Machine Services Wood: 7 Proven Checks Before You Send an RFQ

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  Key takeaways
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  What to check against the part you need
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  Grain direction decides whether the cut is clean or torn
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  Moisture content is the tolerance you cannot measure after shipping
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  Tolerance callouts on wood drawings are usually wrong
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  Tooling, fixturing, and dust control tell you the shop's real experience
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  Sanding and finishing are where the quote gets vague
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  Lead time, MOQ, and quote structure: the commercial checks
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  Certifications and documentation for machine services wood projects
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  How to run a wood CNC job from RFQ to first article

Wood is not isotropic. A cutter moving parallel to the grain shears fibers cleanly. The same cutter moving into the grain lifts and tears them. This is why two identical toolpaths can produce one good part and one scrapped part, depending only on how the blank was laid on the table.

Before you approve a quote for machine services wood, ask how the shop orients the blank. For a visible face, the grain should run with the longest dimension and the finish pass should climb-cut. For a structural part, the grain should run along the load path, not across it.

The check is simple. Send a drawing with a grain direction arrow and see whether the shop acknowledges it. A shop that ignores the arrow will deliver parts that look fine in a photo and fail in assembly because the fibers lifted at the edge.

One more point. End grain cuts differently from face grain. A pocket that crosses both will show two different surface finishes unless the shop adjusts feed and speed between regions, which most do not do by default.

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  Send a grain arrowIf the shop does not reference it, they are not reading the drawing.
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  Climb cut the finish passStandard practice for a clean edge on solid wood and plywood.
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  Watch end grainIt burns and tears at the same feed rate that works on face grain.

A kiln-dried hardwood blank sits around 6–8% moisture content. A shop in a humid climate, or a container crossing an ocean, can push that to 10–12%. The wood expands. A 500 mm panel can grow 2–3 mm across the grain, which is far outside any tolerance a drawing would call out.

This is why moisture content belongs in the purchase order, not in a phone call. Specify kiln-dried stock at 6–8% MC and ask for the reading on the incoming inspection record. If the shop cannot provide it, you are buying an uncontrolled variable.

For parts that will be assembled with metal inserts, the risk is worse. The wood moves, the metal does not, and the joint opens or crushes. If your design mixes materials, ask the shop to machine the wood after it has acclimated to the assembly environment.

There is a practical limit here. No shop can guarantee a wood part stays within ±0.1 mm across a year of seasonal humidity. If your design needs that, wood is the wrong material and you should be talking about aluminum or a dimensionally stable composite.

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  Specify 6–8% MCPut it on the PO. Ask for the meter reading.
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  Acclimate before machiningLet the blank sit in the shop for 24–48 hours before the first cut.
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  Do not mix wood and metal in a tight jointThe two materials move at different rates.

Most wood drawings inherit tolerances from a metal part. That is a mistake. A general callout of ±0.1 mm on a wood part is not achievable across a production run, and a shop that quotes it as if it is achievable is either guessing or planning to sort parts by hand.

The realistic split is between features cut in one setup and features that depend on material movement. Hole positions and pocket depths cut in a single fixturing can hold ±0.2 mm on a rigid hardwood. Overall length across a large panel, measured after the part has relaxed, is a different number.

So the check is this. Separate your tolerances into two groups: those the machine controls and those the material controls. Send the shop a drawing that makes the distinction. A good shop will come back with a tolerance stack based on their own process, not a blanket number.

If you need metal-level tolerance and the part must be wood, the practical answer is a hybrid: machine a metal fixture or insert to ±0.005 mm and let the wood locate against it with clearance. That is how we handle wood parts that sit inside a metal assembly.

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  One setup, one numberFeatures cut without re-fixturing hold tighter than features that do not.
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  Separate machine and material tolerancePut both on the drawing so the shop can respond to each.
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  Use metal where the tolerance is tightWood locates against the metal, not the other way around.

A shop that treats wood like soft aluminum will burn cutters and scorch parts. Wood needs higher surface speed, lower chipload, and sharp tooling with a polished flute. Carbide compression bits handle veneered plywood without chipping the top or bottom face. Down-cut spirals protect a visible top face. Up-cut spirals clear chips in a deep pocket.

Ask what tooling the shop plans to use. If the answer is a generic flat end mill, the edge quality will show it. If the answer names compression bits, down-cut spirals, or a specific chipload range, you are talking to someone who has cut wood before.

Fixturing matters just as much. Wood is light and flexible. A vacuum table holds a flat panel well. A curved or sculpted part needs a machined fixture that supports the back side, otherwise the cutter pushes the part away and the depth wanders.

Dust is a safety and quality issue, not a housekeeping one. Fine wood dust is combustible. A shop running wood without a proper extraction system is a shop that will eventually have a fire, and the insurance question alone should make you look elsewhere.

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  Ask for the tool listCompression, down-cut, and up-cut spirals each solve a specific problem.
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  Check the fixtureSculpted parts need back-side support, not just vacuum.
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  Confirm dust extractionCombustible dust is a real hazard, not a detail.

Machining leaves tool marks. On wood, those marks show through any clear finish, so sanding is not optional. The question is who does it and how it is priced. A quote that lists 'finishing' as a single line hides the difference between a 120-grit hit with a random orbital sander and a full sequence from 80 to 220 grit.

Ask for the grit sequence. For a painted part, 120–150 grit is enough. For a clear coat, 180–220 grit. For a stained part, the sanding must be uniform or the stain will blotch, which means the shop needs to control pressure and direction, not just run a sander over the surface.

Edge break matters too. A sharp machined edge on wood chips easily. A 0.5 mm chamfer or a 1 mm roundover removes the weak corner and holds up in handling. If the drawing does not call it out, ask whether the shop applies a default edge break.

This is also where a shop with metal experience adds value. We run surface finishing as a separate department with documented grit sequences, so the wood part leaves with the same finish record as a metal part.

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  Ask for the grit sequence80 to 220 grit for clear finish, 120–150 for paint.
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  Specify an edge break0.5 mm chamfer or 1 mm roundover prevents chipping.
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  Uniform sanding before stainUneven pressure causes blotching that no finish can hide.

Wood jobs often start as one or two prototypes. A shop with a high minimum order quantity is not set up for that, and you will pay for setup you cannot amortize. We run no minimum order quantity, from one prototype to 10,000+ part runs, because the same programming and fixturing work applies either way.

Lead time on a wood part depends on material availability more than machine time. If the shop has to order a specific species or veneer, add days. If they stock it, a simple routed panel can ship in 3–5 days after programming. Ask which case applies to your material before you commit to a schedule.

Quote structure is the clearest signal. A good quote breaks out programming, material, machining, sanding, and finishing. A vague quote blends everything into one number, which means you cannot tell whether the shop is efficient or just padding the machining line.

One more commercial check. Confirm how the shop handles design changes after the first article. A small change to a pocket depth should be a quick reprogram, not a new setup charge. If the quote does not say, ask before you place the order.

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  No MOQOne prototype is a valid order, not an exception.
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  Check material availabilitySpecial species add lead time beyond machine time.
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  Demand a broken-out quoteProgramming, material, machining, sanding, finishing.

Certifications matter less for a decorative wood panel and more for a wood part that goes into a regulated product. If your wood component is a fixture, a housing, or a prototype for a medical or automotive program, the shop's quality system is part of your audit trail.

GreatLight holds ISO 9001:2015, IATF 16949:2016, ISO 13485:2016, and ISO 27001:2022. For a wood job, the relevant parts are incoming material inspection, in-process monitoring, and a final inspection record. We inspect 100% of parts before shipment and provide reports on request.

Documentation also covers your design files. Uploads are secure and confidential, and we can sign an NDA on request. If your wood part is part of an unreleased product, that matters more than the certification on the wall.

The practical check is to ask for a sample inspection report from a similar job. If the shop can produce one, their process control is real. If they cannot, you are relying on goodwill.

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  ISO 9001:2015 and IATF 16949:2016Documented process control, not just a certificate.
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  100% inspection before shipmentRaw material check, in-process monitoring, final inspection.
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  NDA available on requestYour design files stay confidential.