Miniature Ball Bearings — ZZ-Shielded Precision Rolling Elements for Tight Spaces
When a seized bearing brings a 3D printer, RC drivetrain, or small motor to a halt, finding the right replacement fast matters. Hobbyists, makers, and repair technicians who work with compact rotating assemblies need miniature ball bearings that fit precisely, spin freely, and hold up to repeated use without adding bulk or weight to the build.
Each pack contains 5 ZZ-shielded miniature ball bearings made from chrome steel with dual metal dust shields on both faces. Available in 13 standard models ranging from 623ZZ (3×10×4 mm / 0.12×0.39×0.16 in) up to 629ZZ (9×26×8 mm / 0.35×1.02×0.31 in), covering bore diameters of 3–9 mm and outer diameters of 10–26 mm.
Typical applications include FDM and resin 3D printer carriages and extruder idlers, RC car wheel hubs and differential assemblies, inline skate and skateboard wheel cores, small DC and stepper motor shaft supports, and DIY CNC axis linear motion systems requiring compact radial load support.
🔧 Compatible with standard 6xx and 62x series bearing seats. Verify bore (ID), outer diameter (OD), and width against your housing before ordering.
✅ Key Features of These Miniature Ball Bearings
🛡️ZZ Dual Metal Shields
Both faces sealed with pressed-steel shields to block dust, swarf, and light moisture from reaching the raceway — no additional sealing required in most dry environments.
⚙️Chrome Steel Construction
Rings and balls machined from chrome steel (typically GCr15 equivalent) for consistent hardness and fatigue resistance across the full load cycle.
📐13 Standard Models
Covers 604ZZ through 688ZZ in a single listing — bore sizes 3–9 mm, OD 10–26 mm, widths 4–8 mm — matching the most common miniature bearing seats in hobby and light-industrial equipment.
📦Pack of 5
Five bearings per order lets you stock spares, replace a full axis set, or outfit multiple assemblies in one purchase without over-ordering.
🔄Pre-Greased Raceways
Factory-applied grease between the shields provides immediate lubrication on installation, reducing break-in wear and extending service intervals in low-to-moderate speed applications.
🎯Drop-In Replacement Fit
Dimensions conform to ISO/JIS miniature bearing standards, making these a direct swap for worn OEM bearings in 3D printers, RC vehicles, power tools, and small appliances.
📐 Technical Specifications — Miniature Ball Bearings
| Bearing Type |
Deep groove ball bearing, ZZ (dual metal shield) |
| Series |
6xx / 62x miniature series |
| Available Models |
604ZZ, 605ZZ, 606ZZ, 607ZZ, 608ZZ, 623ZZ, 624ZZ, 625ZZ, 626ZZ, 628ZZ, 629ZZ, 685ZZ, 688ZZ |
| Bore Diameter (ID) |
3–9 mm (0.12–0.35 in) — see variant options |
| Outer Diameter (OD) |
10–26 mm (0.39–1.02 in) — see variant options |
| Width |
4–8 mm (0.16–0.31 in) — see variant options |
| Shield Type |
ZZ — pressed steel, non-contact, both sides |
| Lubrication |
Factory grease (pre-lubricated) |
| Quantity per Pack |
5 pieces |
| Load Direction |
Radial |
| Operating Temperature |
See variant options |
| Tolerance Class |
See variant options |
❓ Frequently Asked Questions
How do I choose the right model for my application?
Match three dimensions to your housing: bore diameter (ID) to your shaft, outer diameter (OD) to your housing bore, and width to the available axial space. All three values are listed in the model name — for example, 608ZZ = 8 mm ID × 22 mm OD × 7 mm wide. Measure your existing bearing with calipers before ordering if you are unsure.
What does "ZZ" mean on a bearing designation?
ZZ indicates that both faces of the bearing are fitted with pressed-steel (metal) shields. These shields block coarse contaminants and retain grease without contacting the inner ring, which keeps friction low. They are suitable for dry or lightly dusty environments. For wet or heavily contaminated conditions, look for RS (rubber-sealed) variants instead.
Are these bearings pre-lubricated?
Yes. Each bearing leaves the factory with grease applied between the shields and the raceway. For most hobby and light-duty applications this is sufficient for the life of the bearing. If you are running at elevated speeds or temperatures, you may wish to add a compatible bearing grease after removing the shields.
Will these fit my 608ZZ skateboard or inline skate wheels?
The 608ZZ variant (8 mm ID × 22 mm OD × 7 mm wide) is the global standard for skateboard, longboard, and inline skate wheels. Select the 608ZZ model from the dropdown and it will drop directly into any standard wheel core without modification.
Can I use these in a 3D printer (e.g., Ender, Prusa, Voron)?
Yes. The 608ZZ is widely used for extruder idler pulleys and Z-axis lead screw supports on many FDM printers. Smaller models such as 604ZZ and 623ZZ are common in compact extruder designs and belt tensioners. Check your printer's BOM or part drawings to confirm the exact model required before selecting.
How do I remove the shields for cleaning or re-greasing?
ZZ metal shields are typically retained by a snap ring seated in a groove on the inner ring. Use a thin pick or dental tool to carefully lever the shield out from the snap-ring groove — work around the circumference gradually to avoid bending. Clean the raceway with isopropyl alcohol, allow to dry, apply fresh bearing grease, and re-seat the shield.
What is the load capacity of these miniature bearings?
Dynamic and static load ratings vary by model size. As a general reference, the 608ZZ carries a dynamic radial load of approximately 3.25 kN and a static load of 1.37 kN under standard conditions. Smaller models (604ZZ, 623ZZ) have proportionally lower ratings. Contact us to confirm load data for your specific model and duty cycle.
🛒 Select your Model above, then add to cart.
