Before you buy any used CNC machine, see it under power if you can. Confirm the control comes up with no standing alarms, measure spindle runout and axis backlash, look at the ways and screws, and get the options list and a parameter backup. Then make sure the size, weight, power and air needs fit your shop.
Before You Go Look
- Know your parts. Write down your largest part, the material, the tightest tolerance and how many you run. That tells you the travels, spindle and taper you need before you fall for a machine.
- Know your shop. Check your incoming power and voltage, your air supply, your floor and the size of your door. A machine that does not fit through the door is a problem nobody wants to solve after the truck shows up.
- Know the category. Browse our used CNC machines, used grinders and industrial liquidations to see what is out there in your size class.
Nameplate and Paperwork
- Photograph the builder's nameplate and the control's nameplate. Model, serial number and build year should match the listing.
- Ask for the manuals, electrical prints and any maintenance records.
- Ask for a backup of the parameters and, on FANUC controls, the ladder. Losing parameters on an old machine can cost you days.
- Write down the options that are turned on. Two machines with the same model name can be set up very differently.
The Control
- Power it up and look for standing alarms. Then check the alarm history for repeat faults.
- Check the memory backup battery. On many controls a dead battery means lost parameters.
- Make sure the screen is readable, every key on the panel works and the handwheel moves each axis.
- Find out if parts are still easy to get for that control. FANUC parts are widely available. We carry FANUC CNC hardware like a FANUC 18i, a FANUC Series 160i, a FANUC Series 160i-M and an A02B-0236-C205, plus a never used Dynapath operator panel.
The Spindle
- Run it through the speed range after a warm up. Listen for rumble or whine and feel for heat.
- Indicate runout on a test bar or on the chuck face.
- On a mill, check that the drawbar grips and releases cleanly and that the taper is free of fretting.
- Spindle trouble is not always the bearings. Drive faults can look similar. We stock a FANUC spindle amplifier by exact part number.
Axes, Ways and Screws
- Check backlash on each axis with an indicator: move a small amount, reverse and read the dial.
- Look for scored ways, torn wipers and chips packed under the covers.
- Make sure the way lube system pumps and the oil reaches the ways.
- Listen to each axis at rapid. Grinding or a change in pitch points to the screw or the bearings.
- Axis faults can come from the servo motor, the amplifier or the cables. Any replacement has to match your part number, including the suffix. We list our FANUC servo amplifiers that way.
Hydraulics, Coolant, Chips and Air
- Look for leaks under the machine and around the hydraulic unit. Check the pressure gauges while it runs.
- Look in the coolant tank. Sludge and tramp oil mean neglect. Run the pump and check the flow.
- Run the chip conveyor. If you want through spindle coolant, check that the spindle is set up for it. A unit like our ChipBlaster high pressure coolant system supplies the pressure.
- Most CNC machines need clean, dry shop air. Make sure your air compressors and dryers can carry the added load.
Tooling
Ask what tooling is included and what taper the spindle takes. A machine with no holders can still be a good buy if you budget for tooling. Our used tool holders include CAT 40 end mill holders, CAT 50 tool holders, an HSK 63 holder and TSD Microbore boring heads.
Machine Types in Stock and What to Check
- Machining centers. Cycle the tool changer through every pocket and check table flatness. See our used vertical machining centers.
- Lathes. Index the turret to every station, check chuck pressure and look at the jaws. See our used CNC lathes and the Emag vertical lathe.
- Grinders. Spindle bearings and ways matter most, then the chuck and coolant filtration. See our used surface grinder.
- Drills and hones. Check the column, arm or stroke for play. We have an Invema radial drill and a Sunnen hone.
Freight and Payment
Get the machine weight and footprint before you book a truck. Everything we sell ships FOB Imlay City, Michigan, and the buyer arranges freight. If you need to spread out the cost, see our equipment financing page.
Related Guides
- Used vertical machining center checklist
- Used CNC lathe buyer's guide
- Surface, internal and tool grinders compared
- Building a tooling package
Selling CNC Equipment?
We buy used CNC machines, grinders and tooling, from one machine to an entire plant. Visit our sell your used CNC equipment page or ask about our machinery appraisal services.
For more on any machine in stock, call 586-752-0090, extension 1 for sales, or contact our sales team.