Bits / Workshop reference
Upcut spiral bits
Clear chips upward from pockets and grooves while accounting for top-edge tear-out and lifting forces.
In everyday language
Clear a pocket for a small tray
An upcut spiral carries removed material upward. A pocket is a recessed area that does not go all the way through the wood.
Imagine a shallow tray with a flat base. The tool needs room to remove chips, and the wood must resist being lifted.
What to notice: Compare the top edge with the pocket floor. A clean floor and a fuzzy top edge tell you different things.
Does upward chip movement hold the wood down?
No. The cutting action can lift the wood. The holding method must resist that force.
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.
- CAM
- Computer-aided manufacturing: software used to prepare the machine's cutting movements.
- Veneer
- A thin layer of wood, often bonded to another material.
- Plunge
- A movement that takes a cutting tool down into material. Not every tool permits this.
- CNC
- Computer numerical control: a computer directs a cutting machine.
5 more words used on this page
- Stock
- The wood or other material you start with.
- Workholding
- The way you keep a piece securely in place while working on it.
- Toolpath
- The route a cutting tool follows through a job.
- RPM
- Revolutions per minute: how many full turns a tool makes each minute.
- Grain
- The direction and pattern of the wood's fibers.
How it works
A helical edge shears along the wall and transports chips toward the shank. The axial cutting action can lift fibers at the top face.
When to consider it
Consider a manufacturer-rated upcut for pockets and slots where chip evacuation matters. Match the exact tool to solid wood, plywood or another approved material.
Where it does not apply
Do not rely on the bit to hold a thin workpiece down. A visible top veneer may need a different tool or finishing strategy.
Before the first cut
- Secure the stock against lifting and lateral movement; check the cutout remains held after separation.
- Use the documented flute count, cutting diameter and material-specific chip-load guidance in CAM.
- Check cutting length, holder clearance and permitted entry method; a spiral appearance alone does not establish plunge capability.
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.
Fuzzy top edge
Check grain, sharpness, workholding and whether a downcut or suitable compression geometry better matches the face requirement.
Chips trapped in a pocket
Stop and inspect extraction and the toolpath. Do not reach into a moving machine.
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.
- Tool part number and flute count
- Material and measured thickness
- Workholding and chip evacuation
- Tested feed, RPM and depth
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.