How can I fix this spiral ramp?

[Cristian]

Hello,

I need to make a spiral ramp. The reference spiral should have a pitch of 2760mm, revolution of 0.25, and radius of 1030mm. The ramp must have a "W" bended shape, begin and end parallel to the floor plane.

I have tried several times whith sheet metal, weldments and surfaces tools but I´ve failed. My last try was with the model attached, but the end of the ramp didn't arrive paralell to the floor plane.

Can someone help me to straighten this last section?

Thanks