{"product_id":"3-mod-10-31-teeth-spur-gears-pinion-30mm-45-steel","title":"3 Mod 10-31 Teeth Spur Gears Transmission Gear Pinion Thickness 30mm 45# Steel","description":"\u003cdiv class=\"hdiy-desc\"\u003e\n\n\u003cdiv class=\"hdiy-overview\"\u003e\n\u003ch2\u003e3 Mod Spur Gears — Precision 45# Steel Pinions for Reliable Power Transmission\u003c\/h2\u003e\n\u003cp\u003eWhen your DIY automation project demands consistent torque transfer without slippage or premature wear, the gear material and tooth geometry make all the difference. Hobbyists, makers, and small workshop engineers building CNC routers, conveyor systems, or robotic arms need spur gears they can trust to mesh cleanly and hold up under load — these 3 Mod 10–31 Teeth Spur Gears are engineered for exactly that.\u003c\/p\u003e\n\u003cp\u003eEach gear is machined from 45# medium-carbon steel, a material known for its balanced hardness and machinability. The module is 3 (Mod 3), with a face width (thickness) of 30mm (approximately 1.18 inches). Tooth counts span from 10T to 31T, giving you a wide selection of gear ratios in a single consistent standard. The bore diameter and keyway dimensions vary by tooth count — see variant options for exact bore specs.\u003c\/p\u003e\n\u003cp\u003eThese 3 Mod spur gears are well-suited for DIY CNC rack-and-pinion drives, motorized linear actuator systems, rotary indexing tables, and light industrial conveyor gear trains. Whether you are building a custom gearbox for a 3D printer upgrade or a reduction drive for a stepper motor project, the Mod 3 standard ensures broad compatibility with off-the-shelf racks and mating gears.\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 Designed to mesh with any standard Module 3 (Mod 3) spur gear, rack, or pinion. Verify bore diameter and keyway dimensions against your shaft specs before ordering.\n\u003c\/div\u003e\n\n\u003cdiv class=\"hdiy-features\"\u003e\n\u003ch2\u003e✅ Key Features of These 3 Mod Spur Gears\u003c\/h2\u003e\n\u003cul class=\"hdiy-list\"\u003e\n  \u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e🔩\u003c\/span\u003e\u003cstrong\u003e45# Steel Construction\u003c\/strong\u003e — Medium-carbon steel delivers a strong balance of tensile strength and wear resistance for demanding drive applications.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e📐\u003c\/span\u003e\u003cstrong\u003eModule 3 Standard\u003c\/strong\u003e — Mod 3 tooth geometry ensures direct interchangeability with standard Mod 3 racks, pinions, and mating gears across your drivetrain.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e📏\u003c\/span\u003e\u003cstrong\u003e30mm Face Width\u003c\/strong\u003e — A generous 30mm (1.18 in) tooth thickness distributes load evenly and reduces edge stress in high-torque applications.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e🎯\u003c\/span\u003e\u003cstrong\u003eWide Tooth Count Range\u003c\/strong\u003e — Available from 10T to 31T, enabling a broad selection of gear ratios for speed reduction or torque multiplication in your build.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e🔄\u003c\/span\u003e\u003cstrong\u003eConsistent Machining Tolerance\u003c\/strong\u003e — Teeth are cut to standard involute profile tolerances for smooth, low-noise meshing and minimal backlash in precision motion systems.\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, or 3 pieces per listing to match your project needs and reduce per-unit cost on multi-gear builds.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/div\u003e\n\n\u003cdiv class=\"hdiy-table-wrap\"\u003e\n\u003ch2\u003e📐 Technical Specifications — Mod 3 Spur Gears\u003c\/h2\u003e\n\u003ctable\u003e\n  \u003ctbody\u003e\n    \u003ctr\u003e\n\u003cth\u003eModule (Mod)\u003c\/th\u003e\n\u003ctd\u003e3\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eTooth Count Range\u003c\/th\u003e\n\u003ctd\u003e10T – 31T (see variant options)\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eFace Width (Thickness)\u003c\/th\u003e\n\u003ctd\u003e30 mm (1.18 in)\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eMaterial\u003c\/th\u003e\n\u003ctd\u003e45# Medium-Carbon Steel\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eTooth Profile\u003c\/th\u003e\n\u003ctd\u003eStandard Involute, 20° Pressure Angle\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003ePitch Diameter\u003c\/th\u003e\n\u003ctd\u003eSee variant options (Mod × Teeth)\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eBore Diameter\u003c\/th\u003e\n\u003ctd\u003eSee variant options\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eKeyway\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\u003eNatural steel (uncoated)\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003ePacking Quantity\u003c\/th\u003e\n\u003ctd\u003e1 pcs \/ 2 pcs \/ 3 pcs\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 choose the right tooth count for my project?\u003c\/summary\u003e\n  \u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eThe tooth count determines your gear ratio. Divide the driven gear teeth by the driving gear teeth to get the ratio. For example, pairing a 10T pinion with a 30T gear gives a 3:1 reduction. Choose a smaller tooth count for higher speed output and a larger tooth count for more torque. All options in this listing share the same Mod 3 standard, so any two can mesh together.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\n\u003cdetails\u003e\n  \u003csummary\u003eWhat is the pitch diameter for each tooth count?\u003c\/summary\u003e\n  \u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eFor Module 3 gears, pitch diameter = Module × Tooth Count. For example, a 3M 10T gear has a pitch diameter of 30mm, a 3M 20T gear has 60mm, and a 3M 30T gear has 90mm. Use this formula to calculate center distance between meshing gears: (PD1 + PD2) ÷ 2.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\n\u003cdetails\u003e\n  \u003csummary\u003eWhat is 45# steel and how strong is it?\u003c\/summary\u003e\n  \u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003e45# steel is a medium-carbon structural steel with a carbon content of approximately 0.42–0.50%. It offers a tensile strength of roughly 600–800 MPa in normalized condition and can be further hardened by quenching and tempering. It is widely used for gears, shafts, and machine parts where moderate strength and good machinability are required.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\n\u003cdetails\u003e\n  \u003csummary\u003eAre these gears corrosion-resistant?\u003c\/summary\u003e\n  \u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003e45# steel is not inherently corrosion-resistant. These gears are supplied with a natural steel finish. For outdoor or humid environments, we recommend applying a light machine oil, grease, or a rust-inhibiting coating after installation. For applications requiring corrosion resistance, consider stainless steel or nylon alternatives.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\n\u003cdetails\u003e\n  \u003csummary\u003eWill these mesh with my existing Mod 3 rack or gear?\u003c\/summary\u003e\n  \u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eYes — as long as your existing rack or mating gear is also Module 3 with a standard 20° pressure angle involute profile, these gears will mesh correctly. Module (Mod) is the international standard for gear tooth sizing; gears of the same module are interchangeable regardless of brand, provided the pressure angle matches.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\n\u003cdetails\u003e\n  \u003csummary\u003eHow do I verify the bore diameter fits my shaft?\u003c\/summary\u003e\n  \u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eBore diameter varies by tooth count. Please refer to the variant detail or contact us to confirm the exact bore size for your selected tooth count before ordering. If your shaft diameter does not match the standard bore, the gear can typically be re-bored by a local machine shop to your required dimension.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\n\u003cdetails\u003e\n  \u003csummary\u003eCan I use these gears for a CNC rack-and-pinion drive?\u003c\/summary\u003e\n  \u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eYes. Mod 3 spur gears are a common choice for DIY CNC rack-and-pinion systems. Pair the pinion gear with a standard Mod 3 steel or nylon rack. Smaller tooth counts (10T–14T) are typically used as pinions on CNC axes for compact drive assemblies. Ensure your motor shaft matches the bore diameter of the selected gear.\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 tooth count (Choose Model) and packing 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 choose the right tooth count for my project?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"The tooth count determines your gear ratio. Divide the driven gear teeth by the driving gear teeth to get the ratio. For example, pairing a 10T pinion with a 30T gear gives a 3:1 reduction. Choose a smaller tooth count for higher speed output and a larger tooth count for more torque. All options in this listing share the same Mod 3 standard, so any two can mesh together.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"What is the pitch diameter for each tooth count?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"For Module 3 gears, pitch diameter = Module × Tooth Count. For example, a 3M 10T gear has a pitch diameter of 30mm, a 3M 20T gear has 60mm, and a 3M 30T gear has 90mm.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"What is 45# steel and how strong is it?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"45# steel is a medium-carbon structural steel with approximately 0.42–0.50% carbon content. It offers tensile strength of roughly 600–800 MPa and can be hardened by quenching and tempering. It is widely used for gears, shafts, and machine parts.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Are these gears corrosion-resistant?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"45# steel is not inherently corrosion-resistant. These gears are supplied with a natural steel finish. Apply machine oil, grease, or a rust-inhibiting coating for humid or outdoor environments.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Will these mesh with my existing Mod 3 rack or gear?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Yes — as long as your existing rack or mating gear is also Module 3 with a standard 20° pressure angle involute profile, these gears will mesh correctly.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"How do I verify the bore diameter fits my shaft?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Bore diameter varies by tooth count. Please refer to the variant detail or contact us to confirm the exact bore size for your selected tooth count before ordering.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Can I use these gears for a CNC rack-and-pinion drive?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Yes. Mod 3 spur gears are a common choice for DIY CNC rack-and-pinion systems. Pair the pinion gear with a standard Mod 3 steel or nylon rack. Smaller tooth counts (10T–14T) are typically used as pinions on CNC axes.\"\n      }\n    }\n  ]\n}\n\u003c\/script\u003e","brand":"HomeDIYer","offers":[{"title":"3M 10T \/ 1 pcs","offer_id":52443225686290,"sku":"GLFBFHHGLBZSJ058177x1","price":19.65,"currency_code":"USD","in_stock":true},{"title":"3M 11T \/ 1 pcs","offer_id":52443225719058,"sku":"GLFBFHHGLBZSJ058178x1","price":30.21,"currency_code":"USD","in_stock":true},{"title":"3M 12T \/ 1 pcs","offer_id":52443225751826,"sku":"GLFBFHHGLBZSJ058179x1","price":34.39,"currency_code":"USD","in_stock":true},{"title":"3M 13T \/ 1 pcs","offer_id":52443225784594,"sku":"GLFBFHHGLBZSJ058180x1","price":44.35,"currency_code":"USD","in_stock":true},{"title":"3M 14T \/ 1 pcs","offer_id":52443225817362,"sku":"GLFBFHHGLBZSJ058181x1","price":44.44,"currency_code":"USD","in_stock":true},{"title":"3M 15T \/ 1 pcs","offer_id":52443225850130,"sku":"GLFBFHHGLBZSJ058182x1","price":62.37,"currency_code":"USD","in_stock":true},{"title":"3M 16T \/ 1 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