Bored hole size before tapping ( for thread forming )

■ for Metric Threads

unit: mm ref.Minor diameter ref.Minor diameter Recommended Recommended

thread of internal threads thread of internal threads

Size Class Hole Size(mm) Size Class Hole Size(mm)

engagement ratio (5H/6H) engagement ratio (5H/6H)

(Estimation %) (Estimation %)

Max.Min.Max.Min.Max.Min.Min. Max.
ISO2X0.920.8980~100ISO2X7.527.3980~100
M1×0.250.7850.729M8×1.256.647 6.912
ISO3X0.910.8975~90ISO3X7.517.4180~95
ISO2X1.111.0980~100ISO2X7.607.4980~100
M1.2×0.250.9850.929M8×16.917 7.153
ISO3X1.111.0975~90ISO3X7.607.5280~95
ISO2X1.301.2680~100ISO2X9.389.2685~100
M1.4×0.31.1421.075M10×1.58.376 8.676
ISO3X1.301.2770~90ISO3X9.419.2980~95
ISO2X1.471.4375~100ISO2X9.529.3880~100
M1.6×0.351.3211.221M10×1.258.647 8.912
ISO3X1.481.4470~95ISO3X9.509.4080~95
ISO2X1.851.8075~100ISO2X11.2711.13 85~100
M2×0.41.6791.567M12×1.7510.441 10.106
ISO3X1.871.8170~95ISO3X11.2611.1785~95
ISO2X2.342.2775~100ISO2X11.4211.25 85~100
M2.5×0.452.1382.013M12×1.510.676 10.376
ISO3X2.342.2975~95ISO3X11.4011.2880~95
ISO2X2.832.7675~100ISO2X11.5111.37 80~100
M3×0.52.5992.459M12×1.2510.912 10.647
ISO3X2.822.7675~95ISO3X11.5011.4080~95
ISO2X3.303.2275~100ISO2X13.1713.00 85~100
M3.5×0.63.0102.850M14×212.210 11.835
ISO3X3.283.2275~95ISO3X13.1513.0585~95
ISO2X3.733.6680~100ISO2X13.3613.23 85~100
M4×0.73.4223.242M14×1.512.676 12.376
ISO3X3.743.6775~95ISO3X13.4013.2880~95
ISO2X4.684.6080~100ISO2X15.1715.00 85~100
M5×0.84.3344.134M16×214.210 13.835
ISO3X4.714.6275~95ISO3X15.1515.0485~95
ISO2X5.605.5080~100ISO2X15.3515.23 85~100
M6×15.1534.917M16×1.514.676 14.376
ISO3X5.615.5380~95ISO3X15.4015.2780~95