Buying a used CNC machine: 10 checks before you pay

Updated: 2026-09-27 · 2 min read

A used CNC machine can save a shop a lot of capital, but a badly worn machine or a failing spindle can cost more to fix than you saved. These are the ten things to check in person before you put down a deposit.

1. Year of manufacture and import rules

Check the year on the nameplate against the documents. Used machines imported into Vietnam are generally limited to 10 years of age and need an inspection certificate. See Importing CNC machines into Vietnam for details.

2. Run hours

Most controls record power-on time and cutting time. High cutting hours mean heavy use, but how well the machine was maintained matters more. Take photos of these screens.

3. Accuracy and backlash

Bring a dial indicator. Check spindle runout, then move the X and Z axes forward and back a small amount to measure backlash. Large backlash usually means worn ball screws or bearings.

4. Spindle

Run the spindle from low to high speed for a few minutes. Listen for unusual noise, feel the housing temperature and watch for vibration. Spindle repair or replacement is one of the most expensive fixes.

5. Bed and ways

Wipe the ways clean and look for deep scoring, dents or signs of a heavy crash. Pay attention to the zones used most often, because they wear first.

6. Turret

Index the turret through every station in both directions. Check indexing speed and repeatability, and run the live-tool motor if there is one.

7. Electrical cabinet and control

Open the cabinet: heavy oil mist, burnt wiring or patched repairs are bad signs. Review the alarm history on the control and check the parameter backup battery.

8. Hydraulics, lubrication and coolant

Look for oil leaks under the machine and around the chuck, and confirm hydraulic pressure, the auto-lube pump and the coolant pump all work normally.

9. A real test cut

This is the most important step. Bring your own stock and drawing, ask for a test cut, then measure size, surface finish and roundness. A machine that runs smoothly with no load does not always cut well.

10. Documents and spare parts

Ask for manuals, electrical drawings, a parameter backup and the maintenance history. Without a parameter backup, future repairs can be very hard. Also check whether spare parts for the model are still available in Vietnam.

Summary

If you cannot inspect the machine yourself, bring an experienced technician; the cost is small next to the risk of buying a bad machine. And compare the total cost of the used machine, including repairs and downtime, with a new machine that comes with a warranty.