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# Oval Helical Sweep??

#### Jamie

##### New member
I'm trying to create a sort of helical sweep thats oval is shape- i.e. greater along the x direction than the y. The length and pitch are the same as would be in a HS but the profile of a HS is always circular.

Any ideas as to how I can get a oval helical sweep???

Here are 2 ways. The first is for a straight trajectory, the second will do complex trajectories.

The first way is to make a helical swept surface, then intersect it with an oval surface. Create a datum curve from the intersection (you might need to change your model accuracy). Then create a swept protrusion along the curve.

The second way is to create a variable section sweep. First sketch your origin trajectory. Then you must sketch an x-trajectory parrallel to your normal trajectory. Then sketch a section consisting of a line attached to the trajectory at one end, and at an angle. Create an angular dimension, then make the relation

dimension=trajpar*360*number of revolutions

Sketch a construction ellipse on the trajectory, and allign the endpoint of the line. Dimension the ellipse as desired. Finish the feature. Then create a swept protrusion using the edge of the surface.

Download my part, it's an example of the second way. Just delete the second surface, and everything after it and use the surface edge for your trajectory.

http://www.proecentral.net/files/other/odds/horseshoe.zip

Also the first method allows you to have a variable pitch!

In Wildfire 2, when I intersect the 2 surfaces to generatea trajectory, my curve is discontinuous. I can open the horrseshoe.prt file and it works fine but when I create my own horseshoe using exactly the same dimensions, my curve is discontinuous. Has anyone else had this problem? I can get it to be continuous by reducing the number of revolutions to 5 but that's about it. What can I do?

You can also write an equation for a datum curve and then do a variable section sweep along it.

I think this is a correct equation for an eliptical trajectory in cartesian csys:

x=5*cos(4*360*t)
y=2*sin(4*360*t)
z=20*t

It will go around 4 times with major axis of 5 & minor axis of 2. You can make it variable pitch by changing the z equation.

dr_gallup,

i have to
say, i really LOVE your solution. Its very creative and very flexable.