Cross dowels / barrel nuts M4–M10 (furniture bolt nuts): barrel diameter and length by thread — dimension sheet Source: Xem Studio, https://xemstudio.com/objects/cross-dowels-barrel-nuts-m4-m10/ (sheet CC BY 4.0) Basis: Essentra Components' cross dowel page (four items) and Fastenright's cross dowel table (52 rows, M4 to M10); numbers only Catalog version: 2026-10-20 Sizes: see table below - Millimetres. A cross dowel (barrel nut, cross-dowel nut) is a cylinder with a threaded hole across its diameter, set in a bored hole in the wood so a bolt in the end of the board threads into it. Essentra lists M6 at Ø10 × 13, 16 and 20 mm (zinc alloy, crossed drive) and M8 at Ø12 × 18 mm (steel, slotted): thread size, outside diameter (barrel diameter), overall length, material and drive; no hole sizes. - Fastenright's table has four columns: thread diameter, barrel diameter, L1 and L2, all mm. It does not define L1 and L2. Fastenright's L1 values include every Essentra overall length (M6 × Ø10: 13, 16, 20; M8 × Ø12: 18), so L1 reads as the overall length; L2 is usually half of L1 (for example 16 / 8, 20 / 10, 30 / 15) but not always (M6 × 10 × 16 has L2 5, 6 and 8; M6 × 10 × 12.5 has 5; M6 × 10 × 25 has 12.5 and 10), so it is not defined here and may be the cross-hole position from one end. The existing page cross-dowel-m6 carries one retailer's M6 × Ø10 × 30 barrel nut, which Fastenright lists with L2 15 and 10. - The standard drill-hole sizes for the bore the barrel sits in and the bolt hole are not printed on either page; furniture makers publish those in their drilling jigs, and none was read here. No file: the cross-hole position and thread depth are not defined in the sheets, so no model is drawn. - Tee nuts for wood: tee-nuts-for-wood-3-4-prong. Flat-pack bolts are usually M6 with a hex or Allen head; see hex-head-screws-metric and socket-head-cap-screws-metric. source thread barrel diameter (mm) length / L1 (mm) L2 (mm, as printed) note Essentra M6 10 13 — zinc alloy, crossed (Pozidriv-type) Essentra M6 10 16 — zinc alloy, crossed Essentra M6 10 20 — zinc alloy, crossed Essentra M8 12 18 — steel, slotted Fastenright M4 8 12 6 L1 and L2 as printed (not defined on the page) Fastenright M4 8 16 8 L1 and L2 as printed (not defined on the page) Fastenright M4 8 20 10 L1 and L2 as printed (not defined on the page) Fastenright M5 8 12 6 L1 and L2 as printed (not defined on the page) Fastenright M5 8 16 8 L1 and L2 as printed (not defined on the page) Fastenright M5 8 20 10 L1 and L2 as printed (not defined on the page) Fastenright M6 10 12 6 L1 and L2 as printed (not defined on the page) Fastenright M6 10 12.5 5 L1 and L2 as printed (not defined on the page) Fastenright M6 10 13 5 L1 and L2 as printed (not defined on the page) Fastenright M6 10 14 5 L1 and L2 as printed (not defined on the page) Fastenright M6 10 14 6 L1 and L2 as printed (not defined on the page) Fastenright M6 10 14 7 L1 and L2 as printed (not defined on the page) Fastenright M6 10 15 6 L1 and L2 as printed (not defined on the page) Fastenright M6 10 15 7.5 L1 and L2 as printed (not defined on the page) Fastenright M6 10 16 5 L1 and L2 as printed (not defined on the page) Fastenright M6 10 16 6 L1 and L2 as printed (not defined on the page) Fastenright M6 10 16 8 L1 and L2 as printed (not defined on the page) Fastenright M6 10 17 6 L1 and L2 as printed (not defined on the page) Fastenright M6 10 18 6 L1 and L2 as printed (not defined on the page) Fastenright M6 10 18 9 L1 and L2 as printed (not defined on the page) Fastenright M6 10 19 9.5 L1 and L2 as printed (not defined on the page) Fastenright M6 10 20 10 L1 and L2 as printed (not defined on the page) Fastenright M6 10 22 11 L1 and L2 as printed (not defined on the page) Fastenright M6 10 25 12.5 L1 and L2 as printed (not defined on the page) Fastenright M6 10 25 10 L1 and L2 as printed (not defined on the page) Fastenright M6 10 30 15 L1 and L2 as printed (not defined on the page) Fastenright M6 10 30 10 L1 and L2 as printed (not defined on the page) Fastenright M6 10 35 17.5 L1 and L2 as printed (not defined on the page) Fastenright M6 10 35 10 L1 and L2 as printed (not defined on the page) Fastenright M6 10 40 20 L1 and L2 as printed (not defined on the page) Fastenright M6 12 12 5 L1 and L2 as printed (not defined on the page) Fastenright M6 12 16 6 L1 and L2 as printed (not defined on the page) Fastenright M6 12 16 8 L1 and L2 as printed (not defined on the page) Fastenright M6 16 12 5 L1 and L2 as printed (not defined on the page) Fastenright M8 12 12 6 L1 and L2 as printed (not defined on the page) Fastenright M8 12 14 7 L1 and L2 as printed (not defined on the page) Fastenright M8 12 16 8 L1 and L2 as printed (not defined on the page) Fastenright M8 12 18 9 L1 and L2 as printed (not defined on the page) Fastenright M8 12 20 10 L1 and L2 as printed (not defined on the page) Fastenright M8 12 20 8 L1 and L2 as printed (not defined on the page) Fastenright M8 12 25 12.5 L1 and L2 as printed (not defined on the page) Fastenright M8 12 30 15 L1 and L2 as printed (not defined on the page) Fastenright M8 12 35 17.5 L1 and L2 as printed (not defined on the page) Fastenright M8 12 40 20 L1 and L2 as printed (not defined on the page) Fastenright M8 12 45 22.5 L1 and L2 as printed (not defined on the page) Fastenright M8 12 50 25 L1 and L2 as printed (not defined on the page) Fastenright M8 12 60 30 L1 and L2 as printed (not defined on the page) Fastenright M10 16 20 10 L1 and L2 as printed (not defined on the page) Fastenright M10 16 25 12.5 L1 and L2 as printed (not defined on the page) Fastenright M10 16 30 15 L1 and L2 as printed (not defined on the page) Fastenright M10 16 40 20 L1 and L2 as printed (not defined on the page) Fastenright M10 16 50 25 L1 and L2 as printed (not defined on the page) Files elsewhere (not hosted by Xem Studio; license as stated by the publisher): - Essentra Components: Cross dowel barrel nuts: M6 13 / 16 / 20 mm and M8 18 mm, outside diameter 10 and 12 mm, overall length, material, drive — web — Maker catalogue page; numbers only — https://www.essentracomponents.com/en-gb/p/cross-dowel-barrel-nuts - Fastenright: Cross dowel barrel nuts: thread diameter, barrel diameter, L1 and L2 (not defined on the page), M4 to M10 — web — Maker catalogue page; numbers only — https://www.fastenright.com/general-fixings/cross-dowel-barrel-nut/ff04 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=cross-dowels-barrel-nuts-m4-m10