Machine-tool iron is nearly immortal — I have run lathes older than me that still hold a tenth. Controls are not. Every used CNC machine is really two purchases: castings and ways that will outlive you, and an electronics package on a countdown clock. When that clock runs out, a $60,000 machine becomes a $15,000 machine overnight, because a dead control board with no replacement turns the whole machine into a boat anchor. Here is how to read the clock before you buy.
How control obsolescence actually bites
It is rarely the whole control that dies — it is one board, one drive, one monitor. The question is whether that part exists. Manufacturers officially support a control generation for roughly 10–15 years after it leaves production; after that you are in the secondhand-board and repair-shop economy, where prices climb and lead times stretch. The failure mode is always the same: a machine that ran perfectly yesterday waits three months for a board that costs a third of the machine’s value.