118 lines
5.6 KiB
Markdown
Executable File
118 lines
5.6 KiB
Markdown
Executable File
This is the OpenSCAD code to create a wafer air flow sensor (and
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backflow preventer) to hold a microswitch to stop the laser from firing
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if the exhaust flow stops. Dimensions have been set to match the exhaust
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nozzle. The current version of the header doesn't quite match, even
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though the nozzle was reverse engineered from it.
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This was printed on 5/1 and it has some issues.
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1. The arms which hold the switch body interfere with the flap plate.
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2. The flap plate axis of rotation could be lowered to improve the
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balance.
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3. The thickness of the wafer can be increased to reduce the warpage of
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the piece.
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Model was redesigned on 5/5:
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1. Switch holder moved to side from top center
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2. Flap axis of rotation lowered
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3. Up arrow added
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4. Thickness increased from 3 to 5 mm
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5. Wire holes relocated 180??
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You can find the stl file here
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![<File:Airflow-switch.stl>](Airflow-switch.stl "File:Airflow-switch.stl")
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<nowiki>
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/*
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exhaust airflow detector
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safety interlock for cheap Chinese laser at Hac DC
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This switch is a lug style wafer for insertion between the exhaust collector and the exhaust nozzle on the back of the laser chassis.
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When the exhaust fan is running and air is flowing the switch will operate to allow the laser to fire. This switch is upstream of
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the exhaust fan so air will leak into the exhaust stream, not exhaust leaking out into room air.
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James Sullivan
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5-5-17, v2
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OpenSCAD version 2015.03-1
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--dimensions from mating exhaust nozzle--
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nid=60; //nozzle inner diameter
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nod=80; //nozzle outer diameter
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mod=100; //maximum outer diameter
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sh=30; //step height
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sw=5; //step width
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oah=50; //over-all height
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tlw=3; //top ledge width
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bcd=46.8*2; //bolt circle diameter
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bhd=3.6; //bolt hole diameter
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fw=12; //foot width
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fh=15; //foot height
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fod=108; //foot outside dimension, from outside edge to outside edge
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fid=(nid+nod)/2;//foot inside dimension, from inside edge to inside edge
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*/
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fid=60; //flange inner diameter, same as nid
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fod=80; //flange outer diameter, same as nod
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bhd=3.6; //bolt hole diameter
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bcd=93.6;//bolt circle diameter
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thick=5; //thickness of flange - originally 3, but warped when removing from printer bed
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flap=3; //thickness of flap - originally 3, but warped when removing from printer bed
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hph=bhd*2; //hinge pin height above center line, i.e. butterfly offset. Reduce to make switch more sensitive. Increse to make switch more stable. - originally 10
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sfw=fid-thick*2; //switch flap width - originally sqrt(fid*fid-4*hph*hph)
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shd=2; //switch hole diameter
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shp=10; //switch hole pitch, i.e. center to center spacing of mounting holes on microswitch
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srh=12; //switch roller height, i.e. height above switch hole centerline where switching action occurs
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sbw=6; //switch body width
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nfw=5; //nut face width
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nt=1; //nut thickness
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$fn=80;
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difference(){ //wafer body
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union(){
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cylinder(d=fod,h=thick);
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for(ang=[0,90]){
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rotate([0,0,ang]) hull(){ //lugs
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translate([bcd/2,0,0]) cylinder(d=3*bhd, h=thick);
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translate([-bcd/2,0,0]) cylinder(d=3*bhd, h=thick);
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}
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}
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translate([sfw/2+thick/2,0,thick]) rotate([-90,0,0]) cylinder(d1=shd*1.6,d2=0,h=shd*2);//up direction arrow head
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translate([sfw/2+thick/2,0,thick]) rotate([90,0,0]) cylinder(d=shd*0.8,h=shd*2); //up direction arrow shaft
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}
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translate([0,0,-thick/2]) intersection(){ //bore
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cylinder(d=fid, h=2*thick); //circular top and bottom
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cube([sfw,fod,thick*4],true); //vertical left and right
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}
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for (angle=[0:90:270]){ //bolt holes in lugs
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rotate([0,0,angle]) translate([bcd/2,0,-thick/2]) cylinder(d=bhd,h=thick*2);
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}
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for (angle=[235:5:245]){ //wire holes through flange
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translate([0,0,thick-flap/2]) rotate([0,90,angle]) cylinder(d=1,h=bcd/2);
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}
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translate([0,hph,flap/2]) rotate([0,90,0]) cylinder(d=1,h=bcd+4*bhd,center=true); //hinge pin axle hole
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} //end of wafer body
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translate([-thick/2-sfw/2,0,flap/2+srh]){ //switch holder
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difference(){
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union(){
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cube([thick,shp+3*shd,3*shd],center=true);//mount flange
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color("blue") translate([0,0,-srh/2-flap/4+thick/2-3*shd/4]) cube([thick,shp+3*shd,srh+flap/2-thick-3*shd/2],center=true); //support for mount flange
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translate([-thick/2,0,-shd*2]) cylinder(d2=shd*1.6,d1=0,h=shd*2.0);//flow direction arrow head
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translate([-thick/2,0,-shd/2]) cylinder(d=shd*0.8,h=shd*2.0); //flow direction arrow shaft
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}
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for (dy=[-shp/2,shp/2]) {
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translate([0,dy,0]) rotate([0,90,0]) cylinder(d=shd,h=2*thick,center=true); //bolt holes
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for (angle=[0:120:240]){
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translate([-thick/2,dy,0]) rotate([angle,0,0]) cube([nt*2,nfw,nfw/sqrt(3)],center=true); //nut sockets
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}
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}
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}
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}
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translate([0,fid/2+bcd/2+bhd*2,0]) difference(){ //flap disk
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intersection(){ //bore
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cylinder(d=fid-0.5, h=flap); //circular top and bottom
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cube([sfw-0.5,fod,flap*2],true); //vertical left and right
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}
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translate([0,hph,flap/2]) rotate([0,90,0]) cylinder(d=1,h=bcd+4*bhd,center=true); //hinge pin axis
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}
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</nowiki>
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[Category: CheapChineseLaser](Category:_CheapChineseLaser "wikilink") |