Sonex Reforming Aluminum Extrusions Installation Instructions

Builder's Guide

Reforming Aluminum Extrusions

sonex aircraft,

Some airframe parts require that the 90-degree aluminum
extrusion from which they are made be reformed to a greater,
or lesser bend angle. This is easily accomplished with com­mon tools.

LLC

Accuracy

Angles are often noted very precisely on the plans (e.g. 93.7
degrees). However, there is NO NEED for an individual
builder to be nearly that precise. Often being with a degree or
two is more than enough.

Measuring the Angle

Angles can be measured a number of ways - an adjustable
protractor, an angle finder, lines drawn on your workbench.
Perhaps the easiest and most useful is to make a template from
a piece of non-corrugated cardboard.

After reforming an extrusion you'll want to check the new
angle in a few spots, to make sure the extrusion has been
uniformly reworked.

Reducing the Bend Angle (Less than 90O)

Extrusion angles are easily reduced using one of two methods:

Squeezing in a Vise: With this method the part is clamped
in a vise and squeezed to a reduced angle. When using this
method you must account for springback and squeeze the part
beyond the desired angle, as it will open up once the vise jaws
are opened.

A file folder has been turned into a template to measure an
angle - in this example 86O.

After the extrusions are reformed they will appear, in cross
section, as seen in the photos. Note that often only one leg is
reformed. This is normal. The angle will never bend perfectly
at the apex (corner), and there will be a small gap near the
apex.

This extrusion's angle is being reduced by being squeezed in a
vise. Pad the vise jaws to reduce marring of the part.

Striking with a Mallet: Clamp one leg in a vise and strike the
other with a rubber mallet. The angle is progressively formed
by walking the mallet across the length of the angle.

This extrusion's angle is being reduced by striking the un­clamped leg with a rubber mallet. Pad the vise jaws to reduce
marring clamped leg.

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Builder's Guide

Reforming Aluminum Extrusions

sonex aircraft,

LLC

Increasing the Bend Angle (More than 90O)

To open an extrusion the best method for the typical builder
is to clamp one leg of the extrusion in the padded jaws of a
vise and use a large adjustable wrench to progressively pry the
unclamped leg to the proper angle.

To avoid marring the extrusion's surface the jaws of the
wrench should be padded and the free leg should be bent a
little at a time, working back and forth across the length of the
extrusion.

This extrusion's angle is being increased by prying up the free
leg with a large adjustable wrench. Pad the wrench's jaws to
reduce marring the extrusion.

Finishing Up

Check each reformed extrusion in several places to make sure
it is uniformly bent.

Remove any scratches caused by the vise or tools while re­forming the extrusion.

sonex aircraft LLC. © 2009 All Rights Reserved.

[e-mail] • www.sonexaircraft.com

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