![NPT & NPTF NPS & NPSF Pipe Tap Size Pitch (TPI) Drill Size* (inch) Pitch (TPI) Drill Size (inch) 1/16 27 0.242 (C) - - 1 NPT & NPTF NPS & NPSF Pipe Tap Size Pitch (TPI) Drill Size* (inch) Pitch (TPI) Drill Size (inch) 1/16 27 0.242 (C) - - 1](https://www.alliedmachine.com/AlliedMachine/media/AlliedMasterPageImages/OnlineTools/Tap%20Drill%20Charts/Thumbnails/LPI_National-Pipe-Threads.jpg)
NPT & NPTF NPS & NPSF Pipe Tap Size Pitch (TPI) Drill Size* (inch) Pitch (TPI) Drill Size (inch) 1/16 27 0.242 (C) - - 1
![Roof Window Pramet e7101/2 HSS Bright NPT Machine Tap Drill Straight Flute ANSI B94.1 1/2" X 14 : Amazon.de: DIY & Tools Roof Window Pramet e7101/2 HSS Bright NPT Machine Tap Drill Straight Flute ANSI B94.1 1/2" X 14 : Amazon.de: DIY & Tools](https://m.media-amazon.com/images/I/61R1-TKwkrL._AC_UF1000,1000_QL80_.jpg)
Roof Window Pramet e7101/2 HSS Bright NPT Machine Tap Drill Straight Flute ANSI B94.1 1/2" X 14 : Amazon.de: DIY & Tools
![1/4-20 x 1 inch Phillips Countersunk Screws (ANSI B18.6.3) - Thread Locking A2 Stainless Steel: Accu.co.uk: Precision Screws 1/4-20 x 1 inch Phillips Countersunk Screws (ANSI B18.6.3) - Thread Locking A2 Stainless Steel: Accu.co.uk: Precision Screws](https://i.accu.co.uk/360/_APC/SIK-A2-R360/0_8.png?cw=100.0000%25&ch=100.0000%25&scale.option=fill&w=500&h=0&q=90)
1/4-20 x 1 inch Phillips Countersunk Screws (ANSI B18.6.3) - Thread Locking A2 Stainless Steel: Accu.co.uk: Precision Screws
What size drill bit would I use to drill hole to then to a 1/4' tap to make threads? Would I be using a 1/4 drill bit or is a 7/32' better
![General Tools Drill Grinding Attachment #825 - Drill Accessories - For use with ANSI, OSHA, and UL: Power Drill Bit Extensions: Amazon.com: Industrial & Scientific General Tools Drill Grinding Attachment #825 - Drill Accessories - For use with ANSI, OSHA, and UL: Power Drill Bit Extensions: Amazon.com: Industrial & Scientific](https://m.media-amazon.com/images/I/71kS31KptDL.jpg)