Bits / Workshop reference
Ball-nose & tapered ball-nose bits
Choose a rounded tip for 3D contours and understand what stepover can—and cannot—predict.
In everyday language
Follow a curved carving
A ball-nose bit has a rounded cutting tip for curved surfaces. Stepover is the sideways spacing between neighboring passes.
Picture a shallow landscape carving. Closely spaced finishing passes can reduce the geometric ridges between them.
What to notice: Compare the curve shape and remaining ridges. Wood grain, tool condition and machine movement affect the real surface too.
Does reducing pass spacing always make a job faster?
No. Smaller spacing usually increases the amount of travel and machining time.
No need to know the vocabulary first
A few words, explained
- Collet
- The gripping sleeve that holds the shank of a cutting bit.
- Shank
- The part of a cutting bit held by the machine, distinct from its cutting diameter.
- Stepover
- The sideways spacing between neighboring cutting passes.
- CAM
- Computer-aided manufacturing: software used to prepare the machine's cutting movements.
- Runout
- Deviation from true rotation, which can make a tool cut wider than intended.
- CNC
- Computer numerical control: a computer directs a cutting machine.
2 more words used on this page
- Toolpath
- The route a cutting tool follows through a job.
- Grain
- The direction and pattern of the wood's fibers.
How it works
The spherical tip follows curved surfaces. Adjacent passes leave a cusp; smaller spacing reduces the ideal geometric cusp but increases travel.
When to consider it
Consider ball-nose tooling for compatible 3D relief and contour finishing. Tapered tools need the actual taper and tip radius represented in CAM.
Where it does not apply
Do not enter the shank diameter as the ball diameter. A flat-surface scallop estimate does not predict finish on every slope or grain direction.
Before the first cut
- Confirm tip radius versus diameter, taper angle and usable cutting reach from the tool drawing.
- Check the shank and tapered body against the model for collisions, not just the tip.
- Separate roughing from finishing where appropriate; calculate scallop geometry without treating it as a cutting-load limit.
Review collet engagement & stickout · Review material setup & zero
If the result looks wrong
Stop the machine and make it safe to inspect before checking the tool or workpiece.
Visible ridges
Check stepover, raster direction and surface slope; runout and deflection also affect finish.
Deep details are damaged
Check whether the taper or shank collides before the tip reaches the intended feature.
Use the matching calculator
Calculator outputs describe geometry, time or cost—not permission to operate at those values.
Make the setup repeatable
In Machine & Bit Settings, keep these details in the standard fields, additional fields and setup notes. Record a test date only after testing that exact setup.
- Tip radius / diameter
- Taper and usable reach
- Finishing stepover and toolpath direction
No cutting settings are automatically supplied or saved by this guide.
References & exact specifications
These public references explain the tool families or software features. Locate your exact part number and machine manual before setup; product families are not interchangeable.
Guidance reviewed September 2026. Diagrams are original simplified explanations, not manufacturer drawings.