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diagonal lines and blisters in the pieces  

Active Member
diagonal lines and blisters in the pieces

Hi !

I want to show you a trouble I have when printing.

When I print some piece ( I usually print in ABS ) some diagonal lines appears too intense , spoiling the finish of the piece. ( white arrows in the pictures )

You have the pictures to explain the problem.
The funny thing is that the lines that appear in the same place with these characteristics :

- I have print ( yopu can see it in the pictures ) both instances of the same model at time. ( In different places of the bed )
- The design, of course , don't have these lines
- I have print another pieces ( some very veru diferents ) and some lines still apearing
-The parts of the image are printed in ABS (I have tried different ABS and they all make the same lines) Bed temperature 100º first layer, 110º the rest and extruder in 243º without layer fan.
-Closed Printer
-The diagonal lines appears since the first layers.

Also I have another issue; in the pictures you can see (I marked some in yellow) the last layer (better explication: the last layer of a different parts, not the last layer of the gcode) have a lot of blisters ... Too much temperature??? 243º??

also (marked in red) the printer creates different textures in the same models ... (as if the liveZ was in another height)

Please!, somebody could I help me?


Posted : 04/10/2018 11:19 am
Veteran Member Moderator
Re: diagonal lines and blisters in the pieces

to me, it looks like over extrusion.

the Slicer decides how to print the surface on any layer, and often prints between one feature in the surface geometry and another, then it prints somewhere else on the same layer...

if you are slightly over extruding, the nozzle lays down a wider than expected run of filament and the next run merges with the previous run, because the plastic is still warm.
when the extruder starts laying down fresh plastic next to cooled plastic, the fresh plastic can't merge with the old cool plastic so it forms a raised line

so if you look those lines occur adjacent to a change in the surface geometry.

if you are over extruding a lot, then the fresh plastic is squeezed into too small a space, and squashes out to the sides then when the extruder runs past that point on the next pass, it ploughs through the excess plastic and causes a ridge on every pass of the extruder...
this often causes a rough surface, with PLA or ABS, however PETG tends to stick to the nozzle and a blob begins to form, the blob will grow until it's size exceeds the adhesion on the nozzle, when it will drop off, usually at the most inopportune moment.
these ripples and blobs are likely to cause collision errors on the Mk3 printer. If crash detection is turned on the printer will try and recover it's X/Y position before continuing with the print.

so try again with either reduced extrusion multiplier, when you slice the model, or reduced flow multiplier on the LCD Display, purely a guess, but 5% reduction is where I would start looking...

regards Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK

Posted : 04/10/2018 12:38 pm
Active Member
Topic starter answered:
Re: diagonal lines and blisters in the pieces

Thanks! I'm going to test it and I will give you a feedback!

Posted : 05/10/2018 3:21 pm
Active Member
Topic starter answered:
Re: diagonal lines and blisters in the pieces

Hi, certanly it was the problem. Too much extrusion. I down the % extrusion and the print improve considerably. Only I had to adjust downer the live Z because the first layer left a lot of unprinted spaces, creating holes. I don't know if exist another solution to take a balance between First layer and the extrusion %.
At the moment I have solved the problem... I think 😀

Posted : 08/11/2018 10:50 am