add screw

2 files changed, 184 insertions, 3 deletions

diff --git a/gimbal.scad b/gimbal.scad
index 192cc54..ff13158 100644
--- a/gimbal.scad
+++ b/gimbal.scad
@@ -4,8 +4,9 @@ cutoff = 3;
 c = 3;
 base = 10;
 
-screw_len = 0.8 * (d - 2*cutoff);
+screw_len = 15;
 screw_dia = 25.4/4;
+screw_head_len = 5;
 
 mount_screw_dia = 4;
 mount_screw_head_dia = 10;
@@ -16,10 +17,29 @@ retainer_dia = 1;
 e = 0.01;
 $fn = 500;
 
+use <simplethreads.scad>;
+
 module screw() {
-    cylinder(r=screw_dia/2, h=screw_len);
+    translate([0, 0, 2*screw_head_len - screw_dia/2])
+    thread_imperial(1/16, screw_dia/25.4, 12, screw_len*16/25.4);
+
+    intersection() {
+	cylinder(r1=2*screw_head_len, r2=0, h=2*screw_head_len);
+	cube([2*screw_head_len, 2*screw_head_len, 10*screw_head_len], center=true);
+    }
 }
 
+module two_half_screws()
+    for (i = [0,1])
+    translate([i*2*screw_head_len, -i*(screw_len + screw_head_len), 0])
+    intersection() {
+	rotate([90, i*180, i*180])
+	screw();
+
+	translate([0, 0, 50])
+	cube(100, center=true);
+    }
+
 module grip()
     for (i = [0:19])
         rotate(i*360/20)
@@ -28,11 +48,23 @@ module grip()
 
 module ball()
     difference() {
+	// sphere with top and bottom cap removed
 	sphere(d/2);
-	translate([0, 0, d/2 - cutoff - screw_len + e]) screw();
 	for (i = [-1,1])
             translate([0, 0, i * (d - cutoff)]) cube(d, center=true);
 
+	// screw hole (thin ot the top, thickening in the center, big
+	// square at the bottom)
+	translate([0, 0, d/2 - cutoff - screw_len/2 + screw_head_len/2]) {
+	    cylinder(r=screw_dia/2, h=d, center=true);
+
+	    mirror([0, 0, 1])
+	    intersection() {
+		cylinder(r1=0, r2=d, h=d);
+		cube([2*screw_head_len, 2*screw_head_len, 10*screw_head_len], center=true);
+	    }
+	}
+
 	// horizontal grip
 	grip();
 	// vertical grip at the upper half sphere (but not at the top)
diff --git a/simplethreads.scad b/simplethreads.scad
new file mode 100644
index 0000000..7ecd2b2
--- /dev/null
+++ b/simplethreads.scad
@@ -0,0 +1,149 @@
+// Metric Screw Thread Library

+// by Maximilian Karl <karlma@in.tum.de> (2014)

+// modified the api to create internal threads, smooth the start and

+// stop threads, and use imperial units: 

+//

+// 

+//

+// use module thread_imperial(pitch, majorD, stepAngle, numRotations, tol, internal) 

+//         or thread(pitch, majorD, stepAngle, numRotations, tol, internal)

+// with the parameters:

+// pitch        - screw thread pitch

+// majorD       - screw thread major diameter

+// step         - step size in degrees (36 gives ten steps per rotation)

+// numRotations - the number of full rotations of the thread

+// tol          - (optional parameter for internal threads) the amount to increase the 

+//                 thread size in mm.Default is 0

+// internal     - (optional parameter for internal threads) - this can be set true or  

+//                false.  Default is true

+

+root3 = sqrt(3);

+root3div3 = root3/3;

+

+//-----------------------------------------------------------------------------------------------

+//EXAMPLES:

+//example: this creates a 3/8-inch 16TPI bolt using metric units

+thread(1.5875,9.5250,12,12);

+

+//the same thread using imperial units

+//thread_imperial(1/16,3/8,12,12);

+

+//an internal thread that will accomodate the two examples above

+translate([15,0,0]){

+difference(){

+   cylinder(r=8,h=8);

+   translate([0,0,-1.5875/2]){thread(1.5875,9.5250,12,8, 0.2, true);}

+}}

+//------------------------------------------------------------------------------------------------

+

+//Creates a thread cross section starting with an equilateral triangle

+//and removing the point.  Internal threads (for creating nuts) will 

+//have a non-zero tolerance value which enlarges the triangle to

+//accomodate a bolt of the same size

+module screwthread_triangle(P, tol) {

+    cylinderRadius=root3div3*(P+2*tol);

+    translate([2*tol,0,0]){

+        difference() {

+            translate([-cylinderRadius+root3/2*(P)/8,0,0])

+            rotate([90,0,0])

+            cylinder(r=cylinderRadius,h=0.00001,$fn=3,center=true);

+            

+            translate([-tol,-P/2,-P/2]){

+                cube([P,P,P]); 

+            }

+

+            translate([-P,-P/2,P/2]){

+               cube([P,P,P]); 

+            }

+            

+            translate([-P,-P/2,-3*P/2]){

+               cube([P,P,P]); 

+            }

+        }

+    }

+}

+

+//Hulls two consecutive thread triangles to create a segment of the thread

+module threadSegment(P,D_maj, step, tol){

+    for(i=[0:step:360-step]){

+    hull()

+        for(j = [0,step])

+        rotate([0,0,(i+j)])

+        translate([D_maj/2,0,(i+j)/360*P])

+           screwthread_triangle(P, tol);

+    }  

+}

+

+//Places enough thread segments to create one full rotation.  The first

+//and last portion of external threads (for making bolts) are tapered 

+//at a 20 degree angle for an easier fit

+module screwthread_onerotation(P,D_maj,step, tol=0, first=false, last=false, internal=false) {

+	H = root3/2*P;

+	D_min = D_maj - 5*root3/8*P;       

+        

+         if(internal==false){ 

+            difference(){ 

+                threadSegment(P,D_maj, step, 0); 

+                if(first==true){

+                   //echo("first thread");

+                    translate([D_maj/2-P/2,0,-P/2]){

+                        rotate(-20,[0,0,1]){translate([0,-P*5,0]){cube([P,P*10,P]); }}}

+                }

+                

+                if(last==true){

+                   //echo("last thread");

+                    translate([D_maj/2-P/2,0,-P/2+P]){

+                        rotate(20,[0,0,1]){translate([0,-P*5,0]){cube([P,P*10,P]); }}}

+                }

+            }

+            

+        }else{

+            threadSegment(P,D_maj+tol, step, tol);          

+        }

+ 

+               

+        //make the cylinder a little larger if this is to be an internal thread

+        if(internal==false){

+            translate([0,0,P/2])

+            cylinder(r=D_min/2,h=2*P,$fn=360/step,center=true);

+        }else{

+            translate([0,0,P/2])

+            cylinder(r=D_min/2+tol,h=2*P,$fn=360/step,center=true);          

+        }

+}

+

+//creates a thread using inches as units (tol is still in mm)

+module thread_imperial(pitch, majorD, stepAngle, numRotations, tol=0, internal = false){

+    p=pitch*25.4;

+    d=majorD*25.4;

+    thread(p,d,stepAngle,numRotations, tol);

+}

+

+//creates a thread using mm as units

+module thread(P,D,step,rotations, tol=0, internal = false) {

+    // added parameter "rotations"

+    // as proposed by user bluecamel

+	for(i=[0:rotations-1])

+	translate([0,0,i*P]){

+            if(i==0&&rotations<=1){

+                screwthread_onerotation(

+                P,D,step, tol, true, true, internal); //first if there is only one rotation

+            }else if(i==0){

+                screwthread_onerotation(

+                P,D,step, tol, true, false, internal); //first if more than one rotation

+            }else if(i==rotations-1){

+                screwthread_onerotation(

+                P,D,step, tol, false, true, internal); //last if more than one rotation

+            }else{

+                screwthread_onerotation(

+                P,D,step, tol, false, false, internal); //middle threads

+            }

+        }

+}

+

+

+

+

+

+

+