problem with heights of two spirals

[Jakka]

Bye to all,
I press that I started using autocad the first time a week ago to realize the 3d model of a maze and are therefore very ignorant in the matter.
I managed to create plant and to extrude everything with a certain height, but the goal would be to succeed in making the two spirals present starting from a height of 2.3 m, the one goes progressively up to the center of the spiral itself to reach a height of 3.6 m, and the other gradually descend, always up to the center of the spiral, 1 m high.
Is there a command that allows me to do all this?
Thank you in advance.

 

[Tristan]

I don't understand, you know? ... try to post an image

 

[Jakka]

the height of the spiral on the left should not be all equal, but gradually increase to the center from the height you see now.
equal for the right only that this instead of going up must go down to the center.

 

[Tristan]

then you have to split in 2 or more parts the plant and use the loft command with the 2 different height sections at the ends

 

[Jakka]

Can I split the 3d directly?
and in any case, even you should do it by force in the plant, how do you do it?
When I try to use the loft command I don't understand what the hell asks me d:

 

[doking]

you can use the size command to divide the solid or explode it to get the plant in 2d.
the loft command basically asks you to create along the path, in this case the spiral, what would be the profile you will then get.
In simple words you will create a sketch that will be the starting profile 2.3 m high, to "meta" a new sketch that will be high half the total height (2.95) and eventually a new sketch that will be high 3.6 m. destroying with the loft command and selecting, in this example, the three sketches will get a solid that starts high 2.3 m and will end high 3.6 m.