24-1
Pinned Interfaces
Stephen Harry Werst
Raytheon Systems Company
Dallas, Texas
Mr. Werst has worked as a mechanical engineer with Texas Instruments Defense Systems and Electronics
Group, now part of Raytheon Systems Company, for more than six years. Most of his work has involved
the design of electro-optic infrared imaging systems and more recently, GD&T training. Mr. Werst
attended the University of Texas at Arlington, graduating summa cum laude with a bachelor’s degree in
mechanical engineering. He recently earned his master’s degree in engineering management from
Southern Methodist University. Prior to his work with Raytheon, he worked as a computer programmer
for Martin Marietta Energy Systems.
24.1
List of Symbols (Definitions and Terminology)
α
Rotation error between parts
β
Installation angle of modified alignment pins
δ
Translation error between parts
σ
Standard deviation
Øh or Øh1 and Øh2
The diameter of the clearance hole(s) or the diameters of the first and
second clearance holes
Øp or Øp1 and Øp2
The diameter of the alignment pin(s) or the diameters of the first and
second alignment pins
c
A measure of the clearance between alignment features in an assembly
cnom
The clearance calculated using the nominal dimensions
cte
Coefficient of thermal expansion
Chapter
24
24-2 Chapter Twenty-four
de
Distance between the center of the clearance hole and the edge of the
part
dh
Distance between the centers of the clearance holes
dhs
Distance between the center of the hole and the center of the slot
dp
Distance between the centers of the alignment pins
dpx
Distance between the centers of the alignment pins in the x direction
dpy
Distance between the centers of the alignment pins in the y direction
lslot
Length of slot
perph or perph1 and perph2
Perpendicularity of the clearance hole(s) or the perpendicularity of the
first and second clearance holes
perpp or perpp1 and perpp2
Perpendicularity of the alignment pin(s) or the perpendicularity of the
first and second alignment pins
t
The distance from the center