Beginner needs help
Hi,
I tried hard to put these fillets in place to no avail (see picture).
I am using the "weld" module from osj1961.
Could anyone point me were I screwed up ?
This item will be finally rendered with $fn=60 or 80.
$fn=20;
//rotate([25,35,15]) {
//rotate([90,0,0])cube([50,50,35], center=true); // relay simulation
difference(){
union() {
weld(1) {
translate([0,0,28.3]) cylinder(h= 4, d= 95, center=true); // top
rim
}
weld(1) {
cylinder(h=60, r1=42.5,r2=42.5, center=true); // outer shell
weld(3) {
translate([0,0,-46]) cylinder(h=20, r=10); // bottom
extension
}
} // weld
rotate([90,0,0]) translate([0,-40,3]) cylinder(h=10,d=6,
center=false); // cylinder for screw
} // union
union() {
translate([0,0,13])
//weld(2) {
cylinder(h=80, r1=40, r2=40, center=true); // inner cavity
//}
translate([0,0,-80]) cylinder(h=180, r=3); // thru hole
rotate([90,0,0]) translate([0,-40,1]) cylinder(h=24,d=2, center=false); //
pre-hole for screw
} //union
} //difference
//} //rotate
module weld(t=1) {
union() {
children(0);
children(1);
hull(){
union(){
intersection() {
minkowski(){
intersection(){
children(0);
children(1);
}
sphere(r=t);
}
children(0);
}
intersection() {
minkowski(){
intersection() {
children(0);
children(1);
}
sphere(r=t);
}
children(1);
}
}
}
}
}
Thanks in advance for any help.
http://forum.openscad.org/file/n20159/cache_help_fillet.jpg .
Dan
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Your design is almost radial symmetric. I would start it in 2D, do the
fillets with offset()
http://forum.openscad.org/how-to-make-round-chamfer-at-2D-object-td19714.html
and then use rotate_extrude() for extrusion.
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re: 2D and doing rotate_extrude()
using this is really helpful: http://daid.eu/~daid/3d/
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On Wed, Jan 18, 2017 at 11:19 AM, Parkinbot rudolf@parkinbot.com wrote:
Your design is almost radial symmetric. I would start it in 2D, do the
fillets with offset()
<http://forum.openscad.org/how-to-make-round-chamfer-at-
2D-object-td19714.html>
and then use rotate_extrude() for extrusion.
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Discuss@lists.openscad.org
http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
When I copy and paste your code into a new OpenSCAD document, and hit F5, I
get 5 "WARNING: Children index (1) out of bounds (1 children)" messages.
The weld function produces a fillet between two parts, so needs two inputs;
you're giving it just one in some cases.
You seem to be using the 'weld' function for two tasks; to add a fillet
between two objects, and to add a radius to individual objects. The error
messages are from where you are doing the latter, which I think is using the
'weld' function incorrectly. It's also causing that part to be bigger than
you expect, as it's basically doing a minkowski operation to the part. I
imagine the 'weld' function wasn't originally intended to produce radii! You
need a different function to do this, and to keep the parts the correct
size, minus the radiused edge. Then you can use the weld function correctly,
in the form:
weld (2) {
(top part with radius edge);
weld (2) {
(middle part with radius edge);
(bottom part with radius edge);
}
}
This will produce the correct shape. Or, alternatively, as others have
suggested, draw it in 2D. nophead helped me produce a really nice function
that would allow you to produce a 2D drawing with the correct fillets and
radii, rather than using lots of circles/squares/union/difference; see this
thread:
http://forum.openscad.org/Script-to-replicate-hull-and-minkoswki-for-CSG-export-import-into-FreeCAD-td16537.html
Ian
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Parkinbot wrote
Your design is almost radial symmetric. I would start it in 2D, do the
fillets with offset()
http://forum.openscad.org/how-to-make-round-chamfer-at-2D-object-td19714.html
and then use rotate_extrude() for extrusion.
Thanks Parkinbot. Extruding 2D is the way to go !
I looked at the link you provide but could not figure out how to integrate
the offset() into my polygon to make radii/chamfers. I then ended up making
chamfers by adding points.
However, I'd love to master the offset(). Could you please give me a couple
of examples for a positive and negative radii/chamfer using my code ? Here
it is :
// * * * * * * * * * * * * *
// File: .../openscad/learn/cache_3_rotate_extrude_2.scad
$fn=20;
/*
// radial tapping stud with prehole
difference() {
rotate([90,0,0]) translate([0,10,2.8])
cylinder(h=7.5,d=6, center=false);
rotate([90,0,0]) translate([0, 10, 0])
cylinder(h=12 ,d=2, center=false);
}
*/
//rotate_extrude(angle=360, convexity=10)
polygon(
points= [
[40,80], // 0
[47.5,80], // 1
[47.5,76], // 2
[44.5,76], // 3
[42.5,74], // 4
[42.5,22], // 5
[40.5,20], // 6
[12.5,20], // 7
[10,18], // 8
[10,2], // 9
[8,0], // 10
[3,0], // 11
[3,24], // 12
[36,24], // 13
[40,28], // 14
[40,40], // 15
],
paths=[[0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15]],
convexity=10
);
// * * * * * * * * * * *
Thanks much for your time.
Dan
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jdawgaz wrote
re: 2D and doing rotate_extrude()
using this is really helpful: http://daid.eu/~daid/3d
Extra Ham Operator: K7AZJ
Registered Linux User: 275424
Raspberry Pi and Openscad developer
Thanks jdawgaz,
It looks like an useful tool. I pasted my polygon code into it but nothing
happened.
I little user's guidance would help.
Dan
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droftarts wrote
When I copy and paste your code into a new OpenSCAD document, and hit F5,
I get 5 "WARNING: Children index (1) out of bounds (1 children)" messages.
The weld function produces a fillet between two parts, so needs two
inputs; you're giving it just one in some cases.
You seem to be using the 'weld' function for two tasks; to add a fillet
between two objects, and to add a radius to individual objects. The error
messages are from where you are doing the latter, which I think is using
the 'weld' function incorrectly. It's also causing that part to be bigger
than you expect, as it's basically doing a minkowski operation to the
part. I imagine the 'weld' function wasn't originally intended to produce
radii! You need a different function to do this, and to keep the parts the
correct size, minus the radiused edge. Then you can use the weld function
correctly, in the form:
weld (2) {
(top part with radius edge);
weld (2) {
(middle part with radius edge);
(bottom part with radius edge);
}
}
This will produce the correct shape. Or, alternatively, as others have
suggested, draw it in 2D. nophead helped me produce a really nice function
that would allow you to produce a 2D drawing with the correct fillets and
radii, rather than using lots of circles/squares/union/difference; see
this thread:
http://forum.openscad.org/Script-to-replicate-hull-and-minkoswki-for-CSG-export-import-into-FreeCAD-td16537.html
Ian
Thanks droftarts,
You're right about the weld function. I clearly misuse it.
As for the link you provided, I must humbly admit it is a bit above my head
at this stage of my learning...
Dan
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stressless wrote
Thanks droftarts,
You're right about the weld function. I clearly misuse it.
As for the link you provided, I must humbly admit it is a bit above my
head at this stage of my learning...
Dan
No problem, we all started somewhere! To get your "radial tapping stud with
prehole" correct, you just need to reorder things a little; eg do it in this
order:
$fn=100;
// radial tapping stud with prehole
difference() {
union () {
rotate_extrude(angle=360, convexity=10) polygon([
[40,80], // 0
[47.5,80], // 1
[47.5,76], // 2
[44.5,76], // 3
[42.5,74], // 4
[42.5,22], // 5
[40.5,20], // 6
[12.5,20], // 7
[10,18], // 8
[10,2], // 9
[8,0], // 10
[3,0], // 11
[3,24], // 12
[36,24], // 13
[40,28], // 14
[40,40]]); // 15
rotate([90,0,0]) translate([0,10,2.8]) cylinder(h=7.5,d=6,
center=false);
}
rotate([90,0,0]) translate([0, 10, 0]) cylinder(h=12 ,d=2,
center=false);
}
The function I alluded to simply replaces your fillets with circles. You can
ignore the module and the function; they just do the maths! Each point has a
circle (the third value in the point list), which can be 0 (for no radius or
fillet), positive (for a radius), or negative (for a fillet). The main
difficulty is that you need to offset the point by the radius of the circle.
Here's your shape using the function:
$fn = 100;
shape1 = [
[40,80,0], // 0
[47.5,80,0], // 1
[47.5,76,0], // 2
[44.5,74,-2], // 3
[40.5,22,2], // 4
[12,18,-2], // 5
[8,2,2], // 6
[3,0,0], // 7
[3,24,0], // 8
[36,28,-4], // 9
[40,40,0]]; // 10
difference() {
union () {
rotate_extrude(angle=360, convexity=10) rounded_polygon(shape1);
rotate([90,0,0]) translate([0,10,2.8]) cylinder(h=7.5,d=6,
center=false);
}
rotate([90,0,0]) translate([0, 10, 0]) cylinder(h=12 ,d=2,
center=false);
}
module rounded_polygon(points)
difference() {
len = len(points);
union() {
for(i = [0 : len - 1])
if(points[i][2] > 0)
translate([points[i].x, points[i].y])
circle(points[i][2]);
polygon([for(i = [0 : len - 1])
let(ends = tangent(points[i], points[(i + 1) %
len]))
for(end = [0, 1])
ends[end]]);
}
for(i = [0 : len - 1])
if(points[i][2] < 0)
translate([points[i].x, points[i].y])
circle(-points[i][2]);
}
function tangent(p1, p2) =
let(
r1 = p1[2],
r2 = p2[2],
dx = p2.x - p1.x,
dy = p2.y - p1.y,
d = sqrt(dx * dx + dy * dy),
theta = atan2(dy, dx) + acos((r1 - r2) / d),
xa = p1.x +(cos(theta) * r1),
ya = p1.y +(sin(theta) * r1),
xb = p2.x +(cos(theta) * r2),
yb = p2.y +(sin(theta) * r2)
)[ [xa, ya], [xb, yb] ];
You can also use "offset (r=1) offset (r=-1) polygon([ ... " (see
https://en.wikibooks.org/wiki/OpenSCAD_User_Manual/Transformations#offset )
however this will apply the same radius to all corners. It also can't be
used if the walls are too thin, or they disappear.
Hope that helps.
Ian
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<< Hope that helps. >>
- Sure does ! This is not just help but a whole tutorial. Thanks a bunch for
that.
I am still chewing on the let() func. (and why a mod. ?) as in :
polygon([for(i = [0 : len - 1])
let(ends = tangent(points[i], points[(i + 1) %
len]))
for(end = [0, 1])
ends[end]]);
Hoping to grasp it soon.
Thanks again for your time. All the best.
Dan
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2017-01-24 9:12 GMT-02:00 stressless wintoweb@gmail.com:
I am still chewing on the let() func. (and why a mod. ?) as in :
polygon([for(i = [0 : len - 1])
let(ends = tangent(points[i], points[(i + 1) %
len]))
for(end = [0, 1])
ends[end]]);
Welcome to list comprehension
https://en.wikibooks.org/wiki/OpenSCAD_User_Manual/List_Comprehensions
stuff!