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When a wobbly spindle or seized shaft brings your project to a halt, the right miniature bearing makes all the difference. Whether you are a maker replacing worn rollers on a 3D printer, an RC hobbyist rebuilding a drivetrain, or a technician sourcing small-batch replacement parts, these double-shielded ZZ-series micro ball bearings deliver consistent, low-friction rotation in a compact form factor.
Each bearing features a chrome steel (GCr15) raceway with pressed steel double shields (ZZ designation) that retain grease and block debris without adding significant drag. Available sizes span from the ultra-compact 623ZZ (3 × 10 × 4 mm / 0.12 × 0.39 × 0.16 in) up to the 629ZZ (9 × 26 × 8 mm / 0.35 × 1.02 × 0.31 in), covering bore diameters of 3–9 mm across twelve standard metric series: 604, 605, 606, 607, 608, 623, 624, 625, 626, 628, 629, and 688ZZ.
Typical use cases include 3D printer extruder and idler pulley replacements (608ZZ, 625ZZ), RC car wheel and differential bearings (604ZZ, 605ZZ), small electric motor end-cap bearings for robotics and automation (606ZZ, 607ZZ), fidget spinner and skateboard truck rebuilds (608ZZ), and precision instrument or camera gimbal pivot points (623ZZ, 624ZZ). Order in packs of 1, 5, 10, 20, or 50 to match your project scale.
| Bearing Series | 604ZZ, 605ZZ, 606ZZ, 607ZZ, 608ZZ, 623ZZ, 624ZZ, 625ZZ, 626ZZ, 628ZZ, 629ZZ, 688ZZ |
|---|---|
| Bore Diameter (ID) | 3 mm – 9 mm (varies by size; see variant options) |
| Outer Diameter (OD) | 10 mm – 26 mm (varies by size; see variant options) |
| Width | 4 mm – 8 mm (varies by size; see variant options) |
| Shield Type | Double-shielded (ZZ) — pressed steel, non-contact |
| Raceway Material | Chrome steel (GCr15) |
| Ball Material | Chrome steel |
| Cage Material | See variant options |
| Lubrication | Factory-applied grease (pre-lubricated) |
| Radial Clearance | See variant options |
| Max RPM (indicative) | See variant options |
| Packing Quantity Options | 1 Pcs / 5 Pcs / 10 Pcs / 20 Pcs / 50 Pcs |
| Unit Weight | See variant options |
Match the bearing's inner diameter (ID) to your shaft diameter and the outer diameter (OD) to your housing bore. For example, a 608ZZ has an 8 mm ID and 22 mm OD — the most common size for 3D printer idler pulleys and skateboard wheels. Check the dimension table in the variant selector above and measure your shaft and housing with calipers before ordering.
ZZ-series miniature bearings are designed primarily for light-to-moderate radial loads and low axial (thrust) loads. They are well-suited for high-speed, low-load applications such as 3D printer extruders, RC car differentials, and small electric motors. For heavy radial or combined load applications, consider angular contact or deep-groove bearings rated for higher dynamic load capacity.
Standard ZZ chrome steel bearings offer limited corrosion resistance. The pressed steel shields provide some protection against splash and light moisture, but prolonged exposure to water, humidity, or corrosive chemicals will cause rust. For wet or outdoor environments, consider stainless steel (2RS or ZZ) variants. These bearings are best used in dry or lightly lubricated indoor conditions.
ZZ bearings use non-contact pressed steel shields that sit close to the inner race without touching it, resulting in lower friction and higher maximum RPM. 2RS bearings use rubber contact seals that physically touch the inner race, providing better contamination and moisture exclusion at the cost of slightly higher drag. For high-speed, low-contamination environments choose ZZ; for dusty or damp conditions choose 2RS.
Yes. The 608ZZ (8 × 22 × 7 mm) is the standard idler pulley bearing for most FDM printers including Ender 3, CR-10, and similar machines. The 625ZZ (5 × 16 × 5 mm) is commonly used in Prusa and Voron extruder assemblies. Select the size that matches your printer's specification — refer to your printer's BOM or parts list to confirm the correct bearing designation.
No. These bearings come factory pre-greased and are ready to install straight from the package. The ZZ shields retain the grease inside the bearing for the service life under normal operating conditions. If you are using them in a high-temperature or high-speed application that exceeds standard parameters, you may wish to supplement with a compatible bearing grease after removing the shields — but for most DIY and hobby applications, no additional lubrication is needed.
For a single repair or prototype, the 1 Pcs option lets you test fit before committing. The 5 or 10 Pcs packs are ideal for a full printer build or RC vehicle rebuild where multiple bearings of the same size are needed. The 20 or 50 Pcs packs offer the best per-unit value for workshop stock, small-batch production, or resale. Pricing scales down per piece as quantity increases.
