Threads and Fasteners
Fasteners
Fasteners
Standard Bolts and Nuts:
American National Standard bolts
and nuts, both inches and metric,
are produced in hexagon form.
Square head bolts and nuts are
only produced in the inch series.
Square bolts and nuts, hexagon
bolts, and hexagon flat nuts are
unfinished. Unfinished bolts and
nuts are not machined on any
surface except for the threads.
Finished bolts and nuts are
characterized by a “washer face”
machined on the bearing surface.
The washer face is 1/64” thick but
drawn at 1/32”. The diameter is
equal to 1 ½ times the body
diameter.
Fasteners
Bolt Proportions:
Regular hexagon
and square bolts
and nuts:
W = 1 1/2D
H = 2/3D
T = 7/8D
Thread Lengths:
For bolts up to 6” in
length: Thread
length = 2D + ¼”
For bolts over 6” in
length: Thread
length = 2D + ½”
Fasteners
Drawing Standard Bolts:
Bolt heads and nuts should
be drawn across corners in all
views regardless of projection
to prevent confusion between
the square and hexagon
heads and nuts.
Only when there is a special
reason should bolts heads
and nuts be drawn across
flats.
In such cases, the
conventional proportions are
used as shown.
Fasteners
Steps in drawing a finished hexagon head bolt and hexagon nut.
Fasteners
Steps in drawing a square-head bold and square nut:
Fasteners
Standard Cap Screws:
Fasteners
Standard Machine Screws:
Fasteners
Keys are used to prevent relative movement between shafts and wheels, couplings, cranks, and
similar machine parts attached to or supported by shafts.
A woodruff key is semicircular in shape. The key fits into a semicircular key slot cut with a
Woodruff cutter as shown, and the top of the key fits into a plain rectangular keyway (figure c).
Fasteners
Machine Pins:
Machine pins include taper pins, straight pins, dowel pins, clevis pins and cotter pins.
The taper pin is effective for fastening hubs or collars to shafts.