Runout before the rush

Two minutes with a dial

Runout is how far the bit wobbles off true centre. A little is normal. Too much shows up as poor finish, oversized slots and bits that snap for no clear reason. The check takes two minutes: test pin in the collet, dial indicator against it, turn the spindle slowly by hand and read the movement.

When to check

Check first thing on a day with an important job, after any crash, and whenever finish suddenly gets worse. Write the reading on the care card. Over a few weeks the numbers tell you whether a collet is wearing or a bearing is starting to go.

What to do with a bad reading

First clean the taper and collet and check again, dust is the usual cause. If it is still high, swap the collet. If a new collet does not fix it, the spindle bearings need attention, and that is a service call, not a guess.

The slip we see most

Checking runout with a bit in the collet instead of a test pin, which measures the bit, not the spindle.

How you know it is working

The care card shows steady readings week after week, and a sudden jump gets spotted before it breaks a bit.

Written by Claire Els, Tooling and Care Lead. Claire looks after the bit sets, care kits and the Friday audit routine.