In automation design, the choice between a Stepper Motor and a Servo Motor is often decided by budget. But looking at the price tag alone is a mistake that leads to machine failure. Steppers are excellent for holding loads stationary (high holding torque). Servos are kings of high-speed motion. If you choose a stepper for a high-speed application, it will lose torque and "miss steps." If you choose a servo for a simple low-speed application, you have wasted $500. This guide explains the physics behind the choice. Table of Contents 1. Open Loop vs. Closed Loop (The Risk) 2. The Torque Curve: Speed Kills Steppers 3. Inertia Mismatch 4. Selection Summary Advertisement 1. Open Loop vs. Closed Loop (The Risk) The biggest difference is not the motor itself, but how it is controlled. Figure 1: Steppers run "blind" (Open Loop). Servos use an encoder to verify position (Closed Loop). ...
Figure 1: Fundamental deviations for shafts and holes relative to the Zero Line. (Click image to search for the Standard Reference ) In the world of Precision Metrology and CNC machining, adhering to the ISO 286 standard for limits and fits is non-negotiable. Whether you are designing a bearing press fit or a sliding shaft, understanding these metric standards is the difference between a smooth assembly and expensive scrap. Essential Reference: Most professional engineers rely on the Machinery's Handbook for the complete tables of tolerances and allowances. It is the industry standard for verifying these calculations. Advertisement 1. The Big Picture: Hole Basis vs. Shaft Basis Before calculating numbers, you must choose a system. Hole Basis System (Most Common): We keep the hole size constant (e.g., exactly 20.00 mm with a tolerance of H7) and machine the shaft to fit. This is preferred because drills and reame...