AN20 at a glance
Where to buy
Specification
| Item | Value |
|---|---|
| Type | Hexagon head machine bolt |
| Material | Non-corrosion-resistant steel, corrosion-resistant steel or aluminum alloy; finish per the procurement specification |
| Status | Check the current issue before design use. Cancelled by Notice 1 (Dec 1999) and superseded by NASM3 thru NASM20; the notice states the part numbers are identical. |
Dimensions by size
| Dimension, in | 1-1/4-12 UNF-3A |
|---|---|
| Thread | 1-1/4-12 UNF-3A |
| A max — A dia, max | 1.249 |
| A min — A dia, min | 1.243 |
| B max — B, max (across flats) | 1.815 |
| B min — B, min (across flats) | 1.802 |
| C — C, ref (across corners) | 2.090 |
| D max — D, max (head height) | .672 |
| D min — D, min (head height) | .640 |
| H — H dia, min | 1.772 |
| J — J drill (shank hole), +.010 −.000 | .141 |
| K — K drill (head hole), +.010 −.000 | .070 |
Dimensions in inches, as tabulated in the standard (letters as on its drawing).
Part numbers
Part numbers by dash number, with grip and length. The standard governs.
1-1/4-12 UNF-3A53 part numbers
| Part no. | Grip, in | Length, in |
|---|---|---|
| AN20-15 | 1/8 | 1-13/16 |
| AN20-16 | 1/4 | 1-15/16 |
| AN20-17 | 3/8 | 2-1/16 |
| AN20-20 | 1/2 | 2-3/16 |
| AN20-21 | 5/8 | 2-5/16 |
| AN20-22 | 3/4 | 2-7/16 |
| AN20-23 | 7/8 | 2-9/16 |
| AN20-24 | 1 | 2-11/16 |
| AN20-25 | 1-1/8 | 2-13/16 |
| AN20-26 | 1-1/4 | 2-15/16 |
| AN20-27 | 1-3/8 | 3-1/16 |
| AN20-30 | 1-1/2 | 3-3/16 |
| AN20-31 | 1-5/8 | 3-5/16 |
| AN20-32 | 1-3/4 | 3-7/16 |
| AN20-33 | 1-7/8 | 3-9/16 |
| AN20-34 | 2 | 3-11/16 |
| AN20-35 | 2-1/8 | 3-13/16 |
| AN20-36 | 2-1/4 | 3-15/16 |
| AN20-37 | 2-3/8 | 4-1/16 |
| AN20-40 | 2-1/2 | 4-3/16 |
| AN20-41 | 2-5/8 | 4-5/16 |
| AN20-42 | 2-3/4 | 4-7/16 |
| AN20-43 | 2-7/8 | 4-9/16 |
| AN20-44 | 3 | 4-11/16 |
| AN20-45 | 3-1/8 | 4-13/16 |
| AN20-46 | 3-1/4 | 4-15/16 |
| AN20-47 | 3-3/8 | 5-1/16 |
| AN20-50 | 3-1/2 | 5-3/16 |
| AN20-51 | 3-5/8 | 5-5/16 |
| AN20-52 | 3-3/4 | 5-7/16 |
| AN20-53 | 3-7/8 | 5-9/16 |
| AN20-54 | 4 | 5-11/16 |
| AN20-55 | 4-1/8 | 5-13/16 |
| AN20-56 | 4-1/4 | 5-15/16 |
| AN20-57 | 4-3/8 | 6-1/16 |
| AN20-60 | 4-1/2 | 6-3/16 |
| AN20-61 | 4-5/8 | 6-5/16 |
| AN20-62 | 4-3/4 | 6-7/16 |
| AN20-63 | 4-7/8 | 6-9/16 |
| AN20-64 | 5 | 6-11/16 |
| AN20-65 | 5-1/8 | 6-13/16 |
| AN20-66 | 5-1/4 | 6-15/16 |
| AN20-67 | 5-3/8 | 7-1/16 |
| AN20-70 | 5-1/2 | 7-3/16 |
| AN20-71 | 5-5/8 | 7-5/16 |
| AN20-72 | 5-3/4 | 7-7/16 |
| AN20-73 | 5-7/8 | 7-9/16 |
| AN20-74 | 6 | 7-11/16 |
| AN20-75 | 6-1/8 | 7-13/16 |
| AN20-76 | 6-1/4 | 7-15/16 |
| AN20-77 | 6-3/8 | 8-1/16 |
| AN20-80 | 6-1/2 | 8-3/16 |
| AN20-81 | 6-5/8 | 8-5/16 |
Part number
What each code means
| Part | Meaning |
|---|---|
| Format | AN20-<dash> |
| Example | AN20-15 — Non-corrosion-resistant steel bolt, 1-1/4 in, grip 1/8, length 1-13/16, drilled shank only |
Notes from the standard
- Dash number sets the length and grip. Add C before the dash number for a corrosion-resistant steel bolt and DD for an aluminum alloy bolt; A after the dash number for an undrilled bolt; H before the dash number for a drilled head and shank; H before and A after for a drilled head only.
- Examples: AN20-10 is the non-corrosion-resistant steel bolt with a drilled shank only; AN20C10 is the corrosion-resistant steel bolt; AN20-10A is undrilled.
- Grip tolerance ±1/64 in; length tolerance +1/32 −1/64 in. Grip is measured from the underside of the head to the end of the full cylindrical portion of the shank; complete threads begin within two thread pitches at most.
- Part number format as commonly written; check the standard for the exact format.
- Approved data governs. Use the bolt the SRM, drawing or IPC calls for.
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Sources
- AN3 thru AN20 Rev. 12, 14 Jan 1991 — Bolt — Machine, Aircraft — dimensions, part numbers and notes. Public domain, distribution unlimited.
Educational reference only. not approved data. Always consult the applicable SRM, AMM, or AC 43.13-1B and your certifying authority.