How Tab-and-Slot Assembly Works

Why tab-and-slot steel holds together under heat without bolts or hinges, and what to check each time you assemble a flat pack grill.

Tab-and-slot is an old metalworking idea: one part has a tongue (the tab), the other has a matching opening (the slot), and when the tab passes through the slot the two parts are locked in position. With thick, precisely cut steel, a handful of tabs can hold a whole box rigid. The Slot Grill specs page describes it simply: the steel panels assemble by hand and hold each other in place.

Why the V shape matters

On the Slot Grill the two side panels interlock into a tight V between the end pieces. A V is a strong shape: the weight of charcoal and food pushes the sides into the joint rather than prying them apart. The remaining side panel's top tabs sit on the end pieces and its three bottom tabs slide into the first side panel, so the whole body is triangulated.

What heat does to the joints

Steel expands when hot. A grill with tight bolted joints can bind or warp at the fasteners; a slotted joint has a little designed clearance, so the parts can move slightly as they heat and cool without fighting each other. The thickness of the steel is what keeps it from flexing. That is one reason the Slot Grill uses 12- and 10-gauge carbon steel rather than thin stamped sheet.

The check that matters

1. Every tab fully through its slot, not riding on the edge.
2. End pieces with the SLOT GRILL text facing out.
3. The grill sitting level, not rocking on a corner.
4. Nothing on the grill bearing a load before the last tab is seated.

If something feels stiff, back it out and line it up again rather than forcing it. A little ash or seasoning in a slot can make a tab tight; a quick wipe fixes it. Full assembly steps are in first setup, step by step.

The two Slot Grills at a glance

Figures from SlotGrill.com. For the full breakdown, see Compact vs Full Size.

Fire safety on any collapsible grill

• Outdoors only. Burning charcoal makes carbon monoxide, which you can't see or smell. Never use it in a garage, tent, camper, vehicle, boat cabin or under a roof or awning.
• Non-combustible, level ground. Soil, gravel, sand, concrete, pavers or a fire-safe pad.
• Clearance. Away from walls, vehicles, tents, overhanging branches and dry grass. Kids and pets kept back.
• Seated tabs. Check every tab is fully in its slot before you add fuel.
• Water and gloves at hand. Hot steel looks exactly like cold steel.
• Leave it alone until cold. Don't move or take apart a lit or warm grill.

Mistakes new flat pack owners make

1. Too much charcoal. A small firebox gets very hot. Start with half a chimney and add.
2. No cool zone. Without an empty end, a flare-up has nowhere to go.
3. Cooking on black coals. Wait for gray ash.
4. Old ash left in. It blocks airflow; empty it before every cook.
5. Heavy oil when seasoning. Thin coats cure; thick coats turn gummy.
6. Packing it warm. Wait until steel and ash are cold, every time.

Questions people ask