How to print non-watertight models / 0mm walls?

[Torgeir 243]

Hi @JaXXoN

 

I'll say this is the biggest printer I've seen in here -covering one cubic meter.. 👍 Self built?  🙂

 

The sphere you have here is a small and high resolution object (20X20X20)mm "approx". So printing this one with 0.2 mm layer height (0.4 mm nozzle) is not easy.  Building up a single sphere model will always end up with a hole in the top, the only way to make this possible without a hole is just like you have done it.

To keep the outside sphere, we'll gradually from inside (at app 75-85 deg) above/below and ofc. done when drawing the model.

 

I've imported your project file into "Cura "Arachne Engine Beta" as this is the best slicer for such models IMO.

 

The first picture is just with your original settings and here it is looking pretty much as in Cura 4.10.0 seen here;

All pictures from above, where you can see the settings and the changes.

 

 

Here are picture no 2, one change selected "Use Adaptive Layers";

Here the effect is seen, but some limited..

 

In this third picture I've reduced layer height from 0.2 mm to 0.1 mm ;

Here you'll see a drastic "improvement", but the last part is a problem as the nozzle stay close for "some" time..

 

This last picture, just changed another parameter line width to 0.55 mm, kind of extreme but you can see this difference.

By using Post processing script controlling those last layers temperature toward the top may be worth the effort.;

 

Thanks

Torgeir

 

 

[JaXXoN 0]

Hi Torgeir,

 

Thanks very much for your detailed answer. Highly appreciate it!

 

I'd like to avoid 0.1mm height or otherwise printing the model will take ages (it already does with 0.2mm).

 

For fixing the hole on the top, I can add another overlay. Please see attached screenshot and Cura project file (don't worry about overhangs/support, that's a separate issue I can tackle).

 

My concern is that there is no smooth transition between the surface mode area and the overlay areas (please see other attached screenshot)

 

Feedback is highly appreciated!

 

TIA and best regards

 

Bernhard

 

 

PS.: The Airframe I intend to print has a length of around 90 cm and a wingspan of of around 90 cm. So just to get a felling on how things will print (flat/upright) I simply created 1x1x1m printer for early inspection 🙂

I certainly need to cut the airframe in pieces for printing on my CR10S4 - and that's what most of the fuzz is about: simply exporting cut parts of the model will introduce additional walls I don't want. Surface mode helps in this respect, but obviously introduces new challanges ...

 

 

SphereWith2HolesBottomAndTop.3mf

Edited July 27, 2021 by JaXXoN
Removed inline-images because they somehow messed up the formatting

[Torgeir 243]

@JaXXoN

 

Hi Bernard.

 

There was a problem with Cura detecting the inner wall.

So I made this sphere in Fusion 360 (Autocad free version) Just 20 mm diameter and strait hole dia. 8 mm.

The wall gradually increased from approx 70 deg. (0.4 mm to top 0.8 mm) and same at the bottom.

Seems to be possible to print, but not sure how it will be.

Here is a picture how it's looking in Cura Arachne Beta.

 

 

Here's the your project file from Cura Arachne Beta;

CFFFP_Sphere_Exp_Arachne_B_0_2mm.3mf

And the gcode, but have not checked this one..

CFFFP_Sphere_Exp_Arachne_B_0_2mm.gcode

 

Torgeir

[JaXXoN 0]

Hi Torgeir,

 

thanks for your hard work - that looks great, in deed! Now I just need to reproduce that over here, somehow 🙂

 

By chance, do you got any hints why Cura detects the surfaces properly when the Sphere is created with Fusion360 but not with MoI3D?

 

Anyway, I guess I need the Arachne Beta slicer - with stock Cura 4.10.0 I get the result as seen in the attached screenshot when opening and slicing your 3mf.

 

best regards

 

Bernhard

 

 

[JaXXoN 0]

 

BTW, what works for me is splitting the sphere in three parts: the bottom part is printed in normal mode with a bottom thickness of 0.8 mm applied, the middle part is printed in surface mode and the top part is again printed in normal mode with top thickness 0.8mm. The top and bottom part have +0.2mm horizontal expansion to compensate the thickness of the surface wall.

 

However, this is a pretty crude method- I'd certainly prefer Torgeir's method where you don't need to split the model.

 

SphereWith2HolesSplitParts.3mf

[Torgeir 243]

@JaXXoN

 

Hi Bernard.

 

I know Fusion 360, Autocad variants and SolidWorks plus some more..

However, this is the first time I've heard about MoI3D. Have seen over the years that some of the CAD software had some problems with not snap lines properly together, resulting in line offset etc.

Those small deviations might be hard to see, -normally, but for our drawn 3D objects this might cause problems.

 

Fusion 360 from Autocad, is free to use for hobbyist use, but you can only save 10 3D files! So if you want to still use it, -you can and you can make a stl file of the drawn object, but you can't save your drawing!

 

However, several in here use/have FreeCad and so do I, but I have not used it much to be honest.

But people in here say FreeCad is a good alternative to make good drawing for Cura to slice..

 

I may try to print this file, but at the moment too busy with other stuff. 🙂

 

Good luck

Cheers

Torgeir

Edited July 29, 2021 by Torgeir
Text error.

[JaXXoN 0]

Hi Torgeir,

 

Thanks for your feedback!

 

I was able to reproduce your results using Arachne Beta. I noticed that your Fusion360 sphere model has a wall thickness (shell operation applied?) and is printed in normal mode (not surface mode). In contrast to Cura 4.10.0, no "print-head dance" (as described, earlier) happens. That's even true when I create the sphere with 0.44 mm wall/shell with Moi3D. So it appears that stock Cura 4.10.0 can't handle "walled/shelled" models very well.

 

Now, I only need to figure out how to get MoI3D do the shell operation properly for more intrinsic objects - I observed that the SubD operation doesn't create enough control points under certain operations, causing varying wall sizes. I'll take this to the MoI3D forum 🙂

 

Nevertheless, I think the surface mode will also be very helpful for certain parts. In worst case, I can mix modes with separate models as described, above.

 

Thanks again and best regards

 

Bernhard