GB308-84 ISO 3290 - Third edition 2001
| Grade | Ball Dia. Variation (µm) | Deviation from Spherical Form (µm) | Surface Roughness (µm) | Lot Dia. Variation (µm) | Gauge Interval (µm) | Preferred Gauge (µm) | Subgauge Interval (µm) | Subgauge (µm) |
| G3 | 0.08 | 0.08 | 0.010 | 0.13 | 0.5 | -5...-0.5 0 +0.5...+5 | 0.1 | -0.2,-0.1, 0, +0.1,+0.2 |
| G5 | 0.13 | 0.13 | 0.014 | 0.25 | 1 | -5...-1 0 +1...+5 | 0.2 | -0.4,-0.2, 0, +0.2,+0.4 |
| G10 | 0.25 | 0.25 | 0.020 | 0.5 | 1 | -9...-1 0 +1...+9 | 0.2 | -0.4,-0.2, 0, +0.2,+0.4 |
| G16 | 0.4 | 0.4 | 0.025 | 0.8 | 2 | -10...-2 0 +2...+10 | 0.4 | -0.8,-0.4 0, +0.4,+0.8 |
| G20 | 0.5 | 0.5 | 0.032 | 1 | 2 | -10...-2 0 +2...+10 | 0.4 | -0.8,-0.4 0, +0.4,+0.8 |
| G24 | 0.6 | 0.6 | 0.040 | 1.2 | 2 | -12...-2 0 +2...+12 | 0.4 | -0.8,-0.4 0, +0.4,+0.8 |
| G28 | 0.7 | 0.7 | 0.050 | 1.4 | 2 | -12...-2 0 +2...+12 | 0.4 | -0.8,-0.4 0, +0.4,+0.8 |
| G40 | 1 | 1 | 0.060 | 2 | 4 | -16...-4 0 +4...+16 | 0.8 | -1.6,-0.8, 0, +0.8,+1.6 |
| G60 | 1.5 | 1.5 | 0.080 | 3 | 6 | -18...-6 0 +6...+18 | 1.2 | -2.4,-1.2, 0. +1.2,+2.4 |
| G100 | 2.5 | 2.5 | 0.100 | 5 | 10 | -40...-10 0 +10...+40 | 2 | -4,-2, 0, +2,+4 |
| G200 | 5 | 5 | 0.150 | 10 | 15 | -60...-15 0 +15...+60 | 3 | -6,-3, 0, +3,+6 |
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Spheric Trafalgar Ltd
Wiston Business Park
London Road
Ashington
West Sussex
RH20 3DJ
Tel : +44 (0)1903 891200
Fax : +44 (0)1903 891220
Spheric-Trafalgar (Thailand) Ltd
Eastern Seaboard Industrial Estate 170
Moo 4, Tambon Pluakdaeng
Amphur Pluakdaeng
Rayong 21140
Thailand
Tel : +66 (0)38 959 164
Fax : +66 (0)38 955 261
Spheric-Trafalgar Inc
9447 London Way
Suite 104
Rancho Cucamonga
California 91730
USA
Tel : +1 909 944 8424
Fax : +1 909 989 1957