bolt with internal and external thread

hi there im wanting to design a hex head bolt which is 1.5"BSW thread with a 50mm thread length, but i need it to have a M16x2.0 thread that runs through the whole bolt, could anyone assist in this please?

Hi Chris,

OK, I don't know about your programming skills, but I guess you are somehow skilled in OpenSCAD.
Let me point you to my threading.scad lib: https://www.thingiverse.com/thing:1659079

I tried to model it. Use this code as a starting point

use <threading.scad>

$fn = 100;
help_threading();


// outer 1.5"BSW thread with a 50mm thread length,
// inner M16x2.0
// hexhead

// https://en.wikipedia.org/wiki/British_Standard_Whitworth
d_head = 61.2;  // mm from wiki
h_head = 10;

h = 50 + h_head;

bswPitch = 4.233;  // mm from wiki
bswOD = 38.1;      // mm from wiki
M16Pitch = 2;
M16OD = 16;

bolt();

module bolt()
  difference()
  {
    // outer 1.5"BSW
    union()
    {
      threading(pitch = bswPitch, full=true, d=bswOD, windings=h/bswPitch, angle = 58);
      cylinder(d = d_head, h= h_head, $fn=6);
    }
    // inner M16
    translate([0,0,-.01])  // just for F5
    threading(pitch = M16Pitch, d = M16OD, windings = h/M16Pitch+1, full = true, angle = 60);
   
  }