Galvanized Double-Ended Hanger Bolts M4 M5 M6 M8 M10, Wood-to-Metal Screws

A hanger bolt has no head. One end has a coarse wood-screw thread that drives directly into timber; the other end has a standard metric machine thread that accepts a nut or screws into a metal insert. You need one when you want to create a threaded stud embedded in wood — for example, to attach a metal furniture leg, mount a caster, or connect a metal bracket to a wooden post without any visible bolt head.

Use the jam-nut method: thread two hex nuts onto the machine-thread end and tighten them firmly against each other. Use a wrench on the outer nut to drive the wood-screw end into a pre-drilled pilot hole. Once the bolt is fully seated, remove both nuts by loosening them against each other. This is the standard installation method and requires no special tools.

Drill approximately 70–80% of the bolt’s root diameter. Recommended pilot hole sizes: M4 → 2.5 mm; M5 → 3.0 mm; M6 → 4.0 mm; M8 → 5.5 mm; M10 → 7.0 mm. Always test on a scrap piece of the same wood species first — harder woods may need a slightly larger pilot hole to avoid splitting.

The galvanized coating provides good corrosion resistance for covered outdoor furniture, garden sheds, and protected structures. For direct rain exposure, ground contact, or coastal salt-air environments, stainless steel hanger bolts would be a more durable choice. For most indoor furniture and sheltered outdoor applications, these galvanized bolts perform well.

Yes — this is one of the most common applications. Drill a pilot hole in the furniture leg, drive the hanger bolt in using the jam-nut method, then screw the caster’s threaded socket onto the exposed machine thread. Make sure the caster’s thread size matches the bolt (e.g., an M8 caster socket requires an M8 hanger bolt).

The flat washers (M4–M8) distribute clamping load over a wider surface area, preventing the nut from pulling into soft wood or thin metal. The wing nuts (M4–M8) allow tool-free hand-tightening — useful for furniture that needs to be assembled and disassembled regularly, such as display fixtures, trade show furniture, or adjustable workshop jigs.

M4 is suitable for light decorative fittings and small furniture. M5 works for medium-duty furniture legs and light brackets. M6 is the most common general-purpose size for dining tables, shelving, and bed frames. M8 handles heavy shelving, workbenches, and structural furniture. M10 is for heavy-duty structural connections such as gym equipment, large workbenches, and load-bearing timber frames. When in doubt, size up.