No infill means NO INFILL !

[baymaker 1]

Hi everyone,

I'm still new to the forum so if this is an already treated issue I apologize, but I couldn't find any answer on my own.

What I'm trying to do is to print a 0,8 thick vase, and as I want a pretty "fast" print and don't need that much strenght to it, I want it to be only two perimeters.

Unfortunately, when I set 0,8 as my shell thickness for my 0,8mm thick model, Cura adds some infill every now and then, on some very small spot.

From what I've been able to understand so far, this is caused by Cura addind extra infill when it feels it's needed because of the slope or the geometry.

However, I'm pretty sure this should print just fine, having printed it on much worse printer than my UM2 without any trouble ... (or at least non related to the lack of infill)

Slic3r is able to slice my model the way I want to, unfortunately I haven't yet found a way to make Slic3r's Gcode readable by the UM (if you have any tips, they are much appreciated => http://umforum.ultimaker.com/index.php?/topic/9479-using-slic3r-on-um2/ )

I've tried with a larger width, staying with multiples of 0,4 so that the "extra infill" Cura adds could be replaced by an extra line of perimeter, but no matter what, I still get some "random" infill ...

So, to sum this up, my question is : Is there any way to set Cura to something like " no infill no matter what " ? I know the spiralize option could probably work, but I'd like to have at least 2 perimeters for minimal strenght and to have it (I hope) a bit waterproof ....

Thanks in advance for any help, as this is for me pretty much the only setting (with the "infill every N layer" and "randomize starting point") that is missing from Cura ... at least for now.

Max.

 

[izzy 33]

Hi max, it could be that the thickness in some parts is over 0.8mm thick, 2 runs of a 0.4mm nozzle, and so adds some infill. Or it could be a problem with the version of Cura you may be using, I have a thin part and it's not putting infill where I want it, and I don't want to print 100% fill.

[pm_dude 27]

Hi Max,

Welcome to the forum.

So the infill added here are there are the additional fill required to get the good shell thickness. The shell thickness of 0.8mm on the z axis doesn't mean it is in diagonal. The more incline you get the more it will test the value for top/bottom shell thickness. If you dont want that you can uncheck the fill bottom and fill top but that will make your object open at the base and at the top which is probably what you dont want.

Then problem is that we cannot really tell Cura that you want a top/bottom shell where there is a top or bottom but not where there are curves. That is kind of counter intuitive for a software. You can try to make the shell thicker and the top/bottom shell thinner but then you will run into other problems.

You can use the SwapAtZ plugin if you are used to playing with plugins:

http://umforum.ultimaker.com/index.php?/topic/7290-new-plugin-swap-at-height/

I will allow you to slice once with given settings, then slice again with another set of settings and mix the results using the plugin.

I hope this help.

PM

 

[dirkdirk 5]

You can also try to hollow out the model with 0.8mm wall thickness in meshmixer. maybe this is exactly and will help for only 2 perimeters.

[Anders Olsson 136]

I think the problem is partly in the conversion from CAD to STL-file.

You loose resolution as you end up with a number of flat surfaces instead of one curved surface.

Cura interprets this as a large number of straight sections with varying wall thickness.

Due to the loss in resolution in the STL-conversion wall ends up a bit thicker than 0.8 mm every now and then.

The easy way to fix this is to design a solid vase instead and use Cura to create the walls.

Just load your solid vase in Cura, select 0.8 mm wall thickness, 0% infill and uncheck the "Solid infill top" under the "..."-button.

 

[pm_dude 27]

without a picture its hard to know what you are after but at least you have a couple of solutions ahead

 

[visu-al 2]

As Anders Olsson said: Cura can only print nice perimeters if you take a solid object and tell 0% infill and no top fill (if its a vase)

Then it only prints exactly 2 lines if set to 0.8 shell ..

 

[baymaker 1]

Wow, so many answers in such small time : SWEET ! Thanks to everyone one who contributed !

I did made the vase full and then hollowed it with a 0,8 shell (in SW, not meshmixer, but I'm guessing it's not much of a difference .. Or is it because Meshmixer would apply that on the .stl, and that way loose a bit less precision ?).

However, due to the vase shape and the .stl export, it's likely that the shell turns out to be not precisely 0,8mm thick.

The "export a full close vase and print it in Cura without top" option sounded amazingly simple and efficient, however when I tried it with one of the vase, either in Cura 14.12.1 or 15, the result is the same. Actually it's a bit better than when I started from the already hollowed model (so the .stl precision loss and horizontal thickness explanation seems to be accurate), but I still get some "random" infill. What's even more surprising is that the layers areas where Cura adds some infill don't even really look to be the one that would require some extra support..

I'll try with some other vases models.

Here are a few screenshots of what I'm working on and the result I'm getting.

 

 

 

Also, as a side note, even with the already hollowed model, Slic3r slices it just fine, with 2 perimeters being 0,4 in width each (but the setting are not defined the same way. You don't select a thickness for the perimeters, but a number of lines, and you can separately set the extrusion width for perimeters, so maybe that explains it, as with these settings Slic3r doesn't really have an other option .. )

I'll run some more test and post updates if I get able to slice my model like I want to.

First, I'll focus on having the regular ones done right, but if I manage to make this work, any idea how I could do that on a model with a surface that has holes in it, so you can't export a "full model" and then just remove the top in Cura.

Basically something like that :

Thanks for the help everyone ! I heard that the UM's community was something special ... seems like I won't be disappointed !

 

[visu-al 2]

With this kind of print i prefer this way:

http://umforum.ultimaker.com/index.php?/topic/3740-challenging-ultimaker-2-prints/

 

[baymaker 1]

I checked this last link (which features some of the sickest print resolutions I've ever seen for not smoothed FDM), but except if I've missed something, I couldn't find an explanation on how to avoid the infill when Cura thinks it's needed. I'm not even sure that the prints showed at that link didn't had some infill.

As said in that post, even though most of the time Cura "auto infill" is pretty useful and not causing any trouble, in some cases it would be a sweet option to be able to either disable it or specify an angle at which it would start to create the extra infill ...

I'll run some more test, and post updates if I find a way to avoid the infill, and the extra printing time that comes with it ..

I already tried to set the walls thickness to a higher value (staying in multiples of 0,4), but no luck so far ..

 

[baymaker 1]

Tried a few more models, pretty much the same result everytime ... It doesn't even look like Cura infills for structural reason, because the layers area where it adds extra infill are not the ones needing extra support the most .. So I'm guessing it's more something about the thickness not being exactly the 0,8 (or whatever else I set it to), so it adds infill where thickness is missing ? Does that makes sense ?

Here are a few screenshots :

 

 

I have been able to get what I want using the "follow mesh" black magic option, however that way I can't have a bottom for my model, which is a bit of a problem for a vase I tried the tweak at Z plugin, however it "only" lets you select different "default" setting. Is there a way to use the "tweak at Z" and to able or disable the "follow mesh only" after a specific height ?

The perimeters only thanks to "black magic" options ... but without bottom :(

 

[pm_dude 27]

Use SwapAtZ plugin

https://www.youmagine.com/designs/swap-at-z

 

[tinkergnome 927]

...

The "export a full close vase and print it in Cura without top" option sounded amazingly simple and efficient, however when I tried it with one of the vase, either in Cura 14.12.1 or 15, the result is the same. Actually it's a bit better than when I started from the already hollowed model (so the .stl precision loss and horizontal thickness explanation seems to be accurate), but I still get some "random" infill.

...

 

Just another suggestion...:

You can try to "tweak" the value of shell thickness a bit. For example: set shell thickness to 0.79 in Cura and take a look at the layer view (a suitable value depends on the geometry).

For me - this is sometimes the easier solution.

Just to clarify: the SwapAtZ plugin is also a great improvement!

 

[baymaker 1]

I tried tweaking the shell thickness, trying almost every value 0,2 more or less from 0,8. Didn't get the result expected. It does in some cases reduce the amount of infill (I think), but doesn't remove it completely.

I've found in this topic an idea that seems to work. Disabling completely the infill for the top and bottom removes the infill and leaves me with only two perimeters ! So, if I'm not mistaken, there should be something to do with the Swap at Z plugin (sorry PM_dude, I confused your plugin with the "tweak at Z" one the first time you suggested it).

I'm running some test now, trying to combine a gcode with bottom infill checked (to get a solid bottom) and one with this unchecked (to avoid the unwanted infill).

I'm still new at using this plugin (and Cura's plugin in general), so maybe I'm doing something wrong, but I can't get the result I'm looking for right now. Or do I need to save the Gcode generated with the plugin and reload it in Cura to get an accurate layer preview ?

Here is my process at the moment :

- Generating a Gcode with the "bottom infill" checked. I've set the bottom/tom thickness to 0,8.

 

- Once generated and saved, I uncheck the "bottom infill", add the plug-in, put the path of the previously sliced one, and set the inital height for the swap at 0,8, and the top one at 150 (higher than the object top. Does it work also if I leave it to 0 to disable it ? I was a bit confused by the negative default value).

Is there some extra step required to "combine" the 2 gcodes ? Because so far, the result I get looks like I was making a new slicing without the plug-in. I'll try some more tests, as I think this is a promising path to get to the result I want, I feel like I'm getting closer, but so far no luck. This would be nice, as once the infill disabled completely, I save about 1 hour on a 3 hour print.

 

[pm_dude 27]

could be a simple matter of using the wrong values. I dont know if Cura as some limitations to using , instead of . for numbers (ie: 0.8 instead of 0,8).

The swap end is at -1 by default because its optional. If the value is smaller then the swap start it wont be used and the swap will be for the entire height left.

Make sure the path to the saved gcode is valid and is complete ex: c:\test\object.gcode

More info available on the youmagine page.

 

[baymaker 1]

YEAH !!!! Finally !

I don't really understand why sometimes Cura will only take 0,8, some other times 0.8, and sometimes won't care, but in this case, this seems to have solved it !

Maybe I was using it in "reverse", swaping the opposite way I wanted too (not sure now after that many tests), but the hotend is heating as I write this, and if everything goes as in the layer view, that should work perfectly !!

Really usefull plug-in you made there pm_dude, I'm just started using it for these vases test, but I'm slowly realising how uncredibly useful it can be ! It makes it possible to "cut" your model in different parts with it, and have specific levels of speed/layer height (or anything else !!) to fit best the geometry of the model ! Per-fect !!

 

[pm_dude 27]

Glad you made it work .

Watch it when changing speeds and layer heights. Big change in speed or layer height will affect the flow (extruded volume) and you could suffer under extrusion for a short while. Again its just a matter of balancing the differences.