How do I get the other end to wrap like the top end. I need the bottom to lay flat like the top but I need it the be tangent to the extruded cylinder.
Are you using this method?
For a high level of control, I prefer this wrapped method to manage the entire spring.
You patch together different feature for a simpler version such as adding revolves at both ends.
You can also manage varying pitch along the helical sweep but a true flat bottom will not be achieved.
Also remember that a sweep orientation can be normal to a selected feature such as a vertical plane. The section profile of the wire will not be perfectly round, but it is easier to merge with other features.
You can create the bottom the same as the top to get it flat. Just have a horizontal section in the sketch with a radius (fillet) where the slope begins.
This is the option to change the orientation of the swept sketch:
This is not normally recommended for sweeping round features but the option is there and should be noted as to the difference. Normally, I could connect a datum curve to the sweep trajectory to make a clean tangent if I needed to do this with a separate feature. It is a bit of work, but the datum curve is good about joining 3D curves where and when needed.
Remember to use a coordinate system in the sketch to assure proper wrapping of the sketch.