Cura 3.04 top layers problem

[dej 0]

Hi guys,

 

I'm using Cura 3.04 and I don't know why but I have a problem with my top layers. The problem is present in different objects but when i print a test rectangle i got awesome top layers. What's happening? All the objects have the same infill density witch is 10% linear. Tnx! 

 

 

BP_MAKE_Robot_V6.gcode

Edited January 8, 2018 by dej

[gr5 2,224]

It looks pretty close to normal.  Realize that in one case your rectangle has a flat top so it's all printed as a single layer making it more uniform.  whereas printing the top of a sphere requires many layers.  You can make it a little nicer by going with thinner layer height but the tradeoff is it will take longer.

[dej 0]

got it but still, i don t think it s a normal top layer in the robot case( arm level). i mean, it can be seen clearly that the top layers don t adhere completly somehow on the walls. And both parts were printed with same profile, 6 layers on top. 

[yellowshark 153]

Hi in my experience it is not just the number of top layers that are important when printing over such thin infill but also the total thickness. E.g. if you are printing with a layer height of 0.10 then you need at least 10 layers. If you are using 0.20 or greater then 6 layers should be OK

[gr5 2,224]

You may have some underextrusion but I'd like to see a side-view to be sure.  I mean it doesn't look like underextrusion to me.  Nor does it look like bad layer adhesion from this top view.  It simply looks like your layer height is thick so you get the "wedding cake" stepped shape.  

 

Is this PLA?  PLA doesn't get adhesion issues but other filaments do and adhesion issues are easy to fix.  But I don't see that on these printa.  From this photo.

[dej 0]

Well i do have 6 layers on the top. I tried also with one or two top skin layers printed at a lower speed (50mm/s) but still no result.  I've recalibrated my steps/mm so I don't think is underextrusion. Yes it's PLA. This problem drives me nut. seriously......

[gr5 2,224]

Okay so the parts you circled look like typical underextrusion.  But it's on the top.  Again I'd like to see a photo from the side.

 

6 layers at 0.2mm for a total of 1.2mm top?  Or 6 layers at 0.1mm for a total of 0.6mm top?  You want at least 1mm top/bottom thickness if this amount of underextrusion is bothering you.

 

Please confirm top/bottom thickness and then I'll give you the likely causes of underextrusion.

[yellowshark 153]

Hmn well if 50mm/s is slow to you then your normal print speed is probably too fast to get a quality finish on most parts. I am not saying that is causing the problem you have highlighted, it is just a general printing observation initiated by your comment. I will admit to occasionally speeding up to 40mm/s 

[yellowshark 153]

Looking at your latest pic more closely, you have more problems than was obvious from  your first pic. It will be really helpful for us  if you tell us your settings used for the latest print

[dej 0]

I got 6 layers on top at 0.2 so I get 1.2mm as top layer. And also I have 6 layers on the bottom but the problem is present even on the bottom layers. Not the first one. The first layer comes really good. I don't know if it's under extrusion. I have two identical printers and the problem can be seen on both. They are Hbot with brand new E3D V6 hotends.  I see here: 

   the problem was present also on Ultimaker 2. From 22 pages of post I got some valuable informations but no one solved my problem. I don't know what do you mean by side photos but I hope this is what you requested. 

 

Printing at 50mm/s it's preety low in my opinion. I used to print inside perimeters with 80, outer perimeter with 40mm, and top/bottom layers at 100, infill at 50. When I saw the problem I was thinking that 100 is too much. So I cut down the top/bottom speed at 50 but what did I got? The same result, so this tells me it's not only the speed. There must be something else. Steps/mm are calibrated for all axis including E motor. The temp I print is 205 but during test i used 210 to see if there is any difference, and it's not. You can also look at my gcode i have posted in the first post, maybe you can see something weird there. I also adjusted the tension on the extruder spring to be sure the filament it's not slipping or grinding. And i increased motor current. I never heard any skippd steps during printing. My retraction is 3.5mm at 80mm/s with costing enabled (0.07mm3). The bowden tube has 750mm lenght.

[Cbur45 0]

Ok my friend, first time writting on this posts, i'm working on Cura 3.31, but having the same problem. Good thing is that i'm having pretty good results with these modifications:

1. I started printing using a layer conunt of 2 in the "0"print (look at the picture), then i changed to 3 in the "1" print.

2. The top surface skin layers i have it in 0, but the top layers was changed from 2 to 6.

3. The top/bottom thickness was changed from 0.78 to 0.45, here i have to explain that im working with a 0.8 nozzle diameter, so, when i turned the thicknes to 0.45, the layers started to squish and i started to have much better results. if your nozzle is 0.4, i think you should change to 0.2 (only in the top/bottom thicknes option !).

 

Now i'm printing my third sample, to see if increasing even more the top layers will give me a perfect top.

[Cbur45 0]

19 hours ago, Cbur45 said:

Ok my friend, first time writting on this posts, i'm working on Cura 3.31, but having the same problem. Good thing is that i'm having pretty good results with these modifications:

1. I started printing using a layer conunt of 2 in the "0"print (look at the picture), then i changed to 3 in the "1" print.

2. The top surface skin layers i have it in 0, but the top layers was changed from 2 to 6.

3. The top/bottom thickness was changed from 0.78 to 0.45, here i have to explain that im working with a 0.8 nozzle diameter, so, when i turned the thicknes to 0.45, the layers started to squish and i started to have much better results. if your nozzle is 0.4, i think you should change to 0.2 (only in the top/bottom thicknes option !).

 

Now i'm printing my third sample, to see if increasing even more the top layers will give me a perfect top.

I got wrong the point 3. , it should say top/bottom WIDTH instead thickness.