Float switch

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Revision as of 20:35, 7 May 2017 by James (talk | contribs) (v3 updated foot section to increase tolerance and socket to add inlet chamfer)

This is the source code for the float switch 3d printed parts for the water level detector for the Cheap Chinese Laser. It is made in two parts: the head and the base. You also need 4 pieces of 1/4-20 all thread to connect the two of them and 8 nuts. The base is internally threaded. The head needs nuts top and bottom. Washers would be good too.

File:Float-switch-head.stl rendered on 5/1/2017

File:Float-switch-base.stl rendered on 5/7/2017

low water level detector
safety interlock for cheap Chinese laser at Hac DC
This water level detector is a two piece assembly connected by threaded rod.  This model uses 1/4-20 rod.  The lower foot has a 40mm home in the bottom to insert a pingpong ball as the float.
James Sullivan
Mk 2 - calculated threads
OpenSCAD version 2015.03-1 
ppbd=40;    //ping pong ball diameter
ppbw=2.7;   //ping pong ball weight in grams
shd=2;  //switch hole diameter
shp=10; //switch hole pitch, i.e. center to center spacing of mounting holes on microswitch
wlh=200;    //water level height
sbw=6;  //switch body width
nfw=4;  //nut face width, switch mounting nuts
nt=1;   //nut thickness, switch mounting nuts
thick=5;    //thickness
eps=0.1;    //epsilon
tol=0.5;    //tolerance
br=50;      //base radius
rod=25.4/4; //rod outer diameter
tpi=20;     //threads per inch
fph=25.4*5/tpi;//foot pillar height
bfw=ppbd+2*thick;  //base flange width
function mod(num,den) = num - floor(num/den)*den; 
//dimensions taken from Front Door Switch Holder
wr=4;			//wrench size for nuts width across flats
nh=1;			//nut height, depth of nut sockets

module head() {
                rotate([0,0,angle]) translate([ppbd/2+rod/2+tol,0,0]) cylinder(d=rod+thick*2,h=thick); //leg cylinders
        translate([0,0,-thick/2]) cylinder(h=thick*2,r=ppbd/2+rod/2+tol-3*thick/2);
            rotate([0,0,angle]) translate([ppbd/2+rod/2+tol,0,-thick/2]) cylinder(d=rod,h=fph); //leg holes
    translate([sbw/2,(ppbd+rod+tol-2*thick)/(-2),0]) cube([thick,ppbd+rod+tol-2*thick,thick]);
    translate([sbw/2,shp/2,thick]) difference(){ //switch mounting block, aligned with z-plane and x-plane, centered on y-plane
        translate([0,-shp/2-nfw,0]) color("green") cube([thick,shp+2*nfw,2*nfw]);
        for (y=[-shp/2,shp/2]) {
            translate([thick/2,y,nfw]) rotate([0,90,0]) cylinder(d=shd,h=thick*2,center=true);    //screw holes
            translate([sbw-nh,y,nfw]) union(){  //nut sockets
                for (ang=[0,120,240]) rotate([ang,0,0]) cube([nh*2,wr,wr/sqrt(3)],center=true);
        translate([sbw/2+thick,bfw/2-nfw-shp,nfw]) union(){  //center nut socket
            rotate([120,0,0]) cube([nh*2,wr,wr/sqrt(3)],center=true);
            rotate([240,0,0]) cube([nh*2,wr,wr/sqrt(3)],center=true);

module socket(nd,tpi,tl,thick) {
    //nd = nominal diameter
    //tpi = threads per inch
    //tl = thread length
    ror=nd/2;       //rod outer radius
    pitch=25.4/tpi; //thread pitch in mm
    td=pitch*3/4;   //thread depth in mm
    rir=ror-td;     //rod inner radius
    sor=ror+thick;  //socket outer radius
    vert= [for (ang=[0:360/$fn:720]) ang<=45 ? [cos(ang),sin(ang)]*rir : ang<180 ? [cos(ang),sin(ang)]*(rir+td*(ang-45)/135) : ang<=225 ? [cos(ang),sin(ang)]*ror : ang<360 ?[cos(ang),sin(ang)]*(rir+td*(360-ang)/135) : [cos(ang),sin(ang)]*sor];
    path1=[for(p=[0:$fn]) mod(p,$fn) ];
    path2=[for(p=[0:$fn]) mod(p,$fn)+$fn ];
        translate([0,0,tl-ror*tan(30)]) cylinder(r2=ror,r1=0,h=ror*tan(30));  //inlet chamfer

module foot(){
            translate([0,0,thick/2]) cube([ppbd+2*thick,ppbd+2*thick,thick],center=true);
            for (angle=[45:90:315]){
                    translate([ppbd/2+rod/2+tol,0,thick]) socket(rod,tpi,fph,thick);  //pillar
                    translate([0,-thick,0]) cube([br-thick,thick*2,thick]); //leg
                    translate([br-thick,0,0]) cylinder(r=thick,h=thick);    //foot
                }  //end rotate
            }  //end for
        }  //end union
        translate([0,0,-eps/2]) cylinder(d=ppbd+tol,h=fph+eps+thick); //ping pong ball entry
    }   //end difference
}   //end foot module