What does an old CNC mill’s maintenance log tell me about a machine shop?
A maintenance log shows whether the shop looks after its machines or only fixes them when they stop. Steady, dated entries suggest care. Gaps, repeated repairs on one part, or no log at all tell you to dig deeper before trusting the machine’s condition or the shop’s habits.
Start by reading the log in date order, not in a pile. You want to see routine work such as lubrication, way cover cleaning, coolant changes and spindle checks, mixed in with the occasional repair. A log that shows only breakdowns means the shop waited for trouble. A log that is suspiciously neat, all written in one pen on one afternoon, may have been filled in for your visit.
Look for patterns. The same axis, drive or spindle bearing coming up again and again points to a fault that was patched and not solved. Ask who did the work: the shop’s own people, the machine maker’s technician, or an outside repair outfit. Ask for the invoices behind the big entries and match them to the log.
Then ask the operators. They know which mill drifts, which one needs a warm-up, and which one the foreman avoids on tight tolerances. Compare their answers with the paper. Finally, ask a qualified machinist or equipment appraiser to inspect the mill with you. A log tells you about habits; only a hands-on check tells you about the machine.
Key takeaways
- Read the log in date order and look for routine care, not only repairs.
- Match big entries to invoices and ask who did the work.
- Compare the paper with what the operators tell you, then bring in an equipment appraiser.
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Sources
This answer is checked against primary sources. Links were last confirmed on the dates shown.
- 01Business Development Bank of CanadaGovernmentHow to conduct due diligence when buying a business
- 02Business Development Bank of CanadaGovernmentEquipment valuation: How to do it
- 03Business Development Bank of CanadaGovernmentWhat are the steps to buying a business?
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