Threads / Size reference
2-4 1/2 UNC
2-4 1/2 has a nominal outside diameter of 50.8 mm and a 5.644444 mm pitch.
50.8 mm
5.644444 mm pitch
Nominal dimensions; no class allowances or acceptance limits applied. Diameter is in inches; the number after the dash is TPI.
nearby diameter comparison
2-4 1/2 vs 1 3/4-5
There is no second pitch at this diameter in the directory. Compare the nearby 1 3/4-5 UNC: its nominal diameter differs by 6.35 mm. It is not a replacement.
Swipe to compare both sizes →
| Property | 2-4 1/2 UNC | 1 3/4-5 UNC |
|---|---|---|
| Nominal diameter · inDifferent | 2 | 1.75 |
| Nominal diameter · mmDifferent | 50.8 | 44.45 |
| Threads per inchDifferent | 4.5 | 5 |
| Pitch · mmDifferent | 5.644444 | 5.08 |
Tapping-hole evidence for 2-4 1/2
No reviewed chart row for 2-4 1/2 UNC
You can calculate a theoretical hole with the cited equation. It is not a stocked-drill selection or a tool-specific hole range.
Need acceptance limits?
The complete class and applicable drawing requirements are needed. These nominal values are not maximum/minimum inspection limits.
Part has no marking?
Measure the correct diameter and pitch, then compare candidates across metric and inch systems.
Basis for this size
Nominal designation and family transcribed from the live directory on 2026-10-19; unit conversions are calculated using exactly 25.4 mm/in. No matching drill row has been reviewed for this exact size. Paid standard limit tables have not been reviewed.
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