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breaking out circular2diameter and diametral2diameter functions from gears

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Andrew Plumb 2012-03-14 14:55:29 -04:00
parent 55aecfb419
commit 29180c5d59
1 changed files with 23 additions and 2 deletions
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gears.scad
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@ -14,41 +14,62 @@
// Circular pitch: Length of the arc from one tooth to the next // Circular pitch: Length of the arc from one tooth to the next
// Clearance: Radial distance between top of tooth on one gear to bottom of gap on another. // Clearance: Radial distance between top of tooth on one gear to bottom of gap on another.
function pitch_circular2diameter(number_of_teeth,circular_pitch) = number_of_teeth * circular_pitch / 180;
function pitch_diametral2diameter(number_of_teeth,diametral_pitch) = number_of_teeth / diametral_pitch;
module gear(number_of_teeth, module gear(number_of_teeth,
circular_pitch=false, diametral_pitch=false, circular_pitch=false, diametral_pitch=false,
pressure_angle=20, clearance = 0) pressure_angle=20, clearance = 0,
verbose=false)
{ {
if(verbose) {
echo("gear arguments:");
echo(str(" number_of_teeth: ", number_of_teeth));
echo(str(" circular_pitch: ", circular_pitch));
echo(str(" diametral_pitch: ", diametral_pitch));
echo(str(" pressure_angle: ", pressure_angle));
echo(str(" clearance: ", clearance));
}
if (circular_pitch==false && diametral_pitch==false) echo("MCAD ERROR: gear module needs either a diametral_pitch or circular_pitch"); if (circular_pitch==false && diametral_pitch==false) echo("MCAD ERROR: gear module needs either a diametral_pitch or circular_pitch");
if(verbose) echo("gear calculations:");
//Convert diametrial pitch to our native circular pitch //Convert diametrial pitch to our native circular pitch
circular_pitch = (circular_pitch!=false?circular_pitch:180/diametral_pitch); circular_pitch = (circular_pitch!=false?circular_pitch:180/diametral_pitch);
// Pitch diameter: Diameter of pitch circle. // Pitch diameter: Diameter of pitch circle.
pitch_diameter = number_of_teeth * circular_pitch / 180; pitch_diameter = pitch_circular2diameter(number_of_teeth,circular_pitch);
if(verbose) echo (str(" pitch_diameter: ", pitch_diameter));
pitch_radius = pitch_diameter/2; pitch_radius = pitch_diameter/2;
// Base Circle // Base Circle
base_diameter = pitch_diameter*cos(pressure_angle); base_diameter = pitch_diameter*cos(pressure_angle);
if(verbose) echo (str(" base_diameter: ", base_diameter));
base_radius = base_diameter/2; base_radius = base_diameter/2;
// Diametrial pitch: Number of teeth per unit length. // Diametrial pitch: Number of teeth per unit length.
pitch_diametrial = number_of_teeth / pitch_diameter; pitch_diametrial = number_of_teeth / pitch_diameter;
if(verbose) echo (str(" pitch_diametrial: ", pitch_diametrial));
// Addendum: Radial distance from pitch circle to outside circle. // Addendum: Radial distance from pitch circle to outside circle.
addendum = 1/pitch_diametrial; addendum = 1/pitch_diametrial;
if(verbose) echo (str(" addendum: ", addendum));
//Outer Circle //Outer Circle
outer_radius = pitch_radius+addendum; outer_radius = pitch_radius+addendum;
outer_diameter = outer_radius*2; outer_diameter = outer_radius*2;
if(verbose) echo (str(" outer_diameter: ", outer_diameter));
// Dedendum: Radial distance from pitch circle to root diameter // Dedendum: Radial distance from pitch circle to root diameter
dedendum = addendum + clearance; dedendum = addendum + clearance;
if(verbose) echo (str(" dedendum: ", dedendum));
// Root diameter: Diameter of bottom of tooth spaces. // Root diameter: Diameter of bottom of tooth spaces.
root_radius = pitch_radius-dedendum; root_radius = pitch_radius-dedendum;
root_diameter = root_radius * 2; root_diameter = root_radius * 2;
if(verbose) echo (str(" root_diameter: ", root_diameter));
half_thick_angle = 360 / (4 * number_of_teeth); half_thick_angle = 360 / (4 * number_of_teeth);
if(verbose) echo (str(" half_thick_angle: ", half_thick_angle));
union() union()
{ {