scad/gears.scad

   1 // OpenSCAD Herringbone Wade's Gears Script
   2 // (c) 2011, Christopher "ScribbleJ" Jansen
   3 //
   4 // Thanks to Greg Frost for his great "Involute Gears" script.
   5 //
   6 // Licensed under the BSD license.
   7 //
   8 // Adapted for Reprap Wilson by Martin Rice
   9 //
  10
  11 include <MCAD/involute_gears.scad>
  12
  13
  14 // WHAT TO GENERATE?
  15 generate = 0;    // GENERATE BOTH GEARS FOR VIEWING
  16 // generate = 1;    // GENERATE STEPPER GEAR FOR PRINTING
  17  generate = 2;    // GENERATE DRIVE GEAR FOR PRINTING
  18
  19 // OPTIONS COMMON TO BOTH GEARS:
  20 distance_between_axels = 42;
  21 gear_h = 10;
  22
  23 // for big
  24 gear_shaft_h = 5;
  25
  26 // for small
  27 //gear_shaft_h = 10;
  28
  29
  30 // GEAR1 (SMALLER GEAR, STEPPER GEAR) OPTIONS:
  31 // It's helpful to choose prime numbers for the gear teeth.
  32 gear1_teeth = 13;
  33 gear1_shaft_d = 5.25;                   // diameter of motor shaft
  34 gear1_shaft_r  = gear1_shaft_d/2;
  35 // gear1 shaft assumed to fill entire gear.
  36 // gear1 attaches by means of a captive nut and bolt (or actual setscrew)
  37 gear1_setscrew_offset = 5;                      // Distance from motor on motor shaft.
  38 gear1_setscrew_d         = 3.5;
  39 gear1_setscrew_r          = gear1_setscrew_d/2;
  40 gear1_captive_nut_d = 6.2;
  41 gear1_captive_nut_r  = gear1_captive_nut_d/2;
  42 gear1_captive_nut_h = 2.9;
  43
  44
  45 // GEAR2 (LARGER GEAR, DRIVE SHAFT GEAR) OPTIONS:
  46 gear2_teeth = 37;
  47 gear2_shaft_d = 8.5;
  48 gear2_shaft_r  = gear2_shaft_d/2;
  49 // gear2 has settable outer shaft diameter.
  50 gear2_shaft_outer_d = 16;
  51 gear2_shaft_outer_r  = gear2_shaft_outer_d/2;
  52
  53 // gear2 has a hex bolt set in it, is either a hobbed bolt or has the nifty hobbed gear from MBI on it.
  54 gear2_bolt_hex_d       = 15;
  55 gear2_bolt_hex_r        = gear2_bolt_hex_d/2;
  56 // gear2_bolt_sink: How far down the gear shaft the bolt head sits; measured as distance from drive end of gear.
  57 gear2_bolt_sink          = 5;
  58 // gear2's shaft is a bridge above the hex bolt shaft; this creates 1/3bridge_helper_h sized steps at top of shaft to help bridging.  (so bridge_helper_h/3 should be > layer height to have any effect)
  59 bridge_helper_h=1;
  60
  61 gear2_rim_margin = 3;
  62 gear2_cut_circles  = 5;
  63
  64 // gear2 setscrew option; not likely needed.
  65 gear2_setscrew_offset = 0;
  66 gear2_setscrew_d         = 0;
  67 gear2_setscrew_r          = gear2_setscrew_d/2;
  68 // captive nut for the setscrew
  69 gear2_captive_nut_d = 0;
  70 gear2_captive_nut_r  = gear2_captive_nut_d/2;
  71 gear2_captive_nut_h = 0;
  72
  73
  74 // Tolerances for geometry connections.
  75 AT=0.02;
  76 ST=AT*2;
  77 TT=AT/2;
  78
  79
  80 module bridge_helper()
  81 {
  82         difference()
  83         {
  84                 translate([0,0,-bridge_helper_h/2])
  85                         cylinder(r=gear2_bolt_hex_r+TT, h=bridge_helper_h+TT,$fn=6,center=true);
  86                 #translate([0,0,-bridge_helper_h/2])
  87                         cube([gear2_bolt_hex_d+ST, gear2_shaft_d, bridge_helper_h+AT], center=true);
  88         }
  89 }
  90
  91
  92
  93 module gearsbyteethanddistance(t1=13,t2=51, d=60, teethtwist=1, which=1)
  94 {
  95         cp = 360*d/(t1+t2);
  96
  97         g1twist = 360 * teethtwist / t1 / 2;
  98         g2twist = 360 * teethtwist / t2 / 2;
  99
 100         g1p_d  =  t1 * cp / 180;
 101         g2p_d  =  t2 * cp / 180;
 102         g1p_r   = g1p_d/2;
 103         g2p_r   = g2p_d/2;
 104
 105         echo(str("Your small ", t1, "-toothed gear will be ", g1p_d, "mm across (plus 1 gear tooth size) (PR=", g1p_r,")"));
 106         echo(str("Your large ", t2, "-toothed gear will be ", g2p_d, "mm across (plus 1 gear tooth size) (PR=", g2p_r,")"));
 107         echo(str("Your minimum drive bolt length (to end of gear) is: ", gear2_bolt_sink+bridge_helper_h, "mm and your max is: ", gear_h+gear_shaft_h, "mm."));
 108         echo(str("Your gear mount axles should be ", d,"mm (", g1p_r+g2p_r,"mm calculated) from each other."));
 109         if(which == 1)
 110         {
 111                 // GEAR 1
 112                 difference()
 113                 {
 114                 union()
 115                 {
 116                         translate([0,0,(gear_h/2) - TT])
 117                                 gear(   twist = g1twist,
 118                                         number_of_teeth=t1,
 119                                         circular_pitch=cp,
 120                                         gear_thickness = gear_shaft_h + (gear_h/2)+AT,
 121                                         rim_thickness = (gear_h/2)+AT,
 122                                         rim_width = 0,
 123                                         hub_thickness = (gear_h/2)+AT,
 124                                         hub_width = 0,
 125                                         bore_diameter=0);
 126
 127                         translate([0,0,(gear_h/2) + AT])
 128                         rotate([180,0,0])
 129                                 gear(   twist = -g1twist,
 130                                         number_of_teeth=t1,
 131                                         circular_pitch=cp,
 132                                         gear_thickness = (gear_h/2)+AT,
 133                                         rim_thickness = (gear_h/2)+AT,
 134                                         hub_thickness = (gear_h/2)+AT,
 135                                         bore_diameter=0);
 136                 }
 137                         //DIFFERENCE:
 138                         //shafthole
 139                         translate([0,0,-TT])
 140                                 cylinder(r=gear1_shaft_r, h=gear_h+gear_shaft_h+ST);
 141
 142                         //setscrew shaft
 143                         translate([0,0,gear_h+gear_shaft_h-gear1_setscrew_offset])
 144                                 rotate([0,90,0])
 145                                 cylinder(r=gear1_setscrew_r, h=g1p_r);
 146
 147                         //setscrew captive nut
 148                         translate([(g1p_r)/2, 0, gear_h+gear_shaft_h-gear1_captive_nut_r-gear1_setscrew_offset])
 149                                 translate([0,0,(gear1_captive_nut_r+gear1_setscrew_offset)/2])
 150                                         #cube([gear1_captive_nut_h, gear1_captive_nut_d, gear1_captive_nut_r+gear1_setscrew_offset+ST],center=true);
 151
 152
 153                 }
 154         }
 155         else
 156         {
 157           // GEAR 2
 158           difference()
 159           {
 160                 union()
 161                 {
 162           // cylinder(h=gear_h+gear_shaft_h , r=gear2_shaft_outer_r);
 163
 164                         translate([0,0,(gear_h/2) - TT])
 165                                 gear(   twist = -g2twist,
 166                                         number_of_teeth=t2,
 167                                         circular_pitch=cp,
 168                                         gear_thickness = gear_shaft_h + (gear_h/2)+AT,
 169                                         rim_thickness = (gear_h/2)+AT,
 170                                         rim_width = gear2_rim_margin,
 171                                         hub_diameter = gear2_shaft_outer_d,
 172                                         hub_thickness = (gear_h/2)+AT,
 173                                         bore_diameter=0,
 174                                         circles = gear2_cut_circles);
 175
 176                         translate([0,0,(gear_h/2) + AT])
 177                         rotate([180,0,0])
 178                                 gear(   twist = g2twist,
 179                                         number_of_teeth=t2,
 180                                         circular_pitch=cp,
 181                                         gear_thickness = (gear_h/2)+AT,
 182                                         rim_thickness = (gear_h/2)+AT,
 183                                         rim_width = gear2_rim_margin,
 184                                         hub_diameter = gear2_shaft_outer_d,
 185                                         hub_thickness = (gear_h/2)+AT,
 186                                         bore_diameter=0,
 187                                         circles = gear2_cut_circles);
 188                 }
 189
 190                         //DIFFERENCE:
 191                         //shafthole
 192                         translate([0,0,-TT])
 193                                 cylinder(r=gear2_shaft_r, h=gear_h+gear_shaft_h+ST);
 194
 195                         //setscrew shaft
 196 if(0) {
 197                         translate([0,0,gear_h+gear_shaft_h-gear2_setscrew_offset])
 198                                 rotate([0,90,0])
 199                                 cylinder(r=gear2_setscrew_r, h=gear2_shaft_outer_d);
 200
 201                         //setscrew captive nut
 202                         translate([(gear2_shaft_outer_d)/2, 0, gear_h+gear_shaft_h-gear2_captive_nut_r-gear2_setscrew_offset])
 203                                 translate([0,0,(gear2_captive_nut_r+gear2_setscrew_offset)/2])
 204                                         #cube([gear2_captive_nut_h, gear2_captive_nut_d, gear2_captive_nut_r+gear2_setscrew_offset+ST],center=true);
 205 }
 206
 207                         //trim shaft
 208                         difference()
 209                         {
 210                                 translate([0,0,gear_h+AT])                      cylinder(h=gear_shaft_h+ST, r=g2p_r);
 211                                 #translate([0,0,gear_h])                             cylinder(h=gear_shaft_h , r=gear2_shaft_outer_r);
 212                         }
 213
 214                         //hex bolt shaft
 215                         translate([0,0,-TT]) cylinder(r=gear2_bolt_hex_r, h=gear2_bolt_sink+AT,$fn=6);
 216
 217                 }
 218
 219 if(1) translate([0,0,1]) {
 220                 // hex bolt shaft bridge aid.
 221                 #translate([0,0,gear2_bolt_sink]) //gear_h+gear_shaft_h-gear2_bolt_sink])
 222                         bridge_helper();
 223                 #translate([0,0,gear2_bolt_sink-bridge_helper_h/3]) //gear_h+gear_shaft_h-gear2_bolt_sink+bridge_helper_h/3])
 224                         rotate([0,0,60]) bridge_helper();
 225                 #translate([0,0,gear2_bolt_sink-(bridge_helper_h/3*2)]) //gear_h+gear_shaft_h-gear2_bolt_sink+((bridge_helper_h/3)*2)])
 226                         rotate([0,0,-60]) bridge_helper();
 227         }
 228         }
 229
 230 }
 231
 232
 233 t1 = gear1_teeth;
 234 t2 = gear2_teeth;
 235 cp = 360*distance_between_axels/(t1+t2);
 236 g1p_d  =  t1 * cp / 180;
 237 g2p_d  =  t2 * cp / 180;
 238 g1p_r   = g1p_d/2;
 239 g2p_r   = g2p_d/2;
 240
 241 if(generate == 1)
 242 {
 243         gearsbyteethanddistance(t1 = gear1_teeth, t2=gear2_teeth, d=distance_between_axels, which=1);
 244 }
 245 else if(generate == 2)
 246 {
 247         gearsbyteethanddistance(t1 = gear1_teeth, t2=gear2_teeth, d=distance_between_axels, which=2);
 248 }
 249 else
 250 {
 251
 252         translate([-g1p_r,0,0]) rotate([0,0,($t*360/gear1_teeth)]) gearsbyteethanddistance(t1 = gear1_teeth, t2=gear2_teeth, d=distance_between_axels, which=1);
 253         translate([g2p_r,0,0])  rotate([0,0,($t*360/gear2_teeth)*-1]) gearsbyteethanddistance(t1 = gear1_teeth, t2=gear2_teeth, d=distance_between_axels, which=2);
 254 }
 255