Printing with no infill.

[Tilleen 0]

Hello.

 

I am new to using cura and 3d printing in general, and I was looking through the animation that the happens in the layers view. Does this animation actually interpret the g-code, so what it does is what the printer would do?

 

The reason I ask is because with a simple model I was making which is about 5mm think and about 100 mm square, and has a lower region at about 2.5 mm thing in the middle. With no infill, the animation shows it building up the bottom layers and then the just the edges, and when it gets to the about 4 slices below the lower region it starts doing the bottom of the this region. Which makes sense except for the fact that it draws this region in the middle of no where and I can not imagine that it will work if printed on a real printer.

 

Shouldn't it realize that there will be this floating area and make supports for it?

 

Thanks,

Tilleen.

[gr5 2,234]

Could you post a photo of what you are talking about.  It's really not clear.  Parts have such an amazing variety of shapes and trying to use words to describe your part is probably futile unless you write for many pages.  But if you write for many pages then likely no one will read it (sorry!).

 

Also are you getting infill and support confused?  Infill is inside your part.  support is in areas where your part isn't.  

[Tilleen 0]

This is an example of what I mean, this is just a square box, and it has started to draw the lower indented top.

 

If you look at this picture, you can see that the yellow first layer top is floating, with 0 infill. I would have thought that the program would be smart enough to not allow this, or to work out that it needs a support structure under the indented top.

 

It is possible that there is something I am missing.

 

There are a few other situations that similar things can happen.

 

Tilleen.

[peggyb 171]

what you ask is what you get... nothing underneath... did you try the infill? Default is 20%, enough to support a flat area. 

[Tilleen 0]

Yes, I tried the infill, I am just trying to work out what is possible. I would have thought that there would be an option for supporting infill, or something. This means that I would have to put infill everywhere, in a print that does not need it just to support it that area.

 

It is just another feature that would be nice to have, and would help stop people from trying to print something that is not possible.

 

[peggyb 171]

but is your lower region not connected to the outside?

because then you have the same problem when the top layers are laid down.

you can experiment with the % of the infill, sometimes 5% is enough to keep everything in place.

[Tilleen 0]

I am expecting the top layers to be able to work because they are a bridge, from the outer edges, it may be too far, and I would have to put in infill anyway. I have not printed anything yet, I am currently getting a feel of the software. There are a lot of options, and could have missed something.

[burtoogle 516]

Hi, I am struggling to understand the problem (duh!), could you please post an image showing the solid view rather than the layer view. Thanks.

[Tilleen 0]

Here is the solid view. I think with no infill this is not possible, but I may be missing something.

[peggyb 171]

it is possible to place some support underneath manually, this is done with 'infill support'

make a box the same size as the space underneath your indent to the bottom and import it in Cura. You can also import a cube and scale it in Cura.

In the preferences untick 'keep models apart'

Select the box and use the 'per model settings' (on the left of your screen and select the settings for this box: infill mesh, infill count, wall line count and top/bottom thickness.

Set the infill density for your support and set the wall/top/bottom to 0

 

 

[burtoogle 516]

Yes, without infill it is not possible. You could use quite low infill density and increase the number of top layers and still achieve a good top surface finish.

[peggyb 171]

here is a tutorial about infill mesh

 

[gr5 2,234]

Peggy's answer is the best - you can put infill only where you need it as shown in the above video.  But alternatively there is a feature called "gradual infill steps" in the infill settings.  It will use very sparse infill until you start to get close to this region you care about and gradually increase the infill density but only under this "inset".  And then again it will increase the infill density under the top of the part.

[Tilleen 0]

Thank you for the suggestions, and the link to Tutorial.

 

Yes, I have been playing with "gradual infill steps" as well, looks good, although it looked to me as if some of the steps did no look possible, but I have not tried it on a real print, so I could be completely wrong.

Edited January 21, 2018 by Tilleen

[peggyb 171]

yes, it is good to have the preview in Cura and the calculated time and material to experiment with. Sometimes you think it can that it can do better but the alternative turns out to have a longer print time or uses more material. And there is reality, like you said, bridging can be surprisingly good depending on a lot of things, same for the gradual infill, it will drop, but who cares, you can't see it. Never tried spaghetti infill yet, can imagine what it does but the preview looks weird..

Hope you can print soon and ask again if you want to know something...

 

[IRobertI 521]

I think the closest setting that would be helpful in this sort of situation is "Hollow out object" which will make the object hollow so you can use support on the inside. For this particular model I don't think it would do much good though. But I thought I'd mention it anyways.

[Tilleen 0]

On 1/22/2018 at 6:45 PM, peggyb said:

. And there is reality, like you said, bridging can be surprisingly good depending on a lot of things, same for the gradual infill, it will drop, but who cares, you can't see it.

The problem with it dropping  is that it is used as a support for the top layers, I did a demo of a different object and it produced a line that when out about a centimetre in to the with no support at the end and then subsequent layers built on top of that, but since it would not work all the layers above would fail and the whole gradual infill would then fail. Gradual infill or any other slicer created structure should never create impossible to print lines. I understand that this may actually be impossible, and that gradual infill is relatively new, so I expect that it will be getting better over time.