# Acme threads 1/4-16 to 2-4 (ASME B1.5): 1/2-10, 5/8-8, 3/4-6, 1-5, 1-1/2-4, 2-4: major, pitch and minor diameter, pitch

> What are the major, pitch and minor diameters and the pitch of 1/2-10, 5/8-8, 3/4-6, 1-5 and 2-4 Acme lead screw threads?

- Category: Hardware › Bearings, rails & motion
- Kind: Standard part
- Basis: Bornemann Gewindetechnik ASME B1.5 nominal-dimension table with formula checks on every row and MachiningDoctor pages for 5/16-14 and 2-4; numbers only
- Page: https://xemstudio.com/objects/acme-threads-asme-b1-5-1-4-to-2-in/ · JSON: https://xemstudio.com/api/geometry?object=acme-threads-asme-b1-5-1-4-to-2-in · Plain text: https://xemstudio.com/objects/acme-threads-asme-b1-5-1-4-to-2-in/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); files CC BY 4.0 or their publisher's license
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**Exact dimensions.** True size, with no tolerance added.

## Notes

- General-purpose Acme (ASME B1.5, 29 degree flank angle) is the inch lead-screw thread: 1/2-10 Acme is a 1/2 in screw with 10 threads per inch, so the pitch (and, single-start, the lead) is 0.100 in. The basic formulas are d2 = d - P/2 and d1 = d - P; the generator checks both, and P = 1/TPI, on every row.
- Numbers: Bornemann Gewindetechnik's ASME B1.5 nominal-dimension table (inches as printed), with MachiningDoctor's 5/16-14 and 2-4 pages as the independent check (5/16-14: major 0.3125, pitch 0.2768, minor 0.2411, pitch 0.07143; 2-4: pitch diameter 1.875, minor 1.75, pitch 0.25). The mm columns are the printed inch values times 25.4 (rounded to 0.01 mm). Bornemann's table runs on to 5-2 Acme; only 1/4 to 2 in are shown here.
- Numbers only, no files: lead, start count and length are the user's choices and the helical form is not a published envelope. The Class 2G / 3G / 4G tolerance bands (MachiningDoctor prints them, e.g. 2-4 external pitch diameter 1.8402 to 1.8637 in) are left out.
- Left out: stub Acme, centralizing Acme, Class 2G / 3G / 4G limits, multi-start leads, sizes above 2 in, the metric Tr thread (separate page).

## Sizes

| thread | TPI | major Ø d, in | pitch P, in | pitch Ø d2, in | minor Ø d1, in | d, mm | P, mm | d2, mm | d1, mm |
|---|---|---|---|---|---|---|---|---|---|
| 1/4-16 Acme | 16 | 0.2500 | 0.0625 | 0.2188 | 0.1875 | 6.35 | 1.59 | 5.56 | 4.76 |
| 5/16-14 Acme | 14 | 0.3125 | 0.0714 | 0.2768 | 0.2411 | 7.94 | 1.81 | 7.03 | 6.12 |
| 3/8-12 Acme | 12 | 0.3750 | 0.0833 | 0.3333 | 0.2917 | 9.53 | 2.12 | 8.47 | 7.41 |
| 7/16-12 Acme | 12 | 0.4375 | 0.0833 | 0.3958 | 0.3542 | 11.11 | 2.12 | 10.05 | 9.00 |
| 1/2-10 Acme | 10 | 0.5000 | 0.1000 | 0.4500 | 0.4000 | 12.70 | 2.54 | 11.43 | 10.16 |
| 5/8-8 Acme | 8 | 0.6250 | 0.1250 | 0.5625 | 0.5000 | 15.88 | 3.18 | 14.29 | 12.70 |
| 3/4-6 Acme | 6 | 0.7500 | 0.1667 | 0.6667 | 0.5833 | 19.05 | 4.23 | 16.93 | 14.82 |
| 7/8-6 Acme | 6 | 0.8750 | 0.1667 | 0.7917 | 0.7083 | 22.23 | 4.23 | 20.11 | 17.99 |
| 1-5 Acme | 5 | 1.0000 | 0.2000 | 0.9000 | 0.8000 | 25.40 | 5.08 | 22.86 | 20.32 |
| 1-1/8-5 Acme | 5 | 1.1250 | 0.2000 | 1.0250 | 0.9250 | 28.58 | 5.08 | 26.04 | 23.50 |
| 1-1/4-5 Acme | 5 | 1.2500 | 0.2000 | 1.1500 | 1.0500 | 31.75 | 5.08 | 29.21 | 26.67 |
| 1-3/8-4 Acme | 4 | 1.3750 | 0.2500 | 1.2500 | 1.1250 | 34.93 | 6.35 | 31.75 | 28.58 |
| 1-1/2-4 Acme | 4 | 1.5000 | 0.2500 | 1.3750 | 1.2500 | 38.10 | 6.35 | 34.93 | 31.75 |
| 1-3/4-4 Acme | 4 | 1.7500 | 0.2500 | 1.6250 | 1.5000 | 44.45 | 6.35 | 41.28 | 38.10 |
| 2-4 Acme | 4 | 2.0000 | 0.2500 | 1.8750 | 1.7500 | 50.80 | 6.35 | 47.63 | 44.45 |

## Where the files are

- Bornemann Gewindetechnik: [ACME thread according to ANSI / ASME B1.5-1977, nominal dimensions: d, d2 = D2, P, d1, 1/4-16 to 5-2 (with 3D model links)](https://www.bornemann-gewindetechnik.de/en/products/acme-screws-and-leadscrews/data/) — web — Publisher's page; dimensions are facts
- MachiningDoctor: [Acme thread basic dimensions (ASME B1.5): 5/16-14 and 2-4 pages (TPI, pitch, major, pitch, minor diameter)](https://www.machiningdoctor.com/threadinfo-acme/?tid=5001) — web — Publisher's page; dimensions are facts

## Questions

**What are the dimensions of a 1/2-10 Acme thread?**

Major diameter 0.5000 in (12.70 mm), 10 TPI (pitch 0.1000 in = 2.54 mm), pitch diameter 0.4500 in, minor diameter 0.4000 in (Bornemann, ASME B1.5).

**What are the dimensions of a 3/4-6 Acme thread?**

Major 0.7500 in, 6 TPI (pitch 0.1667 in), pitch diameter 0.6667 in, minor diameter 0.5833 in.

**What are the dimensions of a 1-5 Acme thread?**

Major 1.0000 in, 5 TPI (pitch 0.2000 in), pitch diameter 0.9000 in, minor 0.8000 in.

**What are the dimensions of a 2-4 Acme thread?**

Major 2.0000 in, 4 TPI (pitch 0.2500 in), pitch diameter 1.8750 in, minor 1.7500 in; MachiningDoctor gives the same.

**How do I get the pitch diameter of an Acme thread?**

d2 = d - P/2 and the minor diameter d1 = d - P, with P = 1/TPI.

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