A DIY essential… Your very own coffee table in your living room. I went with an industrial look with pairing angle iron together with square tubing using a MIG welder.

Level of difficulty: EASY

Cutting, drilling, welding in about 5 hours of work time is all that is required.

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What you’ll need:

Material

1 1/4″ square tubing:

  • 4x 16″ legs
  • 2x 33.5″ long horizontal supports
  • 3x 13.5″ short horizontal supports

(Note: any tubing 1″ and up would work, just make sure to take account of tube thickness to match the wood used for the top)

Wood:

  • 16″ x 36″ x 0.75″ pre-finished wood board (or cut to size)

1 1/4: Angle Iron:

  • 2x 16″ 1.25″ x 1.25″ x 0.125″ angle iron

(Note: 1.5″ angle would work better from experience with the 1 1/4″)

Hardware & Tools

  • Angle grinder with cut-off and grinding discs (or hacksaw)
  • Drill
  • Welder
  • 4- 1/4″ carriage bolts, washers, nuts

Assembly

Step 1:

Align short and long horizontal supports as shown in the picture above ensuring pieces are square. Tack in place.

Step 2:

Align the 4 legs as shown in the picture below. Finish the welds around the legs and horizontal supports. Take note that the welds on the top side of the assembly will need to be ground down to allow proper mating of the wood to the assembly.

Step 3:

Drill 2- 3/8″ holes in angle iron 2-4 inches from either side as seen pictured below. Holes pictured below are 2″ from either side.

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Step 4:

Align angle iron with the legs and weld it to the legs as shown in the pictures below. Allow at least a 3/4″-7/8″ clearance between the angle iron and table top for wood installation, depicted in the left photo below. After staining wood, insert from one side. Drill out holes in wood through the pre-drilled holes in the angle iron. Fasten the wood to the assembly with the 4 carriage bolts.

(Note: wood installation is easier if you bevel the wood corners that will interact with the angle iron. Most angle iron has an inner radius that would normally interfere with the 90 degree corner of the wood.)

 

 

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Step 5:

Take the angle grinder or file to the angle iron sides that feel sharp and any sharp corners. The end of the legs may be sharp from the cutting process as well. Add clear coat or paint to the metal assembly as desired.

(Note: I let my metal assembly get a surface rust finish then cleaned and applied clear coating to seal in the look. Pictured below is a close of showing the surface finish and amount of rounding to the normally sharp corners as well as the bevel I applied to the wood for ease of installing.)

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And you’re done!

A discussion on durability.

I’d like to start including discussions of FEA results on the projects I’m working on. I think it could fit within the topics of this blog. Simulating loads and constraints on a project before the first nail is driven or piece of material is cut can save overall project costs and can ultimately drive the design as well.

The final design pictured above shows a 500 lbf load applied uniformly across the top of the wood surface. I fixed the legs as constraints and added the steel and wood materials into the model. The maximum displacement (0.15mm) solved for appears in the middle of the table as one would assume. The maximum Von-Mises stress (pictured bottom right) occurs at the intersection between the vertical leg and horizontal supports. The result was 80MPa well under the yielding stress of steel.

(Note on stress results: The 80MPa value was at a point contact where normally a weld would be. The weld would add an additional area that will act to spread out the stress of this point solved for by the computer. It is interesting to note however that this will be the area of most concern so take care in welding this area if you want the most robust coffee table.)

Questions? Let us know!

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