Cut list optimizer· 3 min read
Workbench Frame from 6 m Metal Tubes: How Many Lengths to Buy
Steel and aluminium box sections are sold in 6 m lengths. With a 2 × 0.8 m workbench frame we show the cut list, how many lengths to buy and how to use offcuts.
Metal stockists sell square steel and aluminium tube in 6 m lengths (about 19.7 ft). With timber you choose between several lengths; here there is one — so how you lay the pieces out on the bars matters even more. Let's show it on a workshop bench frame.
The brief
- Bench frame 2,000 × 800 mm, frame height 900 mm, 40 × 40 mm tube.
- Legs: 4 × 860 mm (the 40 mm top frame sits on them).
- Top frame: 2 × 2,000 mm along, 3 × 720 mm across between them (two at the ends, one in the middle) — 800 − 2 × 40 = 720 mm.
- Kerf 2 mm, 5 mm squaring cut at the start of every bar.
Step 1: frame without braces
The pieces add up to 9,600 mm, so 2 bars of 6 m are enough. The plan:
- 1Bar 1: 2,000 + 2,000 + 860 + 860 mm, 267 mm left.
- 2Bar 2: 860 + 860 + 720 + 720 + 720 mm, 2,105 mm left.
Waste is 20 % — but most of it is one long piece at the end of the second bar. That can still be used.
Step 2: lower braces from the offcut
A bench that doesn't rock needs the legs tied together at the bottom, at least on the short sides. Add 2 rails of 720 mm. The calculator puts them into the rest of the second bar: 860 + 860 + 5 × 720 mm with 661 mm left. Still 2 bars, waste drops to 8 % — the braces come from material that would otherwise sit in the corner.
Step 3: a full lower shelf
If you also want a shelf underneath, add 2 long rails of 1,920 mm (2,000 − 2 × 40). That no longer fits in two bars:
| Option | 6 m bars | Waste | Largest offcut |
|---|---|---|---|
| Frame + legs | 2 | 20 % | 2,105 mm |
| + 2 lower rails 720 mm | 2 | 8 % | 661 mm |
| + lower shelf 2 × 1,920 mm | 3 | 17.3 % | 2,385 mm |
- 1Bar 1: 2,000 + 2,000 + 1,920 mm, 69 mm left.
- 2Bar 2: 1,920 + 860 + 860 + 860 + 860 mm, 625 mm left.
- 3Bar 3: 5 × 720 mm, 2,385 mm left.
The pieces now add up to 14,880 mm, 2,880 mm more than the combined length of two bars. The third bar leaves a 2,385 mm offcut. Before you put it aside, think about what else the bench needs: a back rail for tools, a holder for clamps, a second middle cross rail. Add the pieces to the calculator and see whether they fit without another bar.
Cut list optimizerOpen this example in the cut list calculatorKerf when cutting metal
With an angle grinder the kerf is at least the thickness of the cutting disc — it is printed on the disc, and common thin discs are 1 mm. For a metal band saw or cold saw, check the blade data. The example uses 2 mm to leave room for deburring the ends.
Workshop tips
- If the stockist cuts the bars for you, ask how much their cut takes — and enter that as the kerf.
- Cut identical pieces (legs, rails) against a stop so they are all exactly the same length. In a frame that matters more than on any single piece.
- Label offcuts over 50 cm with their length and keep them; short bits of tube come in handy as backing pieces when welding.
The calculator only works out material, not load capacity. Choose the tube size and wall thickness, joints and welds for what the bench will carry. Wear eye protection when cutting metal and use a cutting disc rated for your grinder's speed.