Barrel Nut

What a barrel nut (sex bolt) does

A barrel nut is a nut made as a headed tube with a female thread inside. Hobson describes it as one half of the fixing in timber and furniture connections: the screw or bolt goes through the parts from one side, the barrel nut goes in from the other, and the two are tightened together. Matched with a screw that has the same head, the same head shows on both sides of the joint and no thread is left sticking out.

That pair is what the trade calls a sex bolt. Typical jobs are furniture and joinery, bed frames and flat-pack furniture, timber connections, and park, playground and public furniture where a tamper-resistant fixing with no exposed thread is wanted; Hobson publishes no load rating for these nuts, so fixings on play equipment and anything that carries people or loads come from the equipment or structural designer's specification.

Which barrel nut: furniture, security or countersunk Phillips?

• •Furniture barrel nut (M6 x 15, zinc plated or 304 stainless): a plain barrel for building and restoring furniture. Hobson lists the zinc plated one with a slotted drive for turning it into position and a standard M6 coarse thread, recommended with its nickel plated furniture connector bolts (M6, 16 to 80mm).
• •Furniture connector nut (M6 in nickel plated or 304 stainless, M8 nickel plated): a head with a hex socket for a standard Allen key, made to match the head of the furniture connector bolts so both faces look the same. The nut is one length; the bolts come in lengths to suit the material thickness. For wooden furniture and cabinetry.
• •Security barrel nut, countersunk Post Torx (316 stainless, M4 to M10): a two-way security fitting with a pin in the Torx recess, used with Hobson's matching Post Torx screws for an even appearance on both sides. Hobson lists furniture connections, children's playgrounds and other areas where security matters, but publishes no load rating for it, so on play equipment use the fixings the equipment designer specifies.
• •Security barrel nut, button head Post Torx (304 stainless, 3/8 UNC): Hobson lists it for outdoor play equipment and fixings in public facilities, used with Hobson's matching 3/8 UNC Post Torx button screw; Hobson publishes no load rating for it, so fixings on play equipment come from the equipment designer's specification. The M5 to M10 button head Post Torx barrel nuts are on their own page.
• •Countersunk Phillips barrel nut (316 stainless, M5 to M10): a Phillips #3 drive. Hobson lists it for fastening timber and furniture, and as a decorative nut on a protruding male thread.

Barrel nut sizes

Match the thread to the screw or bolt (an M6 barrel nut takes an M6 screw), then check the thread length: the screw has to reach well into the barrel without bottoming out. Select a row to open that nut in the selector.

Zinc, nickel, 304 or 316 stainless?

• •Zinc plated: a 5 micron zinc coating that Hobson recommends for indoor and non-corrosive environments. Indoor furniture only.
• •Nickel plated: Hobson lists the nickel plated connector nuts for their appearance in timber. Indoor furniture and cabinetry.
• •304 stainless: for outdoor and damp work. Hobson's corrosion guide calls for 304 or 316 stainless (or hot dip galvanising) where a fixing is exposed to the weather.
• •316 stainless: Hobson lists its 316 Post Torx barrel nuts for harsh outdoor and marine environments, and its corrosion guide calls for 316 within 2m of a pool. 316 copes better near the sea, but neither 304 nor 316 is made to sit in seawater.

How to fit a barrel nut

1. Drill through both parts so the screw passes from one side and the barrel nut's body fits from the other. Hobson publishes no hole sizes, so drill a test hole in an offcut to suit the body of the nut.
2. Pass the screw or bolt through the hole from one side.
3. Fit the barrel nut onto the screw from the other side.
4. Tighten the barrel nut with the right driver: a slotted screwdriver, the hex key in the table, a Phillips #3 bit, or the Post Torx key or bit for the security nuts (T45 for the 3/8 UNC button nut).
5. Stainless screw into stainless nut: Hobson's galling guide suggests a slower installation speed and a thread lubricant to stop the threads seizing.

Loads and safety

Hobson publishes no load or strength rating for these barrel nuts. Use them for furniture, joinery and fixings; for play equipment, structures or anything that carries people or loads, the fixings and their sizes come from the equipment or structural designer's specification.

Barrel nuts in Adelaide

Allmat supplies barrel nuts, connector bolts, security screws and bits to cabinet makers, joiners, carpenters and park and playground installers across Adelaide and South Australia. Add them to a quote with the matching screws and we will price the lot.

Questions