Mike Williams <nos### [at] econymdemoncouk> wrote:
> Wasn't it Marvin who wrote:
> >
> >I am modeling a screw and nut that are supposed to fit into each other
> >without collision and stay without collision throughout the process of
> >moving nut on screw  from top to end.
> >
> >However, I have used approximation formula that might not be exact:
> >
> >isosurface {
> >  function { f_helix1(x,y,z, 1, 20/3*omega1, dy, inner_r+dy+dy*2/3, 1, 1.5,
> >0) }
> >         // distance_wind, thicknessm, r, shape, 0, cross-section type
> >         // 20/3 is an empiric factor connecting number of windings of helix
> >         // per unit of length with parameter P2 of f_helix1()
> >         // ***********************************
> >         // *** WHAT IS THE EXACT VALUE???? ***
> >         // ***********************************
> >  contained_by {
> >     box { <-2, -l/2, -2>, <2, l/2, 2> }
> >  }
> >  max_gradient 1.5
> >}
>
> If you use the value "2*pi" where you've got "20/3*omega1" then you get
> exactly one complete turn as the y value increases by 1 unit (e.g. from
> -1/2 to +1/2)

Thank you, Mike, this worked exactly, and my screw and nut turn w/o internal
collision now.

I wish there was a better open source screw and nut model already on net,
because I don't have exactly the time to model screw, I am actually doing
the transformer ...

Sorry for digression.

Marvin

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