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PI is a thing that exists in OpenSCAD, dangit.

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Revar Desmera 2018-10-09 20:50:27 -07:00
parent 62ea2f5a8a
commit 924392fe79
2 changed files with 10 additions and 12 deletions
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18
involute_gears.scad
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@ -56,8 +56,6 @@
//
//////////////////////////////////////////////////////////////////////////////////////////////
pi = 3.141592653589793236;
//An involute spur gear, with reasonable defaults for all the parameters.
//Normally, you should just choose the first 4 parameters, and let the rest be default values.
@ -74,12 +72,12 @@ module gear (
clearance = 0.0, //gap between top of a tooth on one gear and bottom of valley on a meshing gear (in millimeters)
backlash = 0.0 //gap between two meshing teeth, in the direction along the circumference of the pitch circle
) {
p = mm_per_tooth * number_of_teeth / pi / 2; //radius of pitch circle
c = p + mm_per_tooth / pi - clearance; //radius of outer circle
p = mm_per_tooth * number_of_teeth / PI / 2; //radius of pitch circle
c = p + mm_per_tooth / PI - clearance; //radius of outer circle
b = p*cos(pressure_angle); //radius of base circle
r = p-(c-p)-clearance; //radius of root circle
t = mm_per_tooth/2-backlash/2; //tooth thickness at pitch circle
k = -iang(b, p) - t/2/p/pi*180; //angle to where involute meets base circle on each side of tooth
k = -iang(b, p) - t/2/p/PI*180; //angle to where involute meets base circle on each side of tooth
difference() {
linear_extrude(height = thickness, center = true, convexity = 10, twist = twist, slices = ceil(abs(twist)/5)+1)
for (i = [0:number_of_teeth-teeth_to_hide-1] )
@ -102,7 +100,7 @@ module gear (
};
//these 4 functions are used by gear
function polar(r,theta) = r*[sin(theta), cos(theta)]; //convert polar to cartesian coordinates
function iang(r1,r2) = sqrt((r2/r1)*(r2/r1) - 1)/pi*180 - acos(r1/r2); //unwind a string this many degrees to go from radius r1 to radius r2
function iang(r1,r2) = sqrt((r2/r1)*(r2/r1) - 1)/PI*180 - acos(r1/r2); //unwind a string this many degrees to go from radius r1 to radius r2
function q7(f,r,b,r2,t,s) = q6(b,s,t,(1-f)*max(b,r)+f*r2); //radius a fraction f up the curved side of the tooth
function q6(b,s,t,d) = polar(d,s*(iang(b,d)+t)); //point at radius d on the involute curve
@ -142,13 +140,13 @@ module rack (
//A gear fits within a circle of radius outer_radius, and two gears should have
//their centers separated by the sum of their pictch_radius.
function circular_pitch (mm_per_tooth=5) = mm_per_tooth; //tooth density expressed as "circular pitch" in millimeters
function diametral_pitch (mm_per_tooth=5) = pi / mm_per_tooth; //tooth density expressed as "diametral pitch" in teeth per millimeter
function diametral_pitch (mm_per_tooth=5) = PI / mm_per_tooth; //tooth density expressed as "diametral pitch" in teeth per millimeter
function adendum (mm_per_tooth=5) = module_value(mm_per_tooth);
function dedendum (mm_per_tooth=5) = 1.25 * module_value(mm_per_tooth);
function module_value (mm_per_tooth=5) = mm_per_tooth / pi; //tooth density expressed as "module" or "modulus" in millimeters
function pitch_radius (mm_per_tooth=5,number_of_teeth=11) = mm_per_tooth * number_of_teeth / pi / 2;
function module_value (mm_per_tooth=5) = mm_per_tooth / PI; //tooth density expressed as "module" or "modulus" in millimeters
function pitch_radius (mm_per_tooth=5,number_of_teeth=11) = mm_per_tooth * number_of_teeth / PI / 2;
function outer_radius (mm_per_tooth=5,number_of_teeth=11,clearance=0.1) //The gear fits entirely within a cylinder of this radius.
= mm_per_tooth*(1+number_of_teeth/2)/pi - clearance;
= mm_per_tooth*(1+number_of_teeth/2)/PI - clearance;
//////////////////////////////////////////////////////////////////////////////////////////////
//example gear train.

4
math.scad
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@ -31,7 +31,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
function Cpi() = 3.141592653589793236;
function Cpi() = PI; // Deprecated! Use the variable PI instead.
// Quantize a value x to an integer multiple of y, rounding to the nearest multiple.
@ -48,7 +48,7 @@ function quantup(x,y) = ceil(x/y)*y;
// Calculate OpenSCAD standard number of segments in a circle based on $fn, $fa, and $fs.
// r = radius of circle to get the number of segments for.
function segs(r) = $fn>0?($fn>3?$fn:3):(ceil(max(min(360.0/$fa,abs(r)*2*Cpi()/$fs),5)));
function segs(r) = $fn>0?($fn>3?$fn:3):(ceil(max(min(360.0/$fa,abs(r)*2*PI/$fs),5)));
// Interpolate between two values or vectors. 0.0 <= u <= 1.0