv class=\"hdiy-faq-body\"\u003e\n        \u003cp\u003eThese bolts use a standard ISO metric M6 coarse thread with a 1.0mm pitch. They are compatible with any M6 metric hex nut, wing nut, or washer. They are \u003cstrong\u003enot\u003c\/strong\u003e compatible with imperial (SAE, UNC, or UNF) fasteners — do not mix metric and imperial hardware.\u003c\/p\u003e\n      \u003c\/div\u003e\n    \u003c\/details\u003e\n\n    \u003cdetails\u003e\n      \u003csummary\u003eHow does the cup square neck stop the bolt from spinning during installation?\u003c\/summary\u003e\n      \u003cdiv class=\"hdiy-faq-body\"\u003e\n        \u003cp\u003eThe square section directly beneath the dome head is slightly larger than the shank. As you tighten the nut, this square shoulder bites into the surrounding wood, locking the bolt in place. This means you only need a wrench on the nut side — no need to hold the bolt head, and no tool marks on the finished face of your workpiece.\u003c\/p\u003e\n      \u003c\/div\u003e\n    \u003c\/details\u003e\n\n    \u003cdetails\u003e\n      \u003csummary\u003eDo I need a washer with these carriage bolts?\u003c\/summary\u003e\n      \u003cdiv class=\"hdiy-faq-body\"\u003e\n        \u003cp\u003eA flat washer under the nut is generally recommended. It distributes the clamping load over a wider area, reducing the chance of the nut pulling through softer wood. The dome head side typically does not require a washer — it sits flush against the material surface by design.\u003c\/p\u003e\n      \u003c\/div\u003e\n    \u003c\/details\u003e\n\n    \u003cdetails\u003e\n      \u003csummary\u003eWhich pack size should I order — 5, 10, or 20 pieces?\u003c\/summary\u003e\n      \u003cdiv class=\"hdiy-faq-body\"\u003e\n        \u003cp\u003eThe 5-piece pack suits small repairs or single-joint projects. The 10-piece pack covers most deck board runs, fence panels, or furniture builds. The 20-piece pack offers the best per-unit value for larger projects or when you want extras on hand for future repairs. All pack sizes are available across all 11 lengths.\u003c\/p\u003e\n      \u003c\/div\u003e\n    \u003c\/details\u003e\n\n  \u003c\/div\u003e\n\n  \u003cdiv class=\"hdiy-cta\"\u003e\n    🛒 Select your size and quantity above, then add to cart — ships from our US warehouse.\n  \u003c\/div\u003e\n\n\u003c\/div\u003e","brand":"HomeDIYer","offers":[{"title":"M6*12 \/ 5","offer_id":52308510408978,"sku":"GLFBCQFGB05941x5","price":3.45,"currency_code":"USD","in_stock":true},{"title":"M6*16 \/ 5","offer_id":52308510441746,"sku":"GLFBCQFGB05942x5","price":3.56,"currency_code":"USD","in_stock":true},{"title":"M6*20 \/ 5","offer_id":52308510474514,"sku":"GLFBCQFGB05943x5","price":3.88,"currency_code":"USD","in_stock":true},{"title":"M6*25 \/ 5","offer_id":52308510507282,"sku":"GLFBCQFGB05944x5","price":4.38,"currency_code":"USD","in_stock":true},{"title":"M6*30 \/ 5","offer_id":52308510540050,"sku":"GLFBCQFGB05945x5","price":4.91,"currency_code":"USD","in_stock":true},{"title":"M6*35 \/ 5","offer_id":52308510572818,"sku":"GLFBCQFGB05946x5","price":5.41,"currency_code":"USD","in_stock":true},{"title":"M6*40 \/ 5","offer_id":52308510605586,"sku":"GLFBCQFGB05947x5","price":5.93,"currency_code":"USD","in_stock":true},{"title":"M6*45 \/ 5","offer_id":52308510638354,"sku":"GLFBCQFGB05948x5","price":6.43,"currency_code":"USD","in_stock":true},{"title":"M6*50 \/ 5","offer_id":52308510671122,"sku":"GLFBCQFGB05949x5","price":6.99,"currency_code":"USD","in_stock":true},{"title":"M6*55 \/ 5","offer_id":52308510703890,"sku":"GLFBCQFGB05950x5","price":7.58,"currency_code":"USD","in_stock":true},{"title":"M6*60 \/ 5","offer_id":52308510736658,"sku":"GLFBCQFGB05951x5","price":7.89,"currency_code":"USD","in_stock":true},{"title":"M6*12 \/ 10","offer_id":52308510769426,"sku":"GLFBCQFGB05941x10","price":5.44,"currency_code":"USD","in_stock":true},{"title":"M6*16 \/ 10","offer_id":52308510802194,"sku":"GLFBCQFGB05942x10","price":6.0,"currency_code":"USD","in_stock":true},{"title":"M6*20 \/ 10","offer_id":52308510834962,"sku":"GLFBCQFGB05943x10","price":6.62,"currency_code":"USD","in_stock":true},{"title":"M6*25 \/ 10","offer_id":52308510867730,"sku":"GLFBCQFGB05944x10","price":7.64,"currency_code":"USD","in_stock":true},{"title":"M6*30 \/ 10","offer_id":52308510900498,"sku":"GLFBCQFGB05945x10","price":8.72,"currency_code":"USD","in_stock":true},{"title":"M6*35 \/ 10","offer_id":52308510933266,"sku":"GLFBCQFGB05946x10","price":9.72,"currency_code":"USD","in_stock":true},{"title":"M6*40 \/ 10","offer_id":52308510966034,"sku":"GLFBCQFGB05947x10","price":10.74,"currency_code":"USD","in_stock":true},{"title":"M6*45 \/ 10","offer_id":52308510998802,"sku":"GLFBCQFGB05948x10","price":11.75,"currency_code":"USD","in_stock":true},{"title":"M6*50 \/ 10","offer_id":52308511031570,"sku":"GLFBCQFGB05949x10","price":12.87,"currency_code":"USD","in_stock":true},{"title":"M6*55 \/ 10","offer_id":52308511064338,"sku":"GLFBCQFGB05950x10","price":14.04,"currency_code":"USD","in_stock":true},{"title":"M6*60 \/ 10","offer_id":52308511097106,"sku":"GLFBCQFGB05951x10","price":14.66,"currency_code":"USD","in_stock":true},{"title":"M6*12 \/ 20","offer_id":52308511129874,"sku":"GLFBCQFGB05941x20","price":9.78,"currency_code":"USD","in_stock":true},{"title":"M6*16 \/ 20","offer_id":52308511162642,"sku":"GLFBCQFGB05942x20","price":10.89,"currency_code":"USD","in_stock":true},{"title":"M6*20 \/ 20","offer_id":52308511195410,"sku":"GLFBCQFGB05943x20","price":12.14,"currency_code":"USD","in_stock":true},{"title":"M6*25 \/ 20","offer_id":52308511228178,"sku":"GLFBCQFGB05944x20","price":14.16,"currency_code":"USD","in_stock":true},{"title":"M6*30 \/ 20","offer_id":52308511260946,"sku":"GLFBCQFGB05945x20","price":16.31,"currency_code":"USD","in_stock":true},{"title":"M6*35 \/ 20","offer_id":52308511293714,"sku":"GLFBCQFGB05946x20","price":18.32,"currency_code":"USD","in_stock":true},{"title":"M6*40 \/ 20","offer_id":52308511326482,"sku":"GLFBCQFGB05947x20","price":20.37,"currency_code":"USD","in_stock":true},{"title":"M6*45 \/ 20","offer_id":52308511359250,"sku":"GLFBCQFGB05948x20","price":22.39,"currency_code":"USD","in_stock":true},{"title":"M6*50 \/ 20","offer_id":52308511392018,"sku":"GLFBCQFGB05949x20","price":24.62,"currency_code":"USD","in_stock":true},{"title":"M6*55 \/ 20","offer_id":52308511424786,"sku":"GLFBCQFGB05950x20","price":26.97,"currency_code":"USD","in_stock":true},{"title":"M6*60 \/ 20","offer_id":52308511457554,"sku":"GLFBCQFGB05951x20","price":28.22,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0884\/8936\/1682\/files\/2_9_1e1f7e73-058c-47a3-a340-ba1885b8d245.jpg?v=1780501929","url":"https:\/\/homediyer.com\/products\/m6-carriage-bolts-a2-stainless-steel-cup-square-coach-bolt","provider":"HomeDIYer","version":"1.0","type":"link"}