{"product_id":"3-mod-spur-pinion-gear-45-steel-12t-55t-30mm","title":"3 Mod 12T~55T Precision Spur Pinion Gear #45 Steel Motor Gear Thickness=30mm","description":"\u003cdiv class=\"hdiy-desc\"\u003e\n\n\u003cdiv class=\"hdiy-overview\"\u003e\n\u003ch2\u003e3 Mod Spur Pinion Gear — #45 Steel Precision Drive for CNC \u0026amp; Automation\u003c\/h2\u003e\n\u003cp\u003eWhen a stripped or undersized gear brings your CNC router, conveyor, or robotic arm to a halt, finding a dimensionally accurate replacement fast is critical. Engineers, makers, and machine builders who need a reliable 3 Mod spur pinion gear with a consistent 30 mm face width will find this series covers tooth counts from 12T all the way to 55T in a single product line.\u003c\/p\u003e\n\u003cp\u003eEach gear is machined from #45 medium-carbon steel and heat-treated for surface hardness. The tooth profile follows standard Module 3 (Mod 3) geometry with a 20° pressure angle. Face width is fixed at 30 mm (1.18 in), and outer diameters range from approximately 42 mm (1.65 in) for the 12T up to approximately 171 mm (6.73 in) for the 55T. Bore diameter varies by tooth count — see variant options for the exact bore of your selected size.\u003c\/p\u003e\n\u003cp\u003eTypical applications include CNC rack-and-pinion linear drives, gearbox input stages for industrial conveyors, rotary indexing tables, and DIY motorized gate openers. The standardized Mod 3 pitch makes these gears interchangeable with any mating rack or gear of the same module, simplifying multi-axis machine builds and replacement sourcing.\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 Mates with any standard Module 3 (Mod 3) rack, gear, or pinion sharing a 20° pressure angle. Verify 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 3 Mod Spur Pinion Gears\u003c\/h2\u003e\n\u003cul class=\"hdiy-list\"\u003e\n\u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e🔩\u003c\/span\u003e\u003cstrong\u003e#45 Steel Construction\u003c\/strong\u003e\u003cbr\u003eMachined from medium-carbon #45 steel with surface hardening for wear resistance under continuous load in power-transmission applications.\u003c\/li\u003e\n\u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e📐\u003c\/span\u003e\u003cstrong\u003eStandard Mod 3 Tooth Profile\u003c\/strong\u003e\u003cbr\u003e20° pressure angle, Module 3 geometry — fully interchangeable with any Mod 3 mating component including racks, worm wheels, and paired pinions.\u003c\/li\u003e\n\u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e📏\u003c\/span\u003e\u003cstrong\u003eFixed 30 mm Face Width\u003c\/strong\u003e\u003cbr\u003eConsistent 30 mm (1.18 in) tooth width across the entire 12T–55T range ensures uniform load distribution and simplifies multi-gear stage alignment.\u003c\/li\u003e\n\u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e🎯\u003c\/span\u003e\u003cstrong\u003eWide Tooth-Count Selection\u003c\/strong\u003e\u003cbr\u003e44 tooth-count options from 12T to 55T in a single series let you dial in the exact gear ratio your drive system requires without custom machining.\u003c\/li\u003e\n\u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e🔄\u003c\/span\u003e\u003cstrong\u003ePrecision-Cut Teeth\u003c\/strong\u003e\u003cstrong\u003e\u003c\/strong\u003e\u003cbr\u003eHobbed tooth flanks deliver smooth meshing, reduced backlash, and quieter operation compared to cast or sintered alternatives in the same module class.\u003c\/li\u003e\n\u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e🛠️\u003c\/span\u003e\u003cstrong\u003eVersatile Bore Options\u003c\/strong\u003e\u003cbr\u003eEach tooth-count variant ships with a bore sized to suit common shaft diameters — see variant options for the bore specification of your chosen tooth count.\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 Pinion Gear\u003c\/h2\u003e\n\u003ctable\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eModule\u003c\/th\u003e\n\u003ctd\u003e3 (Mod 3)\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\u003eTooth Count Range\u003c\/th\u003e\n\u003ctd\u003e12T – 55T\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eFace Width\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\u003e#45 Medium-Carbon Steel\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eSurface Treatment\u003c\/th\u003e\n\u003ctd\u003eHeat-treated (surface hardened)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eOuter Diameter\u003c\/th\u003e\n\u003ctd\u003eSee variant options\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 Standard\u003c\/th\u003e\n\u003ctd\u003eDIN \/ ISO Module 3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eFinish\u003c\/th\u003e\n\u003ctd\u003eNatural steel (uncoated)\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 application?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eDetermine your required gear ratio by dividing the driver tooth count by the driven tooth count. For a rack-and-pinion linear drive, the linear travel per revolution equals π × Module × Tooth Count (in mm). Select the tooth count that delivers your target speed or travel distance at your motor's operating RPM.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eWhat shaft diameter does each tooth-count variant fit?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eBore diameter varies by tooth count. Please check the variant option label for the bore size of your selected tooth count before ordering. If your shaft diameter differs from the listed bore, the gear can typically be re-bored by a local machine shop.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eIs #45 steel strong enough for my load?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003e#45 medium-carbon steel with surface hardening offers a good balance of toughness and surface wear resistance, suitable for moderate-to-high torque drives in CNC machines, conveyors, and automation equipment. For very high-shock or heavy-industrial loads, consult a mechanical engineer to verify the gear's rated torque against your application requirements.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eWill these gears rust or corrode?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eThe gears are supplied with a natural steel finish and are not coated or plated. For outdoor or humid environments, apply a light machine oil or grease to the tooth flanks and bore. For corrosive environments, consider a zinc-phosphate primer or a compatible gear lubricant with rust-inhibiting additives.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eCan I pair this pinion with a Mod 3 rack for a linear drive?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eYes. Any Mod 3 rack with a matching 20° pressure angle will mesh correctly with these pinions. The linear travel per pinion revolution is calculated as: Travel (mm) = π × 3 × Tooth Count. For example, a 20T pinion produces approximately 188.5 mm of travel per revolution.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eWhat is the difference between Module and Diametral Pitch?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eModule (M) is the metric gear sizing standard: M = Pitch Diameter ÷ Tooth Count. Diametral Pitch (DP) is the imperial equivalent: DP = Tooth Count ÷ Pitch Diameter (in inches). Module 3 is approximately equivalent to 8.47 DP. These two systems are not directly interchangeable — always match module to module or DP to DP when selecting mating gears.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eDo these gears require a keyway or set screw for shaft retention?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eThe gears are supplied with a plain bore. Shaft retention method (set screw, keyway, interference fit, or shaft collar) is determined by your application design. If a keyway is required, the bore can be broached by a local machine shop to your specified key size.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\u003c\/div\u003e\n\n\u003cdiv class=\"hdiy-cta\"\u003e\n🛒 Select your Module\/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    {\"@type\": \"Question\", \"name\": \"How do I choose the right tooth count for my application?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"Determine your required gear ratio by dividing the driver tooth count by the driven tooth count. For a rack-and-pinion linear drive, the linear travel per revolution equals π × Module × Tooth Count (in mm). Select the tooth count that delivers your target speed or travel distance at your motor's operating RPM.\"}},\n    {\"@type\": \"Question\", \"name\": \"What shaft diameter does each tooth-count variant fit?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"Bore diameter varies by tooth count. Please check the variant option label for the bore size of your selected tooth count before ordering. If your shaft diameter differs from the listed bore, the gear can typically be re-bored by a local machine shop.\"}},\n    {\"@type\": \"Question\", \"name\": \"Is #45 steel strong enough for my load?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"#45 medium-carbon steel with surface hardening offers a good balance of toughness and surface wear resistance, suitable for moderate-to-high torque drives in CNC machines, conveyors, and automation equipment.\"}},\n    {\"@type\": \"Question\", \"name\": \"Will these gears rust or corrode?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"The gears are supplied with a natural steel finish and are not coated or plated. For outdoor or humid environments, apply a light machine oil or grease to the tooth flanks and bore.\"}},\n    {\"@type\": \"Question\", \"name\": \"Can I pair this pinion with a Mod 3 rack for a linear drive?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"Yes. Any Mod 3 rack with a matching 20° pressure angle will mesh correctly with these pinions. Linear travel per revolution = π × 3 × Tooth Count (mm).\"}},\n    {\"@type\": \"Question\", \"name\": \"What is the difference between Module and Diametral Pitch?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"Module (M) is the metric gear sizing standard. Module 3 is approximately equivalent to 8.47 DP. These two systems are not directly interchangeable.\"}},\n    {\"@type\": \"Question\", \"name\": \"Do these gears require a keyway or set screw for shaft retention?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"The gears are supplied with a plain bore. Shaft retention method is determined by your application design. The bore can be broached by a local machine shop if a keyway is required.\"}}\n  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