{"product_id":"mod-1-bevel-gear-c45-steel-1-1-25-ratio-20-25-tooth-6-12mm-bore-hardened-black","title":"Mod 1 Bevel Gear C45 Steel 1:1.25 Ratio 20 | 25 Tooth 6-12mm Bore Hardened Black","description":"\u003cdiv class=\"hdiy-desc\"\u003e\n\u003cdiv class=\"hdiy-overview\"\u003e\n\u003ch2\u003eMod 1 Bevel Gear C45 Steel — Precision 1:1.25 Ratio Drive for DIY \u0026amp; Industrial Builds\u003c\/h2\u003e\n\u003cp\u003eWhen your project demands a reliable right-angle or angled power transmission and off-the-shelf gears keep letting you down, you need a bevel gear engineered to spec. These Mod 1 bevel gears are designed for hobbyists, makers, and engineers who need consistent tooth engagement, accurate bore sizing, and a durable finish that holds up in real-world conditions. Whether you're building a CNC axis, a custom gearbox, or a robotics drivetrain, getting the gear ratio and bore fit right the first time matters.\u003c\/p\u003e\n\u003cp\u003eEach gear is machined from C45 medium-carbon steel and treated with a hardened black oxide finish for corrosion resistance and reduced surface friction. Available in two tooth counts — 20 tooth and 25 tooth — forming a 1:1.25 gear ratio pair. Bore sizes range from 6mm to 12mm (approximately 0.24\" to 0.47\"), with a Module (Mod) value of 1. Outer diameter varies by tooth count: the 20-tooth gear measures approximately 22mm (~0.87\"), and the 25-tooth gear approximately 27mm (~1.06\").\u003c\/p\u003e\n\u003cp\u003eTypical use cases include DIY power transmission systems requiring a compact bevel gear set, robotics joint drives where a 1:1.25 speed reduction is needed, and light industrial machinery upgrades where a hardened steel bevel gear with a standard metric bore is required. These gears are also well-suited for 3D printer Z-axis drives, RC vehicle differentials, and custom automation rigs.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"hdiy-compat\"\u003e\n\u003cspan class=\"hdiy-compat-icon\"\u003e⚙️\u003c\/span\u003e \u003cstrong\u003eCompatibility:\u003c\/strong\u003e Designed for Module 1 (Mod 1) gear systems. Pairs as a matched 20T\/25T bevel set for a 1:1.25 ratio. Bore sizes 6mm, 8mm, 10mm, and 12mm fit standard metric shafts. Confirm shaft diameter and keyway requirements before ordering.\u003c\/div\u003e\n\u003ch2\u003e✅ Key Features of These Mod 1 Bevel Gears\u003c\/h2\u003e\n\u003cdiv class=\"hdiy-features\"\u003e\n\u003cdiv\u003e\n\u003cdiv class=\"hdiy-icon\"\u003e⚙️\u003c\/div\u003e\n\u003cstrong\u003eModule 1 Standard\u003c\/strong\u003e\n\u003cp\u003eConforms to the Mod 1 metric gear standard, ensuring compatibility with other Mod 1 components in your drivetrain or gearbox assembly.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cdiv class=\"hdiy-icon\"\u003e🔩\u003c\/div\u003e\n\u003cstrong\u003eC45 Steel Construction\u003c\/strong\u003e\n\u003cp\u003eMachined from C45 medium-carbon steel — a widely used engineering material offering a solid balance of machinability, tensile strength, and wear resistance for mechanical drive applications.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cdiv class=\"hdiy-icon\"\u003e🖤\u003c\/div\u003e\n\u003cstrong\u003eHardened Black Oxide Finish\u003c\/strong\u003e\n\u003cp\u003eSurface-hardened with a black oxide treatment that improves corrosion resistance, reduces light reflection, and lowers surface friction for smoother meshing under load.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cdiv class=\"hdiy-icon\"\u003e📐\u003c\/div\u003e\n\u003cstrong\u003e1:1.25 Matched Ratio Pair\u003c\/strong\u003e\n\u003cp\u003eThe 20-tooth and 25-tooth gears are designed to work together as a matched bevel pair, delivering a precise 1:1.25 speed reduction or increase depending on drive direction.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cdiv class=\"hdiy-icon\"\u003e🔧\u003c\/div\u003e\n\u003cstrong\u003eMultiple Bore Sizes\u003c\/strong\u003e\n\u003cp\u003eAvailable with bore diameters of 6mm, 8mm, 10mm, and 12mm to fit a wide range of standard metric shafts — no custom machining required for most common shaft sizes.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cdiv class=\"hdiy-icon\"\u003e📦\u003c\/div\u003e\n\u003cstrong\u003eFlexible Pack Quantities\u003c\/strong\u003e\n\u003cp\u003eOrder in quantities of 1, 2, 3, 4, 5, or 10 pieces to match your project needs — whether you need a single replacement gear or a batch for a production run.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"hdiy-table-wrap\"\u003e\n\u003ch2\u003e📐 Technical Specifications — Mod 1 Bevel Gear\u003c\/h2\u003e\n\u003ctable\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eModule (Mod)\u003c\/th\u003e\n\u003ctd\u003e1\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eGear Ratio\u003c\/th\u003e\n\u003ctd\u003e1:1.25 (20T drives 25T)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eTooth Counts Available\u003c\/th\u003e\n\u003ctd\u003e20 Tooth \/ 25 Tooth\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eBore Sizes Available\u003c\/th\u003e\n\u003ctd\u003e6mm \/ 8mm \/ 10mm \/ 12mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eMaterial\u003c\/th\u003e\n\u003ctd\u003eC45 Medium-Carbon Steel\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eSurface Treatment\u003c\/th\u003e\n\u003ctd\u003eHardened Black Oxide\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eOuter Diameter (20T)\u003c\/th\u003e\n\u003ctd\u003eApprox. 22mm (~0.87\")\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eOuter Diameter (25T)\u003c\/th\u003e\n\u003ctd\u003eApprox. 27mm (~1.06\")\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003ePressure Angle\u003c\/th\u003e\n\u003ctd\u003eSee 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\u003eShaft Fit Type\u003c\/th\u003e\n\u003ctd\u003eSee variant options\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003ePack Quantities\u003c\/th\u003e\n\u003ctd\u003e1 \/ 2 \/ 3 \/ 4 \/ 5 \/ 10 pcs\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/div\u003e\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 20-tooth and 25-tooth gear?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\n\u003cp\u003eThe 20-tooth and 25-tooth gears are designed as a matched pair for a 1:1.25 ratio. If you need to reduce speed (and increase torque), drive the 20-tooth gear and let the 25-tooth gear be the output. If you need to increase speed (and reduce torque), reverse the arrangement. For a 1:1 ratio, you would need two gears of the same tooth count, which is a different product.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eWhich bore size should I select for my shaft?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\n\u003cp\u003eSelect the bore size that matches your shaft diameter exactly. Available options are 6mm, 8mm, 10mm, and 12mm. For a secure fit, the bore should match the shaft with minimal clearance. If your shaft has a keyway, confirm whether the gear bore is also keyed before ordering — contact us to confirm keyway availability for your specific variant.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eAre these gears strong enough for my application?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\n\u003cp\u003eC45 steel is a medium-carbon engineering steel with a tensile strength typically in the range of 600–800 MPa depending on heat treatment. The hardened black oxide surface further improves wear resistance. These gears are suitable for light-to-medium duty mechanical drives, robotics, CNC machines, and DIY automation. For heavy industrial loads or high-RPM continuous duty, consult the load ratings with your mechanical engineer.\u003c\/p\u003e\n\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\n\u003cp\u003eThe black oxide surface treatment provides a degree of corrosion resistance compared to bare steel, but black oxide alone is not a fully waterproof coating. For outdoor or high-humidity environments, we recommend applying a light machine oil or grease to the gear teeth and bore after installation to extend service life.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eCan I use just one gear from this listing, or do I need to buy both the 20T and 25T?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\n\u003cp\u003eYes, you can purchase either the 20-tooth or the 25-tooth gear individually. Each variant is sold separately. If you need a complete 1:1.25 bevel gear pair, simply add one of each tooth count to your cart, making sure the bore sizes match your respective shafts.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eWhat is the difference between Module 1 and other gear modules?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\n\u003cp\u003eThe Module (Mod) number defines the size of the gear teeth — specifically, it is the ratio of the pitch diameter to the number of teeth. Mod 1 gears have relatively small teeth and are common in light-duty and precision applications. Gears of different modules cannot mesh together. Always confirm that all gears in your drivetrain share the same module number.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eAre bulk pack discounts available for larger quantities?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\n\u003cp\u003eYes — this listing offers quantity options of 1, 2, 3, 4, 5, and 10 pieces per order. The per-unit price decreases as quantity increases, so selecting a larger pack is the most cost-effective way to stock up for a project or production run. Select your preferred quantity in the Amount option above.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"hdiy-cta\"\u003e🛒 Select your Model (tooth count), Bore Size, and Amount above, then add to cart.\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cp\u003e \u003c\/p\u003e","brand":"HomeDIYer","offers":[{"title":"Module 1【20 Tooth】 \/ 6mm \/ 1 pcs","offer_id":52439360930066,"sku":"PENGDZ00180x1","price":4.42,"currency_code":"USD","in_stock":true},{"title":"Module 1【20 Tooth】 \/ 8mm \/ 1 pcs","offer_id":52439360962834,"sku":"PENGDZ00181x1","price":4.42,"currency_code":"USD","in_stock":true},{"title":"Module 1【25 Tooth】 \/ 8mm \/ 1 pcs","offer_id":52439360995602,"sku":"PENGDZ00182x1","price":5.7,"currency_code":"USD","in_stock":true},{"title":"Module 1【25 Tooth】 \/ 10mm \/ 1 pcs","offer_id":52439361028370,"sku":"PENGDZ00183x1","price":5.7,"currency_code":"USD","in_stock":true},{"title":"Module 1【25 Tooth】 \/ 12mm \/ 1 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