Local CNC wood processing: 7 checks before you place an order

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  Key takeaways
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  Local versus overseas versus hand tools for wood parts
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  Tolerance and wood species: what local CNC wood processing can actually hold
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  Moisture, grain direction and the tooling questions to ask
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  Finishing, assembly and the hidden cost of soft wood
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  Lead time, order size and what a local quote should contain
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  Seven steps to place a wood machining order that holds up

Wood is not a stable material, and the first mistake buyers make is quoting it like aluminium. A dry, straight-grain hardwood blank can hold ±0.1 mm on a profile cut and ±0.2 mm on pocket depth. Softwoods compress under the cutter, so expect ±0.2 mm to ±0.3 mm unless the shop takes a finishing pass with a sharp up-cut bit at 18,000 rpm and a 2–4 m/min feed.

If your drawing shows ±0.05 mm across a 600 mm panel, that is not a machining problem. It is a material problem. The board will gain or lose 0.2–0.3% of its width for every 1% change in moisture content. In a dry shop that is fine. In a humid warehouse the same part moves 1 mm or more over a season.

Split the drawing instead. Machine the wood to ±0.1 mm and put the tight features on a metal insert, a dowel or a threaded bush. We hold ±0.005 mm on the metal side of the assembly, and the wood simply locates it. That combination is how furniture frames, jigs and fixtures keep their fit after shipping.

Species choice follows the same logic. Maple, beech, ash and dense oak machine with clean edges and take a thread reasonably well. Pine, cedar and other softwoods fuzz at the exit side and need a backing board. MDF and plywood are dimensionally stable and cheap, but the core can chip on deep pockets, and a 12 mm plywood panel will not hold a screw the way solid ash does.

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  Hardwood, dry±0.1 mm profile, ±0.2 mm depth, clean edges
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  Softwood, dry±0.2–0.3 mm; use a backing board
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  Plywood and MDFStable and flat; watch core chip-out on deep cuts
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  Wet or green stockDo not quote tight tolerance; let it dry first

Moisture content is the single number that predicts whether your parts arrive flat. Kiln-dried stock at 6–8% machines well and stays put in a normal indoor environment. Above 12% the board is still shrinking, and a part cut today will not match the same part cut next month. Ask the shop to meter the stock and record the reading on the inspection sheet.

Grain direction sets the cut strategy. Running a climb cut along the grain leaves a clean edge on maple and oak. Cutting across end grain with the same tool lifts fibres and leaves tear-out, especially on open-pore species. For a clean end-grain finish, ask for a down-cut or compression bit, a shallower depth of cut, and a light finishing pass of 0.2–0.3 mm.

Then ask what tooling the shop will use. A straight two-flute router bit behaves very differently from a compression spiral. Feed and speed need to match the bit diameter, the spindle speed and the species. A 6 mm bit in hardwood usually runs best between 12,000 and 18,000 rpm with a chip load of 0.05–0.1 mm per tooth. If the quote does not mention any of this, the shop is pricing a drawing, not a process.

One more variable is cutter wear. Wood is abrasive, and a dull bit burns instead of cuts. Burn marks on maple or cherry are hard to sand out and show through a clear finish. Ask how the shop tracks tool life, and whether they change bits between species.

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  Ask for the moisture readingTarget 6–8%; anything above 12% is a risk
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  Name the grain direction on the drawingA note beats an assumption every time
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  Request the tooling listBit geometry, diameter, rpm and feed rate
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  Ask about tool lifeDull bits burn; burn marks survive sanding

Finishing changes the dimension of a part. A brushed or oiled surface removes almost nothing. A sanded surface removes 0.1–0.2 mm if the operator is generous. A thick film finish such as a heavy lacquer can add 0.05–0.1 mm per coat and fill a sharp corner. If a wood part must fit a metal bracket, decide which surface is the datum before finishing starts, not after.

Assembly is where local sourcing earns its keep. A shop 40 minutes away can test-fit a frame, find that a pocket is 0.3 mm tight, and re-cut the same day. That loop is impossible with an overseas supplier. It is also why local work suits first articles, jigs and fixtures, and low-volume runs where the design is still moving.

The cost that catches people out is soft wood. A softwood part looks cheaper per board foot, but it needs slower feeds, more backing support and more sanding. Hardwood at a higher material price often lands cheaper per finished part. Run the comparison on finished cost, not on stock cost.

For metal-wood assemblies, decide early which features live on which material. We machine the aluminium or stainless bracket to ±0.005 mm and leave the wood side at ±0.15 mm with a clearance slot. The metal controls the fit; the wood handles the look and the weight.

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  Sanding removes material0.1–0.2 mm if the operator is not careful
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  Thick finishes add material0.05–0.1 mm per coat in a tight corner
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  Local iteration is the real savingSame-day re-cut beats a lower unit price
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  Compare finished costSoftwood often loses once sanding is counted

Order size is rarely the blocker for local CNC wood processing. A shop set up for wood will run one prototype or ten thousand parts, because the setup is the same. What changes is stock. A local shop may keep maple and birch plywood on the shelf and order walnut or wenge in, which adds a few days before the spindle ever turns.

Lead time breaks into three parts: stock, programming and machining. Programming a 3D relief or a nested panel layout takes a few hours. Machining a 600 × 400 mm panel with a 6 mm bit and a 3 mm stepover can run 40–90 minutes per side. Add drying or acclimatisation time if the stock arrived from a different climate.

A usable local quote lists the species and grade, the moisture spec, the tolerance per feature, the finish, the inspection method and the delivery window. If any of those are missing, ask. A quote without a tolerance line is not a quote, it is an estimate.

Finally, match the process to the geometry. Flat panels and 2D profiles run fast on a three-axis router. Curved chair backs, angled joints and undercut reliefs need four or five axes, and those machines cost more per hour. Sending a 2D part to a 5-axis quote wastes money. Sending a 5-axis part to a 3-axis quote wastes weeks.

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  Stock availability drives the dateExotic species add days before machining
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  Programming is hours, not daysNested layouts and reliefs included
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  Machining time scales with stepover3 mm stepover is slow; 6 mm is fast and rougher
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  Match axes to geometry2D panels on 3-axis; reliefs on 4 or 5-axis