OpenSCAD source code: Collet pen holder using LM12UU linear bearings for CNC 3018-Pro

CNC 3018-Pro Collet Holder - LM12UU.scad

// Collet Pen Holder in LM12UU linear bearings for CNC3018
// Ed Nisley KE4ZNU - 2019-10-30

Layout = "Build";                       // [Build, Show, Base, Mount, Plate]

/* [Hidden] */

ThreadThick = 0.25;       // [0.20, 0.25]
ThreadWidth = 0.40;       // [0.40, 0.40]

/* [Hidden] */

Protrusion = 0.1;        // [0.01, 0.1]

HoleWindage = 0.2;

inch = 25.4;

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

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

//- Adjust hole diameter to make the size come out right

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);
}

//- Dimensions

PenOD = 3.5;                          // pen cartridge diameter

Bearing = [12.0,21.0,30.0];           // linear bearing body

SpringSeat = [0.56,10.0,3*ThreadThick];        // wire = ID, coil = OD, seat depth = length

WallThick = 4.0;                      // minimum thickness / width

Screw = [3.0,6.75,25.0];                // holding it all together, OD = washer

Insert = [3.0,5.5,8.2];              // brass insert
//Insert = [4.0,6.0,10.0];

Clamp = [43.2,44.5,34.0];             // tool clamp ring, OD = clearance around top

LipHeight = IntegerMultiple(2.0,ThreadThick);   // above clamp for retaining

BottomExtension = 25.0;                         // below clamp to reach workpiece

MountOAL = LipHeight + Clamp[LENGTH] + BottomExtension;     // total mount length
echo(str("Mount OAL: ",MountOAL));

Plate = [1.5*PenOD,Clamp[ID] - 0*2*WallThick,WallThick];   // spring reaction plate

NumScrews = 3;
ScrewBCD = Bearing[OD] + Insert[OD] + 2*WallThick;

echo(str("Retainer max OD: ",ScrewBCD - Screw[OD]));

NumSides = 9*4;                         // cylinder facets (multiple of 3 for lathe trimming)

// Basic mount shape

module CNC3018Base() {

  translate([0,0,MountOAL - LipHeight])
    cylinder(d=Clamp[OD],h=LipHeight,$fn=NumSides);
  translate([0,0,MountOAL - LipHeight - Clamp[LENGTH] - Protrusion])
    cylinder(d=Clamp[ID],h=(Clamp[LENGTH] + 2*Protrusion),$fn=NumSides);
  cylinder(d1=Bearing[OD] + 2*WallThick,d2=Clamp[ID],h=BottomExtension + Protrusion,$fn=NumSides);

}

// Mount with holes & c

module Mount() {

  difference() {
    CNC3018Base();

    translate([0,0,-Protrusion])                    // bearing
      PolyCyl(Bearing[OD],2*MountOAL,NumSides);

    for (i=[0:NumScrews - 1])                       // clamp screws
      rotate(i*360/NumScrews)
        translate([ScrewBCD/2,0,MountOAL - Clamp[LENGTH]])
          rotate(180/8)
            PolyCyl(Insert[OD],Clamp[LENGTH] + Protrusion,8);
  }

}

module SpringPlate() {

  difference() {
    cylinder(d=Plate[OD],h=Plate[LENGTH],$fn=NumSides);

    translate([0,0,-Protrusion])
      PolyCyl(Plate[ID],2*MountOAL,NumSides);

    translate([0,0,Plate.z - SpringSeat[LENGTH]])   //  spring retaining recess
      PolyCyl(SpringSeat[OD],SpringSeat[LENGTH] + Protrusion,NumSides);

    for (i=[0:NumScrews - 1])                       // clamp screws
      rotate(i*360/NumScrews)
        translate([ScrewBCD/2,0,-Protrusion])
          rotate(180/8)
          PolyCyl(Screw[ID],2*MountOAL,8);
  }

}


//-----
// Build it

if (Layout == "Base")
  CNC3018Base();

if (Layout == "Mount")
  Mount();

if (Layout == "Plate")
  SpringPlate();

if (Layout == "Show") {
  Mount();
  translate([0,0,1.25*MountOAL])
    rotate([180,0,0])
      SpringPlate();
}

if (Layout == "Build") {

  translate([0,-0.75*Clamp[OD],MountOAL])
    rotate([180,0,0])
      Mount();
  translate([0,0.75*Plate[OD],0])
    SpringPlate();
}

More details on my blog at https://wp.me/poZKh-8yT