Square shaft linear bearings enable smooth, accurate linear motion in CNC machines, 3D printers, and automation projects. The following selections represent common bore options, dual-seal designs, and robust load capacities to suit various applications. This guide compares key specs and practical use cases to help you choose the right bearing for your setup.
| Product | Bore (dr) | Outer Dia (D) | Length (L) | Seal/Notes | Brand |
|---|---|---|---|---|---|
| uxcell LMK8UU | 8 mm | 15 mm | 24 mm | Sealed on both sides | uxcell |
| HiPicco LMK10LUU | 10 mm | 19 mm | 55 mm | Double sealed | HIPICCO |
| HiPicco LMK25LUU | 25 mm | 40 mm | 112 mm | Double sealed | HIPICCO |
| Skweawert SCS8UU | 8 mm | 34 mm | 30 mm | Double side rubber seal | Skweawert |
| uxcell LMK20UU | 20 mm | 32 mm | 42 mm | Sealed on both sides | uxcell |
uxcell LMK8UU Square Flange Bearing
The uxcell LMK8UU is a square flange linear ball bearing with a nominal shaft diameter of 8 mm and an outer diameter of 15 mm. This model features a 24 mm overall length and is sealed on both sides to help prevent contamination and lubrication loss. Constructed from chromium steel, it offers good abrasion resistance and solid static and dynamic load performance, making it suitable for compact CNC components or 3D printer axes that require precise, repeatable motion.
HiPicco LMK10LUU Square Flange Bearing (4 Pack)
The HiPicco LMK10LUU offers a 10 mm bore with a 19 mm outer diameter and 55 mm total length. The double-sealed design helps keep dust and lubricants inside, supporting longer service life in automated systems. With a static load rating around 1100 N and a dynamic rating near 588 N, these bearings are well-suited for mid-range CNC machines and 3D printers that demand reliable linear motion along standard shafts.
HiPicco LMK25LUU Square Flange Bearing
The LMK25LUU from HiPicco features a 25 mm bore, 40 mm outer diameter, and 112 mm total length with a 50 mm by 50 mm flange base. It employs a double-seal design to resist contaminants and preserve lubricant. With a static load capacity of about 3140 N and a dynamic capacity around 1560 N, this bearing handles heavier loads on longer travel axes, making it a strong option for larger CNC gantries or robust printer beds.
Skweawert SCS8UU Square Type Block
The Skweawert SCS8UU set includes four 8 mm bore bearings, each with a 34 mm outer diameter and 30 mm length. This block-style pillow bearing design uses double-sided rubber seals and high-precision 4-line steel balls to minimize friction and ensure smooth, repeatable motion in CNC rails and 3D printer axes. Its static load rating and dynamic rating indicate solid performance for mid-range applications.
HiPicco LMK8UU Square Flange Bearing
The LMK8UU from HiPicco provides an 8 mm bore, 15 mm outer diameter, and a 24 mm length. It is gasketed with a double-sealed design to protect the internal balls and lubricant. With static capacity around 400 N and dynamic capacity near 260 N, this bearing is a compact choice for lightweight CNC components or small-format 3D printer axes where space is at a premium and consistent motion is critical.
uxcell LMK20UU Square Flange Bearing
The uxcell LMK20UU offers a 20 mm bore with a 32 mm outer diameter and a 42 mm length. This product is sealed on both sides to resist contaminants and maintain lubrication, while a chromium steel shell provides durability and abrasion resistance. Its larger bore and longer travel make it suitable for heavier or longer-axis systems in mid-sized CNC setups and robust 3D printers requiring higher stiffness and stability.
Buying Guide
- Bore diameter and shaft compatibility: Choose a bore that matches your shaft (8, 10, 20, or 25 mm in the examples). Ensure a proper fit without excessive play.
- Seal design: Double-sided seals help keep contaminants out and lubricant in, extending bearing life in dusty environments. Consider single-seal options for lighter-duty or lower-maintenance setups.
- Load ratings: Static (Cor) and dynamic (Cr) ratings indicate resistance to static and moving loads. Higher numbers generally mean better performance under heavier or faster motion.
- Flat flange and mounting: Square flange bearings with flat bases provide stable mounting for linear rails and guideways. Check flange dimensions to match your mounting pattern (L x W) on the part.
- Material and finish: Chromium steel shells offer abrasion resistance and strength. Inspect seals and lubricants compatible with your chosen lubricant type for your project.
- Pack options and availability: Some products are sold in packs (e.g., 4 or 2) which can simplify assembly and reduce order frequency for multi-axis systems.
- Application fit: For small printers or hobby CNCs, 8–10 mm bore parts are common; larger 20–25 mm bearings suit robust gantries and heavier loads. Consider travel length and overall assembly height when selecting.
- Compatibility with shafts and rails: Verify that the square flange bearing is intended for use with cylindrical shafts or guideways that match its bore and outer diameter for smooth operation.