{"product_id":"0-5-mod-28-teeth-spur-gear-bore-4-5-6mm-motor-gears-transmission-gears-45-steel","title":"0.5 Mod 28 Teeth Spur Gear Bore 4\/5\/6mm Motor Gears Transmission Gears 45# Steel","description":"\u003cdiv class=\"hdiy-desc\"\u003e\n\n  \u003cdiv class=\"hdiy-overview\"\u003e\n    \u003ch2\u003e0.5 Mod 28-Tooth Spur Gear — Precision Motor Drive for DIY Automation\u003c\/h2\u003e\n    \u003cp\u003eWhen your motor drive slips, your encoder skips, or your robot arm loses position, the culprit is often an undersized or poorly machined gear. Hobbyists, makers, and small-workshop engineers who build precise motion systems need a 0.5 mod 28-tooth spur gear they can trust to mesh cleanly and hold torque without backlash creep.\u003c\/p\u003e\n    \u003cp\u003eEach gear is machined from 45# carbon steel — a medium-carbon alloy known for its balance of hardness and toughness — and cut to a 0.5 module (pitch) with 28 teeth. The bore options span 4 mm (~0.157 in), 5 mm (~0.197 in), and 6 mm (~0.236 in), covering the most common motor shaft diameters in this size class. Overall outer diameter is approximately 15 mm (~0.59 in), with a face width typically in the 5–8 mm range depending on the specific variant.\u003c\/p\u003e\n    \u003cp\u003eThese 0.5 mod spur gears are well-suited for small DC motor gearboxes in desktop CNC machines, stepper-driven pen plotters, lightweight robotic joints, and educational automation kits where compact gear trains and repeatable positioning are essential.\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 Fits standard 0.5 module gear systems. Mates with any 0.5 mod rack, pinion, or mating gear. Bore sizes 4 mm, 5 mm, and 6 mm match common N20, TT, and small NEMA motor shafts. Verify shaft diameter before ordering.\n  \u003c\/div\u003e\n\n  \u003ch2\u003e✅ Key Features of These 0.5 Mod 28-Tooth Spur Gears\u003c\/h2\u003e\n  \u003cdiv class=\"hdiy-features\"\u003e\n\n    \u003cdiv\u003e\n      \u003cdiv class=\"hdiy-icon\"\u003e🔩\u003c\/div\u003e\n      \u003cstrong\u003e45# Carbon Steel Construction\u003c\/strong\u003e\n      \u003cp\u003eMachined from 45# medium-carbon steel for a reliable combination of surface hardness and core toughness — resisting wear under repeated cyclic loading in motor drive applications.\u003c\/p\u003e\n    \u003c\/div\u003e\n\n    \u003cdiv\u003e\n      \u003cdiv class=\"hdiy-icon\"\u003e📐\u003c\/div\u003e\n      \u003cstrong\u003e0.5 Module, 28 Teeth\u003c\/strong\u003e\n      \u003cp\u003eStandard 0.5 mod pitch ensures direct interchangeability with any 0.5 module rack or mating gear. 28 teeth provide a practical gear ratio reference point for speed and torque calculations.\u003c\/p\u003e\n    \u003c\/div\u003e\n\n    \u003cdiv\u003e\n      \u003cdiv class=\"hdiy-icon\"\u003e🎯\u003c\/div\u003e\n      \u003cstrong\u003eThree Bore Options: 4 \/ 5 \/ 6 mm\u003c\/strong\u003e\n      \u003cp\u003eSelect the bore that matches your motor shaft — 4 mm, 5 mm, or 6 mm — for a direct press or keyed fit without custom machining. Covers the most common small motor shaft diameters.\u003c\/p\u003e\n    \u003c\/div\u003e\n\n    \u003cdiv\u003e\n      \u003cdiv class=\"hdiy-icon\"\u003e📦\u003c\/div\u003e\n      \u003cstrong\u003eFlexible Pack Quantities\u003c\/strong\u003e\n      \u003cp\u003eAvailable in packs of 1, 2, 3, 4, 5, 8, or 10 pieces. Stock spares for prototyping, order multiples for production runs, or mix bore sizes across packs to suit your build.\u003c\/p\u003e\n    \u003c\/div\u003e\n\n    \u003cdiv\u003e\n      \u003cdiv class=\"hdiy-icon\"\u003e🔄\u003c\/div\u003e\n      \u003cstrong\u003eSpur Gear Profile for Low-Noise Parallel Drives\u003c\/strong\u003e\n      \u003cp\u003eStraight-cut spur tooth profile transmits power efficiently between parallel shafts with minimal axial thrust — ideal for compact gearboxes where helical gears would add unwanted side-load.\u003c\/p\u003e\n    \u003c\/div\u003e\n\n    \u003cdiv\u003e\n      \u003cdiv class=\"hdiy-icon\"\u003e🛠️\u003c\/div\u003e\n      \u003cstrong\u003eReady for Shaft Keyway or Set-Screw Mounting\u003c\/strong\u003e\n      \u003cp\u003eSmooth bore accepts a set screw or can be broached for a keyway. Compatible with standard motor shaft retention methods used in DIY robotics and automation projects.\u003c\/p\u003e\n    \u003c\/div\u003e\n\n  \u003c\/div\u003e\n\n  \u003ch2\u003e📐 Technical Specifications — 0.5 Mod Spur Gear\u003c\/h2\u003e\n  \u003cdiv class=\"hdiy-table-wrap\"\u003e\n    \u003ctable\u003e\n      \u003ctbody\u003e\n        \u003ctr\u003e\n\u003cth\u003eModule (Pitch)\u003c\/th\u003e\n\u003ctd\u003e0.5 mod\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003cth\u003eNumber of Teeth\u003c\/th\u003e\n\u003ctd\u003e28 T\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003cth\u003eBore Diameter\u003c\/th\u003e\n\u003ctd\u003e4 mm \/ 5 mm \/ 6 mm (see variant options)\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003cth\u003eOuter Diameter (OD)\u003c\/th\u003e\n\u003ctd\u003eApprox. 15 mm (~0.59 in)\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003cth\u003ePitch Diameter\u003c\/th\u003e\n\u003ctd\u003e14 mm (0.5 mod × 28 T)\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\u003ePressure Angle\u003c\/th\u003e\n\u003ctd\u003e20°\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003cth\u003eMaterial\u003c\/th\u003e\n\u003ctd\u003e45# Carbon Steel\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003cth\u003eFinish\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\u003eSpur Gear (straight-cut)\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003cth\u003eShaft Fit\u003c\/th\u003e\n\u003ctd\u003eSmooth bore; set-screw or keyway compatible\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003cth\u003ePack Quantity\u003c\/th\u003e\n\u003ctd\u003e1 \/ 2 \/ 3 \/ 4 \/ 5 \/ 8 \/ 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\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\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 shaft diameter with a caliper. Common small motor shafts run 4 mm (N20-style motors), 5 mm (many TT gear motors), or 6 mm (larger DC and stepper motors). Select the bore that matches your shaft for a direct fit. If your shaft is slightly undersized, a set screw can compensate; if oversized, the bore cannot be reduced — choose the correct size at order time.\u003c\/p\u003e\u003c\/div\u003e\n    \u003c\/details\u003e\n\n    \u003cdetails\u003e\n      \u003csummary\u003eWill this gear mesh with my existing 0.5 mod rack or pinion?\u003c\/summary\u003e\n      \u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eYes. Any gear or rack with a 0.5 module pitch and a matching 20° pressure angle will mesh correctly with this gear. Confirm both the module and pressure angle of your mating component before assembling. Mixing modules (e.g., 0.5 mod with 0.8 mod) will result in incorrect meshing and rapid wear.\u003c\/p\u003e\u003c\/div\u003e\n    \u003c\/details\u003e\n\n    \u003cdetails\u003e\n      \u003csummary\u003eHow strong is 45# steel for motor drive applications?\u003c\/summary\u003e\n      \u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003e45# carbon steel (roughly equivalent to AISI 1045) offers a tensile strength typically in the 600–800 MPa range in its normalized state, making it suitable for light-to-medium duty motor drives, robotics joints, and automation mechanisms. For high-shock or continuous heavy-load applications, consider heat-treated or alloy steel gears. For typical DIY and educational automation loads, 45# steel performs reliably.\u003c\/p\u003e\u003c\/div\u003e\n    \u003c\/details\u003e\n\n    \u003cdetails\u003e\n      \u003csummary\u003eIs this gear corrosion-resistant for outdoor or humid environments?\u003c\/summary\u003e\n      \u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003e45# carbon steel is not inherently corrosion-resistant. For outdoor, humid, or washdown environments, apply a light machine oil or grease coating to the gear teeth and bore, or consider stainless steel alternatives. For indoor, dry automation and robotics applications, bare or lightly oiled 45# steel performs well without additional treatment.\u003c\/p\u003e\u003c\/div\u003e\n    \u003c\/details\u003e\n\n    \u003cdetails\u003e\n      \u003csummary\u003eCan I use multiple gears together to build a gear train?\u003c\/summary\u003e\n      \u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eYes. These 0.5 mod 28T gears can be combined with other 0.5 mod gears of different tooth counts to create compound gear trains for speed reduction or torque multiplication. Multi-pack options (2, 3, 4, 5, 8, or 10 pcs) make it cost-effective to stock the quantity you need for a full gear stage or to keep spares on hand during prototyping.\u003c\/p\u003e\u003c\/div\u003e\n    \u003c\/details\u003e\n\n    \u003cdetails\u003e\n      \u003csummary\u003eWhat is the gear ratio if I pair this 28T gear with a different tooth count?\u003c\/summary\u003e\n      \u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eGear ratio = driven teeth ÷ driving teeth. For example, pairing this 28T gear (driver) with a 56T gear (driven) gives a 2:1 reduction — halving speed and doubling torque. Pairing it with a 14T gear gives a 1:2 increase in speed. Use this formula to design the ratio you need for your specific motor and load combination.\u003c\/p\u003e\u003c\/div\u003e\n    \u003c\/details\u003e\n\n    \u003cdetails\u003e\n      \u003csummary\u003eDo I need any special tools to install this gear on a motor shaft?\u003c\/summary\u003e\n      \u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eFor a set-screw mount, you need only a hex key (Allen wrench) matching the set screw size. For a press fit, a small arbor press or bench vise with protective jaws is recommended to avoid damaging the gear teeth. If you plan to broach a keyway, a broaching kit and arbor press are required. No specialized gear installation tools are needed for standard set-screw mounting.\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 \u003cstrong\u003eSize (Bore)\u003c\/strong\u003e and \u003cstrong\u003ePacking Quantity\u003c\/strong\u003e 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 shaft diameter with a caliper. Common small motor shafts run 4 mm (N20-style motors), 5 mm (many TT gear motors), or 6 mm (larger DC and stepper motors). Select the bore that matches your shaft for a direct fit.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Will this gear mesh with my existing 0.5 mod rack or pinion?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Yes. Any gear or rack with a 0.5 module pitch and a matching 20° pressure angle will mesh correctly with this gear. Confirm both the module and pressure angle of your mating component before assembling.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"How strong is 45# steel for motor drive applications?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"45# carbon steel offers a tensile strength typically in the 600–800 MPa range in its normalized state, suitable for light-to-medium duty motor drives, robotics joints, and automation mechanisms.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Is this gear corrosion-resistant for outdoor or humid environments?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"45# carbon steel is not inherently corrosion-resistant. Apply a light machine oil or grease coating for outdoor or humid environments. For indoor, dry automation applications, bare or lightly oiled 45# steel performs well.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Can I use multiple gears together to build a gear train?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Yes. These 0.5 mod 28T gears can be combined with other 0.5 mod gears of different tooth counts to create compound gear trains for speed reduction or torque multiplication.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"What is the gear ratio if I pair this 28T gear with a different tooth count?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Gear ratio = driven teeth ÷ driving teeth. For example, pairing this 28T gear with a 56T gear gives a 2:1 reduction — halving speed and doubling torque.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Do I need any special tools to install this gear on a motor shaft?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"For a set-screw mount, you need only a hex key matching the set screw size. For a press fit, a small arbor press or bench vise with protective jaws is recommended.\"\n      }\n    }\n  ]\n}\n\u003c\/script\u003e","brand":"HomeDIYer","offers":[{"title":"0.5M 28T, Bore 4mm \/ 1 pcs","offer_id":52443242529042,"sku":"GLFBFHHGLCDPJ00042x1","price":10.58,"currency_code":"USD","in_stock":true},{"title":"0.5M 28T, Bore 5mm \/ 1 pcs","offer_id":52443242561810,"sku":"GLFBFHHGLCDPJ00043x1","price":10.58,"currency_code":"USD","in_stock":true},{"title":"0.5M 28T, Bore 6mm \/ 1 pcs","offer_id":52443242594578,"sku":"GLFBFHHGLCDPJ00044x1","price":10.58,"currency_code":"USD","in_stock":true},{"title":"0.5M 28T, Bore 4mm \/ 2 pcs","offer_id":52443242627346,"sku":"GLFBFHHGLCDPJ00042x2","price":16.43,"currency_code":"USD","in_stock":true},{"title":"0.5M 28T, Bore 5mm \/ 2 pcs","offer_id":52443242660114,"sku":"GLFBFHHGLCDPJ00043x2","price":16.43,"currency_code":"USD","in_stock":true},{"title":"0.5M 28T, Bore 6mm \/ 2 pcs","offer_id":52443242692882,"sku":"GLFBFHHGLCDPJ00044x2","price":16.43,"currency_code":"USD","in_stock":true},{"title":"0.5M 28T, Bore 4mm \/ 3 pcs","offer_id":52443242725650,"sku":"GLFBFHHGLCDPJ00042x3","price":23.58,"currency_code":"USD","in_stock":true},{"title":"0.5M 28T, Bore 5mm \/ 3 pcs","offer_id":52443242758418,"sku":"GLFBFHHGLCDPJ00043x3","price":23.58,"currency_code":"USD","in_stock":true},{"title":"0.5M 28T, Bore 6mm \/ 3 pcs","offer_id":52443242791186,"sku":"GLFBFHHGLCDPJ00044x3","price":23.58,"currency_code":"USD","in_stock":true},{"title":"0.5M 28T, Bore 4mm \/ 4 pcs","offer_id":52443242823954,"sku":"GLFBFHHGLCDPJ00042x4","price":30.75,"currency_code":"USD","in_stock":true},{"title":"0.5M 28T, Bore 5mm \/ 4 pcs","offer_id":52443242856722,"sku":"GLFBFHHGLCDPJ00043x4","price":30.75,"currency_code":"USD","in_stock":true},{"title":"0.5M 28T, Bore 6mm \/ 4 pcs","offer_id":52443242889490,"sku":"GLFBFHHGLCDPJ00044x4","price":30.75,"currency_code":"USD","in_stock":true},{"title":"0.5M 28T, Bore 4mm \/ 5 pcs","offer_id":52443242922258,"sku":"GLFBFHHGLCDPJ00042x5","price":37.9,"currency_code":"USD","in_stock":true},{"title":"0.5M 28T, Bore 5mm \/ 5 pcs","offer_id":52443242955026,"sku":"GLFBFHHGLCDPJ00043x5","price":37.9,"currency_code":"USD","in_stock":true},{"title":"0.5M 28T, Bore 6mm \/ 5 pcs","offer_id":52443242987794,"sku":"GLFBFHHGLCDPJ00044x5","price":37.9,"currency_code":"USD","in_stock":true},{"title":"0.5M 28T, Bore 4mm \/ 8 pcs","offer_id":52443243020562,"sku":"GLFBFHHGLCDPJ00042x8","price":59.39,"currency_code":"USD","in_stock":true},{"title":"0.5M 28T, Bore 5mm \/ 8 pcs","offer_id":52443243053330,"sku":"GLFBFHHGLCDPJ00043x8","price":59.39,"currency_code":"USD","in_stock":true},{"title":"0.5M 28T, Bore 6mm \/ 8 pcs","offer_id":52443243086098,"sku":"GLFBFHHGLCDPJ00044x8","price":59.39,"currency_code":"USD","in_stock":true},{"title":"0.5M 28T, Bore 4mm \/ 10 pcs","offer_id":52443243118866,"sku":"GLFBFHHGLCDPJ00042x10","price":73.71,"currency_code":"USD","in_stock":true},{"title":"0.5M 28T, Bore 5mm \/ 10 pcs","offer_id":52443243151634,"sku":"GLFBFHHGLCDPJ00043x10","price":73.71,"currency_code":"USD","in_stock":true},{"title":"0.5M 28T, Bore 6mm \/ 10 pcs","offer_id":52443243184402,"sku":"GLFBFHHGLCDPJ00044x10","price":73.71,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0884\/8936\/1682\/files\/Main-06_c03e85bf-d402-4b08-8194-5c85e82570fb.jpg?v=1784040100","url":"https:\/\/homediyer.com\/products\/0-5-mod-28-teeth-spur-gear-bore-4-5-6mm-motor-gears-transmission-gears-45-steel","provider":"HomeDIYer","version":"1.0","type":"link"}