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Electro-Mechanical Design Guidelines

  1. Black Box (Electronic Enclosure) Packaging
  2. Cable Assembly Design should be started early in the design phase.
    Here are some basic specifications to help you through the process. You may find copies of these by going to assist quick search or everyspec.com.
    MIL-W-5088 (s/s by SAE AS50881) wiring, Aerospace Vehicle
    MIL-STD-454 (s/s by MIL-HDBK-454) Standard General Requirements For Electronic Equipment
    ASME Y14.24 Types and Applications of Engineering Drawings
    ANSI Y14.15 Electrical and Electronics Diagrams
    ANSI Y14.15A Interconnection Diagrams
    IEEE-STD-315 (ANSI Y32.2) Graphic Symbols for Electrical and Electronics Diagrams (Including Reference Designation Letters) [click for commonly used industry standard reference designations] If link is broken, click one of these, pcblibraries.com or mentor.com
    ASME Y14.44-2008, IEEE-STD-200 (ANSI Y32.16) Standard Reference Designations for Electrical and Electronics Parts and Equipment.
    MIL-STD-12 (s/s by ASME Y14.38) Abreviations for Use on Drawings, and in Specifications, Standards and Technical Documents
  3. Castings. The Aluminum Association is a good place to start; however, don't overlook the big boys, such as Dow and Dupont when looking for design specifics on plastic hinges. etc.
  4. Charts
  5. Construction
    Table of dressed lumber sizes.
    Designation Actual Size Designation Actual Size
    2 x 4 1 5/8 x 3 5/8 2 x 10 1 5/8 x 9 1/2
    2 x 6 1 5/8 x 5 1/2 2 x 12 1 5/8 x 11 1/2
    2 x 8 1 5/8 x 7 1/2
  6. Drafting.
    DOD-STD-100C standard scales.
    Scale Fraction
    Full size 1/1
    Enlarged 8/1, 4/1, 2/1
    Reduced 1/2, 1/4, 1/8, 1/10, 1/20, 1/30, 1/40, 1/50, 1/60, 1/100
  7. Engineering Drawing Manual. A Manual of Engineering Drawing for Students and Draftsmen by Thomas E. French, M.E., Second Edition.
  8. Engineering Drawing Standards Manual. This is Nasa's 1994 manual. I did not think I would stumble across this one.
  9. Formulas
  10. Hardware
  11. Military Part Numbers and the appropriate dash numbers for ordering cres hardware in sizes #0 to 1/2 up to 3 inches long. Screws and bolts are in Table 1, washers and nuts in Table 2.
  12. Screw Sizes. Screw diameters advance .013 starting with#0(.060)upto1/4.Example:#1=(.060+.013= .073),#2=(.060+.013+.013=.086), etc.
  13. Screw Lengths (Inch). Lengths of pnh screws typically increase by standard increments: (.062) for .125 to .625 long, (.125) for .625 to 1.500, and (.250) for 1.500 to 3.000. Keep in mind each size has length limitations: (.086)#2=1.000 max, (.112)#4=1.500 max, (.138)#6=2.000 max, (.164)#8 through (.375)3/8=3.000 max. Reference MS51957, Screw, Machine, Pan Head, Cross-Recessed, Corrosion-Resistant Steel, UNC-2A. One exception to the rule would be AN3, where screw lengths can be furnished in 1/32 increments, starting at 1/2 inch. Reference AN3, Bolt - Machine, Aircraft (S/S By NASM3THRU20)

    NOTE: You can purchase non- standard lengths of screws and bolts by constructing your part number using the appropriate length code of the style of screw you want (For example a NAS1351N06H32 would yield a 2 inch long screw, not available, according to the specification). Work with the supplier to determine availability.

  14. Thread Binding External UNJ thds iaw MIL-S-8879 are not compatible with standard UNF, UNC, and UNEF nuts or tapped holes. Reference MIL-STD-454, guideline 12, par. 4.1.1.b and MIL-STD-1515, requirement 119, par. f.
  15. Threaded Inserts. Keenserts, T-serts, Helical inserts (helicoils) and Rivet nuts (Rivnuts) are covered here with sizes ranging from no. 1 (.073) to 1 1/2 diameter.
  16. TorqueRequirements. Screws sizes No. 0 to 3/8 are covered.
  17. Rivet upset head dimensions. Here you will find upset head dimensions for rivets ranging in size from 1/16 to 3/8 in diameter. The edge distance to the sheet or joint should not be less than two times the rivet diameter in sheet stock and three times the rivet diameter in non-ferrous materials. Generally, rivet spacing is called out on all drawings in accordance with stress requirements. Reference MIL-STD-403B, Preparation for and installation of rivets and screws , Rocket and Missile Structure.
  18. Holes: Drill point angle.
  19. Machining
  20. Marking, Identification.
  21. Printed Wiring Board
  22. Sheet Metal Forming
  23. Wrench Sizes: Of course Snap-on Tools is always a good resource. And don't forget about the closest equivalent to the old TAD slider chart.

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Last updated on July 5, 2020