No need to know the vocabulary first
A few words, explained
- Stepover
- The sideways spacing between neighboring cutting passes.
- Spindle
- The rotating assembly that turns the cutting tool.
- CNC
- Computer numerical control: a computer directs a cutting machine.
- 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.
5 more words used on this page
- Feed rate
- How quickly a cutting tool moves along the material.
- RPM
- Revolutions per minute: how many full turns a tool makes each minute.
- Chip load
- The calculated forward distance per cutting edge; one way to understand how much each edge cuts.
- Flutes
- Grooves along a cutting bit. Check the manufacturer's stated number of cutting edges for calculations.
- Nominal chip load
- Feed divided by RPM and cutting flutes; actual cutting conditions also depend on tool engagement and the system.
Before you begin
The exact tool manufacturer's data, machine limits, and a calculator. The numerical exercise is arithmetic only, not a cutting recommendation.
What this lesson covers
- Keep feed units and rotation units consistent.
- Calculate nominal feed per tooth from stated assumptions.
- Identify the tooling guidance and test results needed to assess a cutting setup.
Recommended preparation
01 / Understand
How it works
Feed rate and spindle speed work together with the bit, material, cutting depth and workholding. Start with the tool manufacturer’s guidance, then use a controlled test to assess cut quality on your setup.
Start with the whole cutting system
Check the tool diameter and flute count, material, workholding, spindle power and cutting depth. Each affects the range of settings suitable for the finish you need.
Assess the test cut
Inspect chip formation, heat, noise, chatter, tearout, fuzzing, and edge quality. Change one variable at a time so you can tell what actually improved the result.
Build a shop-specific settings library
Record the bit, material, RPM, feed, depth of cut, stepover, workholding and result. Keep these records with the manufacturer’s guidance so you can repeat a setup and recognize when conditions have changed.
Key points
- Feed, RPM, flute count, material, and depth all work together.
- The same bit can behave differently in plywood, hardwood, MDF, and acrylic.
- A clean edge is one data point; chips, sound, heat, and hold-down matter too.
02 / Worked example
How feed rate and RPM change chip load
This calculation uses 1,200 mm/min, 12,000 RPM and two flutes to show the relationship. These example values are not recommended settings for a machine or material.
| Case | Calculation | Nominal feed per tooth |
|---|---|---|
| Starting example | 1,200 ÷ (12,000 × 2) | 0.050 mm/tooth |
| Feed halved | 600 ÷ (12,000 × 2) | 0.025 mm/tooth |
| RPM halved | 1,200 ÷ (6,000 × 2) | 0.100 mm/tooth |
Compare feed rate and chip load
Double the feed rate and check the change in chip load. Reset the example before comparing a change to RPM or flute count.
This exercise demonstrates the formula only. Choosing machine settings also requires tool engagement, cutting depth, tool geometry, material and machine limits.
1200 mm/min ÷ (12000 rev/min × 2 flutes). Dividing by more rotations or flutes reduces this value when feed stays fixed.
03 / Try it with your project
Apply the method
Work through the drawing or setup review first, then use a sample that matches your project. Check the equipment and safety requirements above before starting any machine work.
- Pick one bit and one scrap material.
- Run two or three conservative test passes that change only one setting.
- Label each result, compare the edge and chips, then keep the best starting point.
Common mistakes
- Changing feed, RPM, and depth all at once.
- Copying another shop's setting without matching the bit and material.
- Keeping a setting without recording the setup or checking repeatability.
Take it further
Create a test record with one controlled variable, a manufacturer-supported starting point, acceptance criteria, observations, and a stop condition. Do not change several settings at once.
Workshop checklist
Use this topic checklist alongside your machine’s full setup procedure.
- Identify the bit, flute count, material, and operation.
- Start from manufacturer guidance or a conservative calculator result.
- Test on matching stock before production.
- Inspect chips, sound, heat, and edge quality.
- Record the proven setting with the full setup context.
04 / Review questions
Review the key decisions
Consider each question, then compare your answer with the explanation. Return to the worked example whenever you need it.
1. If RPM doubles while feed and flute count stay fixed, what happens to nominal chip load?
View hint
RPM is in the denominator.
View explanation
Nominal chip load halves. Assess the resulting setting against the tool manufacturer’s guidance and the rest of the machine setup.
2. Why is a value copied from another shop incomplete?
View hint
List everything the formula leaves out.
View explanation
You still need the exact tool, material, engagement, depth, holding, spindle, machine capability, and manufacturer guidance. Record those setup details and use an appropriate controlled test.
05 / Project notes
Notes for your next project
Check off the topics you have reviewed and record anything useful for your next build. This tracks your learning progress; use your equipment’s setup procedure for machine checks.
Record: Bit diameter and flutes, material, RPM, feed, plunge, depth, stepover, hold-down, and observed result.
No notes recorded. Use this space for your observations.
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Check each topic above to mark the lesson as reviewed. You can browse any lesson at any time.
Related calculators
Use your project measurements and costs in the calculators below. Check the results against the stock, equipment and requirements of the job.
Practice with a complete project
Apply the lesson to measured dimensions, then keep the drawing, material list and build checks together.
Sources & further study
WoodWorkCalc writes the exercises and illustrative examples. Named historical cases are attributed separately. These sources support the principles identified in the lesson; their publishers do not endorse WoodWorkCalc. Guidance and platform features can change. Sources retain their own copyright and licensing terms.
- ShopBot Tools — CNC Documentation (opens new tab)
Manufacturer's documentation directory for model-specific CNC setup, software, and accessories. Use the manual for your own machine; ShopBot procedures are not universal.
ShopBot Tools. Support Resources. Accessed September 10, 2026.