16. Bored hole size before tapping ( for thread forming )

■ for Unified 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 (2B) engagement ratio (2B)

(Estimation %) (Estimation %)

Max.Min.Max.Min.Max.Min.Max.Min.
No.2-56UNC2BX2.041.9665~1001.8711.695No.6-40UNF2BX3.293.1970~1003.0222.820
No.2-64UNF2BX2.061.9865~1001.9121.756No.8-32UNC2BX3.893.7875~1003.5303.302
No.3-48UNC2BX2.352.2565~1002.1461.941No.8-36UNF2BX3.913.8175~1003.6063.404
No.3-56UNF2BX2.372.2965~1002.1972.025No.10-24UNC2BX4.444.3075~1003.9623.683
No.4-40UNC2BX2.642.5470~1002.3852.157No.10-32UNF2BX4.534.4480~1004.1653.963
No.4-48UNF2BX2.682.5970~1002.4582.271No.12-24UNC2BX5.074.9680~1004.5974.344
No.5-40UNC2BX2.972.8770~1002.6972.487No.12-28UNF2BX5.135.0380~1004.7244.496
No.5-44UNF2BX2.992.9070~1002.7402.5511/4-20UNC2BX5.865.7380~1005.2574.979
No.6-32UNC2BX3.223.1175~1002.8952.6421/4-28UNF2BX6.005.9180~1005.5885.360