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When a mismatched ball diameter causes a slingshot to shoot wide, or a worn bearing seat starts rattling mid-project, the fix starts with sourcing the right rolling element. These steel ball bearings are stocked for makers, hobbyists, and repair technicians who need a reliable supply of precision-ground balls across a wide size range — without ordering from multiple suppliers.
Each ball is manufactured from either Carbon Steel or Bearing Steel (GCr15 equivalent), with diameters spanning 3 mm to 5.953 mm (approximately 0.118 in to 0.234 in). Balls are available in packs of 50, 100, or 200 pieces, letting you stock exactly what your project demands. Surface finish is smooth and consistent across the batch, with tight spherical tolerances suited to both mechanical and projectile applications.
Typical use cases include slingshot and catapult ammunition where consistent diameter and mass matter for accuracy, replacement rolling elements in small radial bearings and linear slides, and general DIY applications such as ball-end linkages, gravity feeds, and check-valve seats. The 3.175 mm (1/8 in) and 3.969 mm (5/32 in) sizes are particularly popular for standard imperial bearing replacements.
| Product Type | Precision Steel Ball Bearings / Rolling Elements |
|---|---|
| Material Options | Carbon Steel; Bearing Steel (GCr15 equivalent) |
| Diameter Range | 3 mm – 5.953 mm (0.118 in – 0.234 in) |
| Available Diameters | 3 mm, 3.175 mm, 3.5 mm, 3.969 mm, 4 mm, 4.5 mm, 4.763 mm, 4.8 mm, 5.46 mm, 5.48 mm, 5.556 mm, 5.953 mm |
| Package Quantities | 50 pcs / 100 pcs / 200 pcs |
| Surface Finish | Precision-ground, smooth spherical surface |
| Hardness (Bearing Steel) | Typically 60–66 HRC (GCr15 grade) |
| Hardness (Carbon Steel) | See variant options |
| Spherical Tolerance Grade | See variant options |
| Typical Applications | Slingshot ammo, catapult projectiles, radial bearing replacement, linear slides, check-valve seats, DIY linkages |
| Weight per Pack | See variant options (varies by diameter and quantity) |
Match the ball diameter to your slingshot pouch width and band tension. Smaller balls (3 mm – 3.5 mm) suit lighter bands and shorter draw lengths, while larger balls (4.5 mm – 5.953 mm) pair better with heavier bands for more energy transfer. For catapults, check the cup or cradle diameter and select a ball that seats snugly without excessive play.
Carbon Steel balls are a cost-effective choice for general mechanical use and projectile applications where extreme hardness is not required. Bearing Steel (GCr15 equivalent) balls are through-hardened to typically 60–66 HRC, offering superior fatigue resistance and wear life under rolling contact loads — making them the better choice for replacing balls in radial bearings, linear slides, or any application with repeated load cycles.
Both Carbon Steel and Bearing Steel grades offer limited corrosion resistance on their own. For outdoor or humid environments, apply a light coat of machine oil or grease after handling to slow surface oxidation. If corrosion resistance is a primary requirement, consider stainless steel balls instead — these listings cover carbon and bearing steel grades only.
Yes, provided you match the diameter exactly to your bearing's ball complement specification. Measure the existing balls with a micrometer before ordering. The 3.175 mm (1/8 in) and 3.969 mm (5/32 in) sizes correspond to common imperial bearing ball sizes. Always replace the full complement of balls in a bearing — mixing old and new balls of slightly different wear levels can cause uneven load distribution.
The 50-piece pack suits small repair jobs or prototype testing where you need a handful of balls to verify fit and function. The 100-piece pack is a practical middle ground for hobbyist restocking or a single slingshot season's supply. The 200-piece pack offers the lowest per-unit cost and is suited for workshop stock, bulk bearing rebuilds, or regular recreational shooting use.
These balls are precision-ground for consistent diameter within a batch, making them suitable for slingshot ammo, light-duty bearing replacement, and general DIY applications. For instruments requiring certified Grade 10 or Grade 25 tolerances (per ISO 3290), contact us to confirm the specific tolerance grade before ordering, as tolerance documentation varies by batch.
The balls are supplied dry (unlubricated). For bearing applications, apply the appropriate grease or oil for your load and speed conditions before installation. For slingshot or catapult use, no lubrication is needed.
