Best settings for smooth bottom layer (like in UM2 examples from SD Card)

[netsrac 4]

Hi,

the SD Card that came with my UM2 had some really nice samples files included. All those prints (e.g. the Coffin's Cube) produce a really fine bottom layer. They look smooth from all sides!

I try to reproduce the same: Doing some prints always have a bulk bottom layer where you can see the big lines from the filament.

In Cura you have the options to import the printer settings from the gcode. Unfortunately this does not work for any gcode file that Ultimaker has provides.

So can somebody tell me how to change the settings here.

Speed it not important at all....it's all about the quality :-)

Thanks. Netsrac

 

[Daid 295]

Actually, those files are just printed with the default normal profile settings...

 

[netsrac 4]

You mean "Reset Profile to Default" in Cura should do the trick?

 

[netsrac 4]

Tried is and the default settings definitely do not produce the same smooth prints than the supplied sample files does.

If you take the "Coffin's Cube" as a sample - prints from the SD card are close to perfect...if you load the STL files and create the GCode yourself with the default settings in Cura the result is not quite as good....

So Ultimaker must have done some kind of tweaking to the GCode they supplied with the sample files.

Any way to read out the settings (like initial layer and stuff) from a GCode file?

 

[IRobertI 438]

Have you tried lowering the height of the first layer to 0.2mm? (0.1mm is also possible but it requires a perfect bed level) I no longer have the files that came with the printer so I can't check what the initial layer height is on those.

 

[gr5 1,270]

The gcode is quite readable with a little practice.

A few settings are sometimes included in comments at the top.

Pay particular attention to "Z" so search the file for "Z" and then also look for feedrates or "F" commands. These are 60X larger because they are in mm/minute, not mm/sec. So F1800 means 30mm/sec. F6000 is 100mm/sec. Also look at temperatures.

Also look at temperatures of both bed and nozzle. They might not be mentioned at all in the gcode. By default Cura creates "ultigcode" mode files for UM2 which lets the UM2 decide. But the coffin cube may have been sliced in normal "reprap" mode which specifies bed temperature and nozzle temperature.

To get a perfect bottom it helps to print hotter, and to have the heated bed at a higher temp. 60C should be plenty warm - I would print the first layer nice and hot at 230 or even 240C and print it extra slow - 30mm/sec maximum. This allows the filament to flow into cracks better and get a smooth bottom.

Also you want your levelling high enough such that the bottom layer is squished flat a bit but not so high that the extruder skips backwards. Levelling has to be more prefect than normal for a perfect bottom layer.

Also disable combing maybe as that can cause the head to make a diagonal pass through your perfect bottom layer and make a line in it during the travel move - instead it's better to have it retract. Although for the coffin cube there probably isn't much of this kind of movement. I usually leave combing on.

 

[gr5 1,270]

gcodes for Marlin (and a few other firmwares)

great reference:

http://reprap.org/wiki/G-code

scroll way down to the gcodes on this page:

https://github.com/ErikZalm/Marlin/

 

 

[Daid 295]

So Ultimaker must have done some kind of tweaking to the GCode they supplied with the sample files.

 

*wave* *wave* I generated those files, so I'm pretty confident in what I did... and I was way too busy at that point to tweak files.

Now, they where generated with an older and testing version of Cura. So maybe something changed unintentionally.

Can you show some photos? That might help.

 

[netsrac 4]

Hi Daid,

here is a good sample:

That's one part of the Coffin's Cube and a Nut I had loaded into Cura and generated the GCode myself with the default settings.

So any ideas what goes wrong here?

My settings: UM2 set to default PLA settings and Cura "Reset Profile to Default". Glas bed was cleaned and a little glue stick applied.

So I'm still a bit lost...

 

[gr5 1,270]

Very strange. Please post *all* your settings. Do "file" "save profile..." and then post the whole thing please! I'm thinking you might have chosen reprap machine and have some bad gcodes in there. It really looks like some kind of levelling issue. Or maybe your first layer height is too thick (.5mm?).

 

[netsrac 4]

Guys, I guess I found the problem - I did a nozzle clean and all seams to be good now.

The fun thing is, that this only affected the first layer(s). I guess once the nozzle was heated up for a while, it was flowing perfectly.

Not sure why the nozzle got stuck after only a few prints with the original Ultimaker filament.

But anyhow...thanks for all your support. This really helped me a lot.

Netsrac

 

[gr5 1,270]

The black feeder on the back of your machine is made of ABS plastic. If you look at the entrance hole carefully you will see it is getting ground up (UM has some fixes for this planned). This means tiny bits of black ABS is flowing up through your bowden along with the filament and gets embedded into your prints, or worse, gets stuck in the nozzle as ABS flows better at 250C - not so good at 210C. If it is stuck in the nozzle for hours, the cooking converts the ABS into some other chemical that is like solid glue.

Conisder keeping your filament on the floor to reduce this abrasion until UM comes out with a new feeder design: