Home Back

Tap Calculator Feed Speed

Tap Speed and Feed Formulas:

\[ RPM = \frac{SFM \times 3.82}{D} \] \[ Feed = \frac{RPM}{TPI} \]

Unit Converter ▲

Unit Converter ▼

From: To:

1. What is a Tap Feed and Speed Calculator?

Definition: This calculator determines the optimal RPM and feed rate for tapping operations based on material speed (SFM), tap diameter, and thread density.

Purpose: It helps machinists and CNC operators achieve proper thread cutting while maximizing tool life and efficiency.

2. How Does the Calculator Work?

The calculator uses two formulas:

\[ RPM = \frac{SFM \times 3.82}{D} \] \[ Feed = \frac{RPM}{TPI} \]

Where:

Explanation: First calculate RPM from SFM and diameter, then derive feed rate based on the thread pitch.

3. Importance of Proper Tap Speed and Feed

Details: Correct calculations prevent tap breakage, ensure thread quality, and optimize machining time. Too fast can break taps, too slow reduces productivity.

4. Using the Calculator

Tips: Enter the material's recommended SFM, tap diameter in inches, and threads per inch. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: Where do I find SFM values?
A: Refer to material/tap manufacturer charts. Example: 30 SFM for aluminum, 10 SFM for mild steel, 5 SFM for stainless.

Q2: Why is 3.82 used in the formula?
A: It's the conversion factor (12/π) to convert SFM (feet) to RPM (inches).

Q3: How does TPI affect feed rate?
A: Higher TPI (finer threads) requires slower feed to maintain proper thread engagement.

Q4: Should I adjust for different tap materials?
A: Yes, carbide taps can run 2-3× faster than HSS at the same SFM.

Q5: What about thread percentage?
A: For less than 75% thread engagement, you may increase feed by 10-20%.

Tap Calculator Feed Speed© - All Rights Reserved 2025