A sawmill makes or loses its money at the saw. The price of the logs is fixed when you buy them; what you get back depends on what happens between the yard and the stack of boards. Yet in many mills the only production figure anyone knows is “how many logs did we cut today”. This post covers the five figures worth tracking at the saw, how to work each one out, and how to read them.
The five figures to track at the saw
1. Logs into each machine
Count and volume, per machine, per day. It sounds basic, but it is the base for everything else: without knowing which log went to which saw, nothing below can be traced to a machine or an operator.
2. Purchase against mill: the variation
Every log has two measurements: what it was bought as, and what the mill measures when it reaches the saw. A log bought at 28 cm can measure 25 cm at the saw. The difference, the variation, is money already paid for wood that is not there. Track it log by log, and total it by supplier, consignment, grade and machine.
3. Recovery
Recovery is how much sawn timber comes out of the logs that went in:
Recovery % = sawn timber CFT ÷ log CFT × 100
Log volume is usually worked out by the quarter girth (Hoppus) method, (girth ÷ 4)² × length; our free log CFT calculator does it for a single log or a whole list. Sawn timber is length (ft) × width (in) × thickness (in) ÷ 144.
4. What is waiting at each saw
Logs received but not yet sawn, per machine. This shows where the bottleneck is, and how much of each consignment is still to cut.
5. Logs without a tag
Logs that reach the saw with a missing or torn tag are still sawn, but their volume cannot be matched to a purchase. Count them. A rising count usually means tags are being lost in the yard, or scans are being skipped at the machine.
Recovery by grade and length: a worked example
Recovery becomes useful when you split it. Here is an example with made-up but typical figures for one species over a month:
| Grade and length | Log CFT in | Sawn CFT out | Recovery |
|---|---|---|---|
| A grade, 12 ft | 1,200 | 660 | 55% |
| A grade, 16 ft | 1,500 | 945 | 63% |
| B grade, 12 ft | 900 | 414 | 46% |
If A grade costs the same per CFT in both lengths, the 16 ft logs give 8 more CFT of sawn timber for every 100 CFT bought. That is a buying decision for the next consignment, made from the mill’s own figures instead of habit. B grade at 46% may still pay, but only if it was bought cheaper by more than the difference.
Reading the variation
A total variation figure on its own starts arguments. Split it, and it points somewhere:
- By machine or operator. If one saw shows much more variation than the others on the same logs, look at how that machine is measured, not at the supplier.
- By supplier or consignment. If every machine shows a shortfall on one consignment, it is the purchase measurement, and you have the log-by-log figures to raise it with the supplier.
- By grade. Some grades lose more girth to bark and defects. Knowing which ones changes what you are willing to pay for them.
- The outliers. A handful of logs with very large differences are worth checking physically while they are still logs, not after they are boards.
Paper at the saw, or a phone?
Most mills start with a notebook at each machine. It works until someone has to add it up: the purchase figures are in one book, the mill figures in another, and matching them log by log is a day’s work nobody has. That is why the variation is usually discussed, not measured.
Recording on a phone at the machine changes one thing that matters: the operator scans the log and the purchase figures are already there, so he only types what he measures. Matching happens as he works, and the owner sees variation and recovery the next morning, while the logs can still be checked.
How Timbba does it
Timbba is a sawmill management system that keeps all five figures above. Operators scan each log at the saw on their own phones and enter only what the mill measured; the purchase figures come from the consignment. Variation and recovery are shown by machine, grade, length and supplier, untagged logs are recorded and matched back to their consignment later, and what the saw produces goes straight into stock by size for timber stock control, orders and dispatch. It works for pine that arrives tagged and for hardwood measured by girth and hollow at the saw.
Book a demo and we will set it up on your own machines with your operators.
