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Cross dowels / barrel nuts M4–M10 (furniture bolt nuts): barrel diameter and length by thread

What are the diameter and length of an M6 cross dowel (barrel nut) for a bed or table bolt? · Standard part · basis: Essentra Components' cross dowel page (four items) and Fastenright's cross dowel table (52 rows, M4 to M10); numbers only

Also called: m6 cross dowel dimensions, m6 barrel nut size, cross dowel 10 mm diameter, m8 barrel nut dimensions, cross dowel nut sizes, barrel nut 10 x 16, m6 cross dowel 15 mm, m4 barrel nut cross dowel, ikea cross dowel size, furniture barrel nut hole size, m10 cross dowel nut size, cross dowel l1 l2

Exact dimensions. True size, with no tolerance added.

sizes: 56 in table

Notes

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.

Cross dowels / barrel nuts M4–M10 (furniture bolt nuts): barrel… size chart

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)

Where the files are

Other publishers' files are linked, not hosted. "verify" = check the license at the link before commercial use.

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
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

Xem scan

File coming

No downloadable true-size file yet: the published figures do not fix the whole shape, and Xem never guesses a number. A measured scan is planned; request it and it moves up.

Let your AI pull this. Add https://xemstudio.com/mcp to Claude, ChatGPT, Cursor or any MCP client (free, no account, one minute) and it can look up exact sizes, mating fits and free STEP/STL from every chat.

Set it up →

Plain text: sheet.txt · JSON: /api/geometry?object=cross-dowels-barrel-nuts-m4-m10

Schematic, not to scale.