We are fifty-fifty now, I do not understan how did you do the join :-)

here is the principle: the spring is originally a flat iron plate wrapped to a helix



(the construction of the pushed spring is not exact, I have cheated to make it easier)

Could you please describe other words the process of unioning?
I tried to join two of your double buffer body objects - but again failed :-(

...where are the "large circles" coming from??

Thanks
J.