{"product_id":"1-5mod-45-steel-spur-gear-25-teeth-pinion-gear","title":"1.5Mod 45# Steel Spur Gear 25 Teeth Bore 6-17mm Pinion Gear With Step Motor Gear","description":"\u003cdiv class=\"hdiy-desc\"\u003e\n\n\u003cdiv class=\"hdiy-overview\"\u003e\n\u003ch2\u003e1.5 Mod 45# Steel Spur Gear — Reliable 25-Tooth Pinion for CNC, Robotics \u0026amp; Stepper Motor Drives\u003c\/h2\u003e\n\u003cp\u003eWhen a loose or undersized gear causes missed steps, vibration, or premature wear in your motion-control build, the root cause is almost always a mismatch between gear modulus, bore size, and shaft tolerance. Makers, engineers, and small-batch manufacturers who run CNC routers, 3D printer extruder drives, or robotic arm joints need a spur gear that holds tight tolerances without requiring custom machining.\u003c\/p\u003e\n\u003cp\u003eThese 1.5 module, 25-tooth spur gears are machined from 45# medium-carbon steel — a material known for its balanced hardness and machinability. Each gear features a face width (teeth thickness) of either 12 mm (~0.47 in) or 15 mm (~0.59 in), with bore options ranging from 6 mm to 20 mm (~0.24–0.79 in). Select variants include a precision keyway (3×1.4 mm, 4×1.8 mm, or 5×2.3 mm) for positive torque transmission without set-screw slip.\u003c\/p\u003e\n\u003cp\u003eTypical applications include stepper motor pinion drives in CNC plasma tables and laser engravers, rack-and-pinion linear actuators for automated sliding gates, and reduction gear stages in robotic arm elbow joints where a 1.5 mod pitch line keeps backlash under control.\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 to mesh with any 1.5 module (Mod 1.5) mating gear or rack. Verify shaft diameter against your selected bore option before ordering. Keyway variants require a matching keyed shaft.\n\u003c\/div\u003e\n\n\u003cdiv class=\"hdiy-features\"\u003e\n\u003ch2\u003e✅ Key Features of These 1.5 Mod 25-Tooth Spur Gears\u003c\/h2\u003e\n\u003cdiv class=\"hdiy-list\"\u003e\n\u003cdiv\u003e\n\u003cspan class=\"hdiy-icon\"\u003e🔩\u003c\/span\u003e\n\u003cstrong\u003e45# Medium-Carbon Steel Construction\u003c\/strong\u003e\n\u003cp\u003eMachined from 45# carbon steel for a tensile strength typically in the 600–800 MPa range, giving the gear tooth flanks the hardness needed to resist pitting and wear under sustained cyclic loads.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cspan class=\"hdiy-icon\"\u003e📐\u003c\/span\u003e\n\u003cstrong\u003e1.5 Module, 25-Tooth Profile\u003c\/strong\u003e\n\u003cp\u003eA 1.5 mod pitch delivers a tooth height of approximately 3.375 mm and a pitch circle diameter of 37.5 mm, making this gear a direct drop-in for standard Mod 1.5 racks and mating gears without custom modification.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cspan class=\"hdiy-icon\"\u003e🎯\u003c\/span\u003e\n\u003cstrong\u003eMultiple Bore Sizes — Plain \u0026amp; Keyway Options\u003c\/strong\u003e\n\u003cp\u003eBore options from 6 mm to 20 mm cover the most common stepper and servo motor shaft diameters. Keyway variants (3×1.4 mm, 4×1.8 mm, 5×2.3 mm) lock the gear to the shaft for zero rotational slip under reversing loads.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cspan class=\"hdiy-icon\"\u003e📏\u003c\/span\u003e\n\u003cstrong\u003eTwo Face-Width Options: 12 mm \u0026amp; 15 mm\u003c\/strong\u003e\n\u003cp\u003eThe 12 mm face width suits compact drive trains where axial space is limited; the 15 mm face width increases the load-bearing contact area for higher-torque applications such as rack-and-pinion actuators.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cspan class=\"hdiy-icon\"\u003e🔄\u003c\/span\u003e\n\u003cstrong\u003eConsistent Tooth Geometry for Low Backlash\u003c\/strong\u003e\n\u003cp\u003eHobbed tooth profiles maintain consistent involute geometry across the full face width, keeping backlash predictable and minimising positioning error in open-loop stepper motor systems.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cspan class=\"hdiy-icon\"\u003e🛠️\u003c\/span\u003e\n\u003cstrong\u003eReady to Install on Standard Motor Shafts\u003c\/strong\u003e\n\u003cp\u003eBores are finished to an H7 tolerance class (See variant options for exact fit), allowing a light press or slip fit onto standard motor shafts. No additional boring or reaming required for most common shaft diameters.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\n\u003cdiv class=\"hdiy-table-wrap\"\u003e\n\u003ch2\u003e📐 Technical Specifications — 1.5 Mod Spur Gear\u003c\/h2\u003e\n\u003ctable\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eModule (Mod)\u003c\/th\u003e\n\u003ctd\u003e1.5\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eNumber of Teeth\u003c\/th\u003e\n\u003ctd\u003e25\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003ePitch Circle Diameter\u003c\/th\u003e\n\u003ctd\u003e37.5 mm (1.476 in)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eTooth Height (Addendum + Dedendum)\u003c\/th\u003e\n\u003ctd\u003e~3.375 mm (~0.133 in)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eFace Width (Teeth Thickness)\u003c\/th\u003e\n\u003ctd\u003e12 mm (0.47 in) or 15 mm (0.59 in) — See variant options\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eBore Diameter\u003c\/th\u003e\n\u003ctd\u003e6 mm – 20 mm (0.24 – 0.79 in) — See variant options\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eKeyway\u003c\/th\u003e\n\u003ctd\u003eNone (plain bore) or 3×1.4 mm \/ 4×1.8 mm \/ 5×2.3 mm — See variant options\u003c\/td\u003e\n\u003c\/tr\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\u003eSurface Finish\u003c\/th\u003e\n\u003ctd\u003eNatural \/ Lightly Oiled\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\u003eGear Type\u003c\/th\u003e\n\u003ctd\u003eExternal Spur Gear (Pinion)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eCompatible Rack \/ Gear Module\u003c\/th\u003e\n\u003ctd\u003eMod 1.5\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\u003cdetails\u003e\n\u003csummary\u003eHow do I choose between the 12 mm and 15 mm face width?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eThe face width (teeth thickness) directly affects the load capacity of the gear. If your application involves light-duty positioning — such as a 3D printer extruder or a small CNC axis — the 12 mm face width is sufficient and saves axial space. For higher-torque applications like rack-and-pinion linear actuators or robotic joints carrying meaningful loads, the 15 mm face width provides a larger contact area and distributes stress more evenly across the tooth flank.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eWhat bore size should I select for my stepper motor shaft?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eMatch the bore to your motor shaft diameter. Common NEMA 17 stepper motors use a 5 mm shaft — in that case, select the 6 mm bore (smallest available) and use a 5-to-6 mm shaft adapter, or choose a variant closest to your shaft OD. NEMA 23 motors typically use 6.35 mm (1\/4 in) or 8 mm shafts. For shafts requiring positive torque lock, choose a keyway variant whose keyway dimensions match your shaft's key slot.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eIs 45# steel strong enough for my application?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003e45# carbon steel has a typical tensile strength of 600–800 MPa and yield strength around 355–490 MPa in the normalised condition. This is adequate for the majority of CNC, robotics, and automation drive applications at moderate speeds and loads. If your application involves continuous high-speed operation under heavy load, consider whether a hardened or alloy steel gear would be more appropriate for your specific duty cycle.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eWill this gear rust or corrode?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003e45# carbon steel is not inherently corrosion-resistant. For indoor, dry environments — typical of CNC machines and robotics — the lightly oiled surface finish provides short-term protection during storage and initial use. For humid or outdoor environments, apply a light machine oil or grease to the tooth flanks and bore regularly, or consider a zinc-plated or stainless alternative if corrosion is a primary concern.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eCan I use this gear with a Mod 1.5 rack for a linear actuator?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eYes. This 25-tooth, 1.5 module spur gear meshes directly with any standard Mod 1.5 rack. With 25 teeth and a 1.5 module, one full rotation of the gear advances the rack by 25 × π × 1.5 mm ≈ 117.8 mm of linear travel. This makes it straightforward to calculate steps-per-mm for stepper motor control in CNC or automation applications.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eWhat is the difference between a plain bore and a keyway bore variant?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eA plain bore relies on a set screw or interference fit to transmit torque from the shaft to the gear. This is adequate for light-duty or unidirectional loads. A keyway bore uses a machined slot that accepts a matching key on the shaft, creating a positive mechanical lock. Keyway variants are recommended for reversing loads, higher torques, or any application where set-screw loosening under vibration is a concern.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eHow do I verify this gear will mesh correctly with my existing gears?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eFor two spur gears to mesh correctly, they must share the same module (Mod 1.5 in this case) and the same pressure angle (20°). The centre distance between the two gear shafts should equal half the sum of their pitch circle diameters: (PCD₁ + PCD₂) \/ 2. For this 25-tooth gear, PCD = 37.5 mm, so pair it with a mating gear whose PCD you know to calculate the required shaft centre distance.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\u003c\/div\u003e\n\n\u003cdiv class=\"hdiy-cta\"\u003e\n🛒 Select your Modulus and Teeth Thick – Bore(mm) 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 between the 12 mm and 15 mm face width?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"The face width directly affects load capacity. The 12 mm face width suits light-duty positioning applications; the 15 mm face width is better for higher-torque applications like rack-and-pinion actuators or robotic joints.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"What bore size should I select for my stepper motor shaft?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Match the bore to your motor shaft diameter. NEMA 17 motors typically use 5 mm shafts; NEMA 23 motors use 6.35 mm or 8 mm shafts. For positive torque lock, choose a keyway variant matching your shaft key slot.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Is 45# steel strong enough for my application?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"45# carbon steel has a typical tensile strength of 600–800 MPa, adequate for most CNC, robotics, and automation drive applications at moderate speeds and loads.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Will this gear rust or corrode?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"45# carbon steel is not inherently corrosion-resistant. Apply light machine oil or grease regularly for humid environments, or consider a zinc-plated alternative.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Can I use this gear with a Mod 1.5 rack for a linear actuator?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Yes. One full rotation advances a Mod 1.5 rack by approximately 117.8 mm of linear travel (25 × π × 1.5 mm).\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"What is the difference between a plain bore and a keyway bore variant?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"A plain bore uses a set screw or interference fit; a keyway bore uses a mechanical key for positive torque lock. Keyway variants are recommended for reversing loads or high-vibration environments.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"How do I verify this gear will mesh correctly with my existing gears?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Both gears must share the same module (Mod 1.5) and pressure angle (20°). Centre distance = (PCD₁ + PCD₂) \/ 2. This gear's PCD is 37.5 mm.\"\n      }\n    }\n  ]\n}\n\u003c\/script\u003e","brand":"HomeDIYer","offers":[{"title":"1.5 Mod, 25T \/ 12mm - 6mm","offer_id":52442404094226,"sku":"QTLJGLBZSJ057879x1","price":20.54,"currency_code":"USD","in_stock":true},{"title":"1.5 Mod, 25T \/ 12mm - 6.35mm","offer_id":52442404126994,"sku":"QTLJGLBZSJ057880x1","price":20.92,"currency_code":"USD","in_stock":true},{"title":"1.5 Mod, 25T \/ 12mm - 7mm","offer_id":52442404159762,"sku":"QTLJGLBZSJ057881x1","price":20.54,"currency_code":"USD","in_stock":true},{"title":"1.5 Mod, 25T \/ 12mm - 8mm","offer_id":52442404192530,"sku":"QTLJGLBZSJ057882x1","price":20.54,"currency_code":"USD","in_stock":true},{"title":"1.5 Mod, 25T \/ 12mm - 10mm","offer_id":52442404225298,"sku":"QTLJGLBZSJ057883x1","price":20.54,"currency_code":"USD","in_stock":true},{"title":"1.5 Mod, 25T \/ 12mm - 12mm","offer_id":52442404258066,"sku":"QTLJGLBZSJ057884x1","price":20.54,"currency_code":"USD","in_stock":true},{"title":"1.5 Mod, 25T \/ 12mm - 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