Has Anyone Built the CNC Machine in the Woodsmith Article?

• 1
  What a magazine CNC plan actually specifies
• 2
  Stiffness: the number the plan never gives you
• 3
  Motion hardware and what each choice costs you
• 4
  The spindle sets the real limit on material
• 5
  Where the plan stops working, and what to do instead
• 6
  What changes when the part moves to a production machine
• 7
  Build the router or machine the parts elsewhere

A woodworking magazine build plan is not a machine design. It is a set of cut lists, a few assembly drawings, and a list of bought-in parts. The plan assumes you can source the motion hardware, wire the electronics, and tune the machine yourself. Everything that determines whether the finished router holds tolerance is left to the builder.

The typical plan describes a gantry router with a work envelope around 600 × 900 mm, a trim router as the spindle, and a belt or leadscrew drive on each axis. It targets wood, MDF, and plastics. No plan promises metal cutting, and none of them publish a stiffness number.

That gap matters. A router that cuts plywood cleanly can chatter on aluminum at the same feed rate. The difference is not the controller or the software. It is how much the frame and gantry deflect under cutting force.

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  Cut lists are not tolerancesPlans give part dimensions, not the deflection budget those parts must meet.
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  Bought-in parts set the ceilingRails, screws, and spindle determine the best case before assembly starts.
• 3
  Target material decides the designA plywood router and an aluminum router are different machines.

Cutting force pushes the tool sideways. The frame, gantry, and Z axis all bend a little under that force, and the tool follows the bend. Total deflection at the cutter is the sum of every compliant element in the load path: gantry beam, uprights, linear bearings, screw or belt, and the spindle mount.

For wood and MDF, a few hundredths of a millimeter of deflection is invisible. For aluminum, the same deflection shows up as chatter, poor surface finish, and short tool life. That is why builders report the machine works fine on plywood and then struggles the first time they try 6061.

The usual fixes are straightforward but not free. Fill a hollow gantry beam with epoxy granite. Add a second rail per axis. Move from belt drive to ballscrews. Each step adds mass, cost, and assembly time, and each one raises the force the steppers must move.

The practical rule: stiffness and travel fight each other. A 600 mm gantry can be made stiff with modest material. A 1,200 mm gantry needs a much deeper beam section to reach the same deflection. Plans rarely mention this trade.

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  Measure deflection, do not guessPush the spindle with a dial indicator and note the reading before you cut.
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  Shorten the cantileverLower the Z axis travel and the whole machine gets stiffer for free.

Belt drive is cheap, fast, and springy. It suits plywood and foam where cutting force is low. Under a 6 mm carbide end mill in aluminum, belt stretch shows up as poor repeatability on direction changes.

Leadscrews are stiffer than belts but have backlash unless you use anti-backlash nuts, and they wear. Ballscrews remove most backlash and hold preload, at several times the cost and with careful mounting requirements. On a hobby budget, rolled ballscrews are usually the right compromise.

Linear rails are the other half of the picture. Round shaft on unsupported ends flexes. Supported round rail is better. Profile rail with preloaded blocks is what production routers use, and it is the single biggest upgrade most builders can make.

Motor sizing follows from that. Steppers lose torque as speed rises, so a heavy gantry with fine-pitch screws may top out at low feed rates. Servos cost more but hold torque across the speed range. Start with the force you need at the cutter, then size the motor.

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  Backlash under 0.02 mmThat is roughly where aluminum finishing becomes repeatable on a router.
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  Preloaded profile railRemoves the rocking motion that round bearings allow under side load.

A trim router spins fast, around 20,000 to 30,000 rpm, with low torque and a collet that accepts 6 mm or 1/4 in shanks. That combination is built for wood. It will cut aluminum, but only with light radial engagement and a feed rate low enough to keep the tool from rubbing.

A water-cooled spindle with an ER20 or ER25 collet gives more torque at lower rpm and better runout. Runout at the tool tip is what breaks small end mills. If runout exceeds about 0.02 mm, a 3 mm cutter in aluminum will fail early no matter how good the frame is.

Cooling matters more than most plans admit. Wood chips fly clear. Aluminum chips pack into the cut and re-cut, which raises temperature and ruins finish. Air blast is the minimum. Mist or flood coolant changes the enclosure requirements and the mess.

A router spindle also has a duty cycle. Continuous aluminum cutting at high load heats the bearings. If the housing is too hot to touch after a few minutes, the cut is too aggressive for that spindle.

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  Check runout with a dial indicatorMeasure at the tool shank, not the collet nut.
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  Air blast before coolantClearing chips solves most aluminum finish problems on a router.

The plan stops working the moment the part needs a tolerance tighter than the machine can hold, or a material the spindle cannot cut at a reasonable rate. A gantry router built to a magazine plan can hold roughly ±0.1 mm on wood and plastic with careful setup. That is a real capability, and plenty of shops use it every day for templates, jigs, and signage.

It is not the right tool for a bracket that must fit a bearing bore, or a housing with a sealing face, or anything that carries a ±0.005 mm callout. Those parts need a machine with a closed loop, thermal stability, and a metrology step after cutting.

The sensible split is to build the router for what it does well and send the tight metal parts out. Many builders end up doing exactly that: the router makes the fixtures, the fixtures hold the parts, and the critical features come from a machining supplier.

If a design has both kinds of features, split the part. Wood or plastic panels can be cut on the router. Metal inserts, bushings, and mounting plates can be machined to tolerance and assembled into the frame.

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  Router jobsTemplates, spoilboards, jigs, enclosures, signage, foam molds.
• 2
  Machined jobsBearing bores, sealing faces, threaded inserts, precision plates.

A production shop starts from the CAD file and a DFM review. The review checks wall thickness, tool reach, corner radii, and how the part will be held. It runs within 12 hours of upload, before any metal is cut.

The part is then machined on the right machine for its geometry. A flat plate with holes might run on a 3-axis mill. A part with features on five faces, like a manifold or a housing, runs on a simultaneous 5-axis center. Complex round parts run on a mill-turn center.

Inspection closes the loop. Raw material is checked on arrival, dimensions are monitored during the run, and every part is inspected before shipment. Reports are available on request, which is what makes the ±0.005 mm claim verifiable rather than a marketing line.

Volume does not force a jump in method. The same process runs from one prototype to a 10,000+ part run, which means the part you qualify in April is made the same way in September.

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  12-hour quote and DFMFeedback on manufacturability before the first cut.
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  100% inspectionEvery part checked before it ships, not sampled.