Tool presetting determines offset values used by your CNC; runout measurement determines how round your hole or cut will be.
What Is Tool Presetting?
Tool presetting measures tool length and diameter outside the machine, BEFORE loading.
- Offline presetters — Speroni, Zoller, Heidenhain
- On-machine probing — Touch probe + reference standard
- Manual setting blocks — Old-school, slow
Why Presetting Matters
- Reduces machine downtime (set tool while machine cuts)
- Eliminates manual touch-off errors
- Catches damaged tools before spindle
Runout: What Is It?
Difference between highest and lowest readings as tool rotates one full turn.
- 0.005mm — Excellent, shrink-fit
- 0.01mm — Good, hydraulic chucks
- 0.02mm — Acceptable, ER collets when new
- 0.03mm+ — Problem
Why Runout Hurts
- Drilled holes oversized (0.02mm runout = 0.04mm oversize)
- End mill teeth wear unevenly
- Tool life cut by 30-50%
- Surface finish degrades
- Spindle bearings wear faster
Tool Holder Runout (typical)
| Holder Type | Runout (TIR) |
|---|---|
| Shrink-fit | less than 0.003mm |
| Hydraulic chuck | 0.005-0.010mm |
| Milling chuck (TG, OZ) | 0.010-0.020mm |
| ER collet (new) | 0.010-0.020mm |
| ER collet (worn) | 0.030+ mm |
Reducing Runout
- Clean spindle taper before mounting
- Inspect tool shank for damage
- Replace ER collets annually
- Upgrade to shrink-fit or hydraulic for critical tools
Browse measuring tools and tool holders.
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