Second-hand wooden CNC machine: how a sales list really reads

• 1
  What a second-hand wooden CNC machine actually is
• 2
  Spindle hours and bearing condition
• 3
  Rails, racks and the parts that set accuracy
• 4
  Vacuum tables, controls and spare parts
• 5
  Second-hand wooden CNC machine: what to accept and what to walk away from

A wood router is a gantry machine with a spinning tool moving over a fixed bed. The spindle sits on a Z carriage, the carriage rides a beam, and the beam travels along the side rails. Wood and board are soft compared with steel, so the structure is lighter and the feed rates are higher. That difference drives everything about how these machines age.

The cutting forces are low, so a used router rarely fails from structural overload. It fails from wear in the parts that move all day: linear guides, racks and pinions, ball screws on the Z axis, and the spindle bearings. A sales list that only quotes year, brand and table size tells you almost nothing about those four items.

Bed size is the headline number on most listings, and it is the least useful one on its own. A 3,000 × 1,500 mm bed with a 6 kW spindle behaves very differently from the same bed with a 12 kW spindle. Ask what the machine was cutting, not how big it is.

Materials matter too. A router that spent five years trimming MDF panels has a different wear profile from one that cut solid oak stair stringers or nested plywood all day. Both are wood machines, but the duty cycle is not the same.

The spindle is the most expensive single part to replace. Industrial routers usually log spindle run hours in the control, and that counter is the closest thing to an odometer. Under 8,000 hours is a young spindle for a wood router. Past 20,000 hours, budget for a rebuild or a replacement head.

Run the spindle at low speed with no load and listen. A clean bearing set makes a steady tone. Whining, a periodic tick, or a rumble that changes with rpm points to bearing damage. Feel the housing after a few minutes of running. Warm is normal; too hot to hold means the bearings or the cooling path have a problem.

Check runout at the taper with a dial indicator. A wood router spindle that shows more than about 0.02 mm of runout will leave visible marks on edge profiles and will wear collets fast. Also look at the tool holder seats. Scoring or fretting there is a sign of long service with poor cleaning habits.

Ask whether the spindle is air cooled or liquid cooled. Liquid-cooled heads hold rpm better on long panel runs, but they add a pump, a radiator and hoses that can leak. On a used machine, look for dried coolant residue under the gantry.

Linear guides on a wood router are usually sized 20 to 30 mm. They wear slowly under light loads, but they do wear. Push the gantry by hand along its full travel. It should move smoothly with no tight spots and no rattle. Rock the carriage side to side against the rail; any perceptible play means the block preload is gone.

Rack and pinion drives are common on long X axes because they avoid screw whip. The trade-off is that the pinion wears and the rack collects dust. Look at the tooth flanks. A polished, sharp-edged profile with a visible step means the pinion has been running out of mesh for a while.

Backlash is the number that decides whether the machine can still hold a tolerance. On a wood router, 0.1 mm of backlash at the tool is often acceptable for panel work and unacceptable for joinery or jigs. Command a 50 mm move, reverse it, and measure the lost motion with a dial indicator against a stop.

Ball screws appear on the Z axis and on smaller machines. Rotate the screw by hand with the power off. Gritty feel or a dry squeak means the nut is running low on grease or the screw has pitting. Neither is cheap to fix.

Vacuum workholding is standard on nesting routers, and the table is where hidden damage lives. Check the spoilboard for deep gouges that break the vacuum zone seals. If the machine has zoned vacuum, test each zone separately with a sheet of MDF and a vacuum gauge. A zone that will not pull down usually has a leaking gasket or a cracked plenum.

Vacuum pumps are a wear item. Rotary vane pumps need new vanes and filters; regenerative blowers are simpler but move less air. Ask when the pump was last serviced and listen for bearing noise. A replacement pump is a real cost, so treat it as part of the purchase price.

The control is the other long-lead item. Fanuc, Siemens, Heidenhain and Osai all still supply parts for older wood routers, but lead times vary. Ask for the exact control model and serial, then confirm with a distributor that drives and boards are still available. A machine with an orphaned control is a machine you may not be able to repair.

Finally, check what comes with the machine. Collets, wrenches, vacuum hoses, the original manual, and any CAM post-processor files are all small items that cost real money to replace. A seller who kept the paperwork usually kept the machine.