#5-44 tap drill size
#37
- Inches
- 0.1040
- Millimetres
- 2.64
- Thread
- 71%
Drill a #37 hole before cutting a #5-44 thread. That is the standard tap drill for about 75% thread.
#5-44 thread and hole sizes
| Thread | #5 diameter, 44 threads per inch, fine (UNF) |
|---|---|
| Major diameter | 0.1250 in 3.17 mm |
| Pitch | 0.0227 in 0.577 mm |
| Tap drill, about 75% thread | #37 0.1040 in |
| Tap drill, about 50% thread | #35 0.1100 in, for stainless and other hard materials |
| Clearance hole, close fit | #30 0.1285 in |
| Clearance hole, free fit | #29 0.1360 in |
| Nearest metric bit | 2.6 mm |
Why #37
A tap cuts threads into the wall of a hole, so the hole has to be smaller than the screw. For a #5-44 thread the hole that leaves exactly 75% thread is 0.1029 in. The closest standard bit is #37 at 0.1040 in, which leaves 71%.
More thread than that adds almost no strength and makes the tap much easier to break. In hard or tough material, go one step larger.
Tools for this job
- #5-44 tap
- #37 drill bit
- Tap and drill set
- Drill bit size gauge
- Thread pitch gauge
- Cutting oil for tapping
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