What is the practical effect of applying an LMC-based tolerance to a shaft?

What is the practical effect of applying an LMC-based tolerance to a shaft?

• A. It tightens the tolerance as the shaft size moves toward its MMC.
• B. It eliminates tolerance entirely.
• C. It allows the tolerance to expand as the shaft size moves toward its MMC, providing bonus tolerance if specified.
• D. It shifts the tolerance to apply only to the shaft diameter.

Answer: (C)

In GD&T, LMC ties a tolerance to how large or small a feature is relative to its least material condition. For an external feature like a shaft, LMC means the smallest acceptable diameter. When a tolerance is specified as LMC-based, the allowable variation isn’t fixed at one size; it changes as the shaft size moves away from LMC toward MMC. Specifically, as the shaft diameter increases toward its MMC, the tolerance zone expands. If the drawing allows it, that extra room is called bonus tolerance. So the practical effect is that the tolerance gets looser as the shaft gets larger toward its MMC, giving additional allowance if specified. This is not eliminating tolerance, not tightening it toward MMC, and not shifting the tolerance to only the shaft size—it's about the tolerance growing with size toward MMC.

In GD&T, LMC ties a tolerance to how large or small a feature is relative to its least material condition. For an external feature like a shaft, LMC means the smallest acceptable diameter. When a tolerance is specified as LMC-based, the allowable variation isn’t fixed at one size; it changes as the shaft size moves away from LMC toward MMC. Specifically, as the shaft diameter increases toward its MMC, the tolerance zone expands. If the drawing allows it, that extra room is called bonus tolerance. So the practical effect is that the tolerance gets looser as the shaft gets larger toward its MMC, giving additional allowance if specified. This is not eliminating tolerance, not tightening it toward MMC, and not shifting the tolerance to only the shaft size—it's about the tolerance growing with size toward MMC.