You don't. You basically just model a close approximation, a hollow cylinder, and you're on your way. You can fudge the details if you have to with Draw-in-View on the draft sheet.
I'm actually working on a similar problem, though. I know UG allows you to create a helix following a spline, which gets a close approximation. And then that geometry can be brought into Solid Edge. Problem is, when you start modeling helix, your performance goes WAY down. That's why you typically don't bother modeling something like this in detail.
Since SE doesn't have a helical curve command, I'm working out the math to get XYZ data points for a spiral along a helix. Those data points can be used to create a curve by table and then that curve is used as a guide curve to a sweep. If you really want to model your spring, that's how you would have to do it as of v14.
If you want the spring to look realistic for rendering purposes etc. you could create a toroidal ring representing one coil of the wire, then create a radial pattern to fill the spring (if circular) - the wire won't form a helix, but it will take a sharp eye to notice! If the spring's shape is NON circular, the job becomes somewhat more difficult. Hopefully the pattern-along-curve capability in SEv15 will allow tasks like this to be accomplished more easily.
I modeled a garter spring once using a curve by table and a swept protrusion. The curve points in the table were generated by equations as follows:
R = major coil radius
r = minor coil radius
p = pitch
t = increment parameter
x = R*cos(t) + r*cos(pt) * cos(t)
y = R*sin(t) + r*cos(pt) * sin(t)
z = r*sin(pt)
However, even with a relatively low resolution (large increments in variable t), the model was 35MB. D'oh! So I replaced it with a model that looked like an O-ring for 202 KB.
Perhaps it would have been useful if I was *designing* garter springs instead of just using a stock component...
go into the se help file and do a search on "helical protrusion" its in se v16 clear back to v7 for sure maybe further...it takes a few minuntes to figure the command out but you can draw a hexagon or any other shaped spring in no time at all...and for around 800kb have fun w/ this one.
