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When a worn bearing race, a sticking valve seat, or a seized pivot point brings your project to a halt, the root cause is almost always a degraded rolling element — not the housing. These GCr15 chromium-steel loose ball bearings are stocked in 38 diameters from 6.35 mm (¼ in) to 19.05 mm (¾ in) so you can source the exact replacement ball without compromising on geometry or surface finish. Each ball is ground and lapped to ABEC Grade 10 tolerances, giving hobbyists, maintenance technicians, and small-batch manufacturers a reliable source for precision rolling elements without minimum-order constraints.
Every ball in this listing is manufactured from GCr15 bearing steel — the chromium-alloy equivalent of AISI 52100 — and heat-treated to a surface hardness of 60–66 HRC. Diameters span 6.35 mm to 19.05 mm (approximately ¼ in to ¾ in) with both metric and inch-fractional sizes represented, including common imperial sizes such as 7.938 mm (5/16 in), 9.525 mm (3/8 in), 11.1125 mm (7/16 in), 12.7 mm (½ in), 14.2875 mm (9/16 in), 15.875 mm (5/8 in), 16.668 mm (21/32 in), 17.4625 mm (11/16 in), and 19.05 mm (¾ in). Quantity options range from 20 PCS to 800 PCS depending on diameter, making it practical to order exactly what a repair or production run requires.
Typical use cases include repacking angular-contact and deep-groove ball bearings in power tools, bicycles, and skateboard trucks; replacing check-ball elements in hydraulic and pneumatic valves; filling ball-screw and linear-rail recirculation circuits; and serving as precision gauge balls or lapping media in metrology and surface-finishing workflows. The consistent sphericity and low surface roughness of Grade 10 balls also make them suitable for decorative and kinetic art installations where smooth, quiet rolling is essential.
| Material | GCr15 chromium-alloy bearing steel (AISI 52100 equivalent) |
|---|---|
| Grade | Grade 10 (ABEC / ISO 3290) |
| Surface Hardness | 60–66 HRC |
| Diameter Range | 6.35 mm – 19.05 mm (¼ in – ¾ in) |
| Available Diameters | 6.35, 6.5, 6.747, 7, 7.144, 7.5, 7.938, 8, 8.5, 8.731, 9, 9.525, 10, 10.318, 11, 11.1125, 11.5, 11.509, 11.906, 12, 12.303, 12.5, 12.7, 13, 13.494, 14, 14.2875, 15, 15.081, 15.875, 16, 16.668, 17, 17.4625, 18, 18.256, 19, 19.05 mm |
| Quantity Options | See variant options |
| Finish | Lapped, bright |
| Application | Bearing repacking, valve check balls, ball screws, linear rails, gauge balls, lapping media |
Grade 10 refers to the ISO 3290 / ABEC precision classification. It specifies maximum allowable deviation from a perfect sphere (sphericity) and diameter variation across a batch. Grade 10 balls have a maximum spherical error of 0.25 µm, making them suitable for most industrial bearing repacking, valve, and ball-screw applications where low noise and long service life are required.
Yes. Select the diameter that matches the rolling-element size specified on your bearing's datasheet or measure the worn balls with a micrometer. GCr15 Grade 10 balls are the same material and precision class used in most standard deep-groove and angular-contact bearings, so they are a direct functional replacement.
Some diameters listed — such as 7.938 mm, 9.525 mm, 11.1125 mm, 12.7 mm, 14.2875 mm, 15.875 mm, 16.668 mm, 17.4625 mm, and 19.05 mm — are exact metric equivalents of common imperial fractional sizes (5/16 in, 3/8 in, 7/16 in, 1/2 in, 9/16 in, 5/8 in, 21/32 in, 11/16 in, and 3/4 in respectively). If your application specifies an inch fraction, select the corresponding mm value from the variant menu.
The most reliable method is to remove one intact ball from the bearing and measure it with a digital micrometer or ball gauge. Alternatively, consult the bearing manufacturer's datasheet — the rolling-element diameter is usually listed under internal geometry specifications. For check-ball valves, the seat diameter stamped on the valve body typically corresponds to the ball diameter required.
Grade 10 GCr15 balls are commonly used as reference gauge balls in go/no-go gauging and as lapping media for surface finishing. Their tight sphericity and consistent hardness make them effective for both applications. For critical metrology use, verify the specific diameter tolerance against your measurement requirements before ordering.
🛒 Select your Diameter(mm) and Quantity(PCS) above, then add to cart.
