OpenSCAD source code: Adapter ring from 25 mm Tour Easy tube to 35 mm chain catcher / guide clamp

Chain Catcher adapter ring.scad

// Chain catcher adapter ring
// Ed Nisley - KE4ZNU - 2023-05

/* [Hidden] */

ThreadThick = 0.25;
ThreadWidth = 0.40;

HoleWindage = 0.2;

Protrusion = 0.1;     // make holes end cleanly

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

ID = 0;
OD = 1;
LENGTH = 2;

inch = 25.4;

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


TubeOD = 26.0;                          // frame tube with silicone tape

Clamp = [35.0,39.0,12.0];               // Chain catcher clamp ring

Flange = [Clamp[ID],Clamp[OD],3*ThreadThick];

Kerf = 1.0;

Offset = (Clamp[ID] - TubeOD)/2 - 3*ThreadWidth;

NumSides = 2*3*4;

//-----------------------

  $fn=NumSides;

  difference() {
    union() {
      cylinder(d=Flange[OD],h=Flange[LENGTH]);
      cylinder(d=Clamp[ID],h=Clamp[LENGTH]+Flange[LENGTH]);
    }

    cube([2*Flange[OD],Kerf,3*Clamp[LENGTH]],center=true);

    translate([0,Offset,0])
      cylinder(d=TubeOD,h=3*Clamp[LENGTH],center=true);
  }

More details on my blog at https://softsolder.com/2023/05/04/bafang-vs-tour-easy-chain-guide/