1-1/4 NPT tap drill size
1-1/2"
- Inches
- 1.5000
- Millimetres
- 38.10
- Threads per inch
- 11.5
Drill a 1-1/2" hole, then cut the 1-1/4 NPT thread with a taper pipe tap. This is the size for drilling and tapping with no reamer step.
Charts differ on pipe threads. Some list a smaller drill because they assume the hole is taper-reamed first. If you ream, use the drill size your tap or reamer maker lists.
1-1/4 NPT thread and hole sizes
| Thread | 1-1/4 NPT National Pipe Taper, 11.5 threads per inch |
|---|---|
| Tap drill, no reamer | 1-1/2" 1.5000 in, 38.10 mm |
| Pitch | 0.0870 in 2.209 mm |
Tools for this job
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