I want to know the minimum thickness for a steel bracket that attaches a table leg to a table top.
I'm designing a table like this
I'm in the process of designing the steel bracket that joins each leg to the top. The bracket will be held in place with 3/8" steel bolts going into inserts (three of them on each face, with the inserts and bolts penetrating 1/2" into the wood).
The bracket is 16 inches wide and its legs are 4" and 2" long. One bracket-leg is shorter so it can be hidden between the leg and tabletop.
The table legs are 27 inches tall and 2 inches thick. The top is 2 inches thick and weighs about 200 pounds, if that matters.
The questions are:
1. How thick does the steel bracket need to be?
2. Brake-bent sheet material, or extruded angle steel?
I want to be sure that either the bolts or the wood fails before the bracket. The worst-case loads I can think of are:
- Heavy objects falling on the table (e.g., in an earthquake, a few hundred pounds of roof might fall down, and I'd like to be safe beneath it in that scenario)
- Whatever future children might do (e.g., running into it at top speed)
- Careless movers whacking a leg as they go through a doorway
The bracket will be mortised into the leg, so the thicker the metal is, the thinner the wood will be. I don't want to just use the thickest steel I can find because it'll be more work to get it mortised in and will possibly reduce the strength of the wood.