{"product_id":"0-5-mod-brass-spur-gear-40-teeth-bore-4-12mm-pinion-gear","title":"0.5 Mod Brass Spur Gear 40 Teeth Bore 4~12mm Motor Gear Transmission Pinion Gear","description":"\u003cdiv class=\"hdiy-desc\"\u003e\n\n  \u003cdiv class=\"hdiy-overview\"\u003e\n    \u003ch2\u003e0.5 Mod Brass Spur Gear 40T — Versatile Pinion Gear for Compact Transmission Systems\u003c\/h2\u003e\n    \u003cp\u003eFinding a 0.5 module spur gear with the right tooth count and bore to match your motor shaft is a common challenge for robotics builders, RC hobbyists, and small-machine designers. This 40-tooth brass pinion gear covers bore sizes from 4 mm to 12 mm, giving engineers and makers a single SKU family that fits the widest range of compact drive shafts without custom machining.\u003c\/p\u003e\n    \u003cp\u003eEach gear is machined from solid brass, delivering a balance of machinability, moderate corrosion resistance, and low-noise meshing. The module is 0.5 (metric), tooth count is 40T, and bore options span 4 mm to 12 mm (approximately 0.157 in to 0.472 in). At 0.5 module with 40 teeth, the pitch diameter is approximately 20 mm (~0.79 in), making it slightly larger than a 32T variant and suited to applications requiring a lower gear ratio or higher torque multiplication on the output side.\u003c\/p\u003e\n    \u003cp\u003eTypical use cases include servo-driven robotic arm joints using a 0.5 mod 40-tooth spur gear for stage reduction, RC buggy or crawler transmission pinion replacement where a larger tooth count is needed for a specific ratio, and compact automation gearbox stages where a brass pinion gear with a 4 mm to 12 mm bore is specified. Available in packs of 1, 2, 5, or 10 pieces to support prototyping through small-batch production runs.\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 Meshes with any 0.5 module (Mod 0.5) spur gear, rack, or pinion. The mating gear's module must be 0.5 — verify before ordering. Tooth count determines gear ratio, not meshing compatibility.\n  \u003c\/div\u003e\n\n  \u003cdiv class=\"hdiy-features\"\u003e\n    \u003ch2\u003e✅ Key Features of These 0.5 Mod Brass Spur Gears\u003c\/h2\u003e\n    \u003cul class=\"hdiy-list\"\u003e\n      \u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e🔩\u003c\/span\u003e\u003cstrong\u003e40-Tooth Count, 0.5 Module\u003c\/strong\u003e — Standardized metric tooth profile meshes accurately with any Mod 0.5 mating gear or rack; 40T yields a ~20 mm pitch diameter for compact yet capable drive stages.\u003c\/li\u003e\n      \u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e🎯\u003c\/span\u003e\u003cstrong\u003e8 Bore Sizes (4–12 mm)\u003c\/strong\u003e — Options at 4, 5, 6, 6.35, 7, 8, 10, and 12 mm cover the broadest range of motor and drive shaft diameters in this class, including the 6.35 mm (1\/4 in) common in hobby motors.\u003c\/li\u003e\n      \u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e🟡\u003c\/span\u003e\u003cstrong\u003eSolid Brass Construction\u003c\/strong\u003e — Brass provides good machinability, moderate corrosion resistance, and quieter operation compared to steel in low-to-medium load applications.\u003c\/li\u003e\n      \u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e📦\u003c\/span\u003e\u003cstrong\u003eFlexible Pack Quantities\u003c\/strong\u003e — Order 1, 2, 5, or 10 pieces per SKU to match your project scale, from single-unit prototyping to small production runs with volume pricing.\u003c\/li\u003e\n      \u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e📐\u003c\/span\u003e\u003cstrong\u003eCompact Pinion Geometry\u003c\/strong\u003e — 40T at 0.5 module gives a pitch diameter of ~20 mm (0.79 in), suitable for space-constrained gearboxes where a slightly larger gear ratio range is needed versus a 32T variant.\u003c\/li\u003e\n      \u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e🔄\u003c\/span\u003e\u003cstrong\u003eDrop-In Transmission Replacement\u003c\/strong\u003e — Dimensionally consistent across the bore range; swap worn or undersized pinion gears in RC vehicles, robotic joints, or automation stages without redesigning the housing.\u003c\/li\u003e\n    \u003c\/ul\u003e\n  \u003c\/div\u003e\n\n  \u003cdiv class=\"hdiy-table-wrap\"\u003e\n    \u003ch2\u003e📐 Technical Specifications — 0.5 Mod Brass Spur Gear\u003c\/h2\u003e\n    \u003ctable\u003e\n      \u003ctbody\u003e\n        \u003ctr\u003e\n\u003cth\u003eModule\u003c\/th\u003e\n\u003ctd\u003e0.5 (Metric)\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003cth\u003eTooth Count\u003c\/th\u003e\n\u003ctd\u003e40T\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003cth\u003eBore Diameter\u003c\/th\u003e\n\u003ctd\u003e4 \/ 5 \/ 6 \/ 6.35 \/ 7 \/ 8 \/ 10 \/ 12 mm — See variant options\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003cth\u003ePitch Diameter\u003c\/th\u003e\n\u003ctd\u003e~20 mm (~0.79 in)\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003cth\u003ePressure Angle\u003c\/th\u003e\n\u003ctd\u003e20° (standard)\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003cth\u003eMaterial\u003c\/th\u003e\n\u003ctd\u003eBrass\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003cth\u003eFinish\u003c\/th\u003e\n\u003ctd\u003eNatural brass (uncoated)\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003cth\u003eGear Type\u003c\/th\u003e\n\u003ctd\u003eSpur (straight tooth)\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003cth\u003eFace Width\u003c\/th\u003e\n\u003ctd\u003eSee variant options\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003cth\u003eHub \/ Boss\u003c\/th\u003e\n\u003ctd\u003eSee variant options\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003cth\u003eKeyway \/ Set Screw\u003c\/th\u003e\n\u003ctd\u003eSee variant options\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003cth\u003ePack Quantity\u003c\/th\u003e\n\u003ctd\u003e1 \/ 2 \/ 5 \/ 10 PCS — See 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-faq\"\u003e\n    \u003ch2\u003e❓ Frequently Asked Questions\u003c\/h2\u003e\n\n    \u003cdetails\u003e\n      \u003csummary\u003eHow do I confirm this 40T gear will mesh with my existing gearset?\u003c\/summary\u003e\n      \u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eThe critical parameter is the \u003cstrong\u003emodule\u003c\/strong\u003e. This gear is Module 0.5 (metric). Any mating spur gear, rack, or pinion must also be Module 0.5 for correct tooth engagement. Tooth count (40T) affects gear ratio only — not meshing compatibility. A 0.5 Mod gear with any tooth count will mesh with this gear as long as the module matches.\u003c\/p\u003e\u003c\/div\u003e\n    \u003c\/details\u003e\n\n    \u003cdetails\u003e\n      \u003csummary\u003eWhich bore size should I choose for my motor or drive shaft?\u003c\/summary\u003e\n      \u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eMeasure your shaft diameter with calipers. Available bores are 4, 5, 6, 6.35, 7, 8, 10, and 12 mm. The 6.35 mm bore corresponds to a 1\/4-inch shaft, common in North American hobby motors. The 12 mm bore suits larger servo or stepper motor shafts. Select the bore that matches your shaft — a loose fit causes runout and noise; a tight fit requires careful pressing or a set screw.\u003c\/p\u003e\u003c\/div\u003e\n    \u003c\/details\u003e\n\n    \u003cdetails\u003e\n      \u003csummary\u003eWhat is the difference between a 32T and a 40T gear at 0.5 module?\u003c\/summary\u003e\n      \u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eBoth gears share the same 0.5 module and will mesh with each other. The 40T gear has a larger pitch diameter (~20 mm vs ~16 mm for 32T), which changes the gear ratio when paired with a pinion or spur of a different tooth count. A higher tooth count on the driven gear produces more torque and lower output speed; a higher tooth count on the driving gear produces higher speed and lower torque.\u003c\/p\u003e\u003c\/div\u003e\n    \u003c\/details\u003e\n\n    \u003cdetails\u003e\n      \u003csummary\u003eIs brass strong enough for my RC car or robotics application?\u003c\/summary\u003e\n      \u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eBrass is well-suited for low-to-medium torque applications such as RC car pinions, servo-driven robotic joints, and light automation stages. It offers quieter operation and easier machining than steel. For high-torque or high-RPM industrial drives, a steel or hardened alloy gear may be more appropriate. If you are unsure about load requirements, contact us to confirm suitability.\u003c\/p\u003e\u003c\/div\u003e\n    \u003c\/details\u003e\n\n    \u003cdetails\u003e\n      \u003csummary\u003eWill this gear corrode in humid or outdoor conditions?\u003c\/summary\u003e\n      \u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eBrass has moderate natural corrosion resistance and performs reliably in typical indoor and light outdoor environments. It is not recommended for continuous immersion in water or exposure to highly corrosive chemicals. For wet-environment applications, applying a light gear lubricant will extend service life.\u003c\/p\u003e\u003c\/div\u003e\n    \u003c\/details\u003e\n\n    \u003cdetails\u003e\n      \u003csummary\u003eWhy order a multi-pack instead of a single piece?\u003c\/summary\u003e\n      \u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003ePinion gears are wear items, especially in high-cycle applications like RC racing or repetitive robotic movements. Ordering a 5- or 10-pack ensures you have spares on hand for quick replacement without waiting for reshipment. Multi-packs also offer a lower per-unit cost compared to single-piece orders.\u003c\/p\u003e\u003c\/div\u003e\n    \u003c\/details\u003e\n\n    \u003cdetails\u003e\n      \u003csummary\u003eDoes the gear include a set screw or keyway for shaft retention?\u003c\/summary\u003e\n      \u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eSet screw and keyway availability varies by variant. Please check the variant detail page or contact us to confirm the shaft retention method for your selected bore size before ordering.\u003c\/p\u003e\u003c\/div\u003e\n    \u003c\/details\u003e\n\n    \u003cdetails\u003e\n      \u003csummary\u003eCan I use this gear in a CNC machine or automation stage?\u003c\/summary\u003e\n      \u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eYes, for light-duty automation and positioning stages where a 0.5 mod 40-tooth brass spur gear is specified. Brass is commonly used in instrumentation and light automation due to its dimensional stability and low friction. For heavy-duty CNC axes or high-load stages, consult your load and speed requirements before selecting brass over steel.\u003c\/p\u003e\u003c\/div\u003e\n    \u003c\/details\u003e\n\n  \u003c\/div\u003e\n\n  \u003cdiv class=\"hdiy-cta\"\u003e\n    🛒 Select your bore size and pack quantity above, then add to cart.\n  \u003c\/div\u003e\n\n\u003c\/div\u003e\n\n\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 confirm this 40T gear will mesh with my existing gearset?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"The critical parameter is the module. This gear is Module 0.5 (metric). Any mating spur gear, rack, or pinion must also be Module 0.5 for correct tooth engagement. Tooth count affects gear ratio only, not meshing compatibility.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Which bore size should I choose for my motor or drive shaft?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Measure your shaft diameter with calipers. Available bores are 4, 5, 6, 6.35, 7, 8, 10, and 12 mm. The 6.35 mm bore corresponds to a 1\/4-inch shaft. Select the bore that matches your shaft.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"What is the difference between a 32T and a 40T gear at 0.5 module?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Both gears share the same 0.5 module and will mesh with each other. The 40T gear has a larger pitch diameter (~20 mm vs ~16 mm for 32T). A higher tooth count on the driven gear produces more torque and lower output speed.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Is brass strong enough for my RC car or robotics application?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Brass is well-suited for low-to-medium torque applications such as RC car pinions, servo-driven robotic joints, and light automation stages. For high-torque or high-RPM industrial drives, a steel or hardened alloy gear may be more appropriate.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Will this gear corrode in humid or outdoor conditions?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Brass has moderate natural corrosion resistance and performs reliably in typical indoor and light outdoor environments. For wet-environment applications, applying a light gear lubricant will extend service life.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Why order a multi-pack instead of a single piece?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Pinion gears are wear items. Ordering a 5- or 10-pack ensures you have spares on hand for quick replacement. Multi-packs also offer a lower per-unit cost compared to single-piece orders.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Does the gear include a set screw or keyway for shaft retention?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Set screw and keyway availability varies by variant. Please check the variant detail page or contact us to confirm the shaft retention method for your selected bore size before ordering.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Can I use this gear in a CNC machine or automation stage?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Yes, for light-duty automation and positioning stages where a 0.5 mod 40-tooth brass spur gear is specified. For heavy-duty CNC axes or high-load stages, consult your load and speed requirements before selecting brass over steel.\"\n      }\n    }\n  ]\n}\n\u003c\/script\u003e","brand":"HomeDIYer","offers":[{"title":"0.5 Mod 40T 【Bore 4mm】 \/ 1 PCS","offer_id":52442798031122,"sku":"AdaahGFCD04441x1","price":9.93,"currency_code":"USD","in_stock":true},{"title":"0.5 Mod 40T 【Bore 5mm】 \/ 1 PCS","offer_id":52442798063890,"sku":"AdaahGFCD04442x1","price":9.93,"currency_code":"USD","in_stock":true},{"title":"0.5 Mod 40T 【Bore 6mm】 \/ 1 PCS","offer_id":52442798096658,"sku":"AdaahGFCD04443x1","price":9.93,"currency_code":"USD","in_stock":true},{"title":"0.5 Mod 40T 【Bore 6.35mm】 \/ 1 PCS","offer_id":52442798129426,"sku":"AdaahGFCD04444x1","price":9.93,"currency_code":"USD","in_stock":true},{"title":"0.5 Mod 40T 【Bore 7mm】 \/ 1 PCS","offer_id":52442798162194,"sku":"AdaahGFCD04445x1","price":9.93,"currency_code":"USD","in_stock":true},{"title":"0.5 Mod 40T 【Bore 8mm】 \/ 1 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