{"product_id":"40-roller-chain-sprocket-10t-39t-tooth-1-2-pitch-12-7mm-chain-link-c45-steel","title":"#40 Roller Chain Sprocket 10T - 39T Tooth 1\/2\" Pitch 12.7mm Chain Link C45 Steel","description":"\u003cdiv class=\"hdiy-desc\"\u003e\n\u003cdiv class=\"hdiy-overview\"\u003e\n\u003ch2\u003e#40 Roller Chain Sprocket — Precision C45 Steel Drive for 1\/2\" Pitch Chain Systems\u003c\/h2\u003e\n\u003cp\u003eWhen a worn or mismatched sprocket causes chain skip, premature wear, or unexpected downtime, finding a direct-fit replacement in the right tooth count becomes critical. This #40 roller chain sprocket is engineered for makers, machine builders, and mechanical hobbyists who need a reliable, dimensionally accurate drive component without custom machining lead times.\u003c\/p\u003e\n\u003cp\u003eEach sprocket is machined from C45 medium-carbon steel, offering a solid balance of hardness and machinability. The rough bore design allows you to bore and key the hub to your exact shaft size. Available in tooth counts from 10T to 39T with rough bore diameters ranging from 10mm to 16mm (approximately 0.39\" to 0.63\"), these sprockets are sized to match standard ANSI #40 \/ ISO 08B roller chain with a 1\/2\" (12.7mm) pitch. A 1.5-meter roller chain section, standard chain links, and half links are also available as companion variants.\u003c\/p\u003e\n\u003cp\u003eTypical applications include go-kart and mini-bike drive systems requiring a #40 chain sprocket replacement, conveyor and automation builds using 12.7mm pitch roller chain, and DIY power transmission projects such as electric bike conversions, winches, and small engine drives where a C45 steel sprocket with rough bore provides the flexibility to fit custom shaft diameters.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"hdiy-compat\"\u003e\n\u003cspan class=\"hdiy-compat-icon\"\u003e🔗\u003c\/span\u003e \u003cstrong\u003eCompatibility:\u003c\/strong\u003e Fits standard ANSI #40 \/ ISO 08B roller chain — 1\/2\" (12.7mm) pitch. Verify your chain pitch and shaft diameter before ordering.\u003c\/div\u003e\n\u003ch2\u003e✅ Key Features of These #40 Roller Chain Sprockets\u003c\/h2\u003e\n\u003cdiv class=\"hdiy-features\"\u003e\n\u003cdiv\u003e\n\u003cspan class=\"hdiy-icon\"\u003e⚙️\u003c\/span\u003e \u003cstrong\u003eWide Tooth Count Range\u003c\/strong\u003e\n\u003cp\u003eAvailable from 10T to 39T, covering a broad gear ratio spectrum for speed reduction or torque multiplication in custom drive systems.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cspan class=\"hdiy-icon\"\u003e🔩\u003c\/span\u003e \u003cstrong\u003eRough Bore for Custom Shaft Fitting\u003c\/strong\u003e\n\u003cp\u003eSupplied with a rough bore (10mm, 12mm, 14mm, or 16mm) so you can bore, ream, and key the hub to match your exact shaft diameter without starting from solid stock.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cspan class=\"hdiy-icon\"\u003e🏗️\u003c\/span\u003e \u003cstrong\u003eC45 Medium-Carbon Steel Construction\u003c\/strong\u003e\n\u003cp\u003eMachined from C45 steel for a reliable combination of surface hardness, wear resistance, and ease of secondary machining operations.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cspan class=\"hdiy-icon\"\u003e📐\u003c\/span\u003e \u003cstrong\u003e1\/2\" Pitch — ANSI #40 \/ ISO 08B Standard\u003c\/strong\u003e\n\u003cp\u003eDimensioned to the 12.7mm pitch standard, ensuring direct interchangeability with any ANSI #40 or ISO 08B roller chain on the market.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cspan class=\"hdiy-icon\"\u003e🔗\u003c\/span\u003e \u003cstrong\u003eMatching Chain \u0026amp; Links Available\u003c\/strong\u003e\n\u003cp\u003eCompanion variants include a 1.5-meter #40 roller chain section, standard chain links, and half links — so you can source the complete drive assembly in one order.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cspan class=\"hdiy-icon\"\u003e🛠️\u003c\/span\u003e \u003cstrong\u003eVersatile for DIY \u0026amp; Light Industrial Use\u003c\/strong\u003e\n\u003cp\u003eSuited for go-karts, mini-bikes, conveyor systems, electric bike conversions, and small engine power transmission projects where dimensional accuracy matters.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003ch2\u003e📐 Technical Specifications — #40 Roller Chain Sprocket\u003c\/h2\u003e\n\u003cdiv class=\"hdiy-table-wrap\"\u003e\n\u003ctable\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eChain Standard\u003c\/th\u003e\n\u003ctd\u003eANSI #40 \/ ISO 08B\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eChain Pitch\u003c\/th\u003e\n\u003ctd\u003e1\/2\" (12.7mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eTooth Count Options\u003c\/th\u003e\n\u003ctd\u003e10T, 11T, 12T, 13T, 14T, 15T, 16T, 17T, 18T, 19T, 20T, 21T, 22T, 23T, 24T, 25T, 26T, 27T, 28T, 29T, 30T, 31T, 32T, 33T, 34T, 35T, 36T, 37T, 38T, 39T\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eRough Bore Diameter\u003c\/th\u003e\n\u003ctd\u003e10mm, 12mm, 14mm, 16mm (varies by tooth count — see variant options)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eMaterial\u003c\/th\u003e\n\u003ctd\u003eC45 Medium-Carbon Steel\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eBore Type\u003c\/th\u003e\n\u003ctd\u003eRough Bore (requires secondary machining to final shaft size)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eHub Style\u003c\/th\u003e\n\u003ctd\u003eSee variant options\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eOuter Diameter\u003c\/th\u003e\n\u003ctd\u003eSee variant options\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eHub Length\u003c\/th\u003e\n\u003ctd\u003eSee variant options\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eSurface Finish\u003c\/th\u003e\n\u003ctd\u003eSee variant options\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eQuantity per Order\u003c\/th\u003e\n\u003ctd\u003e1 pcs (standard); 1.5m chain section also available\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"hdiy-faq\"\u003e\n\u003ch2\u003e❓ Frequently Asked Questions\u003c\/h2\u003e\n\u003cdetails\u003e\n\u003csummary\u003eHow do I choose the right tooth count for my application?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\n\u003cp\u003eThe tooth count determines your drive ratio. Divide the driven sprocket teeth by the drive sprocket teeth to get the reduction ratio. For example, a 10T drive sprocket paired with a 30T driven sprocket gives a 3:1 reduction — tripling torque while reducing speed by two-thirds. Select a tooth count that achieves your target speed or torque output based on your motor RPM and load requirements.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eWhat does \"rough bore\" mean, and what bore size do I need?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\n\u003cp\u003eA rough bore sprocket is supplied with a smaller-than-final bore diameter. You (or a machine shop) bore, ream, and optionally cut a keyway to match your exact shaft size. The listed rough bore diameter (10mm, 12mm, 14mm, or 16mm) is the starting bore — your final shaft diameter must be equal to or smaller than this value. If your shaft is 15mm, select the 16mm rough bore variant.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eIs this sprocket compatible with my existing #40 roller chain?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\n\u003cp\u003eYes — these sprockets are machined to the ANSI #40 \/ ISO 08B standard with a 1\/2\" (12.7mm) pitch. They are dimensionally interchangeable with any standard #40 roller chain. Confirm your chain's pitch marking (usually stamped on the side plate) before ordering. Do not use with #35, #50, or other pitch chains.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eHow strong is C45 steel, and will it hold up in my application?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\n\u003cp\u003eC45 is a medium-carbon steel with a tensile strength typically in the range of 570–700 MPa in the normalized condition, and higher after heat treatment. It provides good wear resistance for light-to-medium duty power transmission applications such as go-karts, conveyors, and small engine drives. For heavy industrial or high-shock-load applications, consider a hardened or alloy steel sprocket.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eDoes C45 steel rust, and how should I protect the sprocket?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\n\u003cp\u003eC45 steel is not stainless and will oxidize if left unprotected in humid or wet environments. For outdoor or wash-down applications, apply a chain lubricant or anti-corrosion coating after installation. Regular lubrication of both the chain and sprocket teeth is recommended to extend service life and prevent surface rust.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eCan I order just the chain or connecting links separately?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\n\u003cp\u003eYes. This listing includes companion variants: a 1.5-meter #40 roller chain section, a standard chain link (connecting link), and a half link for fine-tuning chain length. Select the appropriate variant from the options above to add them to your order alongside the sprocket.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eWhich rough bore diameter should I select for my tooth count?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\n\u003cp\u003eThe available rough bore diameter increases with tooth count to accommodate the larger hub geometry. As a general guide: 10T–11T are available with 10mm bore; 12T–20T with 12mm bore; 21T–29T with 14mm bore; 30T–39T with 16mm bore. Always verify the specific variant listing before ordering, as bore availability may vary.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"hdiy-cta\"\u003e🛒 Select your Number of Teeth and Rough Bore Diameter above, then add to cart.\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cp\u003e \u003c\/p\u003e","brand":"HomeDIYer","offers":[{"title":"10T \/ 10mm \/ 1 pcs","offer_id":52423444496658,"sku":"GLFBNHHHXCDZH0081x1","price":17.8,"currency_code":"USD","in_stock":true},{"title":"11T \/ 10mm \/ 1 pcs","offer_id":52423444529426,"sku":"GLFBNHHHXCDZH0082x1","price":20.06,"currency_code":"USD","in_stock":true},{"title":"12T \/ 12mm \/ 1 pcs","offer_id":52423444562194,"sku":"GLFBNHHHXCDZH0083x1","price":22.1,"currency_code":"USD","in_stock":true},{"title":"13T \/ 12mm \/ 1 pcs","offer_id":52423444594962,"sku":"GLFBNHHHXCDZH0084x1","price":24.19,"currency_code":"USD","in_stock":true},{"title":"14T \/ 12mm \/ 1 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