{"product_id":"1-mod-20-tooth-spur-gear-bore-4-12-7mm","title":"1 Modulus 20 Teeth Spur Gears Transmission Motor Gear Bore 4-12.7mm Pitch 3.14mm","description":"\u003cdiv class=\"hdiy-desc\"\u003e\n\n\u003cdiv class=\"hdiy-overview\"\u003e\n\u003ch2\u003e1 Modulus 20-Tooth Spur Gear — Reliable Power Transmission for DIY Drives\u003c\/h2\u003e\n\u003cp\u003eWhen your motor coupling slips, your gear ratio drifts, or your existing spur gear strips under load, the root cause is almost always a mismatch between bore size, module, and material. Makers, robotics builders, and workshop engineers who need a drop-in replacement or a fresh drive stage will find this 1 modulus 20-tooth spur gear sized and specified to fit without guesswork.\u003c\/p\u003e\n\u003cp\u003eEach gear is machined to a 1 modulus (Mod 1) standard with 20 teeth and a circular pitch of 3.14 mm (0.124 in). Bore options span 4 mm to 12.7 mm (0.157 in to 0.500 in), covering the most common motor shaft diameters used in hobby and light-industrial applications. Three material grades are available: engineering-grade Nylon for low-noise, low-friction runs; 316-equivalent Stainless Steel for corrosion-resistant environments; and 45# medium-carbon steel for higher-torque mechanical drives.\u003c\/p\u003e\n\u003cp\u003eTypical use cases include DC motor output stages in mobile robots and CNC axis drives, stepper-motor transmission trains in 3D printers and laser cutters, and manual reduction assemblies in DIY conveyor or winch projects where a compact 20-tooth pinion is the first stage of a multi-gear reduction.\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 for Mod 1 gear systems. Meshes with any Mod 1 rack, pinion, or mating spur gear. Verify shaft diameter against your selected bore option before ordering.\n\u003c\/div\u003e\n\n\u003cdiv class=\"hdiy-features\"\u003e\n\u003ch2\u003e✅ Key Features of These 1 Mod 20-Tooth Spur Gears\u003c\/h2\u003e\n\u003cul class=\"hdiy-list\"\u003e\n\u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e📐\u003c\/span\u003e\u003cstrong\u003eMod 1 Standard, 20 Teeth\u003c\/strong\u003e — 3.14 mm circular pitch ensures direct mesh compatibility with any Mod 1 rack or mating gear in your drivetrain.\u003c\/li\u003e\n\u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e🔩\u003c\/span\u003e\u003cstrong\u003eWide Bore Range: 4–12.7 mm\u003c\/strong\u003e — Covers round bores (4, 5, 6, 6.35, 7, 8, 10, 12, 12.7 mm) and keyed\/D-bore options so you can match virtually any motor shaft without custom machining.\u003c\/li\u003e\n\u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e🧱\u003c\/span\u003e\u003cstrong\u003eThree Material Grades\u003c\/strong\u003e — Nylon for quiet, self-lubricating operation; Stainless Steel for moisture-exposed or food-adjacent builds; 45# Steel for torque-demanding mechanical drives.\u003c\/li\u003e\n\u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e🔄\u003c\/span\u003e\u003cstrong\u003eKeyed Bore Variants Available\u003c\/strong\u003e — Select bore options include keyway cuts (e.g., 8 mm 3×1.4 mm, 10 mm 4×1.8 mm) for positive shaft locking under reversing or high-inertia loads.\u003c\/li\u003e\n\u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e⚖️\u003c\/span\u003e\u003cstrong\u003eCompact, Lightweight Profile\u003c\/strong\u003e — 20-tooth Mod 1 geometry keeps the pitch diameter at 20 mm, making this gear ideal for space-constrained gearboxes and multi-stage reduction trains.\u003c\/li\u003e\n\u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e🛠️\u003c\/span\u003e\u003cstrong\u003eDrop-In Replacement Geometry\u003c\/strong\u003e — Standardized Mod 1 tooth profile means this gear replaces worn pinions in existing assemblies without redesigning the gear center distance.\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 1 Spur Gear\u003c\/h2\u003e\n\u003ctable\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eModule\u003c\/th\u003e\n\u003ctd\u003e1 (Mod 1)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eNumber of Teeth\u003c\/th\u003e\n\u003ctd\u003e20\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eCircular Pitch\u003c\/th\u003e\n\u003ctd\u003e3.14 mm (0.124 in)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003ePitch Diameter\u003c\/th\u003e\n\u003ctd\u003e20 mm (0.787 in)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003ePressure Angle\u003c\/th\u003e\n\u003ctd\u003e20°\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eBore Diameter\u003c\/th\u003e\n\u003ctd\u003e4 mm – 12.7 mm (0.157 in – 0.500 in) — See variant options\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eBore Type\u003c\/th\u003e\n\u003ctd\u003eRound bore or keyed bore — See variant options\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eMaterial\u003c\/th\u003e\n\u003ctd\u003eNylon \/ Stainless Steel \/ 45# Steel — See variant options\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 Diameter\u003c\/th\u003e\n\u003ctd\u003eSee variant options\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eFinish\u003c\/th\u003e\n\u003ctd\u003eNatural (Nylon) \/ Polished (Stainless Steel) \/ Oxide or plain (45# Steel)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eGear Standard\u003c\/th\u003e\n\u003ctd\u003eDIN \/ ISO Mod 1\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 bore size for my motor shaft?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eMeasure your motor shaft diameter with a caliper. Select the bore option that matches exactly — for example, a 5 mm shaft needs the 5 mm bore variant. If your shaft has a flat (D-shaft) or keyway, choose the corresponding keyed bore option such as 8 mm (3×1.4 mm) or 10 mm (4×1.8 mm). A bore that is even 0.1 mm too large will cause shaft slip under load.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\n\u003cdetails\u003e\n\u003csummary\u003eWhat is the difference between Nylon, Stainless Steel, and 45# Steel versions?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eNylon gears run quietly and require no lubrication, making them ideal for light-duty robotics, 3D printers, and applications where noise matters. Stainless Steel gears resist moisture and mild chemicals, suited for outdoor or humid environments. 45# Steel gears offer the highest torque capacity and wear resistance for demanding mechanical drives, but they require lubrication and are not corrosion-resistant without a protective coating.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\n\u003cdetails\u003e\n\u003csummary\u003eWill this gear mesh with my existing Mod 1 rack or pinion?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eYes. Any gear or rack manufactured to the Mod 1 (Module 1) standard with a 20° pressure angle will mesh correctly with this gear. The 3.14 mm circular pitch and 20 mm pitch diameter are fixed by the Mod 1 standard, so center distance calculations are straightforward: center distance = (teeth of gear A + teeth of gear B) ÷ 2 mm.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\n\u003cdetails\u003e\n\u003csummary\u003eHow strong is this gear under continuous load?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eLoad capacity depends on material and operating conditions. As a conservative guide: Nylon variants handle light-duty intermittent loads up to approximately 5–10 N·m at low RPM; Stainless Steel variants support moderate continuous loads; 45# Steel variants are suited for the highest torques in this size class. For precise load ratings, refer to your gear design standard (e.g., AGMA or DIN 3990) using the gear geometry data in the specifications table above.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\n\u003cdetails\u003e\n\u003csummary\u003eDo I need a set screw or keyway to secure the gear to the shaft?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eRound bore variants rely on a set screw (not included) tightened against the shaft flat or directly onto a round shaft. Keyed bore variants (e.g., 8 mm 3×1.4 mm, 10 mm 3×1.4 mm, 10 mm 4×1.8 mm) use a standard key and keyway for positive torque transmission, which is recommended for reversing loads or high-inertia applications. Check your bore option description to confirm whether it is a plain round bore or a keyed bore.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\n\u003cdetails\u003e\n\u003csummary\u003eIs this gear suitable for outdoor or corrosion-prone environments?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eThe Stainless Steel variant is the best choice for outdoor, humid, or mildly corrosive environments. Nylon is inherently moisture-resistant for light-duty outdoor use. The 45# Steel variant will oxidize if exposed to moisture without a protective coating such as grease, paint, or a zinc finish applied by the user. For marine or chemical environments, consult a materials engineer before selecting any steel variant.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\n\u003cdetails\u003e\n\u003csummary\u003eWhat is the face width and overall hub length of this gear?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eFace width and hub length vary by bore and material variant. Please refer to the variant detail page or contact us to confirm exact dimensions for your selected option before designing your gearbox housing.\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 material 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 bore size for my motor shaft?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Measure your motor shaft diameter with a caliper. Select the bore option that matches exactly. If your shaft has a flat or keyway, choose the corresponding keyed bore option. A bore that is even 0.1 mm too large will cause shaft slip under load.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"What is the difference between Nylon, Stainless Steel, and 45# Steel versions?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Nylon gears run quietly and require no lubrication, ideal for light-duty robotics and 3D printers. Stainless Steel gears resist moisture for outdoor or humid environments. 45# Steel gears offer the highest torque capacity for demanding mechanical drives but require lubrication.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Will this gear mesh with my existing Mod 1 rack or pinion?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Yes. Any gear or rack manufactured to the Mod 1 standard with a 20° pressure angle will mesh correctly with this gear. Center distance = (teeth of gear A + teeth of gear B) ÷ 2 mm.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"How strong is this gear under continuous load?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Load capacity depends on material. Nylon handles light-duty intermittent loads; Stainless Steel supports moderate continuous loads; 45# Steel suits the highest torques in this size class. Refer to AGMA or DIN 3990 for precise load ratings.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Do I need a set screw or keyway to secure the gear to the shaft?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Round bore variants use a set screw (not included). Keyed bore variants use a standard key and keyway for positive torque transmission, recommended for reversing loads or high-inertia applications.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Is this gear suitable for outdoor or corrosion-prone environments?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"The Stainless Steel variant is best for outdoor or humid environments. Nylon is inherently moisture-resistant for light-duty outdoor use. The 45# Steel variant will oxidize without a protective coating.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"What is the face width and overall hub length of this gear?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Face width and hub length vary by bore and material variant. Please contact us to confirm exact dimensions for your selected option.\"\n      }\n    }\n  ]\n}\n\u003c\/script\u003e","brand":"HomeDIYer","offers":[{"title":"1 Mod 20 Teeth \/ 5mm \/ Nylon","offer_id":52443256160530,"sku":"LXDGLCDPJ00499x1","price":11.29,"currency_code":"USD","in_stock":true},{"title":"1 Mod 20 Teeth \/ 6mm \/ Nylon","offer_id":52443256193298,"sku":"LXDGLCDPJ00500x1","price":11.29,"currency_code":"USD","in_stock":true},{"title":"1 Mod 20 Teeth \/ 6.35mm \/ Nylon","offer_id":52443256226066,"sku":"LXDGLCDPJ00501x1","price":11.29,"currency_code":"USD","in_stock":true},{"title":"1 Mod 20 Teeth \/ 7mm \/ Nylon","offer_id":52443256258834,"sku":"LXDGLCDPJ00502x1","price":11.29,"currency_code":"USD","in_stock":true},{"title":"1 Mod 20 Teeth \/ 8mm \/ Nylon","offer_id":52443256291602,"sku":"LXDGLCDPJ00503x1","price":11.29,"currency_code":"USD","in_stock":true},{"title":"1 Mod 20 Teeth \/ 10mm \/ 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