1. What is CNC Feeds and Speeds for Wood?

Definition: This calculator determines the optimal spindle speed (RPM) and feed rate (IPM) for CNC routers when cutting wood materials.

Purpose: Helps woodworkers and CNC operators achieve clean cuts while maximizing tool life and efficiency.

2. How Does the Calculator Work?

The calculator uses two fundamental formulas:

Where:

• \( RPM \) — Spindle speed (revolutions per minute)
• \( SFM_{wood} \) — Surface feet per minute for wood
• \( D \) — Tool diameter (inches)
• \( IPM \) — Feed rate (inches per minute)
• \( IPT \) — Inches per tooth (chip load)
• \( Z \) — Number of teeth on the cutter

Explanation: The first formula converts SFM to RPM based on tool diameter. The second calculates feed rate based on RPM, chip load, and number of cutter teeth.

3. Importance of Proper Feeds and Speeds

Details: Correct settings prevent tool breakage, burning, poor finish quality, and inefficient machining. They vary by wood type, tool material, and cut type.

4. Using the Calculator

Tips:

• SFM values: Softwoods 1000-1500, Hardwoods 600-1000 ft/min
• IPT values: Typically 0.005-0.020 inches for wood
• Always start with conservative values and adjust based on results

5. Frequently Asked Questions (FAQ)

Q1: What's a typical SFM for hardwood vs softwood?
A: Hardwoods generally use 600-1000 SFM, softwoods 1000-1500 SFM.

Q2: How do I determine the right IPT value?
A: Consult tool manufacturer recommendations or start with 0.010" for 1/4" bits, adjusting based on results.

Q3: Why does tool diameter affect RPM?
A: Smaller diameters must spin faster to maintain the same cutting speed (SFM) at the tool's edge.

Q4: Should I change settings for different wood densities?
A: Yes, denser woods typically require lower SFM and IPT values.

Q5: How does number of teeth affect feed rate?
A: More teeth allow higher feed rates at the same RPM, as each tooth takes a smaller bite.