{"product_id":"linear-ball-bearing-lm4uu-lm20uu-sealed-cnc-shaft-bushing","title":"Linear Ball Bearing LM 4\/6\/8\/10-20 UU Bushing Bearings with Seal for CNC Shaft","description":"\u003cdiv class=\"hdiy-desc\"\u003e\n\n\u003cdiv class=\"hdiy-overview\"\u003e\n\u003ch2\u003eLinear Ball Bearings LM4UU–LM20UU — Sealed Bushing Bearings for Smooth CNC Shaft Motion\u003c\/h2\u003e\n\u003cp\u003eWhen your CNC router, 3D printer, or linear actuator suffers from shaft wobble, binding, or premature wear, the culprit is often an undersized or unsealed bearing. Engineers, makers, and machine builders who demand repeatable, low-friction linear travel need a sealed linear ball bearing they can trust across a wide range of shaft diameters.\u003c\/p\u003e\n\u003cp\u003eThese linear ball bearings are manufactured from chrome steel (GCr15) with a sealed design that retains grease and blocks contamination. Available in sizes from LM4UU (4 mm bore, 8 mm OD, 12 mm length) through LM20UU (20 mm bore, 32 mm OD, 42 mm length), with specialty variants LMH8UU and LMH8LUU for extended-length applications. Sold individually or in packs of 5 or 10 for multi-axis builds.\u003c\/p\u003e\n\u003cp\u003eTypical use cases include: linear ball bearing for 3D printer X\/Y\/Z axis (LM8UU is the most common RepRap standard), CNC router carriage guide rail systems using LM12UU or LM16UU, and robotic arm linear slide assemblies where LM10UU or LM13UU provide the right bore-to-load balance.\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 for use with smooth hardened steel linear shafts (typically 4–20 mm diameter). Verify your shaft diameter matches the bearing bore before ordering. Compatible with standard LM-series housing blocks and pillow blocks.\n\u003c\/div\u003e\n\n\u003cdiv class=\"hdiy-features\"\u003e\n\u003ch2\u003e✅ Key Features of These Linear Ball Bearings\u003c\/h2\u003e\n\u003cdiv class=\"hdiy-list\"\u003e\n\u003cdiv\u003e\n\u003cspan class=\"hdiy-icon\"\u003e🔩\u003c\/span\u003e\n\u003cstrong\u003eWide Size Range\u003c\/strong\u003e\n\u003cp\u003eCovers LM4UU through LM20UU plus LMH8UU and LMH8LUU — one source for your entire multi-axis build.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cspan class=\"hdiy-icon\"\u003e🛡️\u003c\/span\u003e\n\u003cstrong\u003eSealed Design\u003c\/strong\u003e\n\u003cp\u003eIntegrated rubber seals on both ends retain lubrication and exclude dust, chips, and moisture for longer service life.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cspan class=\"hdiy-icon\"\u003e⚡\u003c\/span\u003e\n\u003cstrong\u003eLow-Friction Ball Recirculation\u003c\/strong\u003e\n\u003cp\u003ePrecision ball tracks enable smooth, consistent linear travel with minimal stick-slip — critical for accurate CNC positioning.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cspan class=\"hdiy-icon\"\u003e📐\u003c\/span\u003e\n\u003cstrong\u003eMetric Dimensional Accuracy\u003c\/strong\u003e\n\u003cp\u003eManufactured to standard LM-series tolerances so bearings drop into compatible housings and pillow blocks without modification.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cspan class=\"hdiy-icon\"\u003e📦\u003c\/span\u003e\n\u003cstrong\u003eFlexible Pack Quantities\u003c\/strong\u003e\n\u003cp\u003eOrder 1, 5, or 10 pieces per size — ideal for prototyping single axes or stocking a full multi-printer workshop.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cspan class=\"hdiy-icon\"\u003e🔧\u003c\/span\u003e\n\u003cstrong\u003eBroad Application Fit\u003c\/strong\u003e\n\u003cp\u003eSuited for 3D printers (RepRap, Prusa, Ender-style), CNC routers, laser cutters, linear actuators, and robotics platforms.\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 — Linear Ball Bearings\u003c\/h2\u003e\n\u003ctable\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eBearing Type\u003c\/th\u003e\n\u003ctd\u003eLinear Ball Bearing (LM-series)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eAvailable Sizes\u003c\/th\u003e\n\u003ctd\u003eLM4UU, LM5UU, LM6UU, LM8UU, LM10UU, LM12UU, LM13UU, LM16UU, LM20UU, LMH8UU, LMH8LUU\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eBore Diameter Range\u003c\/th\u003e\n\u003ctd\u003e4 mm – 20 mm (see variant options)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eOuter Diameter Range\u003c\/th\u003e\n\u003ctd\u003e8 mm – 32 mm (see variant options)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eLength Range\u003c\/th\u003e\n\u003ctd\u003e12 mm – 42 mm (see variant options)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eMaterial\u003c\/th\u003e\n\u003ctd\u003eChrome steel (GCr15) bearing body; rubber seals\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eSeal Type\u003c\/th\u003e\n\u003ctd\u003eDouble-sealed (both ends)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eLubrication\u003c\/th\u003e\n\u003ctd\u003ePre-greased\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eCompatible Shaft Type\u003c\/th\u003e\n\u003ctd\u003eHardened smooth linear shaft\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003ePack Quantity Options\u003c\/th\u003e\n\u003ctd\u003e1 pcs \/ 5 pcs \/ 10 pcs\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\u003cdetails\u003e\n\u003csummary\u003eHow do I choose the right LM bearing size for my shaft?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eMatch the bearing bore to your shaft diameter exactly. For example, an 8 mm shaft requires LM8UU (8 mm bore, 15 mm OD, 24 mm length). Check your machine's specification or measure the shaft with calipers before ordering. The variant option names include bore × OD × length in mm for easy reference.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eWhat is the difference between LMH8UU and LM8UU?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eBoth fit an 8 mm shaft, but LMH8UU has a larger outer diameter housing compared to the standard LM8UU. This makes LMH8UU suitable for applications requiring a wider bearing seat or higher radial load capacity. LMH8LUU is the long version of LMH8UU, offering greater contact length for improved stability.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eAre these bearings suitable for 3D printers like Prusa or Ender?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eYes. LM8UU is the standard linear bearing used in most RepRap-derived printers including Prusa i3 variants and Creality Ender-series machines. LM6UU is commonly used on smaller delta printers. Always verify your printer's carriage housing inner diameter matches the bearing's outer diameter before installing.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eDo the seals affect travel smoothness?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eSealed bearings have a marginally higher initial drag than open bearings due to seal contact, but this is negligible in most CNC and 3D printing applications. The seals significantly extend bearing life by keeping lubricant in and contaminants out, making them the preferred choice for workshop environments.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eCan these bearings handle both radial and axial loads?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eLinear ball bearings are designed primarily for radial loads during linear motion. They are not intended to carry significant axial (thrust) loads. For applications with combined loading, pair with appropriate end stops or thrust bearings to protect the linear bearing from axial forces.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eHow many bearings should I order for a typical 3-axis CNC or printer build?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eA standard Cartesian 3D printer typically uses 6–12 LM8UU bearings (2–4 per axis). A CoreXY build may use fewer. CNC routers vary widely by design. Ordering a 10-pack is cost-effective for full builds or to keep spares on hand for maintenance.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eDo these bearings require additional lubrication before use?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eThese bearings come pre-greased from the factory. For most applications they can be installed directly. In high-cycle or high-speed environments, adding a small amount of compatible lithium grease through the seal gap every few months will extend service life.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\u003c\/div\u003e\n\n\u003cdiv class=\"hdiy-cta\"\u003e\n🛒 Select your bearing size and pack 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 LM bearing size for my shaft?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Match the bearing bore to your shaft diameter exactly. For example, an 8 mm shaft requires LM8UU (8 mm bore, 15 mm OD, 24 mm length). Check your machine's specification or measure the shaft with calipers before ordering.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"What is the difference between LMH8UU and LM8UU?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Both fit an 8 mm shaft, but LMH8UU has a larger outer diameter housing. LMH8LUU is the long version offering greater contact length for improved stability.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Are these bearings suitable for 3D printers like Prusa or Ender?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Yes. LM8UU is the standard linear bearing used in most RepRap-derived printers including Prusa i3 variants and Creality Ender-series machines.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Do the seals affect travel smoothness?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Sealed bearings have marginally higher initial drag but significantly extend bearing life by keeping lubricant in and contaminants out.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Can these bearings handle both radial and axial loads?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Linear ball bearings are designed primarily for radial loads during linear motion. They are not intended to carry significant axial loads.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"How many bearings should I order for a typical 3-axis CNC or printer build?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"A standard Cartesian 3D printer typically uses 6–12 LM8UU bearings. Ordering a 10-pack is cost-effective for full builds or to keep spares on hand.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Do these bearings require additional lubrication before use?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"These bearings come pre-greased. In high-cycle environments, adding a small amount of compatible lithium grease every few months will extend service life.\"\n      }\n    }\n  ]\n}\n\u003c\/script\u003e","brand":"HomeDIYer","offers":[{"title":"LM13UU(13*23*32） \/ 1 pcs","offer_id":52448880623890,"sku":"QMBJT00185x1","price":4.34,"currency_code":"USD","in_stock":true},{"title":"LM20UU(20*32*42） \/ 1 pcs","offer_id":52448880656658,"sku":"QMBJT00186x1","price":6.24,"currency_code":"USD","in_stock":true},{"title":"LM4UU \/ 1 pcs","offer_id":52448880689426,"sku":"QMBJT00187x1","price":3.11,"currency_code":"USD","in_stock":true},{"title":"LM6UU(6*12*19） \/ 1 pcs","offer_id":52448880722194,"sku":"QMBJT00188x1","price":1.97,"currency_code":"USD","in_stock":true},{"title":"LM8UU(8*15*24） \/ 1 pcs","offer_id":52448880754962,"sku":"QMBJT00189x1","price":1.97,"currency_code":"USD","in_stock":true},{"title":"LMH8UU \/ 1 pcs","offer_id":52448880787730,"sku":"QMBJT00190x1","price":4.34,"currency_code":"USD","in_stock":true},{"title":"LM10UU(10*19*29） \/ 1 pcs","offer_id":52448880820498,"sku":"QMBJT00191x1","price":2.71,"currency_code":"USD","in_stock":true},{"title":"LM12UU(12*21*30） \/ 1 pcs","offer_id":52448880853266,"sku":"QMBJT00192x1","price":2.98,"currency_code":"USD","in_stock":true},{"title":"LMH8LUU \/ 1 pcs","offer_id":52448880886034,"sku":"QMBJT00193x1","price":9.45,"currency_code":"USD","in_stock":true},{"title":"LM5UU(5*10*15） \/ 1 pcs","offer_id":52448880918802,"sku":"QMBJT00194x1","price":2.65,"currency_code":"USD","in_stock":true},{"title":"LM16UU（16*28*37） \/ 1 pcs","offer_id":52448880951570,"sku":"QMBJT00195x1","price":5.1,"currency_code":"USD","in_stock":true},{"title":"LM13UU(13*23*32） \/ 5 pcs","offer_id":52448880984338,"sku":"QMBJT00185x5","price":18.21,"currency_code":"USD","in_stock":true},{"title":"LM20UU(20*32*42） \/ 5 pcs","offer_id":52448881017106,"sku":"QMBJT00186x5","price":27.73,"currency_code":"USD","in_stock":true},{"title":"LM4UU \/ 5 pcs","offer_id":52448881049874,"sku":"QMBJT00187x5","price":12.36,"currency_code":"USD","in_stock":true},{"title":"LM6UU(6*12*19） \/ 5 pcs","offer_id":52448881082642,"sku":"QMBJT00188x5","price":4.34,"currency_code":"USD","in_stock":true},{"title":"LM8UU(8*15*24） \/ 5 pcs","offer_id":52448881115410,"sku":"QMBJT00189x5","price":5.83,"currency_code":"USD","in_stock":true},{"title":"LMH8UU \/ 5 pcs","offer_id":52448881148178,"sku":"QMBJT00190x5","price":18.21,"currency_code":"USD","in_stock":true},{"title":"LM10UU(10*19*29） \/ 5 pcs","offer_id":52448881180946,"sku":"QMBJT00191x5","price":10.19,"currency_code":"USD","in_stock":true},{"title":"LM12UU(12*21*30） \/ 5 pcs","offer_id":52448881213714,"sku":"QMBJT00192x5","price":11.63,"currency_code":"USD","in_stock":true},{"title":"LMH8LUU \/ 5 pcs","offer_id":52448881246482,"sku":"QMBJT00193x5","price":43.04,"currency_code":"USD","in_stock":true},{"title":"LM5UU(5*10*15） \/ 5 pcs","offer_id":52448881279250,"sku":"QMBJT00194x5","price":6.73,"currency_code":"USD","in_stock":true},{"title":"LM16UU（16*28*37） \/ 5 pcs","offer_id":52448881312018,"sku":"QMBJT00195x5","price":21.83,"currency_code":"USD","in_stock":true},{"title":"LM13UU(13*23*32） \/ 10 pcs","offer_id":52448881344786,"sku":"QMBJT00185x10","price":35.62,"currency_code":"USD","in_stock":true},{"title":"LM20UU(20*32*42） \/ 10 pcs","offer_id":52448881377554,"sku":"QMBJT00186x10","price":54.66,"currency_code":"USD","in_stock":true},{"title":"LM4UU \/ 10 pcs","offer_id":52448881410322,"sku":"QMBJT00187x10","price":24.0,"currency_code":"USD","in_stock":true},{"title":"LM6UU(6*12*19） \/ 10 pcs","offer_id":52448881443090,"sku":"QMBJT00188x10","price":7.87,"currency_code":"USD","in_stock":true},{"title":"LM8UU(8*15*24） \/ 10 pcs","offer_id":52448881475858,"sku":"QMBJT00189x10","price":11.0,"currency_code":"USD","in_stock":true},{"title":"LMH8UU \/ 10 pcs","offer_id":52448881508626,"sku":"QMBJT00190x10","price":35.75,"currency_code":"USD","in_stock":true},{"title":"LM10UU(10*19*29） \/ 10 pcs","offer_id":52448881541394,"sku":"QMBJT00191x10","price":19.57,"currency_code":"USD","in_stock":true},{"title":"LM12UU(12*21*30） \/ 10 pcs","offer_id":52448881574162,"sku":"QMBJT00192x10","price":22.43,"currency_code":"USD","in_stock":true},{"title":"LMH8LUU \/ 10 pcs","offer_id":52448881606930,"sku":"QMBJT00193x10","price":85.39,"currency_code":"USD","in_stock":true},{"title":"LM5UU(5*10*15） \/ 10 pcs","offer_id":52448881639698,"sku":"QMBJT00194x10","price":12.77,"currency_code":"USD","in_stock":true},{"title":"LM16UU（16*28*37） \/ 10 pcs","offer_id":52448881672466,"sku":"QMBJT00195x10","price":42.96,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0884\/8936\/1682\/files\/Picture1of6_80af3fbd-77da-4402-a878-45d260db04dc.jpg?v=1783670406","url":"https:\/\/homediyer.com\/products\/linear-ball-bearing-lm4uu-lm20uu-sealed-cnc-shaft-bushing","provider":"HomeDIYer","version":"1.0","type":"link"}