OpenSCAD - Solid parts not solid...

Newbie here. I am messing around with OpenSCAD and a Flashforge Creater Pro and have run into an interesting problem:

I am printing a tube with reinforcing fins inside to increase stiffness. When the fins are at o and 90 degrees, all is well, but when a fin is oriented at 45 degrees, the resulting structure is hollow(!). I have confirmed that the 45 degree orientation is the problem by successively commenting out the fins. The 0 and 90 degree ones print well and are solid. The 45 degree one results in both the fins and the surrounding tube being hollow.

In all cases, the slicing was performed in the same fashion.

Any thoughts?


module tube (od, thickness, length){
// od = outer diameter
// thickness = wall thickness
// length = length
difference(){
cylinder(h=length, d=od);
translate([0,0,length-.5]);
cylinder(h=length+1, d=od-2*thickness);
}
}
//--------------------------------------------------------------------------------------------------------------
module tube_with_reinforcement (od, thickness, length, web_thickness){
// od = outer diameter
// thickness = wall thickness
// length = length
// web_thickness= reinforcement web thickness
union(){
tube(od, thickness,length);
translate ([-od/2,-web_thickness/2,0]) cube([od, web_thickness, length]);
rotate([0,0,90]) translate ([-od/2,-web_thickness/2,0]) cube([od, web_thickness, length]);
rotate([0,0,45]) translate ([-od/2,-web_thickness/2,0]) cube([od, web_thickness, length]); <== THIS ONE CAUSES A PROBLEM!
}
}

what numbers are you using ?
Also you are using variables but I can't see anywhere to set them ?

What slicing software are you using ? If rep-g try makerware. never had any infill issues with that.

Definitely sounds like a slicer issue. Openscad doesn't do anything but solid.

A couple of suggestions....

First, you need a 'top level' to the OpenScad program. You need a tube_with_reinforcement(); in order to instantiate the modules you have written. I also instantiated a tube(); at (x,y,z) of (25,25,0). You can't see that in the pictures.

Also, it is nice to add defaults. I put the sizes in the top level tube_with_reinforcement(); but decided to move them to the module declarations so there are always meaningful values there.

Here is what your current code does with my changes so it can instantiate an object:


Attachment 5716

Is that what you want it to look like?

Here is the code to do that:

Code:

---

translate([25,25,0]) tube();
tube_with_reinforcement();


module tube (od=10, thickness=1, length=10){
// od = outer diameter
// thickness = wall thickness
// length = length
difference(){
cylinder(h=length, d=od);
translate([0,0,length-.5]);
cylinder(h=length+1, d=od-2*thickness);
}
}
//--------------------------------------------------------------------------------------------------------------
module tube_with_reinforcement (od=10, thickness=1, length=10, web_thickness=.5){
// od = outer diameter
// thickness = wall thickness
// length = length
// web_thickness= reinforcement web thickness
union(){
tube(od, thickness,length);
translate ([-od/2,-web_thickness/2,0]) cube([od, web_thickness, length]);
rotate([0,0,90]) translate ([-od/2,-web_thickness/2,0]) cube([od, web_thickness, length]);
rotate([0,0,45]) translate ([-od/2,-web_thickness/2,0]) cube([od, web_thickness, length]); //<== THIS ONE CAUSES A PROBLEM!
}
}

---

You can make the tube smoother (at the cost of increasing the computational time) if you add the $fn=75 to the definition for tube():

Attachment 5717

that's all it does ?

Bloody hell lol
I could do that in about 10 lines and no modules and make it parametric. I guess there are some advantages to keeping it simple after all :-)

And if that's the model - then yep - it's your slicer that's causing the issues. that's a pretty basic model and can't see openscad having any problems with that.

Quote:

---

Originally Posted by curious aardvark

that's all it does ?

Bloody hell lol
I could do that in about 10 lines and no modules and make it parametric. I guess there are some advantages to keeping it simple after all :-)

And if that's the model - then yep - it's your slicer that's causing the issues. that's a pretty basic model and can't see openscad having any problems with that.

---

I would appreciate any education that you can give me Yes, that is all it does - gotta start somewhere ;-)

I think I have it nailed down to the slicer. When I set "Number of shells" to 0, the model prints properly. When "number of shells" is set to 1, I get the (to me) unexpected behavior that I described.

So now I have kicked the can down the road. The model is fine, but the slicer settings are not understood by me.

BTW - this was all part of a minor effort on my part to make a bit of reusable code for my own use.

What Slicer are you using? Are you using Slic3r ? If so... It won't be hard to get it setup to slice this correctly. I thought you were having a problem getting OpenScad to render it correctly. If you are using Cura, somebody else will have to jump in.

Sorry I was not clear on the source of the problem. Since I had luck printing some objects, I leapt to the conclusion that OpenSCAD was the issue.

I am using ReplicatorG. I have (just now) successfully pronted the design, but I had to set the number of shells to 0 - guess I am not understanding that part. Is Slic3r the "go to" program for slicing? Seems like there are a zillion programs available - not sure I have any idea how to choose between them.

I don't know what setting the number of shells to 0 does in Replicator-G. My guess is that tells Replicator-G to do what ever it thinks makes sense. In Slic3r (if I understand what a 'shell' is in Replicator-G) the equivalent term would be perimeter. You can set how many layers the perimeter has.

For people that use OpenScad, Slic3r is the usual slicer. But it depends a lot on where your head is at. I don't use it, but the people I interact with feel Replicator-G has fallen behind. The last release was over 2 years ago. If you are willing to switch to Slic3r and PronterFace, I think you will find more people to help you in the forums and probably, you won't need much help because both of those tools are pretty good.

Quote:

---

Originally Posted by curious aardvark

that's all it does ?

Bloody hell lol
I could do that in about 10 lines and no modules and make it parametric. I guess there are some advantages to keeping it simple after all :-)

And if that's the model - then yep - it's your slicer that's causing the issues. that's a pretty basic model and can't see openscad having any problems with that.

---

Just for kicks.... Without deleting white space... 4 Lines !

difference() {
cylinder(r=10, h=10);
cylinder(r=8,h=10); }
for(i=[1:1:8]) rotate([0,0,i*45]) cube([9,.5,10]);


Attachment 5720

Hmmm. Aren't your reinforcing fins offset from one another? And in my defense - the original code does not have that many more active lines, but I clearly can reduce the number a bit. Sure I will get better as I learn more. Off to go look at Slic3r...

I don't know... I'm not a Mechanical Engineer. But it would seem having the extra material at the center would make the reinforcement stronger. But if you want it to look more like intersecting planes... This will do it:

difference() {
cylinder(r=10, h=10);
cylinder(r=8,h=10); }
for(i=[1:1:8]) rotate([0,0,i*45]) translate([0,-.25,0]) cube([9,.5,10]);

Attachment 5721

If you want it the same as what your code did... Without being symmetrical, you can do this:


Attachment 5722

Bur really.... What you were doing with the module definitions is the right way to do it. I was just messing around because of the "I could do it in 10 lines" comment. I certainly am not taking any shots at your code!

A similiar thing - but fully parametric.
And if you don't count the variables - it's five lines of actual instructions :-) Like I said - keep it simple.
If you're wondering about the half mm translate on the cylinder you remove to make the actual cylinder hollow. It's just there so you don't have to hit f6 to see everything without the horrible green shading in.

Quote:

---

$fn=100;
cd=20; // cylinder diameter
wt=1; // cylinder wall thickness
ch=50; //cylinder height
nr=3; // number of reinforcements
tr=1; // thickness of reinforcements

difference() {
cylinder(d=cd,h=ch);
translate([0,0,-0.5]) cylinder(d=cd-wt*2, h=ch+1);
}

for (i=[1:nr]){

translate([0,0,ch/2]) rotate([0,0,(360/nr)*i]) cube([cd,tr,ch],center=true);
}

---

Just change numbers at top and hit f5 :-)

And yes there are lots of programs - but you can only use rep-g (don't , just don't !) Makerwre desktop - way way better than rep g. And simplify3d - costs money but is worth it long term.
This is because you have a makerbot clone with a mightyboard. And those are the only out of the box compatible programs available.

I would suggest using makerware desktop. But not the one you download from makerbot. You want version 2.4

There is a thread in the flashforge forum with it available for download.

Quote:

---

Originally Posted by curious aardvark

A similiar thing - but fully parametric.
And if you don't count the variables - it's five lines of actual instructions :-) Like I said - keep it simple.
If you're wondering about the half mm translate on the cylinder you remove to make the actual cylinder hollow. It's just there so you don't have to hit f6 to see everything without the horrible green shading in.



Just change numbers at top and hit f5 :-)

And yes there are lots of programs - but you can only use rep-g (don't , just don't !) Makerwre desktop - way way better than rep g. And simplify3d - costs money but is worth it long term.
This is because you have a makerbot clone with a mightyboard. And those are the only out of the box compatible programs available.

I would suggest using makerware desktop. But not the one you download from makerbot. You want version 2.4

There is a thread in the flashforge forum with it available for download.

---

Thanks for the advice ( and the code). My end game here is that I am writing some code for kids to use to design and print up some rocket components. Thought I would get a few of the basic bits coded up for them as simple examples of how to do things. I am placing a premium on readability so that they can easily follow the logic of what is happening. Sometimes makes for verbose code, but hopefully makes things easier to get them going. Need to keep the frustration level to a minimum.