ABS Print Surface Finish - Vertical Lines/Striations

[Eraser 31]

Hi!

I have been printing cube/rectangular shaped parts for a project.  The problem I have been having is that when I print in ABS, I get vertical lines/striations/ridges on flat vertical surfaces.  See picture. Part in picture is about 1cm x 1cm x 2cm.  

This doesn't happen when I print with PLA.

My print settings are:

Machine - Ultimaker 2

Temperature - 230C

Bed - 90C

Flow - 107%

Fan - 50%

Speed - 30 mm/s (top/bottom - 15mm/s)

Layer - 0.08mm

Wall - 0.4mm

Fill - 25%

Note - my Ultimaker 2 is fully enclosed with plexiglas

Filament - Filaments.ca black ABS (brand new spool), stored with large pack of dessicant

I have tried the following variations, separately (not in combination):

- decreasing flow to 100% (I thought maybe the excess 7% was getting pushed out to the outer wall).  No effect.

- rotating part 45 degrees about Z-axis.  No effect.

- increasing temperature to 260C - got rid of the lines, but now the surface is very rough (see pic)

Is this expected print quality with ABS or can I do better?  With PLA, the surface is silky smooth (save for the small horizontal layer lines).  Has anyone else experienced this?  Help?

Edited July 27, 2015 by Guest

[Eraser 31]

I did more testing. I believe there are two causes of the ripples/ridges:

1. "Ringing" (small, higher frequency) caused by print head vibrations after sharp changes in direction, and

2. Larger, lower frequency ridges caused by the infill impressing upon the outer shell.

Ringing

These ridges/ripples start intense near the sharp turn and taper off (dampen).

- Acceleration: I lowered the acceleration to 1500 mm/s2 but this didn't make any difference

- Adding several (3) extra outer shell layers actually intensifies the ridges/ripples (makes them worse) - I think because the ripples of each layer are additive to the next. However, increasing the shell thickness to 2 layers from 1 layer didn't have much impact - but it solves the infill ridges (see next)

Infill Ridges

I have been able to address this by increasing the outer shell thickness to 2 layers (0.8mm). I see in Cura there is a setting for reducing overlap between your infill and our shell layers. Decreasing the overlap would probably also help.