{"product_id":"0-5-mod-brass-pinion-spur-gear-25-teeth-bore-4-5-6-6-35-7mm-transmission-gear","title":"0.5 Mod Brass Pinion Spur Gear 25 Teeth Bore 4\/5\/6\/6.35\/7mm Transmission Gear","description":"\u003cdiv class=\"hdiy-desc\"\u003e\n\n\u003cdiv class=\"hdiy-overview\"\u003e\n\u003ch2\u003e0.5 Mod Brass Spur Gear 25T — Reliable Transmission for Precision Mechanical Drives\u003c\/h2\u003e\n\u003cp\u003eWhen your RC car, robotic arm, or small-scale drive system demands consistent torque transfer without slop or premature wear, finding a correctly sized pinion gear becomes critical. Hobbyists, makers, and mechanical engineers who work with compact gear trains know that a mismatched bore or wrong module can derail an entire build. This 0.5 module 25-tooth brass spur gear is engineered for those who need dimensional accuracy and dependable mesh engagement across a range of shaft sizes.\u003c\/p\u003e\n\u003cp\u003eEach gear is machined from brass, offering a balance of machinability, moderate corrosion resistance, and low-friction meshing against steel or plastic mating gears. The module is 0.5 (metric), with 25 teeth and bore options spanning 4 mm, 5 mm, 6 mm, 6.35 mm (1\/4 inch), and 7 mm — covering the most common motor shaft diameters in this class. The 6 mm with-step variant accommodates shaft shoulder designs. Overall gear diameter is approximately 13.5 mm (0.53 in), with a face width typically in the 3–5 mm range depending on variant.\u003c\/p\u003e\n\u003cp\u003eTypical use cases include RC car transmission pinion replacement, small servo-driven robotic joints requiring a 0.5 mod spur gear for robotics, and compact automation mechanisms where a brass pinion gear 25 teeth configuration provides quiet, smooth power delivery compared to plastic alternatives.\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 0.5 module (Mod 0.5) spur, rack, or pinion gear. Verify bore diameter matches your motor or shaft before ordering. The 6.35 mm bore suits standard 1\/4-inch shafts common in North American hobby motors.\n\u003c\/div\u003e\n\n\u003cdiv class=\"hdiy-features\"\u003e\n\u003ch2\u003e✅ Key Features of These 0.5 Mod Brass Spur Gears\u003c\/h2\u003e\n\u003cul class=\"hdiy-list\"\u003e\n\u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e🔩\u003c\/span\u003e\u003cstrong\u003eBrass Construction\u003c\/strong\u003e — Machines cleanly, resists moderate corrosion, and runs quietly against steel or plastic mating gears without galling.\u003c\/li\u003e\n\u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e📐\u003c\/span\u003e\u003cstrong\u003e0.5 Module, 25 Teeth\u003c\/strong\u003e — Standard metric module ensures interchangeability with any Mod 0.5 gear system; 25T count delivers a practical reduction ratio for compact drives.\u003c\/li\u003e\n\u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e🎯\u003c\/span\u003e\u003cstrong\u003eMultiple Bore Options\u003c\/strong\u003e — Available in 4 mm, 5 mm, 6 mm, 6.35 mm, and 7 mm bores, plus a 6 mm stepped variant, to fit the widest range of motor shafts without adapters.\u003c\/li\u003e\n\u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e⚡\u003c\/span\u003e\u003cstrong\u003eLow Backlash Mesh\u003c\/strong\u003e — Precision-cut tooth profile maintains tight mesh engagement, reducing lost motion in servo-driven or stepper-motor applications.\u003c\/li\u003e\n\u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e📦\u003c\/span\u003e\u003cstrong\u003eFlexible Pack Quantities\u003c\/strong\u003e — Order as 1, 2, 5, or 10 pieces to match prototyping needs or production runs without overstocking.\u003c\/li\u003e\n\u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e🔄\u003c\/span\u003e\u003cstrong\u003eDrop-In Replacement\u003c\/strong\u003e — Dimensionally consistent across the range; swap worn pinions in RC transmissions or robotic joints without re-aligning the gear train.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/div\u003e\n\n\u003cdiv class=\"hdiy-table-wrap\"\u003e\n\u003ch2\u003e📐 Technical Specifications — 0.5 Mod Brass Spur Gear\u003c\/h2\u003e\n\u003ctable\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eModule\u003c\/th\u003e\n\u003ctd\u003e0.5 (Metric)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eNumber of Teeth\u003c\/th\u003e\n\u003ctd\u003e25T\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003ePitch Diameter\u003c\/th\u003e\n\u003ctd\u003e12.5 mm (0.49 in)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eOutside Diameter\u003c\/th\u003e\n\u003ctd\u003eApprox. 13.5 mm (0.53 in)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eBore Diameter\u003c\/th\u003e\n\u003ctd\u003e4 \/ 5 \/ 6 \/ 6.35 \/ 7 mm (see variant options)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eFace Width\u003c\/th\u003e\n\u003ctd\u003eSee variant options\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eMaterial\u003c\/th\u003e\n\u003ctd\u003eBrass\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\u003eSpur Gear (Pinion)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eFinish\u003c\/th\u003e\n\u003ctd\u003eNatural brass (uncoated)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003ePacking Quantity\u003c\/th\u003e\n\u003ctd\u003e1 \/ 2 \/ 5 \/ 10 PCS (see variant options)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWeight (per piece)\u003c\/th\u003e\n\u003ctd\u003eApprox. 2–5 g (varies by bore)\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 bore size for my motor shaft?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eMeasure your motor or drive shaft diameter with calipers before ordering. Common sizes: 4 mm and 5 mm suit micro gear motors; 6 mm fits many standard DC and brushless motors; 6.35 mm (1\/4 in) matches North American hobby motor shafts; 7 mm suits larger servo or stepper shafts. If your shaft has a shoulder step, select the \"6 mm with Step\" variant.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\n\u003cdetails\u003e\n\u003csummary\u003eWhat does \"0.5 module\" mean and will it mesh 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. Two gears mesh correctly only when they share the same module and pressure angle. This gear is Mod 0.5 with a 20° pressure angle, compatible with any other Mod 0.5 spur gear, rack, or pinion regardless of tooth count.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\n\u003cdetails\u003e\n\u003csummary\u003eIs brass strong enough for my application?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eBrass offers tensile strength in the 300–500 MPa range depending on alloy, making it suitable for light-to-medium torque applications such as RC car transmissions, robotic joints, and small automation mechanisms. For high-shock or continuous heavy-load drives, consider steel gears. Brass excels where quiet operation and corrosion resistance matter more than maximum load capacity.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\n\u003cdetails\u003e\n\u003csummary\u003eHow corrosion-resistant is this brass gear?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eBrass has inherent corrosion resistance against moisture and mild chemicals, making it suitable for indoor robotics, hobby builds, and light outdoor use. It is not recommended for prolonged saltwater or highly acidic environments. If corrosion is a primary concern, consider stainless steel alternatives or apply a light machine oil coating for added protection.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\n\u003cdetails\u003e\n\u003csummary\u003eCan I use this gear with plastic mating gears?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eYes. Brass-on-plastic pairings are common in RC and robotics because the softer plastic acts as the sacrificial wear component, protecting the brass pinion. Ensure the plastic gear is also Mod 0.5 with a 20° pressure angle. Avoid pairing brass with very soft plastics under high RPM, as the plastic teeth may wear rapidly.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\n\u003cdetails\u003e\n\u003csummary\u003eShould I buy 1 piece or a multi-pack?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eFor prototyping or a single repair, the 1 PCS option is ideal. If you are building multiple robots, running a small production batch, or want spares on hand, the 5 PCS or 10 PCS packs offer better per-unit value. The 2 PCS pack suits differential or dual-motor drive setups that require matched pinions.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\n\u003cdetails\u003e\n\u003csummary\u003eDoes the gear come with a set screw or keyway?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eThe bore is a plain through-hole. Set screw, keyway, or D-bore configurations are not included in this listing. For secure shaft attachment, use a shaft collar, adhesive retainer (e.g., Loctite 638), or have a machinist add a set screw hole. Contact us to confirm if a specific bore modification is available.\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 bore size and quantity 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 bore size for my motor shaft?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Measure your motor or drive shaft diameter with calipers before ordering. Common sizes: 4 mm and 5 mm suit micro gear motors; 6 mm fits many standard DC and brushless motors; 6.35 mm (1\/4 in) matches North American hobby motor shafts; 7 mm suits larger servo or stepper shafts. If your shaft has a shoulder step, select the 6 mm with Step variant.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"What does 0.5 module mean and will it mesh with my existing gears?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Module (Mod) is the metric standard for gear tooth size. Two gears mesh correctly only when they share the same module and pressure angle. This gear is Mod 0.5 with a 20° pressure angle, compatible with any other Mod 0.5 spur gear, rack, or pinion regardless of tooth count.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Is brass strong enough for my application?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Brass offers tensile strength in the 300–500 MPa range, suitable for light-to-medium torque applications such as RC car transmissions, robotic joints, and small automation mechanisms. For high-shock or continuous heavy-load drives, consider steel gears.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"How corrosion-resistant is this brass gear?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Brass has inherent corrosion resistance against moisture and mild chemicals, suitable for indoor robotics, hobby builds, and light outdoor use. It is not recommended for prolonged saltwater or highly acidic environments.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Can I use this gear with plastic mating gears?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Yes. Brass-on-plastic pairings are common in RC and robotics. Ensure the plastic gear is also Mod 0.5 with a 20° pressure angle. Avoid pairing brass with very soft plastics under high RPM.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Should I buy 1 piece or a multi-pack?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"For prototyping or a single repair, the 1 PCS option is ideal. The 5 PCS or 10 PCS packs offer better per-unit value for production runs. The 2 PCS pack suits dual-motor drive setups.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Does the gear come with a set screw or keyway?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"The bore is a plain through-hole. Set screw, keyway, or D-bore configurations are not included. For secure shaft attachment, use a shaft collar, adhesive retainer, or contact us to confirm if a bore modification is available.\"\n      }\n    }\n  ]\n}\n\u003c\/script\u003e","brand":"HomeDIYer","offers":[{"title":"0.5 Mod 25T 【Bore 4mm】 \/ 1 PCS","offer_id":52442800652562,"sku":"AdaahGFCD04377x1","price":8.32,"currency_code":"USD","in_stock":true},{"title":"0.5 Mod 25T 【Bore 5mm】 \/ 1 PCS","offer_id":52442800685330,"sku":"AdaahGFCD04378x1","price":8.32,"currency_code":"USD","in_stock":true},{"title":"0.5 Mod 25T 【Bore 6mm】 with Step \/ 1 PCS","offer_id":52442800718098,"sku":"AdaahGFCD04379x1","price":8.32,"currency_code":"USD","in_stock":true},{"title":"0.5 Mod 25T 【Bore 6mm】 \/ 1 PCS","offer_id":52442800750866,"sku":"AdaahGFCD04380x1","price":8.58,"currency_code":"USD","in_stock":true},{"title":"0.5 Mod 25T 【Bore 6.35mm】 \/ 1 PCS","offer_id":52442800783634,"sku":"AdaahGFCD04381x1","price":8.58,"currency_code":"USD","in_stock":true},{"title":"0.5 Mod 25T 【Bore 7mm】 \/ 1 PCS","offer_id":52442800816402,"sku":"AdaahGFCD04382x1","price":8.58,"currency_code":"USD","in_stock":true},{"title":"0.5 Mod 25T 【Bore 4mm】 \/ 2 PCS","offer_id":52442800849170,"sku":"AdaahGFCD04377x2","price":12.97,"currency_code":"USD","in_stock":true},{"title":"0.5 Mod 25T 【Bore 5mm】 \/ 2 PCS","offer_id":52442800881938,"sku":"AdaahGFCD04378x2","price":12.97,"currency_code":"USD","in_stock":true},{"title":"0.5 Mod 25T 【Bore 6mm】 with Step \/ 2 PCS","offer_id":52442800914706,"sku":"AdaahGFCD04379x2","price":12.97,"currency_code":"USD","in_stock":true},{"title":"0.5 Mod 25T 【Bore 6mm】 \/ 2 PCS","offer_id":52442800947474,"sku":"AdaahGFCD04380x2","price":13.45,"currency_code":"USD","in_stock":true},{"title":"0.5 Mod 25T 【Bore 6.35mm】 \/ 2 PCS","offer_id":52442800980242,"sku":"AdaahGFCD04381x2","price":13.45,"currency_code":"USD","in_stock":true},{"title":"0.5 Mod 25T 【Bore 7mm】 \/ 2 PCS","offer_id":52442801013010,"sku":"AdaahGFCD04382x2","price":13.45,"currency_code":"USD","in_stock":true},{"title":"0.5 Mod 25T 【Bore 4mm】 \/ 5 PCS","offer_id":52442801045778,"sku":"AdaahGFCD04377x5","price":23.66,"currency_code":"USD","in_stock":true},{"title":"0.5 Mod 25T 【Bore 5mm】 \/ 5 PCS","offer_id":52442801078546,"sku":"AdaahGFCD04378x5","price":23.66,"currency_code":"USD","in_stock":true},{"title":"0.5 Mod 25T 【Bore 6mm】 with Step \/ 5 PCS","offer_id":52442801111314,"sku":"AdaahGFCD04379x5","price":23.66,"currency_code":"USD","in_stock":true},{"title":"0.5 Mod 25T 【Bore 6mm】 \/ 5 PCS","offer_id":52442801144082,"sku":"AdaahGFCD04380x5","price":25.66,"currency_code":"USD","in_stock":true},{"title":"0.5 Mod 25T 【Bore 6.35mm】 \/ 5 PCS","offer_id":52442801176850,"sku":"AdaahGFCD04381x5","price":25.58,"currency_code":"USD","in_stock":true},{"title":"0.5 Mod 25T 【Bore 7mm】 \/ 5 PCS","offer_id":52442801209618,"sku":"AdaahGFCD04382x5","price":25.43,"currency_code":"USD","in_stock":true},{"title":"0.5 Mod 25T 【Bore 4mm】 \/ 10 PCS","offer_id":52442801242386,"sku":"AdaahGFCD04377x10","price":42.28,"currency_code":"USD","in_stock":true},{"title":"0.5 Mod 25T 【Bore 5mm】 \/ 10 PCS","offer_id":52442801275154,"sku":"AdaahGFCD04378x10","price":42.15,"currency_code":"USD","in_stock":true},{"title":"0.5 Mod 25T 【Bore 6mm】 with Step \/ 10 PCS","offer_id":52442801307922,"sku":"AdaahGFCD04379x10","price":41.96,"currency_code":"USD","in_stock":true},{"title":"0.5 Mod 25T 【Bore 6mm】 \/ 10 PCS","offer_id":52442801340690,"sku":"AdaahGFCD04380x10","price":46.31,"currency_code":"USD","in_stock":true},{"title":"0.5 Mod 25T 【Bore 6.35mm】 \/ 10 PCS","offer_id":52442801373458,"sku":"AdaahGFCD04381x10","price":46.17,"currency_code":"USD","in_stock":true},{"title":"0.5 Mod 25T 【Bore 7mm】 \/ 10 PCS","offer_id":52442801406226,"sku":"AdaahGFCD04382x10","price":45.9,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0884\/8936\/1682\/files\/Picture2of13_5f3903ae-ce2f-41c0-955e-a848f7052853.jpg?v=1783596303","url":"https:\/\/homediyer.com\/products\/0-5-mod-brass-pinion-spur-gear-25-teeth-bore-4-5-6-6-35-7mm-transmission-gear","provider":"HomeDIYer","version":"1.0","type":"link"}