Figure 1: Visual comparison . Steppers (Left) are dense and simple. Servos (Right) are longer and include a visible feedback encoder housing on the rear. The Million Dollar Question: "Which Motor Do I Need?" If you are designing a CNC machine, a packaging robot, or a conveyor system, you face the same dilemma every time: Stepper or Servo? Make the wrong choice, and you face two disasters: The Stepper Trap: Your machine "loses steps" (positional error) without knowing it, scrapping parts. The Servo Trap: You spend $5,000 on a system that could have been done for $500, blowing your budget. This guide bridges the gap between mechanical requirements and electrical reality. 1. The Stepper Motor: The "Digital Ratchet" Think of a Stepper Motor like a very strong, magnetic ratchet. It divides a full rotation into equal steps (typically 200 steps per revolution, or 1.8°). Pros: Incredible Holding Torque: Ste...
The Engineer's Bible: ISO 286 Limits and Fits 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. 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 d...