1/4" - 20  x  1/2" U.N.R.C. Coarse Thread
Product Code Number 20040


Nominal Size or Basic Screw Diameter Head Diameter Head Height Head Side Height Hexagon Socket Size Key Engagement Fillet Extension Length
Max Min Max Min Ref Nom Min Max Min Nom
1/4 (0.2500) 0.437 0.419 0.132 0.122 0.031 5/32 (0.156) 0.087 0.290 0.280 0.50
SEE NOTES 1     2   13    8 3, 4, 5, 6

NOTES:
(1) Nominal Size (7) Screw Point Chamfer  (13) Hexagon Socket Dimensions
(2) Head Height (8) Fillet (14) Dimensional Conformance
(3) Length (9) Bearing Surfaces (15) Designation
(4) Standard Lenghts (10) Concentricity (16) Gaging of Hexagon Sockets
(5) Length Tolerances  (11) Threads (17) Screw Thread Limits
(6) Thread Length (12) Material (18) Mechanical Properties

Reprinted from ASME/ANSI B18.3 by permission of The American Society of Mechanical Engineers.  All rights reserved.  For a full copy of the standards, contact the ASME at http://www.asme.org/codes/.

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