UNCcoarse60° flank
1-3/4-5 UNC Thread Dimensions
1-3/4-5 UNC is a coarse pitch UNC thread. There are 5 threads per inch, giving a pitch of 5.08 mm. The recommended tap drill leaves roughly 75% thread engagement.
Nominal Ø44.45 mm
Pitch5.08 mm
Threads per inch5
Pitch Ø-39.36 mm
Tap drill-84.58 mm
Thread profile
millimetres unless stated- Designation
- 1-3/4-5 UNC
- Thread system
- UNC
- Series
- coarse
- Flank angle
- 60°
- Major diameter
- 44.45 mm / 1.75"
- Pitch
- 5.08 mm
- Threads per inch
- 5
- Pitch diameter
- -39.36 mm
- Minor diameter (external)
- -113.86 mm
- Minor diameter (internal)
- -95.23 mm
- Thread depth
- 79.15 mm
- Recommended tap drill
- Ø -84.58 mm / -3.33"
How these values are derived
Basic ISO thread geometry uses the fundamental triangle height H = 0.866025 × P. External minor diameter d₃ = d − 1.226869 × P, internal minor diameter D₁ = d − 1.082532 × P. Tap drill is given as nominal diameter minus pitch, which approximates a 75% thread engagement — adjust for tough materials or deep holes.