OpenSCAD source code: Cylindrical cell adapters

Cylindrical Cell Adapters.scad

// Cylindrical cell adapters
// Ed Nisley KE4ZNU April 2017

//- Extrusion parameters must match reality!

ThreadThick = 0.25;
ThreadWidth = 0.40;

HoleWindage = 0.2;

Protrusion = 0.1;			// make holes end cleanly

inch = 25.4;

function IntegerMultiple(Size,Unit) = Unit * ceil(Size / Unit);

//----------------------
// Dimensions

OutCell = "AA";                  // cell sizes
InCell = "AAA";

BottomClear = 3*ThreadThick;      // shorten outer shell to allow base protrusion
Terminal = [3.0,4.0,2.0];         // terminal: OD = nub dia, length = nub thickness

NAME = 0;
ID = 0;       // for non-cell cylinders
OD = 1;
LENGTH = 2;

Cells = [
  ["AAAA",8.3,42.5],
  ["AAA",10.5,44.5],
  ["AA",14.5,50.5],
  ["C",26.2,50],
  ["D",34.2,61.5],
  ["A23",10.3,28.5],
  ["CR123",17.0,34.5],
  ["18650",18.6,65.2]
];

Outer = search([OutCell],Cells,1,0)[0];
Inner = search([InCell],Cells,1,0)[0];

echo(str("Outer cell: ",Cells[Outer][NAME]));
echo(str("Inner cell: ",Cells[Inner][NAME]));

echo(str("Wall: ",Cells[Outer][OD] - (Cells[Inner][OD]/cos(180/NumSides) + 2*ThreadWidth)));

Delta = Cells[Outer][LENGTH] - Cells[Inner][LENGTH];

echo(str("Terminal OAL: ",Delta));
echo(str(" ...    head: ",Terminal[LENGTH]));
echo(str(" ...   shaft: ",Delta - Terminal[LENGTH]));

NumSides = 3*4;

//----------------------
// Useful routines

module PolyCyl(Dia,Height,ForceSides=0) {			// based on nophead's polyholes

  Sides = (ForceSides != 0) ? ForceSides : (ceil(Dia) + 2);
  FixDia = Dia / cos(180/Sides);
  cylinder(r=(FixDia + HoleWindage)/2,h=Height,$fn=Sides);

}

//----------------------
// Construct adapter

module Adapter() {

  difference() {
      cylinder(d=Cells[Outer][OD],
               h=Cells[Outer][LENGTH] - BottomClear - Terminal[LENGTH],
               $fn=NumSides);

      translate([0,0,Delta - Terminal[LENGTH]])
        PolyCyl(Cells[Inner][OD] + 2*ThreadWidth,
                Cells[Inner][LENGTH] + Protrusion,
                NumSides);

      translate([0,0,-Protrusion])
        PolyCyl(Terminal[ID],
                2*Cells[Outer][LENGTH],
                6);
  }
}

//----------------------
// Build it

  Adapter();

More details on my blog at http://wp.me/poZKh-6GE

The D cell outer diameter is just a hair heavy for MagLites. They'll go in, but I'll likely never get anything other than AA cells in that particular torch again …