(b)
Drive Screws. Special screws, made to be driven with
a hammer, are called drive screws (Figure 138). They may have a
roundhead but are usually made with a flathead, and they may have no
slot for a screwdriver. (They also come in larger sizes with square
or round heads.) The
Figure 1-38. Drive screw
threads are far apart. Drive screws are available in the same size
as wood screws.
(c) Special Screws. Many special hanging and fastening
devices have a screwtype body (Figure 139). The screw eye is often
used on picture frames, screen doors, and many other items. The
curved screw hook and square screw hooks are mainly used for hanging
articles. The curved screw hook is usually used in the ceiling,
while the square screw hook is more often used on vertical walls.
Figure 1-39.
Special screws
c. SheetMetal
Screws.
Like wood screws, sheetmetal
screws can also be slotted or
Phillips head. They are used
for the assembly of metal parts.
They are steel or brass with
four types of heads: flat,
round, oval, and fillister, as
shown in Figure 140.
Figure 1-40.
Sheet metal screws
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