Tooling
Runout is costing you thousands
12 August 2026
Runout doesn't announce itself. It shows up as tool wear that seems a bit faster than it should be, a surface finish that's not quite right, or a hole that's a few microns off centre. It's one of the most common, and most overlooked, sources of cost in CNC machining.
What causes it
Runout usually comes from something mechanical rather than the program itself: a worn tool holder taper, a mismatched or worn collet, a chipped or bent tool, spindle bearing wear, or simply chips and contamination stopping the tool seating properly. Heat and vibration during a long run can shift things further as the day goes on.
What it actually costs you
Even a small amount of runout unbalances the load across a tool's cutting edges. One edge does more work than the others, wears faster, and the tool fails sooner than it should. The same imbalance shows up in the part: uneven surface finish, oversized or undersized features, holes that wander off their true position. None of that shows up as a line item on an invoice. It shows up as tools replaced more often than they should be, parts scrapped or reworked, and time spent chasing a quality problem that turns out to be mechanical, not programmed.
What to do about it
Runout is straightforward to check, with a dial indicator or a tool presetter, and it's worth checking regularly rather than waiting until quality drifts. Catching it early is far cheaper than the tooling and scrap it causes if it's left to run.
Get in touch if you'd like to talk through how this applies to your operation.