bridge issue . 10x10 square test - top layer

[lemmings 0]

Hi everyone,

For a project, I will have to success a print that end with a opened square of 10x10 mm²
I can't figure out what parameters I need in order to have a not collapsing top layer that it bridging between the three wall of the openend cube.

I read a lot of tuto and played with a lot of experimental parameters (bridge : slower, cooler...) but it still dont work.

 

I'm on Cura 3.3.1 with a Anet E10
My test cube is 10x10 mm² with wall as thick as possible (0.8mm)

I guess if I could have straigth line instead of diagonal ones and if the filament would go a little on the wall instead of going back immediately, it would be great.

[Framar 38]

Can you included a support wall into your 3D design. That would be easy to remove once printed and that would cut the bridge in half,

[lemmings 0]

Thank you for your response .

I know it would 🙂. But no, I can't because it would be very difficult to remove inside the cube.

I'm not a complete beginner, but supports are still something I avoid if I can, because every time I use it, it is very difficult to remove or it is not very supporting.

Edited January 10, 2019 by lemmings

[yellowshark 153]

A few points

 

? print the top part separately and glue the two pieces together.

 

I see you have 4 layers on the bottom; can you have 4 layers on the top, or 3? If you are using 0.3 layer height then your final layer should be fine. Of course you may need to do a bit of cleaning up inside the cube, depending on what is going in the cube. The first layer will never be great.

 

Make sure your fans are running 100% to cool the bridge material as quickly as possible.

 

Print as a cold as possible, this will enhance cooling and make sure you are not over extruding

 

Reduce print speed, this will enhance cooling

 

And make sure your printer is in tip top condition.

 

I have bridged >10mm a lot in architectural prints, it is not difficult.

 

Returning to your photo - white is probably the most difficult colour, you may get instant improvement if you change that. And it is easier with high quality filament

 

I bet you are not printing as cool as you can 😎

[yellowshark 153]

… oh a quick thought, using a 0.8mm nozzle instead of a 0.4mm might help, it certainly does on curve overhangs; although possibly not on an absolute 90  degree angle, trying to get my head around that😵

[geert_2 557]

Maybe try this method for overhangs? In CAD design a custom support structure into the model, and optimise it for ease of removal.

 

In this example, all bridge pilars and plates are 1mm thick. Ribs on top of the supports are 0.5mm wide, with 1mm gaps. Gap between ribs and underside is 0.2 or 0.3mm (don't remember exactly, I use both). Horizontal connection strands are 0.5mm wide and 0.2mm high (=2 layers of 0.1mm). Long overhang is 35mm or so.

 

Print cool and slow.

 

In my designs, this is *very easy* to remove with a sharp cutter knife or scalpel.

 

The concept is based on an idea of another user (smartavionics if I remember well?) who was developing alternate supports for use in Cura.

 

Maybe you could get this done with more advanced settings in Cura too, but I am not using the latest version, so I can't tell about that.

 

 

 

 

 

 

[lemmings 0]

Thank you for all the responses. 

I soon as I come back home I will try cooler. I'm already really slow, how slow can we go?

I will try to explain my project : the opened square will be at the end of a baguette with a square section (please excuse me for my french english ^^') , with the open in his opponent direction. In it, I will plug a wood baguette with a 10*10 mm square section. So I guess it is ok if I can't remove support perfectly.

I will send screenshots when I get back Home.

[lemmings 0]

so my project is to plug this :

into this :

.One stick for each "side" 
this is not the final 3d , because I also want the two stick to have 8 degrees (they are noot parallelle)

 

One of the solution is to turn the part 90° and have the opening on top. But would take a modification of the part or a big support
One solution is to put support in the opened cube.

But one of the "simpliest" solution would be to have this :

or at least this :

instead of this :

But no one know if there is such parameters?

[Framar 38]

Can you rotate the part to have the opening on the bed? That migh improve the top bridge support.

[lemmings 0]

7 minutes ago, Framar said:

Can you rotate the part to have the opening on the bed? That migh improve the top bridge support.

If I do that, do not I have the same issue with a horizontale plan?

The only solution is to rotate with the opening on top. But it include major modification to the part.

I just tought to one more solution : print 1 more part for each extremity. I print it upside down, and I use it to close the cube ^^

the layers would be horizontal so the 2 parts will fit and stay together

 

Also I tried what was purposed to me : slower and cooler, but it was no better. kind of worst because the temperature difference between the cube and the top layer make them not attached.

 

Edited January 10, 2019 by lemmings

[geert_2 557]

Apart from all printing problems: does that model need to survive mechanical loads, after the wood stick is inserted? If yes, you would need to make the walls much thicker and stronger. Now they will break at the slightest bending of the sticks, due to the large lever.

 

If purely decorative, it might be okay of course.

 

And indeed, as said above, I would print this with the backside on the glass, and the opening on top. Then there is no top layer, thus no problem. For best layer adhesion, print slow and rather hot. If printed in PLA, layer adhesion should not be a problem (I never had any troubles). If printed in PET, switch off cooling fans.

 

[lemmings 0]

Hi,

It is PLA, and it will be some loads on it. Approximatively 5 or 6 oranges for each paires of paralele stick. I will send pictures at the end of the project if you want it.

I'm not yet sure for the thickness, I will do some tests.
For the adherence, I got for my christmas the "CCTREE 3D Printer Build Surface" It is insaly adhesive, I don't use "skirt brim raft" any more.

For my part I could put the opening on the the top.
But I'm still wondering why I can't have this : 
So I made some tests :

There is two factor here : the shell was the thing that prevent me to have the bridge over the wall instead of inside.
And the straight lines can be obtain by reducing my top layer height.

So I guess I can Close this topic.
Thank you for all those who helped me 😄