{"product_id":"mod-4-45-steel-spur-gears-pinion-gear-35mm-10t-39t","title":"Mod 4 45# Steel Spur Gears Pinion Gear Thickn 35mm 10T - 39T Transmission Gear","description":"\u003cdiv class=\"hdiy-desc\"\u003e\n\n  \u003cdiv class=\"hdiy-overview\"\u003e\n    \u003ch2\u003eMod 4 45# Steel Spur Gears — Reliable Pinion Gear for Heavy-Duty Transmission\u003c\/h2\u003e\n    \u003cp\u003eWhen your CNC machine, robotic arm, or industrial drive system demands consistent torque transfer without slippage or premature wear, the choice of pinion gear matters. Engineers and makers working with high-load transmission assemblies need a Mod 4 spur gear that holds tight tolerances across extended duty cycles — these 45# carbon steel gears are built for exactly that application.\u003c\/p\u003e\n    \u003cp\u003eEach gear is machined from 45# medium-carbon steel, offering a balance of hardness and machinability suited for power transmission components. The tooth thickness is a fixed 35mm (~1.38 in), with a Module 4 pitch. Tooth counts range from 10T to 39T, covering pitch circle diameters from approximately 40mm (~1.57 in) for the 10T up to approximately 156mm (~6.14 in) for the 39T variant. Bore diameter varies by tooth count — see variant options for exact bore specs.\u003c\/p\u003e\n    \u003cp\u003eThese Mod 4 pinion gears are well-suited for CNC router Z-axis and rack-and-pinion drives, rotary indexing tables and servo motor output shafts, and custom gearbox assemblies in automation and conveyor systems where a reliable steel spur gear transmission component is required.\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 Module 4 (Mod 4) gear systems. Pairs with Mod 4 racks, mating spur gears, and standard metric bore shafts. Confirm bore diameter against your shaft size before ordering.\n  \u003c\/div\u003e\n\n  \u003cdiv class=\"hdiy-features\"\u003e\n    \u003ch2\u003e✅ Key Features of These Mod 4 Steel 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# Carbon Steel Construction\u003c\/strong\u003e — Machined from medium-carbon 45# steel for solid load-bearing capacity and resistance to deformation under sustained torque loads.\u003c\/li\u003e\n      \u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e📏\u003c\/span\u003e\u003cstrong\u003e35mm Fixed Face Width\u003c\/strong\u003e — Consistent 35mm (~1.38 in) tooth thickness across all tooth counts ensures uniform contact width and stable power transmission in your drivetrain.\u003c\/li\u003e\n      \u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e⚙️\u003c\/span\u003e\u003cstrong\u003eModule 4 Standard Pitch\u003c\/strong\u003e — Mod 4 pitch geometry provides broad compatibility with standard metric rack-and-pinion systems, mating gears, and servo motor pinions used in CNC and automation builds.\u003c\/li\u003e\n      \u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e🔢\u003c\/span\u003e\u003cstrong\u003eWide Tooth Count Range (10T–39T)\u003c\/strong\u003e — Thirty tooth-count options from 10T to 39T let you dial in the exact gear ratio needed for your speed-torque requirements without custom machining.\u003c\/li\u003e\n      \u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e🛡️\u003c\/span\u003e\u003cstrong\u003eMachined Tooth Profile\u003c\/strong\u003e — Gear teeth are precision-cut to standard involute profile, supporting smooth meshing, reduced backlash, and consistent transmission efficiency across the operating range.\u003c\/li\u003e\n      \u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e🔧\u003c\/span\u003e\u003cstrong\u003eMetric Bore for Standard Shafts\u003c\/strong\u003e — Bore dimensions follow metric standards compatible with common servo and stepper motor output shafts. Verify bore size in variant options to match your shaft diameter.\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 4 Spur Gear\u003c\/h2\u003e\n    \u003ctable\u003e\n      \u003ctbody\u003e\n        \u003ctr\u003e\n\u003cth\u003eModule\u003c\/th\u003e\n\u003ctd\u003e4 (Mod 4)\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003cth\u003eMaterial\u003c\/th\u003e\n\u003ctd\u003e45# Carbon Steel\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003cth\u003eFace Width (Tooth Thickness)\u003c\/th\u003e\n\u003ctd\u003e35mm (~1.38 in)\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003cth\u003eTooth Count Range\u003c\/th\u003e\n\u003ctd\u003e10T – 39T (30 variants)\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003cth\u003ePitch Circle Diameter\u003c\/th\u003e\n\u003ctd\u003eSee variant options (Module × 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\u003eTooth Profile\u003c\/th\u003e\n\u003ctd\u003eStandard Involute\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\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\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\u003eSelect your tooth count based on the gear ratio you need. Divide the driven gear's tooth count by the driving gear's tooth count to get the ratio. For example, pairing a 10T pinion with a 30T gear gives a 3:1 reduction. Smaller tooth counts (10T–15T) suit high-reduction, high-torque setups; larger counts (30T–39T) are better for lower reduction or speed-matching applications.\u003c\/p\u003e\u003c\/div\u003e\n    \u003c\/details\u003e\n\n    \u003cdetails\u003e\n      \u003csummary\u003eWhat is the bore diameter for each tooth count variant?\u003c\/summary\u003e\n      \u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eBore diameter varies by tooth count and is listed in the variant options on this page. Always verify the bore size matches your motor or shaft diameter before ordering. If you need a custom bore, the steel material is machinable for post-purchase boring by a machine shop.\u003c\/p\u003e\u003c\/div\u003e\n    \u003c\/details\u003e\n\n    \u003cdetails\u003e\n      \u003csummary\u003eAre these gears compatible with Mod 4 racks and other Mod 4 gears?\u003c\/summary\u003e\n      \u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eYes. All gears in this listing use Module 4 pitch with a standard 20° pressure angle involute tooth profile, which is fully compatible with any other Mod 4 rack, pinion, or spur gear of the same module and pressure angle. Do not mix with Mod 3 or Mod 5 components — module must match for proper meshing.\u003c\/p\u003e\u003c\/div\u003e\n    \u003c\/details\u003e\n\n    \u003cdetails\u003e\n      \u003csummary\u003eHow strong is 45# carbon steel for power transmission?\u003c\/summary\u003e\n      \u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003e45# carbon steel (equivalent to AISI 1045) has a tensile strength of approximately 600–800 MPa in the normalized condition, making it a solid choice for moderate-to-heavy duty gear applications. It is commonly used in industrial gearboxes, machine tool drives, and automation systems. For very high-shock or extreme-load environments, consider whether a hardened or alloy steel variant better suits your torque requirements.\u003c\/p\u003e\u003c\/div\u003e\n    \u003c\/details\u003e\n\n    \u003cdetails\u003e\n      \u003csummary\u003eWill these gears rust or corrode over time?\u003c\/summary\u003e\n      \u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eCarbon steel is susceptible to surface oxidation if left unprotected in humid or wet environments. For indoor CNC and automation use, applying a light machine oil or grease to the gear teeth during operation provides adequate protection and lubrication. For outdoor or high-moisture environments, consider adding a protective coating or using stainless steel alternatives.\u003c\/p\u003e\u003c\/div\u003e\n    \u003c\/details\u003e\n\n    \u003cdetails\u003e\n      \u003csummary\u003eCan I use these gears with stepper motors and servo motors?\u003c\/summary\u003e\n      \u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eYes, these Mod 4 pinion gears are commonly used with both stepper and servo motors in CNC and robotics builds. Confirm that the bore diameter of your selected tooth count matches your motor shaft diameter. A keyway or set-screw bore style may be required depending on your motor shaft — check the variant details or contact us to confirm bore configuration.\u003c\/p\u003e\u003c\/div\u003e\n    \u003c\/details\u003e\n\n    \u003cdetails\u003e\n      \u003csummary\u003eWhat is the pitch circle diameter for each tooth count?\u003c\/summary\u003e\n      \u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003ePitch circle diameter (PCD) for a Mod 4 gear is calculated as: PCD = Module × Tooth Count. For example: 4 × 10T = 40mm PCD; 4 × 20T = 80mm PCD; 4 × 39T = 156mm PCD. Use this formula to calculate center distance between mating gears: Center Distance = (PCD₁ + PCD₂) \/ 2.\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 (Types) 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\": \"Select your tooth count based on the gear ratio you need. Divide the driven gear's tooth count by the driving gear's tooth count to get the ratio. Smaller tooth counts (10T–15T) suit high-reduction, high-torque setups; larger counts (30T–39T) are better for lower reduction or speed-matching applications.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"What is the bore diameter for each tooth count variant?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Bore diameter varies by tooth count and is listed in the variant options on this page. Always verify the bore size matches your motor or shaft diameter before ordering.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Are these gears compatible with Mod 4 racks and other Mod 4 gears?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Yes. All gears use Module 4 pitch with a standard 20° pressure angle involute tooth profile, fully compatible with any Mod 4 rack, pinion, or spur gear of the same module and pressure angle.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"How strong is 45# carbon steel for power transmission?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"45# carbon steel has a tensile strength of approximately 600–800 MPa in the normalized condition, suitable for moderate-to-heavy duty gear applications including industrial gearboxes and automation systems.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Will these gears rust or corrode over time?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Carbon steel is susceptible to surface oxidation if unprotected. Applying light machine oil or grease during operation provides adequate protection for indoor use. For high-moisture environments, consider a protective coating.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Can I use these gears with stepper motors and servo motors?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Yes, these Mod 4 pinion gears are commonly used with both stepper and servo motors in CNC and robotics builds. Confirm the bore diameter matches your motor shaft diameter before ordering.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"What is the pitch circle diameter for each tooth count?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"PCD = Module × Tooth Count. For Mod 4: 10T = 40mm, 20T = 80mm, 39T = 156mm. Center distance between mating gears = (PCD₁ + PCD₂) \/ 2.\"\n      }\n    }\n  ]\n}\n\u003c\/script\u003e","brand":"HomeDIYer","offers":[{"title":"4M 10T \/ 1 Pcs","offer_id":52442583105810,"sku":"GYFYGLBZSJ058241x1","price":38.01,"currency_code":"USD","in_stock":true},{"title":"4M 11T \/ 1 Pcs","offer_id":52442583138578,"sku":"GYFYGLBZSJ058242x1","price":40.73,"currency_code":"USD","in_stock":true},{"title":"4M 12T \/ 1 Pcs","offer_id":52442583171346,"sku":"GYFYGLBZSJ058243x1","price":47.53,"currency_code":"USD","in_stock":true},{"title":"4M 13T \/ 1 Pcs","offer_id":52442583204114,"sku":"GYFYGLBZSJ058244x1","price":55.69,"currency_code":"USD","in_stock":true},{"title":"4M 14T \/ 1 Pcs","offer_id":52442583236882,"sku":"GYFYGLBZSJ058245x1","price":73.37,"currency_code":"USD","in_stock":true},{"title":"4M 15T \/ 1 Pcs","offer_id":52442583269650,"sku":"GYFYGLBZSJ058246x1","price":77.45,"currency_code":"USD","in_stock":true},{"title":"4M 16T \/ 1 Pcs","offer_id":52442583302418,"sku":"GYFYGLBZSJ058247x1","price":86.97,"currency_code":"USD","in_stock":true},{"title":"4M 17T \/ 1 Pcs","offer_id":52442583335186,"sku":"GYFYGLBZSJ058248x1","price":93.77,"currency_code":"USD","in_stock":true},{"title":"4M 18T \/ 1 Pcs","offer_id":52442583367954,"sku":"GYFYGLBZSJ058249x1","price":118.25,"currency_code":"USD","in_stock":true},{"title":"4M 19T \/ 1 Pcs","offer_id":52442583400722,"sku":"GYFYGLBZSJ058250x1","price":126.41,"currency_code":"USD","in_stock":true},{"title":"4M 20T \/ 1 Pcs","offer_id":52442583433490,"sku":"GYFYGLBZSJ058251x1","price":126.41,"currency_code":"USD","in_stock":true},{"title":"4M 21T \/ 1 Pcs","offer_id":52442583466258,"sku":"GYFYGLBZSJ058252x1","price":152.25,"currency_code":"USD","in_stock":true},{"title":"4M 22T \/ 1 Pcs","offer_id":52442583499026,"sku":"GYFYGLBZSJ058253x1","price":161.77,"currency_code":"USD","in_stock":true},{"title":"4M 23T \/ 1 Pcs","offer_id":52442583531794,"sku":"GYFYGLBZSJ058254x1","price":168.57,"currency_code":"USD","in_stock":true},{"title":"4M 24T \/ 1 Pcs","offer_id":52442583564562,"sku":"GYFYGLBZSJ058255x1","price":175.37,"currency_code":"USD","in_stock":true},{"title":"4M 25T \/ 1 Pcs","offer_id":52442583597330,"sku":"GYFYGLBZSJ058256x1","price":227.05,"currency_code":"USD","in_stock":true},{"title":"4M 26T \/ 1 Pcs","offer_id":52442583630098,"sku":"GYFYGLBZSJ058257x1","price":244.73,"currency_code":"USD","in_stock":true},{"title":"4M 27T \/ 1 Pcs","offer_id":52442583662866,"sku":"GYFYGLBZSJ058258x1","price":265.13,"currency_code":"USD","in_stock":true},{"title":"4M 28T \/ 1 Pcs","offer_id":52442583695634,"sku":"GYFYGLBZSJ058259x1","price":281.45,"currency_code":"USD","in_stock":true},{"title":"4M 29T \/ 1 Pcs","offer_id":52442583728402,"sku":"GYFYGLBZSJ058260x1","price":301.85,"currency_code":"USD","in_stock":true},{"title":"4M 31T \/ 1 Pcs","offer_id":52442583761170,"sku":"GYFYGLBZSJ058261x1","price":333.13,"currency_code":"USD","in_stock":true},{"title":"4M 30T \/ 1 Pcs","offer_id":52442583793938,"sku":"GYFYGLBZSJ058262x1","price":319.53,"currency_code":"USD","in_stock":true},{"title":"4M 32T \/ 1 Pcs","offer_id":52442583826706,"sku":"GYFYGLBZSJ058263x1","price":364.41,"currency_code":"USD","in_stock":true},{"title":"4M 33T \/ 1 Pcs","offer_id":52442583859474,"sku":"GYFYGLBZSJ058264x1","price":365.77,"currency_code":"USD","in_stock":true},{"title":"4M 34T \/ 1 Pcs","offer_id":52442583892242,"sku":"GYFYGLBZSJ058265x1","price":397.05,"currency_code":"USD","in_stock":true},{"title":"4M 35T \/ 1 Pcs","offer_id":52442583925010,"sku":"GYFYGLBZSJ058266x1","price":422.89,"currency_code":"USD","in_stock":true},{"title":"4M 36T \/ 1 Pcs","offer_id":52442583957778,"sku":"GYFYGLBZSJ058267x1","price":448.73,"currency_code":"USD","in_stock":true},{"title":"4M 37T \/ 1 Pcs","offer_id":52442583990546,"sku":"GYFYGLBZSJ058268x1","price":475.93,"currency_code":"USD","in_stock":true},{"title":"4M 38T \/ 1 Pcs","offer_id":52442584023314,"sku":"GYFYGLBZSJ058269x1","price":490.89,"currency_code":"USD","in_stock":true},{"title":"4M 39T \/ 1 Pcs","offer_id":52442584056082,"sku":"GYFYGLBZSJ058270x1","price":522.17,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0884\/8936\/1682\/files\/Main-01_eb4b9ba2-3097-480e-8d0f-abf6a92d130a.jpg?v=1783566425","url":"https:\/\/homediyer.com\/products\/mod-4-45-steel-spur-gears-pinion-gear-35mm-10t-39t","provider":"HomeDIYer","version":"1.0","type":"link"}