Cura Setting Suggestions

[mark10970 0]

Hello all,

Can someone make Cura setting suggestions for the following "object". It is a rectangular box with walls 1.5mm thick on two sides and 2.0mm thick on the other two. The center of the rectangle is empty and there is no top or bottom. Just 4 thin vertical PLA walls.

I want to use .2mm layers. I am using the stock .4mm nozzle. Can someone suggest settings for Wall Thickness, Bottom/Top thickness, Fill Density, and Infill Overlap. I am using version 13.04 because I need to control some things that are only available in this version.

Thank you.

Mark

 

[illuminarti 18]

I'd probably start just setting it to 0.4mm wall thickness, and whatever fill density seems best for you application, depending on how much tolerance you have for empty space between the inner and outer shells.

For top and bottom thickness, if you want the tops of these thin walls to be totally filled in, then I'd set the thickness to be a few times that layer thickness. Since the distances to bridge are so small, probably just two or three times the layer thickness would be enough.

Infill overlap is generally set at 15%, although the new slicer engine does things differently, and it's possible that you'll get some marking of the outer surface with a 15% overlap - so you might want to try it and see.

Another approach might be to set your nozzle size to 0.5mm and wall thickness to 1mm. That would give you exactly three or four 'nozzle widths' around the perimeter then. And so you might get more concentric walls, and less diagonal zig zag infill. But you'd need to try slicing it and see how it behaves. I'd assume that the 2mm walls would print with 4 passes along the wall, while the thinner walls would get a 0.5mm bead along each side and I'm not sure how it will fill the remaining 0.5mm in between - try it and see what happens.

The main thing to remember is going to be to set your minimum layer time to at least 7 seconds, so the plastic has time to cool between layers, otherwise it will start to sag.

 

[mark10970 0]

 

Thank you, Illuminarti. I've used settings similar to your first suggestion, but get consistant artifacts like this

 

The outer covering is very thin and actually peels off easily. Is this due to infill overlap problems? These artifacts are consistant from print to print.

 

Mark

 

 

[illuminarti 18]

That's really weird. It might be due to the infill overlap, yes. Or else the head is traveling along the very thin walls, and oozing over the finished surface - from that photo it looks more like a fluff that has somehow gotten attached to the finished wall, than the actual finished surface. The wall behind the loose stuff looks like the intended finished surface - and looks to be pretty good from what I can see of it.

Can you post the gcode for something that prints like this, so that I can take a look at it?

 

[gr5 2,172]

That's the infill pattern sticking through the wall (I'm pretty sure but could be wrong). You can confirm by checking before the top layer is printed.

You could set overlap to around -15% or I would turn it off (set infill to 0) and infill using "shell" only as Illuminarti kind of suggested. Or see if you can get cura 13.03.X (or older) which doesn't overlap the infill quite so badly.

I would try Illuminarti's suggestion of lying to cura and telling it your head size is .5 with shell thickness 1.0 (you can set shell thickness to 100mm if you want and it will stop making shell when it meets in the middle). See what it looks like in gcode.

 

[cesar-rodriguez 0]

Suddenly my Ultimaker 1 started to print weak walls. After analyzing the object I noticed there is a small space within walls (2 shells or 0.8 mm). This space makes the walls breakable with a simple squeeze. Any solution to this?

 

By the way. I have change nothing in Cura (not a single parameter). The only thing I thing I remember doing to my U1 is giving maintenance to the extruder (which I have done before with no problems at all).

 

[gr5 2,172]

You have some play (also known as backlash). This commonly creates a gap between walls. It also creates the pattern I see on the top (bottom?) of your part where there are two diagonal lines close together and then a gap. More on how play creates that pattern here:

See both post #7 (click on picture and read text) and post #8 (explains it) in this thread:

http://umforum.ultimaker.com/index.php?/topic/1872-some-calibration-photographs/?p=14396

So how to figure out where the play is? It's usually in the short belt but in your case it might be in the head itself. Turn off the printer and hold the long belts for X and Y axis still and then push the nozzle around - see if it is loose. Then repeat for the other axis. If it seems tight then you need to instead concentrate on the belts. Could be long belts but it is almost always the short belts.

 

[gr5 2,172]

Oh also (but very rare) sometimes you get play from very high friction in X and/or Y axes.