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Cura release notes and continued very bad prints.

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Posted · Cura release notes and continued very bad prints.

IRobertI,

That looks absolutely perfect! I did not ignore your print, ... I was right in the middle of writing this response to you. You responded while I was writing my response.

I got your gcode and opened it in Cura (14.09). In Cura I can only observe the model in layer mode, however I can see right away from observing the tiny blue lines, that this is exactly the way I wanted the nozzle to move. From the blue lines it is obvious that the nozzle only moves within the thickness of the wall, which is .8 mm thick, so it prints two passes side by side for each layer.

Even when I set the fill to 0 and turn spiralize on or off like others have suggested, the blue lines in layer view are still all over the place for me when I load my model in Cura. Which will result in unwanted artifacts. Your gcode has none of that.

Would you please tell me your pertinent Cura settings since I cannot see those from loading your gcode. I can only see that your layer height is .1 mm since your gcode gives me 320 layers. But I cannot see any other of your settings, like Basic, Advanced or Expert settings.

I wonder if I can achieve your same results with Cura 14.09 or if I should downgrade to 14.07. That is why I would like to know your settings, to see if I can get the same results in 14.09

Please understand that I did not ignore your print, it is beautiful and exactly what I am after. I had just not completed this longer response yet. And of course I had to download and examine your gcode first too. I also spent a bit of time loading my model and trying to get to the same looking results for the blue lines as yours. I was not able to achieve that, which is why I would like to know your settings.

 

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Posted · Cura release notes and continued very bad prints.

Ah ok, no worries. I thought it was a bit weird hehe.

You can load the settings into cura with File -> Load profile from GCode. Remember to save your own settings in case you want to return to them later via File -> Save profile

 

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Posted · Cura release notes and continued very bad prints.

I'm sorry?

gallery 35617 1088 152078

IMG 2044

And printed at 2.5 times your speed & 2x layer height just to get a quick result for you

 

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Posted · Cura release notes and continued very bad prints.

IRobertI,

When I load your settings, a weird thing happens. In Basic, shell thickness and bottom/top thickness are ,8 (comma) instead of .8 (period), but layer height say 0.1. You also seem to have no platform adhesion. Your travel speed in Advanced is also much higher at 250 than what I had at 150. Nothing seems to change in Expert config.

What temperature did you print at?

When I load my model with your settings in Cura 14.09 I still see blue lines all over the place and not at all like yours. I will try to reinstall 14.07 and see if I can get your results.

 

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Posted · Cura release notes and continued very bad prints.

shiremog,

That is a very different photo than the one you posted yesterday. Your result is definitely better than mine, and as I stated earlier, it still shows a fair amount of internal artifacts.

The kind of print I am after is like the one IRobertI showed. Obviously the hardware is capable of that. The blue lines in layer view tell the story.

 

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Posted · Cura release notes and continued very bad prints.

Same part, different angle. Remember, it was printed at 2.5x your speed & 2x your layer height.

 

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Posted · Cura release notes and continued very bad prints.

Yeah, sorry about the mix of . and , It's because I'm a Swede and over here we use the decimal point while in the US they use the period. Sometimes I use one and other times the other. Thankfully cura can handle both.

Yes, travel speed is higher, you can set it back down if you prefer.

Nope, I don't use a brim. For a print like this I feel it's rarely needed and I hate cleaning up prints when it can be avoided.

It was printed at 220C with an ancient roll of Ultimaker Silver.

I installed and tried it in 14.09 and it looks like it creates more travel moves than 14.07 with the same settings. I guess I made the right choice in staying with the old version...

 

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Posted · Cura release notes and continued very bad prints.

Nope, I don't use a brim. For a print like this I feel it's rarely needed and I hate cleaning up prints when it can be avoided.

 

Tell me about it :wink:

I reinstalled 14.07, loaded my .stl file and generated the gcode with your settings. Bingo! It showed the blue travel lines they way I wanted them, exactly as in your gcode.

I then printed the part, and the result was exactly like yours, ... and the way I intended. The only, very minor, flaw are the spots where the Z axis travels down, where you get those bumps on the surface. However, in this case these bumps are much smaller than I have ever had them. I wonder if I activate spiralize these bumps may diminish or even go away.

I printed at 190 degrees C.

This is now the very first perfect print I have made since I have had this printer, which has been almost 6 months. Thank you very much for your support. Not just IRobertI, everyone who has chimed in too.

I assume I the conclusion of this exercise is, ... Cura version 14.09 is defective.

 

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Posted · Cura release notes and continued very bad prints.

I completed my prints for this project. I am very happy with the results.

Here are a couple of photos. It is a funnel and coupler for a home made pastry bag from a large Ziploc bag. The Dutch people here may appreciate what I am making today as an appetizer for a Thanksgiving party we are going to today. Saucijzenbroodjes!

 

 

 

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Posted · Cura release notes and continued very bad prints.

You need to remember how Cura, and the modeling process works. Cura has no direct way to know that you modeled that piece with a 0.8mm wall. That info is in your original CAD file, not in the STL. All the STL has is lots of triangles that conform reasonably well to a couple of curved surfaces that may or may not be 0.8mm apart.

Cura has to take all those triangles and load up the coordinates, then intersect that with a series of planes corresponding to the layers that you are going to print. That gives a series of many sided polygons, that Cura then has to approximate down to something that it can actually print - your original STL files have many thousands of triangles around each layer - which would give an incredibly over-detailed path that the printer probably couldn't process fast enough while trying to draw a ring that is just a couple of cm across. So Cura is simplifying and approximating these many-sided polygons that correspond to the inner and outer surfaces of your funnel. And then trying to figure out how to print it. All without actually knowing anything more about it than the coordinates of a random assemblage of triangles that describe the shape it is starting with. When we as humans look at the shape, we can see that it's intended to be a tapering tube, and have your description that the wall is 0.8mm thick. Cura has none of that. Only the coordinates of the corners of 40,000 triangles that aren't even listed in any particular order.

Cura has to try to generate a tool path for the outside surface, and then another one for the inside. And then compare the two, and try to figure out if any infill is needed. Technically, you are wrong to ask for 0.8mm shell thickness in Cura - that is how thick to make both the inside, and the outside surface - and there isn't room to put two lots of 0.8mm inside a single roughly 0.8mm thick object. You would do better to just set the shell thickness to 0.4mm so you are only asking for 1 pass around the outside, and one around the inside of the shape. Rather than asking for two, and then having to have Cura decide not to do one of them.

Secondly, there are inevitably going to be some slight rounding errors that might cause Cura to get a bit confused as it tries to match up the two paths, especially as they won't exactly line up within the limits of the resolution that the STL gets mapped down to for printing. If Cura thinks there is a slight gap, it might try to fill it. Probably Cura could be smarter about this, but if you simply turn off infill, then it won't try to fill in any slight gaps that are left.

A much better approach for this kind of print would be to model the shape as a closed solid, that just defines the outside of the cone, and then print it with a 0.8mm shell, and no infill. Then you are explicitly telling Cura that you just want it to follow the outside contour of each layer, and do two concentric passes to give the desired shell thickness, rather than asking it to print an outside edge, and an inside edge, and then figure out if there is any space between those two, and to put 20% infill into any space left.

 

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Posted · Cura release notes and continued very bad prints.

As others have noted, given the small size of the object, you may also be keeping the nozzle dwelling rather too long over each layer, so it doesn't have time to cool properly. You'd probably do better to print it with a faster head speed, and print multiple copies at once, so the head can finish one layer and allow it to cool while it is printing the next copy.

 

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Posted · Cura release notes and continued very bad prints.

@illuminarti nicely explained :) expect that i tought that you also need to disable the solid top and bottom infill as well? i remember printing 0% infill vase and always forgot to disable top solid infill and then my printer bridget the top of my vase haha wich is annoying (usualy one should check layer view in cura but in that time i was more noobish then today^^)

 

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Posted · Cura release notes and continued very bad prints.

illuminarti,

Thank you for your explanation of how Cura (and probably slicers in general) interprets the multiple polygons of meshes that are STL files.

That does not explain however how IRobertI, and I after him, was able to produce a near perfect print of the part in question with a setting for shell thickness of .8 mm in Cura 14.07, and I failed to do the same in version 14.09

The blue lines of the nozzle movement tell the story.

 

A much better approach for this kind of print would be to model the shape as a closed solid, that just defines the outside of the cone, and then print it with a 0.8mm shell, and no infill. Then you are explicitly telling Cura that you just want it to follow the outside contour of each layer, and do two concentric passes to give the desired shell thickness, rather than asking it to print an outside edge, and an inside edge, and then figure out if there is any space between those two, and to put 20% infill into any space left.

 

I will try this next time I make this part, which I will have to do with slightly different dimensions. It seems counterintuitive to have to tell Cura to do it this way though as it seems a workaround for an issue that one would expect Cura and other slicers to understand, because the model the mesh was made from is a "closed solid polysurface" (Rhino lingo). I purposely chose .8 mm as the wall thickness, this being 2x the nozzle diameter, thinking that this would make things easier.

Would Expert config > Balck Magic > Spiralize the outer contour achieve the same result?

 

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