Tap Size Drill Size Tap and Drill Set
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1/4" NPT Tap 7/16" Drill Bit 1/4" NPT Tap and Drill Set
3/8" NPT Tap 37/64" Drill Bit 3/8" NPT Tap and Drill Set
1/2" NPT Tap 23/32" Drill Bit 1/2" NPT Tap and Drill Set
3/4" NPT Tap 59/64" Drill Bit 3/4" NPT Tap and Drill Set
What size drill bit do I use for a 1/4 20 tap?
For a 1/4-20 bolt, the optimal drill bit size is #7 or 13/64th.