Stick Out
Stick-out is the length of a tool or workpiece extending beyond its support point. For tooling, it is the distance from the cutting tip to where the shank enters the holder or collet. For turning, it refers to how much bar or part material extends beyond the chuck or support. Minimizing stick-out maximizes rigidity and reduces deflection, chatter, and dimensional error.
On the shop floor, stick-out is the first thing to scrutinize when a cutter chatters or finishes drift. A tool held too far out acts like a cantilever, so even a small increase in unsupported length sharply raises deflection under load. In milling, operators may need extra reach to clear clamps or reach deep pockets, but the standard move is to use the shortest stick-out that still clears the work and reaches the cut, then verify flute length, holder clearance, and programmed depth. In turning and Swiss machining, minimizing bar overhang prevents whip, taper, and poor concentricity; guide bushings deliberately shorten exposed stock. Edgebanding and routing show the same pattern: excessive reach creates tearout and inconsistent edges. Many shops standardize approved stick-out lengths by tool diameter so consistency and rigidity are built into every setup rather than left to operator judgment.
- Chatter that appears only deeper into the cut: Operators often add extra reach just to be safe, but the added unsupported length drops stiffness sharply. The cut loses stability under load, leaving washboard finishes or ringing that changes with depth.
- Tool stalls or snaps despite enough flute length: Flute length only defines the cutting portion; bending risk comes from the unsupported shank below the holder. A cutter can have adequate flute reach yet fail when too much shank is exposed.
- Taper and part whip on slender stock: Holding too little material while leaving too much bar exposed lets the workpiece flex under cutting forces. The problem is often blamed on jaws or spindle, but the real cause is support length versus diameter.
What is the difference between stick-out and overhang?
They are often used interchangeably, but the precise CNC definition of stick-out is the measured distance from holder support to tool tip. Overhang can refer more broadly to any unsupported length, so the bending risk is best tied to actual stick-out.
Why do long-stick-out tools chatter even at conservative feeds?
Because stiffness decreases quickly as unsupported length grows, and lowering feed or speed cannot fully compensate once the tool enters a resonance-prone state. Excessive stick-out causes finish and size control to degrade regardless of conservative parameters.
Why is Swiss machining better for long slender parts?
The guide bushing supports the material close to the cut, which minimizes exposed length, reduces deflection and vibration, and holds tighter tolerances on small-diameter work. This makes Swiss machining ideal for slender parts where conventional lathe overhang would cause whip and taper.