Published: · Cutting · ~2 min read
In a workshop, part of the steel is lost at the saw: the offcut left on each bar after the last part. With a better cutting order the same job comes out of fewer bars. Here is an example with numbers so you can see the difference.
The example: a parts list on 6 m bars
You need to cut from 40×40×2 square tube, in 6 m bars: 10 parts of 1.8 m, 12 parts of 1.2 m and 8 parts of 0.9 m. The total is 18 + 14.4 + 7.2 = 39.6 m. Divided by 6 m, the theoretical minimum is 6.6 bars, so at least 7 bars.
Cutting in list order: 8 bars
If you cut parts in the order of the list and start a new bar when the next part does not fit, you end up with 8 bars. Out of 48 m bought you use 39.6 m and 8.4 m is left, which is 17.5% waste.
With planning: 7 bars
If you fit parts together (nesting), the same order comes out of 7 bars:
| Bar | Parts | Total | Offcut |
|---|---|---|---|
| 1–5 | 1.8 + 1.8 + 1.2 + 1.2 | 6.0 m | 0 |
| 6 | 4 × 0.9 + 2 × 1.2 | 6.0 m | 0 |
| 7 | 4 × 0.9 | 3.6 m | 2.4 m |
Out of 42 m bought, 2.4 m is left, which is 5.7% waste. The saving is one whole 6 m bar out of 8, without changing the order. The saw kerf (2–3 mm per cut) is not included in the example: in practice combinations of exactly 6.0 m need adjusting, and cutting software takes it into account automatically.
What else helps
- Stock offcuts. The 2.4 m left on bar 7 is not scrap; if you log it into stock you can use it on the next job instead of buying a new bar.
- Bar length. With 2.0 m parts, three fit exactly in a 6 m bar; with 2.2 m only two fit and 1.6 m is lost. Sometimes it is worth adjusting the part length slightly or choosing another bar length.
- Mitre cuts. Parts cut at 45° can be placed alternately, end to end, so the triangles are not wasted. See mitre cutting nesting.
- Operator sheet. A clear list of the cutting order for each bar reduces mistakes in the shop.
How to do it without manual calculation
On long lists, matching parts by hand gets hard. Steel Cut Pro nests automatically, uses offcuts from your stock, handles mitre cuts, and produces operator sheets and Excel export. You can try the free version in the demo. More about the method is on the cutting optimisation page.
The example tube at MatHaus
If you need 6 m bars for the job, below you can see the 40×40×2 tube from the MatHaus catalogue, with current prices.
Links to MatHaus are affiliate links: if you buy through them, e-utilio.ro may earn a commission at no extra cost to you. Details.
Try optimised cutting
Steel Cut Pro nests automatically and uses your stock offcuts. Start with the free demo.