How to Install Furniture Bolts (Joint Connector Bolts)

Make installing furniture bolts go smoothly. Avoid cross-threading and other pitfalls common to furniture bolts.

What Is A Furniture Bolt

Furniture bolt is the shorthand for a commonly used socket head and barrel nut combo often seen in flat-pack furniture. It’s also called a Joint Connector Bolt, or JCB.

Furniture bolts are popular because they make assembly and disassembly easy, while providing a secure connection between parts. The low profile head offers a clean appearance, and typically has a hex socket for tightening.

A pair of hands holding a bolt and barrel nut, demonstrating how to connect two pieces of furniture hardware.

Tools Needed

2x 4mm hex key

A hand holding a hex key, which is used to tighten or loosen bolts during furniture assembly.

It is important to use the right size hex key. If you use a hex key that's too small, it can round out the corners of the hex socket making it unusable. This can also happen if you over tighten the bolts.

All Grid Kit furniture bolts use a 4mm hex key.

What Sizes To Use

With Grid Kit there are a few different scenarios that use different bolt/nut combinations.

Beam to beam
Beam to 12mm panel
Beam to beam to 12mm panel
Beam to 18mm panel
Beam to beam to 18mm panel

Close-up of two wooden beams connected by a bolt. The bolt head and a nut are visible, securing the connection between the beams.

Two wooden beams are placed perpendicularly, joined with a metal bolt passing through a 12mm panel. The bolt's head is visible on top of the panel.

Two wooden beams are joined by a bolt passing through a 12mm panel, with a second beam visible beneath the panel, creating a stacked connection.

Two wooden beams are placed perpendicularly, joined with a metal bolt passing through a 18mm panel. The bolt's head is visible on top of the panel.

Two wooden beams are joined by a bolt passing through a 18mm panel, with a second beam visible beneath the panel, creating a stacked connection.

All of these common scenarios can be made with just 2 sizes of bolt and 3 sizes of barrel nut

Bolts

33mm length M6 bolt
73mm length M6 bolt

Nuts

12mm length M6 barrel nut
25mm length M6 barrel nut
30mm length M6 barrel nut

Beam To Beam Connections

Grid Beam : Grid Beam

73mm length M6 bolt
12mm length M6 barrel nut

Beam To 12mm Panel Connections

Grid Beam : 12mm Panel

33mm length M6 bolt
25mm length M6 barrel nut

Grid Beam : Grid Beam : 12mm Panel

73mm length M6 bolt
25mm length M6 barrel nut

Beam To 18mm Panel Connections

Grid Beam : 18mm Panel

33mm length M6 bolt
30mm length M6 barrel nut

Grid Beam : Grid Beam : 18mm Panel

73mm length M6 bolt
30mm length M6 barrel nut

Here's How To Determine Which Size Combo To Use

How many beams?

1 beam = 33mm length M6 bolt
2 beams = 73mm length M6 bolt

For other less common scenarios like 3+ beam connections larger 113mm bolts or threaded rods can be used.

Which panel?

No Panel = 12mm length M6 barrel nut
12mm Panel = 25mm length M6 barrel nut
18mm Panel = 30mm length M6 barrel nut

A decision tree for selecting the correct nut and bolt pair based on connection type and panel thickness. The tree starts with the question "Picking The Right Nut/Bolt Pair." It branches into two main categories: "Is the connection Beam to Beam?" and "Is the connection Beam to Panel?" For Beam to Beam connections: If connecting 2 beams, it suggests using a 73mm bolt with a 12mm barrel nut. If connecting 3 beams, use a 100mm threaded rod with two 25mm barrel nuts. For 3+ beams, it notes this is uncommon but possible with a threaded rod and two barrel nuts. For Beam to Panel connections: A 12mm panel branches further: For 1 beam, use a 33mm bolt with a 25mm barrel nut. For 2 beams, use a 73mm bolt with a 25mm barrel nut. For 3+ beams, similar to Beam to Beam, it notes this is uncommon but achievable with a threaded rod and two barrel nuts. An 18mm panel also branches: For 1 beam, use a 33mm bolt with a 30mm barrel nut. For 2 beams, use a 73mm bolt with a 30mm barrel nut. For 3+ beams, as above, it suggests a threaded rod with two barrel nuts. Each decision point is connected with color-coded shapes, distinguishing between connection types and panel thickness.

How To Install

First put the bolt through the connection you would like to make. Then insert the barrel nut from the opposite side until the bolt and nut meet.

Listen For The Click (How To Avoid Cross-Threading)

Before starting to tighten the bolt, press the nut and bolt together and twist the nut and/or bolt counterclockwise until you hear an audible click. This is the sound of the start of the threads aligning. If you do not hear this sound your bolt and nut may not be aligned. If you start to tighten before you hear this click there is a risk of cross threading the nut and bolt. This will damage the threads and make it very difficult or impossible to install.
After you hear the click start tightening the bolt. It should be easy to tighten by hand for the first few rotations of the bolt.

Troubleshooting: If you don’t hear a click there are a few things to check.

Make sure there is no debris between the bolt and the nut.
check that you have the right nut/bolt combo for the connection
Nut and bolt may not be aligned and seated correctly. Try moving the bolt around, to adjust the alignment.
Other installed bolts may be overly tightened causing a misalignment of the joint currently being assembled.

Loose Fit

Once the bolt/nut pair has been tightened by hand, continue assembling the rest of your project before tightening the joint with the 4mm hex keys. If you tighten your joints as you go, it may be difficult to connect some joints later in the assembly process.

Final Tightening

Once your project has been assembled it’s now time to tighten all of the joints using a 4mm hex key on the nut and on the bolt side to tighten the joint the rest of the way. If you only use a hex key on one side (e.g. Hex key on Just the bolt side or just the nut side), the bolt will spin endlessly.

Maintenance Tightening

Because wood can compress under pressure, you may need to retighten the bolts after a few days. Repeat this process until the wood has fully compressed and is stable.

For further tips, advice, and inspiration, visit the Grid Kit discussion board.