Determine the type of fit necessary (eg. loose running, free running, etc.). Find the fit at the top of one of the columns. Find the row on the left that contains the nominal size of the shaft or machined hole. Find where the column and the row intersect to find the correct values. Example: Running fit with a system that has a nominal size of 25. Preferred Metric Hole Basis Clearance Fits American National Standard – Dimensions are in millimeters. Running Free Running Basic Size Hole Shaft Hole Shaft Fit Fit H11 c11 H9 d9 1 Max 1.060 0.940 0.180 1.025 0.980 0.070 Min 1.060 0.880 0.060 1.000 0.955 0.020 Max 20.130 19.890 0.370 20.052 19.935 0.169 Min 20.000 19.760 0.110 20.000 19.883 0.065 Max 25.130 24.890 0.370 25.052 24.935 0.169 Min 25.000 24.760 0.110 25.000 24.833 0.065 From ANSI B4.2 1978 For larger diameters, see the standard. – Appendix Reading Dimensions – .1 one of an inch .01 one hundredth of an inch .001 one thousandth of an inch .0001 one ten-thousandth of an inch .00001 one millionth of an inch
Determine the type of fit necessary (eg. loose running, free running, etc.). Find the fit at the top of one of the columns. Find the row on the left that contains the nominal size of the shaft or machined hole. Find where the column and the row intersect to find the correct values. Example: Running fit with a system that has a nominal size of 25. Preferred Metric Hole Basis Clearance Fits – American National Standard Dimensions are in millimeters. Basic Size Running Free Running Hole H11 Shaft c11 Fit Hole H9 Shaft d9 Fit 1 Max Min 1.060 1.060 0.940 0.880 0.180 0.060 1.025 1.000 0.980 0.955 0.070 0.020 Max Min 20.130 20.000 19.890 19.760 0.370 0.110 20.052 20.000 19.935 19.883 0.169 0.065 Max Min 25.130 25.000 24.890 24.760 0.370 0.110 25.052 25.000 24.935 24.833 0.169 0.065 From ANSI B4.2 – 1978 For larger diameters, see the standard. Appendix – Reading Dimensions .1 one of an inch .01 one hundredth of an inch .001 one thousandth of an inch .0001 one ten-thousandth of an inch .00001 one millionth of an inch