Fix blanks spaces between Shapes!!

Hello!

I am trying to draw a spring but i am doing one turn at once and then another turn until n(number of turns), but when i use BRepOffsetAPI_MakePipeShell or another function to do a pipe always remains a blank space where the Shapes doesn\'t fits, so my final shape when a use the BRepAlgoAPI_Fuse is not correctly. How can i fix this? I left a image of what i am saying!!

Thanks for your help!
Regards