Re: [OpenSCAD] Help with two problems with SCAD
If you stick render() before each union in the difference it works,
highlights lots of coincident faces. (takes a while to preview the first
time)
difference (){
union(){
difference()
{
// Cutting 120 Degrees of Circle, Screw Holes from
render()
union(){
...
} // End of Union of first group for Difference
render()
union(){
...
} // End of Union of Cuting elements
} // End of Difference for Paddle making
} // End of Union of everything
// Note NO difference
} // End of Difference
Admin - PM me if you need anything, or if I've done something stupid...
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I have dine that this morning by myself, no changes in problem, Object is
intentionaly hollowand cavitied serve special mpurpose, Just latr
Differencewere usung object with heavy thicknessand not positioned right so
it cut trough center instead at offset from center.
It is new Wind turbine composed of conical walls and vertical ones. After
half day of rendering it is more normal looking but is I touch anythinmg it
wipes screen and is non responding again. It should be centered on 0,0,0 as
it is circular and multy symetrical. it is as should be but I cannot see it
except as overlarge, so only part of surface fir the screen.
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render() Helped, at least it is not "not respondimg"........
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Your code is very crude and seems to create and use a bunch of empty
differences. No wonder that it does not behave very well.
Just one example out of many: Look at the call
makeMantle (he=th, ro=tr+1, ri=tr, mccr=ccr);
It is not properly defaulted (which is bad style) and it F6-renders into a
non-valid 2-manifold. No way to head on already at this point ...
Some hints:
-
If you compose a design from multiple components, every component has to
be a valid 2 manifold, otherwise you are in trouble. -
When debugging a component, try to successfully render each of its
components first. Do this in a bottom-up fashion. -
If you don't see what you expect, omit Boolean operations first by
commenting them out. To "find" a component within a composed object mark it
with #. -
use well chosen default values to ease testing and simplify calls as much
as possible. -
Reduce complexity (and increase readability) as much as possible, by:
-
poperly indenting your code with aligned brackets and bodies;
-
omitting (tons of) superfluous curly bracket pairs for operators like
translate() rotate() and for() that have only a single operand. E.g. it is
perfectly ok to stack something like: /scale(A) linear_extrude(B) for(i=C)
rotate(D) translate(E) myModule(...);/ without putting a single curly
bracket pair. -
omitting explicit unions, where OpenSCAD puts implicit unions. This is
essentially almost everywhere possible. An exception would be a boolean
expression like difference() where the first (!) operand is explicitly
composed by the union of several objects or an intersection with such an
operand. Operators like translate(), scale() rotate(), for() use an implict
union, if they operate over a list of operands. See also the difference
between intersection() and intersection_for().
Good code is: readable and well structured into meaningful modules,
submodules and functions. Each chunk of code should be designed in a way, so
that can be easily tested on its own. It omits lengthy and crude sequences
of badly organized and wildly transformed components. If you want to keep
control over code, try to keep the body of any module as small as possible
and test it and its parameter range properly before you use it as component
in a larger context. Otherwise it will start to play with you and you will
spend 99% of your time with debugging.
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Thanks for lecture. Unfortunately I do not understand You entirely. First
English is not my Native Language, and second this is progran in works, I am
adding and commenting out lot of things while testing results. How would I
know module is properly defaulted? Whsat is "valid 2 manifold"? I am usualy
making indentatiions, and when program finally work I clean up and make
order, and Differences it seems empty to You are actually necesary and not
empty. Maybe when I would use SCAD longer, I would find some shortcuts. but
I reason that putting curly brackets cannot make code less readable. What I
try to achieve are thin conical walls joined together on top, to be strong
and light, and I think 3D printer can print it, if it would do exactly what
I programmed it for. As there is no function to make pipe of desired
diameter I am making it by making difference from two cylinders, but i need
only parts of this pipe of certain number of degrees and that is also not
easy to do, so I am forced to improvise, and do best I can. Global variables
do not exist in SCAD so Modules do not see what is not explicitely passed as
parameter, and that goes double for modules called from other modules, as
they have to be nested and defined within module that call them
what means same module cannot be called in another that can use itif I
understood some rules I have to find hard way.
This not easy for me because I am from another time and carry legacy of 26+
programming languages some in several generations add on different Platforms
and from different Vendors on same Platform.
But in ganeral I find SCAD usefull for my work as Inventor, and I have done
lot for few months I am using it. I am asking for help only when I cannot
finf solution by my own efforts.
right now next problem I am facing is to construct machine that use lot of
pipes that must be positioned precosely and have bends thar are half
circular, and my method of creating pipes from difference of two cilinders
is good only for straight pipes. if anyone know function to create such
pipes, please tell me where to find it.
http://forum.openscad.org/file/n21446/PerpetumMobiusDupliIstostraniPomaknutProziran.jpg
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Actualy it is not that simple:
http://forum.openscad.org/file/n21447/Photo-0001.jpg
i have made this by hand from just ONE piece of pipe, it would be much
better 3D printed.
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On 13. mai 2017 02:21, Marijan Pollak wrote:
right now next problem I am facing is to construct machine that use lot of
pipes that must be positioned precosely and have bends thar are half
circular, and my method of creating pipes from difference of two cilinders
is good only for straight pipes. if anyone know function to create such
pipes, please tell me where to find it.
http://forum.openscad.org/file/n21446/PerpetumMobiusDupliIstostraniPomaknutProziran.jpg
So basically you have 2 closed pipe loops consisting of straight and
circular segments, and the 2 loops are independent of each other (not
connected to each other) and rotated 45 degrees relative. Is that right?
I tried to open the OpenSCAD file of your original post, but it didn't
look anything like the photo above. To get any further I think it would
be a good idea to clarify whether the above photo is indeed what you
want to create.
Parts of your hand made thing below seems to be in loose agreement with
the above photo, but the details are unclear.
http://forum.openscad.org/file/n21447/Photo-0001.jpg
I have no idea if this thing would do anything meaningful, it just seems
like a few bent pipes with no entrance/exit, but it should be possible
to model if the top photo is representative.
So is it the "PerpetumMobiusDupliIstostraniPomaknutProziran.jpg" layout
as shown you are attempting to recreate, with the dimensions from the
.scad file in your original post?
Carsten Arnholm
Hi, I must correct You, there is no overlaping FACES, just overlaping EDGES,
as conical and vertical walls are joined on top. that creates walls that
have no external faces as verticall walls are inside between two conical
walls. I do not see why this shouls be preblem as every wallis created
separatelly and joined to others with union () while each wall is difference
betveen two cylinders or two conuses. So if each is rendered and then joined
together as it is written all should be as intended to be.
I followed adwice to remove as many curly brackets and use implied unions,
asnd found that object wihin for loop are not impilcitely part of union in
fact thex are not created at all if union doed not precede for loops and
have curly brackets.
I tried to simplifa program cut results are still slower rendering with both
f5 ans f6 use.
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Well sory for confusion. This is not strictly related to first example and
first picture is simplified version to show what I need while photo is of
actual machine built by hand that has to be made precisely an symetrically
drawn in SCAD, and which is more complicated specially as it is made from
one piece of hose. There could be two or more systems turned certain numbers
of dehrees in relatiom to one another.It is Gravity motor, but I did not
asked for help with that, only in creating round pipes or cylinders which I
can made difference from cylindrical plate to get pipes inside. I intend to
put it in bottom of turbine in first example, or any of my hawt turbines so
they would turn even without wind.
I got example of "Macaroni Maker" exanple wihich I have to study jet, but as
I ecplained I would prefer that to be cylinders instead of pipes so I can
hide system from ones who does not believe such things is possible, and also
because Patent Office would Label it Perpetum Mobile and that is forbidden
for patenting.
Thank You in advance.
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On 14. mai 2017 16:26, Marijan Pollak wrote:
It is Gravity motor, but I did not
asked for help with that, only in creating round pipes or cylinders which I
can made difference from cylindrical plate to get pipes inside.
I would recommend something like below for creating pipes, instead of
subtracting cylinders. This avoids the problem that the inner cylinder
has to extend at both ends, to avoid numerical problems:
$fn=30;
module StraightPipe(ro=10, th=1, l=100)
{
linear_extrude(l)
difference() { circle(ro); circle(ro-th); }
}
module CurvedPipe(ro=10, th=1, radius=100, angle=60)
{
rotate([90,0,0])
translate([-radius,0,0])
rotate_extrude(angle=angle,$fn=60)
translate([radius,0,0])
difference() { circle(ro); circle(ro-th); }
}
translate([-50,0,0]) CurvedPipe();
translate([+50,0,0]) StraightPipe();
The angle parameter in rotate_extrude requires a recent version of OpenSCAD.
Btw. the "PerpetumMobius" photo or the model you made with hoses imply
non-planar bent pipes. That isn't possible with rotate_extrude in OpenSCAD.
Carsten Arnholm
