When machining a rectangular part on a milling machine, to finish the third side must be placed in the vise against

When machining a rectangular part on a milling machine, to finish the third side must be placed in the vise against

• A. the moveable jaw
• B. the base
• C. the solid jaw
• D. a pair of parallels

Answer: (C)

The last surface is finished against the fixed, or solid, jaw because it provides a rigid, unmoving reference for the workpiece. The solid jaw is part of the vise and stays stationary when you tighten the handle, so the surface you machine against remains true and acts as the datum for the other two sides already cut. If you used the movable jaw, its position can shift slightly under clamping pressure, introducing error and changing the alignment of the finished face. The base and parallels may help position the part, but the actual finishing contact needs the fixed jaw to ensure a stable, repeatable, square reference.

The last surface is finished against the fixed, or solid, jaw because it provides a rigid, unmoving reference for the workpiece. The solid jaw is part of the vise and stays stationary when you tighten the handle, so the surface you machine against remains true and acts as the datum for the other two sides already cut. If you used the movable jaw, its position can shift slightly under clamping pressure, introducing error and changing the alignment of the finished face. The base and parallels may help position the part, but the actual finishing contact needs the fixed jaw to ensure a stable, repeatable, square reference.