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Perpendicularity : GD&T Basics

  • Perpendicularity can be called out on any surface or axis of any feature of a part.
  • Perpendicularity tolerance on surface controls perpendicularity between two  surfaces perpendicular to each other.  Tolerance zone in this case will be two parallel planes.
  • Perpendicularity tolerance on axis controls the perpendicularity of any surface w.r.t. datum plane. Tolerance zone will be a cylindrical surface.
  • Datum plane is required to control the perpendicularity of any surface or axis.
  • MMC and LMC can be applicable with perpendicularity tolerance. 

Perpendicularity tolerance on a Surface

  • Perpendicularity tolerance on any surface controls perpendicularity between two  surfaces perpendicular to each other.
  • Perpendicularity tolerance controls the 90° angle between two surfaces of a parts by controlling the location where the surfaces have to lie.
  • Perpendicularity controls the angle of the feature w.r.t datum plane by controlling all points on that surface within two parallel planes.

 


Tolerance Zone for perpendicular tolerance on Surface

Tolerance zone for perpendicular tolerance on surface will be two parallel planes. All points on that surface should lie within two parallel planes.


Measurement of Perpendicular tolerance on a Surface

 

 

Perpendicularity of a surface is measured with height gauge, Gauge is placed with reference to datum place and variation in surface is measured with dial gauge. 

 

 

 


 

Perpendicularity on an axis

 

  • Perpendicularity tolerance on any axis controls the perpendicularity of any surface w.r.t. datum plane. Tolerance zone will be a cylindrical surface.
  • Perpendicularity of an axis control can be used with MMC

 

 

 


Tolerance Zone on Perpendicularity on an Axis:

Tolerance zone for perpendicularity on axis will be a cylinder at theoretical exact axis perpendicular to datum feature  .


Related Articles

 


Straightness

 

Flatness

 

Circularity

 

Cylindricity

 

Profile of Line Control

 

Profile of Surface Control

 

 

Perpendicularity

 

Parallelism

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