Resolution Issue
Hello I am pretty new to OpenSCAD and CAD in general, but I am working my way
through a basic stand.
It has three sections, top, middle, and bottom, and the middle section I
have curving between the top and bottom by way of a difference call with the
middle section and a torus around it.
The issue is that no matter what I set $fn to, the middle section doesn't
smooth out. I keep getting flat faces all the way around.
Here is how I am doing it:
startDiam = 37;
endDiam = 15; //diameter at top of stand
flareHeight = 12; //height of middle section
flatHeight = 3;//height of bottom section
topHeight = 10;//height of top section
layerRes = 60;//number of layers that make up middle section
nFaces = 100;//number of faces for cylinders
deltaDiam = (startDiam - endDiam) / layerRes;//change in diameter per layer
in middle section
deltaHeight = flareHeight / layerRes;//height of a layer in the middle
section
module stand()
{
union()
{
//bottom stand
cylinder(d = startDiam, h = flatHeight , $fn = nFaces);
//middle stand
difference(){
translate([0,0,flatHeight]){
hull()
{
for(i = [0:layerRes]){
translate([0,0,deltaHeight*i]){
cylinder(d = startDiam - (deltaDiam* i), h =
deltaHeight, $fn = nFaces);
}
}
}
}
translate([0,0,flatHeight + flareHeight]){
#donut();
}
}
//top stand
translate([0,0,flatHeight + flareHeight + deltaHeight]){
cylinder(d = endDiam, h = topHeight, $fn = nFaces);
}
}
}
module donut()
{
rotate_extrude(){
translate([(startDiam/2)+1,0,0]){
circle(r = flareHeight, $fn = nFaces);
}
}
}
stand();
In the render you can see the green section is not nearly as smooth as the
top and bottom.
http://forum.openscad.org/file/n20524/JgiUOwr.png
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Hello Justin.
Maybe you forgot to add $fn to your rotated extrusion?
rotate_extrude($fn = nFaces)
Also, all those 3D hull() are slow. Have you considered working in 2D and
then rotate_extrude everything?
2017-02-21 19:34 GMT+01:00 justin_ISO justin@iso-form.com:
Hello I am pretty new to OpenSCAD and CAD in general, but I am working my
way
through a basic stand.
It has three sections, top, middle, and bottom, and the middle section I
have curving between the top and bottom by way of a difference call with
the
middle section and a torus around it.
The issue is that no matter what I set $fn to, the middle section doesn't
smooth out. I keep getting flat faces all the way around.
Here is how I am doing it:
startDiam = 37;
endDiam = 15; //diameter at top of stand
flareHeight = 12; //height of middle section
flatHeight = 3;//height of bottom section
topHeight = 10;//height of top section
layerRes = 60;//number of layers that make up middle section
nFaces = 100;//number of faces for cylinders
deltaDiam = (startDiam - endDiam) / layerRes;//change in diameter per layer
in middle section
deltaHeight = flareHeight / layerRes;//height of a layer in the middle
section
module stand()
{
union()
{
//bottom stand
cylinder(d = startDiam, h = flatHeight , $fn = nFaces);
//middle stand
difference(){
translate([0,0,flatHeight]){
hull()
{
for(i = [0:layerRes]){
translate([0,0,deltaHeight*i]){
cylinder(d = startDiam - (deltaDiam* i), h =
deltaHeight, $fn = nFaces);
}
}
}
}
translate([0,0,flatHeight + flareHeight]){
#donut();
}
}
//top stand
translate([0,0,flatHeight + flareHeight + deltaHeight]){
cylinder(d = endDiam, h = topHeight, $fn = nFaces);
}
}
}
module donut()
{
rotate_extrude(){
translate([(startDiam/2)+1,0,0]){
circle(r = flareHeight, $fn = nFaces);
}
}
}
stand();
In the render you can see the green section is not nearly as smooth as the
top and bottom.
http://forum.openscad.org/file/n20524/JgiUOwr.png
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Resolution-Issue-tp20524.html
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Saludos,
Antonio
You can set $fn in the rotate_extrude to get more fragments. See
https://en.wikibooks.org/wiki/OpenSCAD_User_Manual/2D_to_3D_Extrusion#Rotate_Extrude
.
On 21 February 2017 at 18:34, justin_ISO justin@iso-form.com wrote:
Hello I am pretty new to OpenSCAD and CAD in general, but I am working my
way
through a basic stand.
It has three sections, top, middle, and bottom, and the middle section I
have curving between the top and bottom by way of a difference call with
the
middle section and a torus around it.
The issue is that no matter what I set $fn to, the middle section doesn't
smooth out. I keep getting flat faces all the way around.
Here is how I am doing it:
startDiam = 37;
endDiam = 15; //diameter at top of stand
flareHeight = 12; //height of middle section
flatHeight = 3;//height of bottom section
topHeight = 10;//height of top section
layerRes = 60;//number of layers that make up middle section
nFaces = 100;//number of faces for cylinders
deltaDiam = (startDiam - endDiam) / layerRes;//change in diameter per layer
in middle section
deltaHeight = flareHeight / layerRes;//height of a layer in the middle
section
module stand()
{
union()
{
//bottom stand
cylinder(d = startDiam, h = flatHeight , $fn = nFaces);
//middle stand
difference(){
translate([0,0,flatHeight]){
hull()
{
for(i = [0:layerRes]){
translate([0,0,deltaHeight*i]){
cylinder(d = startDiam - (deltaDiam* i), h =
deltaHeight, $fn = nFaces);
}
}
}
}
translate([0,0,flatHeight + flareHeight]){
#donut();
}
}
//top stand
translate([0,0,flatHeight + flareHeight + deltaHeight]){
cylinder(d = endDiam, h = topHeight, $fn = nFaces);
}
}
}
module donut()
{
rotate_extrude(){
translate([(startDiam/2)+1,0,0]){
circle(r = flareHeight, $fn = nFaces);
}
}
}
stand();
In the render you can see the green section is not nearly as smooth as the
top and bottom.
http://forum.openscad.org/file/n20524/JgiUOwr.png
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Resolution-Issue-tp20524.html
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The middle resolution is the resolution of the rotate_extrude, that you
haven't set.
Try with:
module donut()
{
rotate_extrude($fn=nFaces){
translate([(startDiam/2)+1,0,0]){
circle(r = flareHeight, $fn = nFaces);
}
}
}
Besides, you can avoid all hull and unions by defining the conic section
using linear_extrude:
//middle stand
difference(){
translate([0,0,flatHeight]){
linear_extrude(height = flareHeight+deltaHeight,
scale=endDiam/startDiam)
circle(r=startDiam/2,$fn=nFaces);
}
translate([0,0,flatHeight + flareHeight]){
#donut();
}
}
Or even using a simple cylinder instead of a cone trunk:
difference(){
translate([0,0,flatHeight]){
cylinder(r=startDiam/2,h=flareHeight+deltaHeight);
}
translate([0,0,flatHeight + flareHeight]){
#donut();
}
}
But, the best solution to your model would be to define a 2D form whose
revolution with rotate_extrude generates your full stand without any 3D
boolean operation.
Thank you for the help!
I have noticed that this does take a bit longer to render, but it is beyond
my ability to draw the curve I want in 2D and extrude it.
Thanks again!
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It is not. You have devised a very sofisticated solution. To define a 2D
shape to apply rotate_extrude, use boolean operations with 2D primitives
squares and circles correctly dimensioned and positioned. And show us what
you got.
2017-02-21 16:23 GMT-03:00 justin_ISO justin@iso-form.com:
Thank you for the help!
I have noticed that this does take a bit longer to render, but it is beyond
my ability to draw the curve I want in 2D and extrude it.
Thanks again!
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tp20524p20528.html
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A simple example of what is being suggested (design in 2D and rotate
extrude):
rotate_extrude($fn=360)
offset(r=-3,$fn=360)
offset(delta=3)
union()
{
square([2,8]);
square([5,1]);
}
On 22 February 2017 at 06:15, Ronaldo Persiano rcmpersiano@gmail.com
wrote:
It is not. You have devised a very sofisticated solution. To define a 2D
shape to apply rotate_extrude, use boolean operations with 2D primitives
squares and circles correctly dimensioned and positioned. And show us what
you got.
2017-02-21 16:23 GMT-03:00 justin_ISO justin@iso-form.com:
Thank you for the help!
I have noticed that this does take a bit longer to render, but it is
beyond
my ability to draw the curve I want in 2D and extrude it.
Thanks again!
--
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lution-Issue-tp20524p20528.html
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