TM 1-1500-204-23-6
(3)
Fillister head screws. Use general purpose fillister head screw, MS35265 and MS35275 coarse thread,
and MS35266, fine thread, as capscrews in light mechanisms, such as for attaching cast aluminum gearbox cover plates.
These screws have no grip, and those larger than No. 6 have one hole drilled through the head for safe tying. Fillister
head screws, AN502, fine thread, and AN503, coarse thread, are heat treated. They have a small grip and are used as
capscrews where greater strength is required. The coarse threaded screws are commonly used as capscrews in tapped
aluminum alloy and magnesium castings because of the softness of the material. Fillister head screws are shown in
figure 2-39.
e. Self Tapping Screws. Self-tapping screws include machine, sheet-metal, and drive screws.
CAUTION
Never use self-tapping screws to replace standard bolts, nuts, screws, or
rivets in the original structure Damage to components may otherwise
result.
(1)
Machine screws. Use AN504 machine self-tapping screws, as shown in figure 2-40, to attach removable
parts such as nameplates and other similar Items to castings. These screws tap their own mating threads when driven
into untapped drilled or punched holes slightly smaller than the outside diameter of the screw itself.
(2)
Sheet-metal screws. Use MS51861 and MS51862 screws in temporary attachment of sheet metal for
riveting, and for permanent assembly on nonstructural assemblies where ability to insert screws in blind applications is
required. To install, drill a hole and insert screw.
Figure 237. Flat-Head Screws
2-39
