Buying guide · Printable checklist

How to Evaluate a Used Machining Center: Shop-Floor Checklist

A used VMC or HMC that “looks clean” can still carry a tired spindle, an orphaned control, or a missing tooling package. This is the checklist to run before a deposit moves. Print it, bring it to the walkthrough, or use the photo list to screen a listing remotely.

Print this checklist Second opinion: call / text 508-343-1219

1. Identity and history

• Machine plate photographed: model, serial number, build year.
• Control family and software version noted (Fanuc, Haas NGC/Classic, Mazatrol, OSP, Siemens, Mitsubishi, etc.).
• Options list compared with what is actually enabled on the control.
• Why it is for sale: capacity change, shop closing, or “we’re done fighting it.”
• What it cut: aluminum, steel, stainless, cast iron, or abrasive alloys. Abrasive work wears ways and seals faster than hours alone show.

2. Hours: read both clocks

• Spindle (cutting) hours and power-on hours, pulled from the control screen, not just quoted.
• Hours make sense next to what you see on the wear surfaces.
• No hour screen or maintenance log? Not an automatic walk, but dig harder on wear.

3. Control, options and backups

• Options your work needs are present: rigid tapping, high-speed look-ahead, probing, 4th/5th axis prep, through-spindle coolant.
• Parameter backup exists (and ladder/PMC notes where they apply).
• Screen, softkeys, MDI, handwheel/MPG and I/O all respond.
• Memory backup battery status checked.

4. Spindle and taper

• Taper (CAT/BT 40/50, HSK) is clean, with no fretting, galling or witness marks.
• Runout (TIR) checked in a clean taper with a test bar or qualified holder.
• Spindle runs up through its range without unusual noise or heat.
• Any spindle rebuild is backed by an invoice with dates and who did the work.

5. Ways, screws and wear surfaces

• Way covers and wipers intact; way oil is reaching the surfaces.
• Ballscrew boots and bellows not torn (torn boots let grit into the screws).
• Backlash / lost motion checked with an indicator on a known surface, not only from the control.
• No crash evidence, cracked castings, welds or “shop repairs” on guarding.
• Chip pan, coolant tank and conveyor condition: sludge and rust tell you how coolant was managed.

6. Geometry (bigger tickets and tight work)

• Ballbar test allowed, if the seller will permit a short run.
• Level and geometry notes, especially if the machine was moved without a proper re-level.
• If your parts live inside a few tenths on position, do not skip geometry because the paint is nice.

7. Functional check under power

• Tool changer cycles through every pocket cleanly.
• Door and pallet interlocks work.
• Coolant, through-spindle coolant, chip conveyor and probing cycle (if equipped) run.
• Electrical cabinet is neat: no burned insulation, rodent damage or heavy dust.

8. What is actually included

• Toolholders, vises, fixtures, probes and manuals inventoried in writing.
• “Tooling available separately” priced out. A bare machine often loses its discount in the first tooling order.
• Documentation: manuals (mechanical and electrical), maintenance logs, rebuild invoices, alignment or ballbar reports.

Remote screening: the 8 photos to ask for

1. Control screen showing hours and software version
2. Spindle taper, lit, clean and close up
3. Way covers open (if safe) showing oil
4. Ballscrew boots on X, Y and Z
5. Chip conveyor and coolant tank
6. Electrical cabinet, doors open
7. Full machine plate (model, serial, year)
8. Any crack, weld or repair on the casting or guarding

If a seller won’t shoot those, you are negotiating blind. Price it that way or pass.

Pay, renegotiate or walk

Rule of thumb: if the discount versus a known-good comparable doesn’t cover the punch list plus moving, rigging and re-leveling, you’re buying a project, not production capacity.