{"product_id":"45-steel-4mod-spur-gears-35mm-motor-pinion-transmission-gear","title":"45# Steel 4Mod 10T-80T Spur Gears Thickness 35mm Motor Pinion Transmission Gear","description":"\u003cdiv class=\"hdiy-desc\"\u003e\n\n  \u003cdiv class=\"hdiy-overview\"\u003e\n    \u003ch2\u003e4Mod Spur Gears in 45# Steel — Reliable Pinion Transmission for DIY Automation\u003c\/h2\u003e\n    \u003cp\u003eWhen your CNC router, robotic arm, or motorized DIY project demands consistent torque transfer without slippage, the right spur gear makes all the difference. Makers, hobbyists, and small-workshop engineers who need a wide tooth-count selection in a single standardized module will find these 4Mod spur gears a dependable foundation for their drivetrain builds.\u003c\/p\u003e\n    \u003cp\u003eEach gear is machined from 45# medium-carbon steel, offering a solid balance of hardness and machinability. The module is 4M (4mm pitch diameter per tooth), with a uniform face width of 35mm (~1.38 in). Tooth counts span from 10T to 80T, giving pitch diameters that range from approximately 40mm (~1.57 in) for the 10T up to 320mm (~12.6 in) for the 80T variant.\u003c\/p\u003e\n    \u003cp\u003eTypical use cases include motor pinion assemblies in CNC gantry systems, gear-reduction stages in conveyor and indexing tables, and custom rotary actuators in educational robotics labs — all scenarios where a standard 4Mod tooth profile ensures interchangeable meshing with off-the-shelf 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 Meshes with any standard Module 4 (4M) spur or helical gear. Bore diameter varies by tooth count — confirm bore size against your shaft before ordering.\n  \u003c\/div\u003e\n\n  \u003cdiv class=\"hdiy-features\"\u003e\n    \u003ch2\u003e✅ Key Features of These 4Mod 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# Medium-Carbon Steel Construction\u003c\/strong\u003e — Machined from 45# steel for a reliable combination of surface hardness and core toughness suited to moderate-to-heavy load applications.\u003c\/li\u003e\n      \u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e📐\u003c\/span\u003e\u003cstrong\u003eModule 4 (4M) Tooth Profile\u003c\/strong\u003e — Standardized 4M module ensures direct interchangeability with any Module 4 mating gear, rack, or pinion in your drivetrain.\u003c\/li\u003e\n      \u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e📏\u003c\/span\u003e\u003cstrong\u003e35mm Face Width\u003c\/strong\u003e — A generous 35mm (~1.38 in) tooth face distributes load evenly across the gear width, reducing localized wear under sustained operation.\u003c\/li\u003e\n      \u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e🔢\u003c\/span\u003e\u003cstrong\u003eWide Tooth-Count Range (10T–80T)\u003c\/strong\u003e — Sixty tooth-count options from 10T to 80T let you dial in the exact gear ratio your project requires without custom machining.\u003c\/li\u003e\n      \u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e⚖️\u003c\/span\u003e\u003cstrong\u003eConsistent Dimensional Accuracy\u003c\/strong\u003e — Each gear is turned and hobbed to maintain pitch-circle concentricity, keeping backlash predictable and motion smooth across the full speed range.\u003c\/li\u003e\n      \u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e🛠️\u003c\/span\u003e\u003cstrong\u003eVersatile Application Fit\u003c\/strong\u003e — Suitable for motor pinion stages, reduction gearboxes, conveyor drives, and rotary indexing fixtures in CNC, robotics, and automation projects.\u003c\/li\u003e\n    \u003c\/ul\u003e\n  \u003c\/div\u003e\n\n  \u003cdiv class=\"hdiy-table-wrap\"\u003e\n    \u003ch2\u003e📐 Technical Specifications — 4Mod Spur Gears\u003c\/h2\u003e\n    \u003ctable\u003e\n      \u003ctbody\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\u003eModule\u003c\/th\u003e\n\u003ctd\u003e4M (Module 4)\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003cth\u003eFace Width (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 – 80T (see variant options)\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003cth\u003ePitch Diameter Range\u003c\/th\u003e\n\u003ctd\u003e40mm – 320mm (varies by tooth count)\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\u003eBore Diameter\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\u003eSee variant options\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003cth\u003eGear Type\u003c\/th\u003e\n\u003ctd\u003eExternal Spur Gear\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003cth\u003eTooth Profile Standard\u003c\/th\u003e\n\u003ctd\u003eModule 4 (ISO\/DIN compatible)\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003cth\u003eQuantity per Order\u003c\/th\u003e\n\u003ctd\u003e1 Piece\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    \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\u003eSelect your tooth count based on the gear ratio you need. Divide the driven gear teeth by the driver gear teeth to get the ratio. For example, pairing a 20T pinion with a 60T gear gives a 3:1 reduction. Use smaller tooth counts (10T–20T) for high-speed pinion stages and larger counts (40T–80T) for the driven wheel in reduction stages.\u003c\/p\u003e\u003c\/div\u003e\n    \u003c\/details\u003e\n    \u003cdetails\u003e\n      \u003csummary\u003eWhat shaft diameter does this gear fit?\u003c\/summary\u003e\n      \u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eThe bore diameter varies by tooth count variant. Please check the variant detail or contact us to confirm the bore size before ordering. Most variants can be re-bored or keyed by a local machine shop if the standard bore does not match your shaft.\u003c\/p\u003e\u003c\/div\u003e\n    \u003c\/details\u003e\n    \u003cdetails\u003e\n      \u003csummary\u003eWill this gear mesh with my existing Module 4 gears?\u003c\/summary\u003e\n      \u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eYes. Any gear with a Module 4 (4M) tooth profile and a 20° pressure angle will mesh correctly with these gears, regardless of brand. Confirm that your existing gear is labeled \"M4\" or \"Module 4\" before ordering.\u003c\/p\u003e\u003c\/div\u003e\n    \u003c\/details\u003e\n    \u003cdetails\u003e\n      \u003csummary\u003eHow strong is 45# steel for gear applications?\u003c\/summary\u003e\n      \u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003e45# steel (equivalent to AISI 1045) has a tensile strength of approximately 600–800 MPa in its normalized state and can be heat-treated to increase surface hardness. It is widely used for moderate-load power transmission gears in industrial and DIY machinery where a balance of machinability and strength is required.\u003c\/p\u003e\u003c\/div\u003e\n    \u003c\/details\u003e\n    \u003cdetails\u003e\n      \u003csummary\u003eIs this gear corrosion-resistant?\u003c\/summary\u003e\n      \u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003e45# carbon steel is not inherently corrosion-resistant. For outdoor or humid environments, apply a light machine oil or grease coating during storage and operation. If corrosion resistance is critical, apply a rust-inhibiting surface treatment after installation.\u003c\/p\u003e\u003c\/div\u003e\n    \u003c\/details\u003e\n    \u003cdetails\u003e\n      \u003csummary\u003eCan I use these gears in a CNC router or 3D printer build?\u003c\/summary\u003e\n      \u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eYes. These 4Mod spur gears are commonly used in CNC gantry drives, rotary axis assemblies, and extruder gear stages where a robust metal gear is preferred over plastic. Verify that your motor pinion is also Module 4 to ensure proper meshing and backlash control.\u003c\/p\u003e\u003c\/div\u003e\n    \u003c\/details\u003e\n    \u003cdetails\u003e\n      \u003csummary\u003eWhat is the size difference between the 10T and 80T variants?\u003c\/summary\u003e\n      \u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eThe pitch diameter equals the module multiplied by the tooth count. For Module 4: the 10T gear has a pitch diameter of 40mm (~1.57 in), while the 80T gear has a pitch diameter of 320mm (~12.6 in). All variants share the same 35mm face width and 4M tooth profile.\u003c\/p\u003e\u003c\/div\u003e\n    \u003c\/details\u003e\n  \u003c\/div\u003e\n\n  \u003cdiv class=\"hdiy-cta\"\u003e\n    🛒 Select your tooth count (Number of tooth) 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    {\"@type\": \"Question\", \"name\": \"How do I choose the right tooth count for my project?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"Select your tooth count based on the gear ratio you need. Divide the driven gear teeth by the driver gear teeth to get the ratio. For example, pairing a 20T pinion with a 60T gear gives a 3:1 reduction.\"}},\n    {\"@type\": \"Question\", \"name\": \"What shaft diameter does this gear fit?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"The bore diameter varies by tooth count variant. Please check the variant detail or contact us to confirm the bore size before ordering.\"}},\n    {\"@type\": \"Question\", \"name\": \"Will this gear mesh with my existing Module 4 gears?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"Yes. Any gear with a Module 4 (4M) tooth profile and a 20 degree pressure angle will mesh correctly with these gears, regardless of brand.\"}},\n    {\"@type\": \"Question\", \"name\": \"How strong is 45# steel for gear applications?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"45# steel (equivalent to AISI 1045) has a tensile strength of approximately 600–800 MPa in its normalized state and can be heat-treated to increase surface hardness.\"}},\n    {\"@type\": \"Question\", \"name\": \"Is this gear corrosion-resistant?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"45# carbon steel is not inherently corrosion-resistant. Apply a light machine oil or grease coating during storage and operation for humid or outdoor environments.\"}},\n    {\"@type\": \"Question\", \"name\": \"Can I use these gears in a CNC router or 3D printer build?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"Yes. These 4Mod spur gears are commonly used in CNC gantry drives, rotary axis assemblies, and extruder gear stages where a robust metal gear is preferred over plastic.\"}},\n    {\"@type\": \"Question\", \"name\": \"What is the size difference between the 10T and 80T variants?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"For Module 4: the 10T gear has a pitch diameter of 40mm, while the 80T gear has a pitch diameter of 320mm. 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