The tangential cutting force is what the spindle pushes against and what tries to deflect the tool. It follows directly from horsepower and cutting speed.
Force (lbf) = (33,000 × HP) / SFM
What the variables mean
| Symbol | Meaning |
|---|---|
| Force | Tangential cutting force (pounds) |
| HP | Spindle horsepower at the cut |
| SFM | Cutting speed (surface feet per minute) |
| 33,000 | ft·lbf per minute in one horsepower |
Worked example
3.75 HP at 300 SFM: Force = 33,000 × 3.75 / 300 = 413 lbf. Lower SFM at the same power means higher force.
Run it instantly with the Cutting Force calculator in Material & Weight.