Double-end studs, inch (ASME B18.31.2): clamping-type and tap-end studs 1/4 to 4 in, thread length B, body diameter, UNC / UNF — dimension sheet Source: Xem Studio, https://xemstudio.com/objects/double-end-studs-inch-asme-b18-31-2/ (sheet CC BY 4.0) Basis: fasten.it's ASME B18.31.2 Tables 2 (clamping type) and 3 (tap-end, 1.5D engagement) cross-checked with Torqbolt's inch and mm tables (same B min values, plus body diameter DS and length tolerance); numbers only Catalog version: 2026-10-20 Sizes: see table below - Inches (thread size also in mm). ASME B18.31.2 covers continuous-thread and double-end studs. Clamping-type double-end studs (equal thread at both ends, a nut on each end) and tap-end studs (a long thread to screw into a tapped hole, 1.5D engagement). Columns: threads per inch for the UNC and UNF series; Bm, the nominal thread length of the tap end (fasten.it Table 3, 1.5D engagement); B min, the minimum full-thread length at each end, for stud length L ≤ 10 in, 10 < L ≤ 16 in and L > 16 in (fasten.it and Torqbolt agree on every B min value; Torqbolt also prints them in mm, e.g. 1/4 in: 19.050, 25.400, 38.100); and the minimum body diameter DS (Torqbolt) for UNC and NC-5 HF threads, UNF threads, and 8UN threads (for 1-1/8 in and up). - Where a table gives no value (a dash) the standard lists none: e.g. no UNF series above 1-1/2 in, and no 'L ≤ 10 in' value from 3 in thread size up. The sources do not give the body diameter for the smaller sizes in the 8UN column. - The DIN equivalents (DIN 938 / 939, metric) are on studs-din-938-din-939. Length tolerance (Torqbolt, inches): ±0.04 for stud lengths 3/4 to 2-1/2 in, ±0.08 over 2-1/2 to 4, ±0.10 over 4 to 8, ±0.12 over 8 to 16 and ±0.18 over 16. - No files: a double-end stud with a body only slightly smaller than the thread is a plain stepped cylinder, and a plain cylinder is not worth a model. Left out: the thread-end point and chamfer (not published as numbers in the pages read). thread size (in) mm UNC (tpi) UNF (tpi) Bm tap end (in) B min, L ≤ 10 in B min, 10 < L ≤ 16 in B min, L > 16 in DS min body, UNC (in) DS min body, UNF (in) DS min body, 8UN (in) 1/4 6.35 20 28 0.375 0.75 1 1.5 .241 .243 — 5/16 7.94 18 24 0.469 0.875 1.125 1.625 .303 .304 — 3/8 9.53 16 24 0.563 1 1.25 1.75 .364 .367 — 7/16 11.11 14 20 0.656 1.125 1.375 1.875 .426 .428 — 1/2 12.7 13 20 0.75 1.25 1.5 2 .488 .491 — 9/16 14.29 12 18 0.844 1.375 1.625 2.125 .550 .552 — 5/8 15.88 11 18 0.938 1.5 1.75 2.25 .611 .615 — 3/4 19.05 10 16 1.125 1.75 2 2.5 .735 .739 — 7/8 22.23 9 14 1.313 2 2.25 2.75 .859 .863 — 1 25.4 8 12 1.5 2.25 2.5 3 .983 .987 — 1-1/8 28.58 7 12 1.688 2.5 2.75 3.25 1.106 1.112 1.108 1-1/4 31.75 7 12 1.875 2.75 3 3.5 1.231 1.237 1.233 1-3/8 34.93 6 12 2.063 3 3.25 3.75 1.354 1.362 1.358 1-1/2 38.1 6 12 2.25 3.25 3.5 4 1.479 1.487 1.483 1-5/8 41.28 — — 2.438 3.5 3.75 4.25 — — 1.608 1-3/4 44.45 5 — 2.625 3.75 4 4.5 1.727 — 1.733 1-7/8 47.63 — — 2.813 4 4.25 4.75 — — 1.858 2 50.8 4.5 — 3 4.25 4.5 5 1.975 — 1.983 2-1/4 57.15 4.5 — 3.375 4.75 5 5.5 2.225 — 2.233 2-1/2 63.5 4 — 3.75 5.25 5.5 6 2.473 — 2.483 2-3/4 69.85 4 — 4.125 5.75 6 6.5 2.723 — 2.733 3 76.2 4 — 4.5 — 6.5 7 2.973 — 2.982 3-1/4 82.55 4 — 4.875 — 7 7.5 3.223 — 3.232 3-1/2 88.9 4 — 5.25 — 7.5 8 3.473 — 3.482 3-3/4 95.25 4 — 5.625 — 8 8.5 3.723 — 3.732 4 101.6 4 — 6 — 8.5 9 3.973 — 3.982 length tolerance (inches), Torqbolt — — — — ±0.04 for L 3/4 to 2-1/2; ±0.08 over 2-1/2 to 4 ±0.10 over 4 to 8; ±0.12 over 8 to 16 ±0.18 over 16 — — — Files elsewhere (not hosted by Xem Studio; license as stated by the publisher): - fasten.it: ASME B18.31.2 continuous and double-end studs, inch series: Table 2 (clamping type) and Table 3 (tap end, 1.5D engagement): B min by stud length, Bm, UNC / UNF — web — Reference page; numbers only — https://www.fasten.it/en/norms/norm/asme_b18.31.2 - Torqbolt: ASME B18.31.2 clamping-type full-body studs: B min in inches and mm, minimum body diameter DS, length tolerance — web — Publisher's page; dimensions are facts — https://torqbolt.com/asme-b18-31-2-clamping-type-full-body-studs-dimensions-standards-specifications - Fasteners Clearinghouse: Double-ended studs (ASME B18.31.2) listing — web — Distributor listing; numbers only — https://fastenersclearinghouse.com/ansi-search=ansi-b18.31.2-double-end-studs&us-length=2_1/2&Cat1=PRM249D751F1014;&Cat2=FLF2F52C3045;&Cat7=b18.31.2; No true-size file yet: the published figures do not fix the whole shape; a measured scan is planned. API: https://xemstudio.com/api/geometry?object=double-end-studs-inch-asme-b18-31-2