5/8 Tap Drill Size and Drill Bit for a 5/8
Use a 17/32 drill bit
5/8-11 · 0.5313 in / 13.49 mm · ~75% thread
A 5/8 inch tap is the 5/8-11 coarse UNC thread. A 17/32 inch bit is the correct tap drill for a strong thread at 75% engagement.
At a glance
| Tap drill | 17/32 |
|---|---|
| Inches | 0.5313 in |
| Millimetres | 13.49 mm |
| Major diameter | 0.6250 in |
| Pitch | 0.0909 in |
| Threads per inch | 11 |
Why this size
5/8-11 tap drill: drillØ = major − (pitch × 0.75) = 0.6250 − (0.0909 × 0.75) = 0.5568 in → nearest standard bit = 17/32 (0.5313 in)
Large threads need accurate pilot holes. The 5/8-11 tap drill of 17/32 in leaves about 75% thread engagement. The 5/8-24 fine thread uses a 37/64 in bit (0.5781 in).