TABLE OF CONTENTS ANSI Standard Limits and Fits (ANSI B4.1-1967, R1979). This American National Standard for Preferred Limits and Fits for Cylindrical Parts presents definitions of terms applying to fits between plain (non-threaded) cylindrical parts and makes recommendations on preferred sizes, allowances, tolerances, and fits for use wherever they are applicable. This standard is in accord with the recommendations of American-British-Canadian (ABC) conferences for diameters of up to 20 inches. They should have application for a wide range of products.
Preferred Basic Sizes. In specifying fits, the basic size of mating parts may be chosen from the decimal series or the fractional series in the following Table 1.
| Decimal | Fractional | |||||||
|---|---|---|---|---|---|---|---|---|
| 0.010 | 2.00 | 8.50 | | 0.015625 | 2 | 2.2500 | 9 | 9.5000 |
| 0.012 | 2.20 | 9.00 | | 0.03125 | 2 | 2.5000 | 10 | 10.0000 |
| 0.016 | 2.40 | 9.50 | | 0.0625 | 2 | 2.7500 | 10 | 10.5000 |
| 0.020 | 2.60 | 10.00 | | 0.09375 | 3 | 3.0000 | 11 | 11.0000 |
| 0.025 | 2.80 | 10.50 | ? | 0.1250 | 3 | 3.2500 | 11 | 11.5000 |
| 0.032 | 3.00 | 11.00 | | 0.15625 | 3 | 3.5000 | 12 | 12.0000 |
| 0.040 | 3.20 | 11.50 | | 0.1875 | 3 | 3.7500 | 12 | 12.5000 |
| 0.05 | 3.40 | 12.00 |
| 0.2500 | 4 | 4.0000 | 13 | 13.0000 |
| 0.06 | 3.60 | 12.50 | | 0.3125 | 4 | 4.2500 | 13 | 13.5000 |
| 0.08 | 3.80 | 13.00 | ? | 0.3750 | 4 | 4.5000 | 14 | 14.0000 |
| 0.10 | 4.00 | 13.50 | | 0.4375 | 4 | 4.7500 | 14 | 14.5000 |
| 0.12 | 4.20 | 14.00 |
| 0.5000 | 5 | 5.0000 | 15 | 15.0000 |
| 0.16 | 4.40 | 14.50 | | 0.5625 | 5 | 5.2500 | 15 | 15.5000 |
| 0.20 | 4.60 | 15.00 | ? | 0.6250 | 5 | 5.5000 | 16 | 16.0000 |
| 0.24 | 4.80 | 15.50 | | 0.6875 | 5 | 5.7500 | 16 | 16.5000 |
| 0.30 | 5.00 | 16.00 |
| 0.7500 | 6 | 6.0000 | 17 | 17.0000 |
| 0.40 |
