Structural steel cut lists vs DXF plasma files: how Australian fab shops nest work
Plain-English guide for Australian fabricators: when you need a cut list for RHS/SHS/CHS, when you need metric DXFs for plasma, kerf and end-trim rules, and how to stop wasting stock.
Two different downloads get mixed up in fab shops: a cut list / nesting plan (how to saw bar and tube into lengths) and a DXF pack (flat patterns for plasma, laser or waterjet). Both save time. They solve different problems.
The short answer
- A cut list tells the saw which stock lengths to buy and where to cut, allowing for kerf and end trim, and preferably using rack offcuts first.
- A DXF is a 2D outline in millimetres at 1:1 that a CNC cutter can nest on plate. Base plates, gussets, welding squares and pipe saddles are the everyday files.
- Australian structural tube is commonly stocked in 6 m, 7.5 m, 8 m, 9 m and 12 m lengths depending on the mill and section. Plan to the lengths your supplier actually holds.
- Saw kerf on a band saw is often around 1.5 to 3 mm. Always measure your own blade. End trim of 5 to 10 mm is common when the mill end is out of square.
Cut list rules that stop waste
- List every piece with section, length (mm), quantity and mark/number.
- Add kerf between cuts and end trim on each stock bar.
- Decide a minimum usable offcut (many shops use 600 mm). Shorter pieces go in the scrap bin, not back on the rack.
- Nest longest pieces first, then fill gaps. Prefer one stock length family so the yard stays tidy.
- Print a buy list (how many bars) and a saw sheet (cut order per bar).
When to buy or draw a DXF instead
- Anything cut from plate or sheet on a CNC: base plates, gussets, fish plates, end plates, stiffeners, welding squares.
- Pipe/tube saddles and fish-mouths that are tedious to mark by hand.
- Repeat parts you make every week – keep a controlled folder of metric DXFs so nobody redraws them from scratch.
DXFs should be millimetres, 1:1, closed outlines, no duplicate lines, and named so the operator can tell hole sizes and plate thickness from the file name or a parts catalogue.
Questions the other guides don't answer
Can I nest tube the same way I nest plate?
Not really. Tube nesting is a 1D bin-packing problem (lengths on a bar). Plate nesting is 2D. Use a cut-list tool for bar/tube and a CAM nest for plate DXFs.
What kerf should I use if I haven't measured the blade?
Measure it. Guessing 2 mm when the blade is 2.8 mm will leave every piece short. Cut a scrap, measure the kerf, and put that number in the nest.
Do free online DXFs work on Australian SHS?
Many free packs are imperial or drawn for US tube sizes. Check the file is metric, matches your actual SHS/RHS outside sizes, and that hole centres suit your bolts (typically metric coarse).
How does this tie to steel weight?
Once you know the sections and lengths, weight is section mass (kg/m) × length. See our steel weight per metre formulas for the density-based checks.
Quick answers
What is the difference between a steel cut list and a DXF?
A cut list nests linear pieces into stock bar or tube lengths for the saw. A DXF is a 2D flat pattern for a CNC plasma, laser or waterjet to cut from plate or sheet.
What stock lengths should Australian fab shops plan for?
Common mill lengths for structural tube include 6 m, 7.5 m, 8 m, 9 m and 12 m depending on section and supplier. Always plan to the lengths your supplier stocks.
How much saw kerf should I allow?
Measure your own blade. Band-saw kerf is often about 1.5 to 3 mm. Using a guessed kerf is a common reason every piece comes up short.
Are free DXF packs safe to run on a plasma table?
Only after you check units (mm), scale (1:1), closed outlines, hole sizes and that the geometry matches Australian section sizes. Imperial or US-tube packs will cut the wrong part.
Sources
- Australian Steel Institute – industry resources and section information
- Andwat Trade Guides – Steel weight per metre formulas
- Safe Work Australia – Welding processes Code of Practice (PDF)
Related guides
- Steel cut list calculator
- Plasma DXF base plate files
- Steel weight per metre: the formulas
- Fabrication ITP under AS/NZS 5131
- WPS, PQR and welder quals
General information only, summarised from the official sources above as at the review date. It isn't legal, WHS or engineering advice. Rules change and your situation may differ, so check the source or ask a professional.