Metal cut list planning: stock lengths, kerf and worked example
A metal cut list tells you what to make. A stock allocation tells you which bar or tube each piece comes from. To turn one into the other, group compatible material, measure usable stock and allow for every cut. This guide walks through that length check before you open the planner.
Group compatible stock first
Keep different grades, profiles, wall thicknesses and sizes in separate lists. Square tube cannot substitute for flat bar just because both are long enough. Record measured stock lengths and quantities; include suitable remnants in the same material group. Check supplier lengths against what is actually on the rack.
Write the finished lengths and quantities
Use one unit throughout the list, such as millimetres. Record each finished length and its quantity, then check against the drawing. For mitres, identify the long point, short point or other measurement reference before entering a length. A square-cut example cannot account for angled-end geometry.
Allow for kerf and end trims
Kerf is the material removed by the blade or cutting process. Use the width of your actual setup. End damage, squaring cuts and required trims reduce usable stock too. For square cuts with a usable starting end and a remainder left over, one separating cut per finished piece is a straightforward assumption. A piece that uses the final stock end can change the cut count.
Review the allocation before cutting
Check each bar as well as the totals: the plan must fit each available length and produce every requested piece. Confirm clamping limits and the cutting sequence in the workshop. Compare remaining lengths with future jobs; reusable remnants and unusable scrap have different value, even when their lengths are equal.
Worked example: pieces, cuts and remaining stock
Fictional teaching example — static sample data, not a customer job or calculated result.
Available stock: Two 6,000 mm lengths of the same square tube.
Required pieces: 1,800 mm × 3; 1,200 mm × 3; 900 mm × 2. Eight pieces total 10,800 mm.
Assumptions: square cuts, usable starting ends, no end trims or defects, and a 3 mm kerf. Each finished piece needs one separating cut because each stock length leaves a remainder. Cut counts change if the final stock end becomes a finished piece or extra trimming is needed. These allocations illustrate a feasible plan; they are not a claim of an optimal layout.
| Stock | Length | Finished pieces | Piece total | Cuts / kerf | Remaining |
|---|---|---|---|---|---|
| Tube 1 | 6,000 | 1,800 + 1,800 + 1,200 + 900 | 5,700 | 4 / 12 | 288 |
| Tube 2 | 6,000 | 1,800 + 1,200 + 1,200 + 900 | 5,100 | 4 / 12 | 888 |
Check the arithmetic: 12,000 mm stock = 10,800 mm finished pieces + 24 mm kerf + 1,176 mm remaining stock. The 288 mm and 888 mm remnants are not automatically waste; reuse depends on your next job and workshop requirements.
For each stock length, check: finished piece lengths + (separating cuts × kerf) + trim allowance ≤ usable stock length. Then reconcile piece quantities across the whole plan. Here, usable stock means the measured length before the separately stated trim allowance.
Common metal cut planning questions
Can I mix tube, bar and extrusion in one cut list?
Only stock that can make the same requested pieces belongs in the same allocation. Create separate plans for incompatible profiles, sizes or materials, even if they share a stock length.
Why does a list that totals 6,000 mm fail to fit a 6,000 mm bar?
The finished lengths leave no room for kerf or trims. In this example, four separating cuts use 12 mm. Check the actual cut count and allowances before treating an exact length match as feasible.
Can a 1D plan optimise sheet metal?
A length-only allocation suits linear stock such as tube, bar and extrusion. Sheet layouts also need width, orientation and nesting information; use a suitable 2D planning workflow for those jobs.
Before you run the planner
- Material, grade and profile match for every piece.
- Stock lengths and available quantities are measured.
- Finished lengths, quantities, kerf and trims are checked.
- Every requested piece appears in the plan before cutting.