Figure 16-6.--Layout for a seven-hole flange.
PROBLEM II--Lay out a seven-hole flange. (See
1. Draw a circle of the required diameter (AB) and
construct CD perpendicular to AB at center point C.
1. Draw a circle with the required pitch diameter
2. Bisect line AC, locating point E. Then with E as
(AB). Then construct a line that bisects and is
a center and distance ED as the radius, draw arc DE
perpendicular to radius CB (point D). Extend this line
3. With D as the pivot point and distance DF as a
until it intersects the circumference at E and F.
radius, scribe arc FG. Distance DF (or DG) is the length
2. With F as the center and distance DF as a radius,
of the pitch chord and one-fifth of the circumference of
locate point G. Distance FG (also FD and DE) is
the circle. Step off this distance (DF) around the
one-seventh of the circumference or the true length of
circumference. Points G, D, H, I, and J are centers for
the pitch chord. With the dividers set for this distance,
the holes of a five-hole flange.
step off the circumference and locate points F, G, H, I,
If you step off the circumference using
J, K, and L. These points are the centers for a seven-hole
measurement GB instead of DG, you get a 20-bolthole
flange of the given pitch circle.
flange. Each spot where your dividers make an arc on
the circle's circumference will be the center point for a
PROBLEM III--Lay out a nine-hole flange. (See
Figure 16-7.--Layout for a nine-hole flange or flanges having any number of holes.