Sonex Wing Rib Forming Instructions (Scratch Building) - Manual (Page 2)

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Forming Wing Ribs
Crush Plate
10. Assemble the form block, rib blank, and crush plate as
shown in the following illustration.
Note: In the following steps a main wing rib is shown, how-
ever the same technique applies to leading edge ribs.
11. Bend the flanges of the rib blank to shape by striking them
with a plastic or rubber tipped mallet until they conform
to the outline of the form block as closely as possible.
Note: The flanges will not conform perfectly to the curves
of the form blocks. The process of fluting the flanges in
step 7 will make the flanges conform to the proper shape.
Form Block
12. After the flanges have been formed, mark the location of
each flute on the rib blank.
D
E
13. Remove the rib from the form block and flare each light-
ening hole by sliding the male half of the die (D, below)
through the lightening hole and clamping the female half
of the die (E) firmly against it. Refer to the illustration.
Important: There are two different sized lightening
holes. Make sure you use the correct sized die for each
hole.
Note: An alternate method of forming the flares is to:
a. secure the male half of the die to the top of the work-
bench
b. place the rib over the die
c. place the female half of the die over the male half and
strike the female half with the plastic tipped mallet or
small arbor press.
14. After the lightening holes have been flared, use a fluting
pliers to form the flutes. You will also have to work the
flanges with the rubber mallet to achieve the proper flange
angle. Your goal in fluting each wing rib is to get it to lie
perfectly flat on your workbench with the flanges bent to
the proper angle.