{"product_id":"steel-spur-gear-mod-4-pinion-gear-10-24-teeth-48-104mm-od-motor-flat-gears","title":"Steel Spur Gear Mod 4 Pinion Gear 10-24 Teeth 48-104mm OD Motor Flat Gears","description":"\u003cdiv class=\"hdiy-desc\"\u003e\n\n  \u003cdiv class=\"hdiy-overview\"\u003e\n    \u003ch2\u003eSteel Mod 4 Spur Gear — Precision Pinion Gears for Demanding Drive Systems\u003c\/h2\u003e\n    \u003cp\u003eWhen a slipping or undersized gear stalls your CNC router, robotics arm, or automation drive mid-cycle, the cost is more than downtime — it's lost accuracy and rework. Engineers, makers, and small-batch manufacturers who need a reliable, drop-in pinion gear for Mod 4 drive trains will find this steel spur gear series purpose-built for the task.\u003c\/p\u003e\n    \u003cp\u003eEach gear is machined from carbon steel and features a flat (spur) tooth profile with a Module 4 pitch. The series spans 10 to 24 teeth, yielding outer diameters from approximately 48 mm (≈1.89 in) at 10T up to 104 mm (≈4.09 in) at 24T, with a standard bore sized to suit common motor shafts — confirm your shaft diameter against the variant options before ordering.\u003c\/p\u003e\n    \u003cp\u003eTypical applications include CNC rack-and-pinion linear drives, stepper and servo motor output stages, conveyor indexing systems, and open-frame robotics joints where a Mod 4 steel pinion gear with consistent tooth geometry is required for repeatable positioning.\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 4 (Module 4) gear systems. Meshes with any Mod 4 rack, ring gear, or mating spur gear of the same module. Verify bore diameter and keyway requirements against your motor shaft before ordering.\n  \u003c\/div\u003e\n\n  \u003ch2\u003e✅ Key Features of These Steel Mod 4 Spur Gears\u003c\/h2\u003e\n  \u003cdiv class=\"hdiy-features\"\u003e\n\n    \u003cdiv\u003e\n      \u003cdiv class=\"hdiy-icon\"\u003e🔩\u003c\/div\u003e\n      \u003cstrong\u003eCarbon Steel Construction\u003c\/strong\u003e\n      \u003cp\u003eMachined from carbon steel for the strength and wear resistance needed in continuous-duty drive applications, including CNC and robotics.\u003c\/p\u003e\n    \u003c\/div\u003e\n\n    \u003cdiv\u003e\n      \u003cdiv class=\"hdiy-icon\"\u003e📐\u003c\/div\u003e\n      \u003cstrong\u003eModule 4 Precision Tooth Profile\u003c\/strong\u003e\n      \u003cp\u003eStandard Mod 4 involute tooth geometry ensures accurate meshing with any compatible Mod 4 rack or mating gear, minimizing backlash in precision drives.\u003c\/p\u003e\n    \u003c\/div\u003e\n\n    \u003cdiv\u003e\n      \u003cdiv class=\"hdiy-icon\"\u003e🔢\u003c\/div\u003e\n      \u003cstrong\u003e10–24 Tooth Range in One Listing\u003c\/strong\u003e\n      \u003cp\u003eSelect from 15 tooth-count variants (10T through 24T) to dial in your exact gear ratio without sourcing from multiple suppliers.\u003c\/p\u003e\n    \u003c\/div\u003e\n\n    \u003cdiv\u003e\n      \u003cdiv class=\"hdiy-icon\"\u003e📏\u003c\/div\u003e\n      \u003cstrong\u003e48–104 mm Outer Diameter Span\u003c\/strong\u003e\n      \u003cp\u003eOD scales predictably with tooth count (OD = Module × Teeth + 2 × Module), giving you a reliable reference for envelope clearance in tight assemblies.\u003c\/p\u003e\n    \u003c\/div\u003e\n\n    \u003cdiv\u003e\n      \u003cdiv class=\"hdiy-icon\"\u003e⚡\u003c\/div\u003e\n      \u003cstrong\u003eFlat Spur Profile for Motor Output Stages\u003c\/strong\u003e\n      \u003cp\u003eThe flat spur (straight-tooth) design transmits torque efficiently on parallel shafts — ideal for stepper and servo motor pinion applications where axial load is minimal.\u003c\/p\u003e\n    \u003c\/div\u003e\n\n    \u003cdiv\u003e\n      \u003cdiv class=\"hdiy-icon\"\u003e🛠️\u003c\/div\u003e\n      \u003cstrong\u003eDrop-In Replacement Geometry\u003c\/strong\u003e\n      \u003cp\u003eStandard Mod 4 dimensions mean these gears serve as direct replacements for worn pinions in existing Mod 4 drive systems without custom machining.\u003c\/p\u003e\n    \u003c\/div\u003e\n\n  \u003c\/div\u003e\n\n  \u003ch2\u003e📐 Technical Specifications — Mod 4 Spur Pinion Gears\u003c\/h2\u003e\n  \u003cdiv class=\"hdiy-table-wrap\"\u003e\n    \u003ctable\u003e\n      \u003ctbody\u003e\n        \u003ctr\u003e\n\u003cth\u003eModule (Mod)\u003c\/th\u003e\n\u003ctd\u003e4\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003cth\u003eTooth Count Range\u003c\/th\u003e\n\u003ctd\u003e10T – 24T (15 variants)\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003cth\u003eOuter Diameter Range\u003c\/th\u003e\n\u003ctd\u003e48 mm – 104 mm (1.89 in – 4.09 in)\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003cth\u003eTooth Profile\u003c\/th\u003e\n\u003ctd\u003eInvolute spur (flat \/ straight tooth)\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003cth\u003eMaterial\u003c\/th\u003e\n\u003ctd\u003eCarbon steel\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003cth\u003ePressure Angle\u003c\/th\u003e\n\u003ctd\u003e20° (standard involute)\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\u003eHub \/ Face Width\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\u003eSee variant options\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003cth\u003eCompatible Module\u003c\/th\u003e\n\u003ctd\u003eMod 4 rack, ring gear, or mating spur gear\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003cth\u003eWeight\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-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 application?\u003c\/summary\u003e\n      \u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eYour gear ratio is determined by dividing the tooth count of the driven gear by the tooth count of the driving pinion. For example, pairing a 10T pinion with a 40T gear gives a 4:1 reduction. Select a tooth count that achieves your target ratio while keeping the outer diameter within your assembly envelope. The OD formula for Mod 4 is: OD (mm) = 4 × (Teeth + 2).\u003c\/p\u003e\u003c\/div\u003e\n    \u003c\/details\u003e\n\n    \u003cdetails\u003e\n      \u003csummary\u003eWhat is Module 4 and is it compatible with my existing gears?\u003c\/summary\u003e\n      \u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eModule (Mod) is the metric standard for gear tooth size — it equals the pitch diameter divided by the number of teeth. Mod 4 gears will only mesh correctly with other Mod 4 gears or Mod 4 racks. They are not interchangeable with Mod 2, Mod 3, or imperial diametral-pitch gears. Check your existing gear's module marking or measure the tooth pitch before ordering.\u003c\/p\u003e\u003c\/div\u003e\n    \u003c\/details\u003e\n\n    \u003cdetails\u003e\n      \u003csummary\u003eAre these gears strong enough for my CNC or robotics drive?\u003c\/summary\u003e\n      \u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eCarbon steel spur gears in Mod 4 are well-suited for moderate-to-high torque CNC rack-and-pinion drives, stepper\/servo motor output stages, and robotics joints operating at typical automation speeds. For very high-speed or shock-load applications, confirm the face width and bore specifications of your chosen variant against your torque and RPM requirements.\u003c\/p\u003e\u003c\/div\u003e\n    \u003c\/details\u003e\n\n    \u003cdetails\u003e\n      \u003csummary\u003eDo these gears resist corrosion for outdoor or humid environments?\u003c\/summary\u003e\n      \u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eCarbon steel has moderate corrosion resistance. For outdoor, humid, or washdown environments, we recommend applying a light machine oil or grease coating during installation and re-lubricating periodically. If your application demands higher corrosion resistance, consider stainless steel alternatives or apply a protective coating after installation.\u003c\/p\u003e\u003c\/div\u003e\n    \u003c\/details\u003e\n\n    \u003cdetails\u003e\n      \u003csummary\u003eWhat bore diameter do these pinion gears have?\u003c\/summary\u003e\n      \u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eBore diameter varies by variant. Please check the variant options or contact us to confirm the bore size matches your motor or shaft diameter before ordering. Many Mod 4 pinions in this size range use bores from approximately 8 mm to 20 mm, but verify against the specific variant you select.\u003c\/p\u003e\u003c\/div\u003e\n    \u003c\/details\u003e\n\n    \u003cdetails\u003e\n      \u003csummary\u003eCan I use these as a direct replacement for a worn pinion gear?\u003c\/summary\u003e\n      \u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eYes — as long as your existing system uses Mod 4 gearing, these pinions serve as direct replacements. Match the tooth count, bore diameter, and face width of your worn gear to the appropriate variant. Standard Mod 4 tooth geometry ensures correct meshing without additional machining in most cases.\u003c\/p\u003e\u003c\/div\u003e\n    \u003c\/details\u003e\n\n    \u003cdetails\u003e\n      \u003csummary\u003eWhat is the difference between a spur gear and a helical gear for my drive?\u003c\/summary\u003e\n      \u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eSpur gears (like these) have straight teeth parallel to the shaft axis. They are simpler, less expensive, and generate no axial thrust — making them ideal for parallel-shaft drives where axial load management is not required. Helical gears offer quieter operation and higher load capacity but introduce axial forces that require thrust bearings. For most CNC and robotics pinion applications, spur gears are the practical choice.\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 Mod x Teeth 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 application?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Your gear ratio is determined by dividing the tooth count of the driven gear by the tooth count of the driving pinion. For example, pairing a 10T pinion with a 40T gear gives a 4:1 reduction. Select a tooth count that achieves your target ratio while keeping the outer diameter within your assembly envelope. The OD formula for Mod 4 is: OD (mm) = 4 × (Teeth + 2).\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"What is Module 4 and is it compatible with my existing gears?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Module (Mod) is the metric standard for gear tooth size — it equals the pitch diameter divided by the number of teeth. Mod 4 gears will only mesh correctly with other Mod 4 gears or Mod 4 racks. They are not interchangeable with Mod 2, Mod 3, or imperial diametral-pitch gears.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Are these gears strong enough for my CNC or robotics drive?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Carbon steel spur gears in Mod 4 are well-suited for moderate-to-high torque CNC rack-and-pinion drives, stepper\/servo motor output stages, and robotics joints operating at typical automation speeds.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Do these gears resist corrosion for outdoor or humid environments?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Carbon steel has moderate corrosion resistance. For outdoor or humid environments, apply a light machine oil or grease coating during installation and re-lubricate periodically.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"What bore diameter do these pinion gears have?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Bore diameter varies by variant. Please check the variant options or contact us to confirm the bore size matches your motor or shaft diameter before ordering.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Can I use these as a direct replacement for a worn pinion gear?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Yes — as long as your existing system uses Mod 4 gearing, these pinions serve as direct replacements. Match the tooth count, bore diameter, and face width of your worn gear to the appropriate variant.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"What is the difference between a spur gear and a helical gear for my drive?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Spur gears have straight teeth parallel to the shaft axis — simpler, no axial thrust, ideal for parallel-shaft drives. Helical gears offer quieter operation and higher load capacity but introduce axial forces requiring thrust bearings.\"\n      }\n    }\n  ]\n}\n\u003c\/script\u003e","brand":"HomeDIYer","offers":[{"title":"4M 10T","offer_id":52442526089490,"sku":"GLFBDMHGLBZSJ058241x1","price":27.95,"currency_code":"USD","in_stock":true},{"title":"4M 11T","offer_id":52442526122258,"sku":"GLFBDMHGLBZSJ058242x1","price":29.8,"currency_code":"USD","in_stock":true},{"title":"4M 12T","offer_id":52442526155026,"sku":"GLFBDMHGLBZSJ058243x1","price":35.22,"currency_code":"USD","in_stock":true},{"title":"4M 13T","offer_id":52442526187794,"sku":"GLFBDMHGLBZSJ058244x1","price":40.53,"currency_code":"USD","in_stock":true},{"title":"4M 14T","offer_id":52442526220562,"sku":"GLFBDMHGLBZSJ058245x1","price":54.81,"currency_code":"USD","in_stock":true},{"title":"4M 15T","offer_id":52442526253330,"sku":"GLFBDMHGLBZSJ058246x1","price":57.36,"currency_code":"USD","in_stock":true},{"title":"4M 16T","offer_id":52442526286098,"sku":"GLFBDMHGLBZSJ058247x1","price":64.04,"currency_code":"USD","in_stock":true},{"title":"4M 17T","offer_id":52442526318866,"sku":"GLFBDMHGLBZSJ058248x1","price":68.98,"currency_code":"USD","in_stock":true},{"title":"4M 18T","offer_id":52442526351634,"sku":"GLFBDMHGLBZSJ058249x1","price":87.3,"currency_code":"USD","in_stock":true},{"title":"4M 19T","offer_id":52442526384402,"sku":"GLFBDMHGLBZSJ058250x1","price":92.93,"currency_code":"USD","in_stock":true},{"title":"4M 20T","offer_id":52442526417170,"sku":"GLFBDMHGLBZSJ058251x1","price":93.51,"currency_code":"USD","in_stock":true},{"title":"4M 21T","offer_id":52442526449938,"sku":"GLFBDMHGLBZSJ058252x1","price":112.58,"currency_code":"USD","in_stock":true},{"title":"4M 22T","offer_id":52442526482706,"sku":"GLFBDMHGLBZSJ058253x1","price":119.91,"currency_code":"USD","in_stock":true},{"title":"4M 23T","offer_id":52442526515474,"sku":"GLFBDMHGLBZSJ058254x1","price":124.55,"currency_code":"USD","in_stock":true},{"title":"4M 24T","offer_id":52442526548242,"sku":"GLFBDMHGLBZSJ058255x1","price":129.57,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0884\/8936\/1682\/files\/Picture1of7_5eec926a-d1fc-4433-aa47-fbe8890308f0.jpg?v=1783563605","url":"https:\/\/homediyer.com\/products\/steel-spur-gear-mod-4-pinion-gear-10-24-teeth-48-104mm-od-motor-flat-gears","provider":"HomeDIYer","version":"1.0","type":"link"}