Normally with the Flow function any volume like your can be applied on any spiral...of any length!

So nothing particular to do! Except use the Flow function and draw the good spiral length if wanted! :)
Line can be under or inside the middle of the object...with maybe small deformations...I don't verified...



PS For this volume it's stricly the same when the start line in pasted under the Object or inside the middle of it!

Hi mdesign, the Helix command in MoI has a "Flat spiral" option that you can use for making a base curve like that.

Here's an example:



- Michael