Thread Inserts for Wood

What are thread inserts for wood? Thread inserts for wood are solid bushings with aggressive external threads that cut into timber and a standard machine thread on the inside. They exist because wood cannot hold a machine thread on its own and a wood screw driven into the same hole twice loses most of its grip the second time. An insert converts a wood joint into a bolted one, so it can be assembled and taken apart repeatedly without wearing out. AlbanyCountyFasteners.com stocks solid brass wood inserts in inch sizes from #4-40 through 3/8-24 and metric from M3 through M8.

Thread Inserts for Wood

Why brass for wood inserts?

Three reasons, and the first is the one people notice. Brass will not stain timber. Steel hardware in contact with damp wood, particularly oak, cedar, and other tannin-rich species, produces black staining around the fastener that no finish hides, and on a visible joint that ruins the piece. Brass does not react that way. Second, it resists corrosion in humid conditions and outdoor furniture where a plated steel insert would eventually seize its bolt. Third, brass is softer than steel, so it cuts into wood without the aggressive splitting force a hardened steel insert can generate in a marginal pilot hole. The trade is strength, since brass carries less torque than steel, so drive carefully and do not overtighten.

Why choose brass thread inserts for wood

Will not stain oak, cedar, and other tannin-rich woods
Corrosion resistant for humid interiors and outdoor furniture
Softer body reduces splitting risk compared with hardened steel
Warm tone blends with most timbers on visible joints
Converts a wood joint into a bolted joint that survives disassembly

Sizes stocked

Inch coarse including #4-40, #6-32, #8-32, #10-24, 1/4-20, and 5/16-18
Inch fine including #10-32, 1/4-28, 5/16-24, and 3/8-24
Metric including M3, M4, M5, M6, and M8
Lengths from 0.375 inch through 0.625 inch depending on thread size

Common applications

Fine furniture and cabinetmaking with visible joinery
Outdoor and garden furniture exposed to moisture
Oak, cedar, and tannin-rich timbers where steel would stain
Boat interiors and marine woodwork
Instrument builds and speaker cabinets
Knockdown furniture taken apart repeatedly

For higher torque capacity in interior work, our hex drive inserts for wood in zinc alloy steel drive harder without deforming. For metal rather than wood, see thread inserts for metal.

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Wood Thread Insert FAQs

What size pilot hole do I drill?

Specified per insert, and it is the single most important variable in wood. Too small and the insert splits the workpiece or stalls partway. Too large and the external threads have nothing to bite. Always test in scrap of the same species before drilling the real piece.

How do I drive a brass insert without damaging it?

Slowly and squarely. Brass is softer than steel, so the drive slot or socket deforms more readily under excessive torque. Start the insert by hand to ensure it enters straight, and back off if resistance climbs sharply, which usually means the pilot is undersized.

Will brass inserts hold as well as steel?

Pull-out strength depends mainly on the wood and the external thread engagement rather than the insert material, so holding power is comparable. Where brass gives ground is installation torque and internal thread wear under repeated heavy loading.

Can I use these outdoors?

Yes, and it is one of their main advantages. Brass resists corrosion far better than plated steel in outdoor furniture, garden structures, and marine woodwork, where a zinc plated insert would eventually corrode and seize.

Why does steel stain oak?

Tannins in the wood react with iron in the presence of moisture, producing iron tannate, which is black. Oak, cedar, chestnut, and walnut are all prone to it. Brass contains no iron, so the reaction does not occur.

Can I install these in end grain?

You can, but expect lower pull-out strength than face grain, since end grain fibers give the threads less to grip. Use the longest insert that fits and consider epoxy reinforcement where end grain is unavoidable.