Ugly top layer on round objects

[Nicolinux 288]

Hi,

Do you have some advice on how to improve the top layer quality? For this object the nozzle drags filament strands upwards when it finishes the objects which results in an ugly top layer:

 

This same objects (printed some time ago) does not feature the same problems. Sadly I forgot to write down the print settings :/

Thanks.

 

[Nicolinux 288]

Print settings:

 

• layer height: 0.1
  
• shell: 0.8
  
• retraction: on
  
• bottom/top: 1.2
  
• fill: 0
  
• speed: 30
  
• temperature: 230
  
• combing: on
  

 

[mnis 11]

 

Sorry Nico,

But you print extremely hot, and too slow for the selected temperature.

Or do you do first experiments with ABS?

Or allow the material chosen by you no lower temperatures?

Experiments at the selected speed, with temperatures well below 200 degrees to print.

To me it looked as if your layer thickness well above 0.1mm.

Markus

[Nicolinux 288]

Hey thanks. I got used to print at 230° on the UM2 so much that I forgot to lower the temperature for slow prints. Will try again at 190°-200°.

 

[illuminarti 18]

There's absolutely nothing wrong with printing that at 230, in my opinion. All of my best prints were are 230 and 30mm/s. I might consider printing two at once to avoid printing quite so slowly... but mostly the issue with the stringing at the end just comes down to the end gcode that the printer is running automatically, and how it's handling moving away and retracting at the end.

Won't it clean up simply with a sharp knife at the end?

 

[Nicolinux 288]

Ok. I am using the standard gcode for the UM2. Didn't touch anything (now with UltiGcode I understand that you don't have custom gcode at the start/end).

Cleaning with a knife helps of course, but it still leaves visible artifacts. Most filament colors are brighter when cut/roughed.

I still wonder how the heck I printed the orange turtle (and I didn't print two at once)

 

[mnis 11]

Why then see the surfaces look as sausages have been printed?

So ugly surfaces I have only to highly selected print temperature, in combination with a very low speed, seen, or for very thick layers.

One can recognize each strand at a great distance.

If I want to have such objects, then I try it with a Doodle ...

Well, maybe you have just a very good camera Nico.

But you can find it out for sure by trial and error.

Edit: Aside from the obvious wrong choice of filament diameter, with you, I get the best results at low temperatures in combination with slow print speed, and not the other way around. Point ...

Markus

[Nicolinux 288]

Lol, nice comparisoin. I don't know. Maybe it overextrudes because I didn't care to set the filament diameter correctly. I set it at 2.9mm because most filament I own has a diameter around 2.83mm - 2.94mm.

But I'd be very glad for any tips for improvement.

Here is the Cura profile string for that object (Cura 14.02 I think).

 

;CURA_PROFILE_STRING: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

 

[illuminarti 18]

Allowing a longer layer cooling time would probably help with general over-extrusion; but that might slow the head excessively and cause its own problems. Certainly a lower print temp might be an option, to a point, but I wouldn't go 'well below 200'. Since Markus has a different extruder motor, I'm really not sure his experiences can be generalized at all.

Printing multiples would probably help overall print quality. I think the bit at the end is just down to the firmware... I'm not sure there's a lot you can do about it - I think that the end-of-print routine just isn't very good.

Mineral oil (or baby oil) is good for restoring color to PLA after clean-up/sanding.

 

[mnis 11]

Even with the old extruder motor I got generally better results at lower temperatures. In many details, it is then also for each clearly visible.

Course you have to grope only once every filament species, this fact can not be changed.

And yes, the default engine, it has securely issuing severe constant material at low temperature. This does not mean the high print temperatures are generally a good choice. This focuses more on problems from the machine to avoid.

Not for nothing allowed PLA temperatures of 190-260 degrees.

I also noticed that some PLA grades, lose some of their natural luster with very high print temperatures.

But of course I'm no expert and still have to learn a lot more.

Markus

[mnis 11]

Experiments with each new material to print a small and finely detailed object.

Change your settings for each object always slightly and make you notes.

You'll find out what settings provide the best possible results very quickly.

And you will, by the way, find out the limits of your machine.

Exactly as you have once advised me there.

[Nicolinux 288]

Hehe, should follow my own advice then. I am still thinking about the perfect object to test new filament. Ideally it should be quick to print, don't waste much filament and test many cases.

 

[mnis 11]

You'll already determined somehow manage. :cool:

But anyway, I have told you that I have learned from your words to me something very important. :mrgreen:

Edit:

I think the "Ulti-Robot" and the "tetra-Wire" are quite useful objects. They are relatively quickly generated and printed. Using these objects can be very good most of the impacts of setting changes seen. Shrinkage, overhangs, temperature, speed, precision, and overall quality of materials, can be quite well read here.

Markus

[gr5 2,172]

This problem on the top of the turtle is very common and also occurrs on the robot antennas. It's because the head is making tiny circles and the PLA doesn't get a chance to freeze and it is like stirring soup on the top layers.

The 2 most commonly used fixes are:

1) cool head lift

2) print 2 of them

I did cool head lift on a print today - sometimes it works well - sometimes not so well. Today results were in betwen - got 2 strings going - well diagonally up, lol. While cooling the head kept extruding a tiny .4mm diameter drop. Very slowly - it took 5 seconds to get to full size drop.

If it were me I would print a 5mm diameter cylinder next to the turtle that is 2 layers taller than the turtle. That will move the head away while it prints the cylinder. Cool head lift tends to cause more stringing. Also I would lower the temp to 210 to reduce stringing between turtle and cylinder and print at 30mm/sec if I wanted really nice quality.

 

[mnis 11]

In addition, it can be said that higher temperatures have visible effect on the object quality. Existing problems in the production process are mostly not better with increasing temperature.

Unfortunately, there is no ultimate recipe for various PLA variants, each material must be tested in advance if a particular object quality to be achieved.

Different printing temperatures may material can appear darker and brighter. I can not currently say whether materials are generally darker with increasing temperature, because I mean it to have already experienced differently.

These small examples show that higher temperatures are changing Quality of color and gloss, as well as general object-quality. There were only changed temperatures, and no further adjustments.

To this material, I can then make the following statement:

The surfaces feel most smoothly when it is processed above 190 degrees and below 210 degrees.

 

Markus

[celso-santos 11]

Hi Nicolinux

The problem with the finishing of the top of your turtle has nothing to do with the printing method, temperature or the machine. Your turtle 3D drawing must have on the top what we call a degenerative point. If you add a bunch of U and V isolines to the surface of your 3d drawing, you will easily observe that all converge to one point.

When any CNC machine tries to produce this surface it usually makes a mess in the final point due to the poor geometry that produced it.

There are some different methods to create domed surfaces to avoid this problem.

Celso

 

[Nicolinux 288]

Hi Celso,

Thanks for the hint. The thing is, I printed the very same model and it didn't happen so I assume it has something to do with the printing technique.

 

[m3dical 0]

Did you maybe change the minimal layer time? This slows down your print speed on parts of the model with small cross sections (like the top of a dome).

It might heat up the plastic too much creating the defects you describe.

[Nicolinux 288]

I didn't change it - left it at 5s. But this setting is problematic anyway. If the minimal layer time is too low, then layers on small objects don't have enough time to cool down. If it is too high, then on the last layer the nozzle spends too much time and the layer is messed up.

Kind of a chicken egg problem.

 

[Dim3nsioneer 557]

Just fry the egg and the chicken together in a pan... :wink:

What about the cool head lift feature? It gives you a short contact time but enough layer time...

 

[peggyb 170]

the cool head lift works very well for thin pointed objects.

Here an exemple: with and without the setting

 

[Nicolinux 288]

Cool head lift ist great but I wish I could activate it only for the last few layers. Otherwise when the head moves away, it oozes a bit and when it comes back it leaves the excess filament on the model. Doing so for couple of layers adds ugly artefacts at the top.

 

[Dim3nsioneer 557]

Cool head lift ist great but I wish I could activate it only for the last few layers. Otherwise when the head moves away, it oozes a bit and when it comes back it leaves the excess filament on the model. Doing so for couple of layers adds ugly artefacts at the top.

 

You could write the CoolHeadLift plugin which is activated at a certain height or layer number...

 

[Nicolinux 288]

You know what? Maybe I will. If time permits and if I start to dig Python (or I copy&paste&modify your plugin )