Ripping optimization in a sawmill: how to choose widths for a multi-rip (without chaos)

“Optimization” is not only for fully automated lines. In most sawmills, ripping optimization is simply the decision:

• which target widths you want to make today,
• how to apply them to variable unedged boards (wane, warp, width variability),
• and how to keep the process repeatable without manual positioning on every board.

This post focuses on what actually works on real multi-rip production lines.

1) Start with the objective: yield or margin?

Two common objectives:

• maximize volume yield (more m³ out of the same input),
• maximize value (sometimes fewer m³ but better mix).

If you don’t separate these goals, operators will improvise, patterns will drift, and results will be inconsistent.

2) Fixed saw spacing vs adjustable spacing: what changes

Fixed saw spacing (very common)

The rip pattern is “mostly fixed”, and your biggest levers are:

• board positioning before the saw (offset + angle),
• width sets per shift,
• sorting boards into “easy” and “difficult” groups.

Adjustable spacing

Gives flexibility, but you still need:

• stable infeed reference,
• repeatable rules (otherwise you create maintenance complexity and production noise).

3) Width sets: fewer options usually means higher yield

High-performing lines tend to run:

• 3–5 target widths as the primary set,
• 1–2 fallback patterns for boards that don’t “close” cleanly,
• a rule for when to use the fallback.

This reduces ad-hoc decisions that typically create waste.

4) Wane + geometry: optimization without a reference is a lottery

With unedged boards, the bottleneck is often not saw spacing but the fact that boards enter:

• with different wane distribution,
• shifted and skewed.

That makes the same pattern produce different waste on different boards.

The practical lever is to stabilize infeed reference. Many mills do it with an add-on positioning module that:

• detects board position + angle,
• computes best placement for the chosen width set and saw spacing,
• positions the board in real time so cuts are repeatable.

See the technical overview: /blog/board-centering-before-multi-rip-saw/.

5) Don’t ignore kerf — but treat it as “second optimization”

Kerf matters, especially when you make many cuts, but in practice:

• first stabilize infeed and repeatability,
• then optimize kerf and blade parameters.

How to convert kerf into m³ loss: /blog/saw-kerf-vs-yield/.

6) A realistic implementation checklist

1. Measure yield consistently (log vs stage): /blog/how-to-calculate-sawmill-yield/.
2. Define width sets per shift + a fallback.
3. Split input boards into at least 2 groups (easy/difficult).
4. Verify infeed reference stability (offset + angle).
5. Only then tune kerf and blade/throughput parameters.

If you want us to review your width targets and infeed layout and point to the biggest yield lever, reach out: /contact/.