Uneven Board Thickness? Sort Logs by Diameter First: Matching YuanChuang MDY Multi-Blade Saws to Log Caliber
Feeding mixed log diameters into one multi-blade saw makes large logs come out thin and small logs thick, with 5-8 spec changes per shift. Sorting by diameter and matching YuanChuang MDY saws to each class cuts that to 1-2 and holds recovery at 76%-80%.
Sort Logs by Diameter First, or Board Thickness Will Drift
Walk into many sawmills and you will see the same log yard: thick and thin logs piled together, cut to length, then fed straight into the multi-blade saw. It feels convenient, but the boards come out uneven — in the same batch, large-diameter logs yield thinner boards and small-diameter logs yield thicker ones. Send that batch to a blockboard core-layer line and the thickness simply will not match. Fujian Yuanchuang Mechanical & Electrical sees this pattern constantly in after-sales visits: uneven board thickness is usually not a precision problem of the saw itself, but a missing step upstream — sorting logs by diameter.
Where the Thickness Drift Comes From
Board thickness on a multi-blade saw is not set by eye. It is set by spacer rings: once the spacer thickness is fixed, the saw spacing is fixed, and so is the thickness of the whole batch.
That is exactly where the problem starts. Log diameters in one batch often span a wide range — 8 cm to 24 cm, for example. Set the saw spacing for one specification and a large-diameter log gets its cut layers squeezed thin, so single boards come out thin; a small-diameter log cannot be split into as many layers, so boards come out thick. One machine fed a mixed pile produces thickness that simply follows log diameter.
There is a second cause inside the machine itself: worn centering and feeding mechanisms, excessive spindle bearing clearance, and insufficient saw plate flatness. All three make thickness wander. So when you troubleshoot, check first whether the logs were sorted, then check these three machine components.
The Structural Account: How Much Downtime You Are Paying For
Resetting spacers means re-assembling all three arbors of a multi-blade saw. Industry figures: about 15 minutes per thickness change, about 25 minutes per saw-plate group change. With unsorted logs, spec changes can reach 5–8 per shift.
- Item — Mixed logs on one machine — Sorted by diameter, one class per machine
- Spec changes per shift — 5–8 — 1–2
- Cumulative downtime per shift — 1.5–4 h — under 0.5 h
- Board thickness consistency — drifts with log diameter — consistent within a diameter class
- Sorting labor — 1 full-time worker — 0 (auto stacking)
- Downstream recovery rate — fluctuates — stable at 76%–80%
One extra sorting step before the shift buys back about two hours of lost runtime. With average equipment effectiveness in the industry around 66.8%, cutting spec-change downtime is worth roughly half a machine of productive capacity per day.
The Worker You Are Paying to Sort Logs
In 2026, labor demand in wood processing is up 18.7% year on year, and skilled workers are increasingly hard to hire. Keeping one person at the pile just to sort logs is pure loss; once logs are sorted and stacked by diameter, that position can be removed entirely.
How Well-Run Mills Do It
A smooth workflow usually looks like this:
Cut-off and sorting upstream: a cut-off saw or an automatic cut-off and sorting machine (YuanChuang MJD5-25FX, cut-off diameter 5–25 cm, cut length 1–4 m) cuts long logs to fixed lengths and stacks them by diameter in six classes — 4–9 / 10–12 / 13–15 / 16–19 / 20–22 / 23–25 cm, customizable to your usual log mix.
One diameter class per machine: match multi-blade saws to your usual classes — one machine for small logs, one for medium, one for large.
Edging downstream: after squaring, wane-edged boards go through the TT-300 intelligent edger so finished boards and waste are separated.
Can one machine do the job alone? Yes. The key is simply not to feed large and small logs into the same machine together. Even with a single multi-blade saw, sort the logs by diameter first and cut one class at a time — thickness stays stable and waste drops.
Model Guide: How the YuanChuang MDY Series Maps to Log Diameters
- Model — Log diameter range — Processing length — Saw blade spec
- MDY5-12 — 5–12 cm — 50 cm and up — 210
- MDY8-20 — 8–19 cm — 50 cm and up — 305
- MDY10-24 — 10–24 cm — 50 cm and up — 355
- MDY20-35 — 20–34 cm — 100 cm and up — 480
- MDY25-40 — 25–39 cm — 100 cm and up — 550
- MDY30-60 — 30–59 cm — 200 cm and up — 800
These classes cover diameters from 5 cm to 59 cm. All of them use automatic centering, automatic feeding and steplessly adjustable feed speed: a square cant in the middle, equal-thickness boards on both sides, with thickness tolerance held to ±0.2–0.5 mm. Power ratings are marked on the official product pages as "subject to actual configuration" — the final build follows the material you usually cut.
FAQ
Q: Logs are already cut to length — why sort by diameter too? Can't they go straight into the multi-blade saw?
A: Cutting to length only fixes the log length; diameters are still mixed. Set the saw spacing for one specification and large logs come out thin while small logs come out thick. Blockboard core layers require uniform thickness, so one uneven batch is a wasted batch.
Q: After sorting by diameter, how should the multi-blade saws be matched? How many machines do I need?
A: Match them to the log classes you usually cut. Small logs (5–12 cm) go to the MDY5-12, medium logs (8–19 cm) to the MDY8-20, large logs (10–24 cm) to the MDY10-24, with actual ranges subject to your configuration. Running a few machines side by side takes spec changes from 5–8 per shift down to 1–2.
Q: My volume is small — can I just get by with one machine?
A: Yes, small volume can be handled in batches after sorting; three machines are not mandatory. The key is not feeding large and small logs into the same machine together. Even with a single MDY, sort by diameter first and cut one class at a time so thickness stays stable and waste stays low.
Sort the logs and the boards come out even; feed them as one mixed pile and your waste doubles.
Send us your material and we will run the trial cut for you. The YuanChuang log multi-blade saw is matched to your log diameters and fitted with 80CrV2 alloy blades ground in-house on the Changgong seven-axis blade grinder — every tooth at the same angle, so the cut face stays stable.
Uneven Board Thickness? Sort Logs by Diameter First: Matching YuanChuang MDY Multi-Blade Saws to Log Caliber · All technical resources