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There are many clever methods for modeling
unique helical, spring-like or coiled shapes. For example
you could use a 3D spline on surface method or sweep a helical
shape and intersect it with a square surface and again produce
a 3D spline. While they may look good, upon closer inspection
many of those methods will not reproduce a square spring the
way it is manufactured and the end result may be hard to control.
A square spring in the real world would be wound on a square
mandrel. Here is a modeling method that produces a True Square
Spring. Start by creating a sketch and surface extrude for
the mandrel shape.
Then create five sketches built on
four consecutive equal angled planes, each one built off the
last, all based from the original sketch. The sketch entities
are created where the four planes intersect with the mandrel
shape. Use the sketch intersection tool.
In this example you would start by creating a sketch in the
first plane use the sketch intersection tool, selecting the
first three faces of the mandrel, then create the second angled
plane based off the last straight line in the first plane,
insert a sketch, again use the intersection tool and select
the next two faces, continue with this process until you have
made one complete rotation around the mandrel.
Next the mandrel
surface is hidden and a 3D sketch is created to convert the
four sketches into one path for a swept feature. A profile
plane is created at the beginning, normal to the 3D sketch
and a profile sketch is added.
Finally the swept
feature is created and then a linear pattern is added to repeat
the shape and create the true Square Spring. If you want to
add more control to the square spring, linking dimensions
and adding formulas for the angled planes would automate updates
to the model.
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