First layer help appreciated!

[zaph 1]

I don't know what is going on and I would appreciate some advice from a 3D-Print-Pro!
slicing my stl-file with Cura 4.4.0 and having leveled the build plate of my UM2+ several times,
I'll get this "uneven" first layer that is in certain areas not smooth at all.
I tried cleaning, apply an adhesive and different plate-adhesion methods with the same result.

BIG thanks in advance for pointing me the right direction to get a perfect first layer!

[Smithy 1,141]

Which material do you use? I get similar results when using PETG.

 

[zaph 1]

sorry forgot to mention that I'm using the Ultimaker PLA with a 0.15mm layer-height and trying to solve this with a default normal-profile in Cura.

[Smithy 1,141]

OK, PLA is fine to test this out.

I am 99% sure it is cause by your bed or leveling. There is no setting in Cura which could partly cause this issue.

You can try to level nearer to the bed, just a little bit. You want to squish the filament into the bed. If if gets transparent, then the distance is too small. 

 

Another reason could be, that your glass (I hope you print on glass?) is not really flat.

[zaph 1]

THX Smithy for your input!
yes I print on the original UM2+ glass. is it possible that the glass-plate can deform after a while? (I had no problems so far!).
although I tried leveling with a good scratch on the calibration-card and another barley touching it,
but I'll give it another shot!
I decided to let the print run despite the first layer and look at the dark colored areas after a few layers ...
looks like "burn-marks"?
.

[yellowshark 153]

It could be over extrusion; what extruder temp, bed temp and print speed are you using for layer 1 and like wise for layer 2 onwards? Are you using 100% flow? I have the settings set the same for all layers except for layer1 I have the print speed set to 20mm/s and to avoid over extrusion I set the flow % to 70% and then increase it back to 100% over the next couple of layers - I do this with the printer control software not in Cura, although maybe these days Cura lets you control it?

[zaph 1]

not perfect yet ... but a whole lot better!
THX yellowshark!
I took your tip's and applied it in Cura for the initial-layer.
here a screenie of the settings I used and I hope somebody could help to make that first layer even better?!

.

[geert_2 557]

To me the second photo looks like overextrusion in general. Then molten material is likely to accumulate on the outside of the nozzle, after some time it gets burned, sags, and then gets deposited on the print in ugly brown blobs. Happens easily with PET, but I have also seen it with PLA. Watch closely while printing: it will be well visible if this is the case indeed.

 

Printing slow and cool generally improves this in my prints (on UM2). But I don't mind some overextrusion in the first layers (=nozzle too close to glass), because that gives shiny flat undersides and good bonding.

 

The first photo is difficult to see. Could be overextrusion, but it could also be poor bonding to the glass, for whatever reason (temp, speed, cleanness,...). If some areas would not bond and curl up, this might give similar results on the first layers. But first check the overextrusion stuff, preferably in a small test print.

 

 

[zaph 1]

14 hours ago, geert_2 said:

..... But first check the overextrusion stuff, preferably in a small test print.

 

 

Thank you geert_2 .... very good and helpful input!
there is a lot of info on the net about under-extrusion but very little about over-extrusion.
anyway it was time to do some maintenance work and cleaning the print-head did the job I think.
had done some nylon-printing and I guess that left some residue in the print-head and after cleaning and doing a test-print ... all looks good even with a standard-cura-profile.

[andrefccastro 3]

1 hour ago, zaph said:

had done some nylon-printing and I guess that left some residue in the print-head and after cleaning and doing a test-print ... all looks good even with a standard-cura-profile.

 

Usually I have problems when I switch from PC and Nylon back to PETG or PLA. I advise you to run some cleaning filament between changes to avoid this.

[yellowshark 153]

16 hours ago, geert_2 said:

>>snip

 

Printing slow and cool generally improves this in my prints (on UM2). But I don't mind some overextrusion in the first layers (=nozzle too close to glass), because that gives shiny flat undersides and good bonding.

 

The first photo is difficult to see. Could be overextrusion, but it could also be poor bonding to the glass, for whatever reason (temp, speed, cleanness,...). If some areas would not bond and curl up, this might give similar results on the first layers. But first check the overextrusion stuff, preferably in a small test print.

 

 

I must say that when I first looked at this thread my view was really an unclean bed but I thought I would mention the possibility of over-extrusion too.

It was several years ago that I changed my setup and put my nozzle closer to the glass, following some great posts by @gr5. Around the same time, within 6 months, I had made another change whereby I changed to use the same extruder temp for layer 1 as I did for the rest of the print, i.e. not having a lower temp to match the speed of 20mm/s for layer 1.

I found I was getting results similar to the first pic in this thread; it took me a long time to figure out it was over-extrusion and in the end I resolved it by setting the flow % for layer 1 to 70%. My un-researched guess was that I was getting away with it when the nozzle was further away from the bed but not when I was squidging the filament against the bed.

Edited December 12, 2019 by yellowshark

[zaph 1]

sometimes I run into a problem and all the solutions I know ... don't work and I get stuck.
to get then an input gives food for thoughts with new approaches.
resetting the frustration-level to zero with new motivation to solve the problem from a different angle.
in short: thanks to you all for your inputs! great community!

[Mariano_Seewald 0]

On 12/11/2019 at 1:24 PM, yellowshark said:

 I set the flow % to 70% and then increase it back to 100% over the next couple of layers - I do this with the printer control software not in Cura, although maybe these days Cura lets you control it?

 Hello Yellowshark and thanks for the answers to zaph's post that happened to be the same issue i had, tried your solution and it worked perfectly, my question is how fast do you go back to 100% ? Is it like in intervals of 5% per layer or even more abrupt than that?so i can have an idea , thanks in advance. And also what are the tradeoffs if i just leave it like that and do 70% all layers

Edited June 6, 2020 by Mariano_Seewald