Rough surface

[blind-anguis 0]

Hello there!

I recently got my Ultimaker 2 and i love it, though i have a small "problem" with the surface of my prints, the surface is a but rough, only where there is a overhang (see the bad picture in the link)

https://dl.dropboxusercontent.com/u/25961194/IMG_20140826_162255.jpg

I was wondering if i can do anything about this, do i have wrong temperature? For this print i used PLA with

Layerheight: 0.02mm

Shell thickness: 0.8mm

Fill density: 15%

Speed for outer shell: 30mm/s

Temperature: ~200° C

Fanspeed: 100%

Thanks

/ Blind Anguis

 

[gr5 2,069]

That's a pretty mild overhang. You should try .1mm layer height. I think you are getting that because your layer height is so thin.

I can print up to about 45 degrees from vertical with the same quality as vertical. Much steeper and the quality slowly starts to degrade until it looks horrible at 80 degrees from vertical (but good enough for practical parts - just not good enough for artwork).

The pattern you see on overhangs in your picture is closer to the pattern I'm used to seeing on underextrusion. But I suspect it is not underextrusion (it might be) and instead I think it's a combination of overhang with extra thin layer height.

You could try an intermediate layer thickness, say .05mm or .08mm.

There is a layer height that achieves the best quality surface. I'm not sure where the top of the quality curve is. .2mm is definitely worse quality than .1mm. And .05mm I think is worse than .1mm (many will disagree). I'm not sure where the best quality point is.

I think the problem is that with .02mm layers the amount of plastic coming out of the nozzle is so tiny that you have surface tension issues.

 

[blind-anguis 0]

Thank you for the answer! I will try to use thicker layerheigt, although i think 0.02 looks alot better than 0.1, at least on vertical surfaces ! Oh and is it posible to sand the surface? Or does the PLA turn white?

 

[gr5 2,069]

You have to keep it very cool when sanding so the only way to do it is with wet sanding. Some people wet ordinary sandpaper. I'm not an expert on wet sanding (never tried it). PLA melts at a ridiculously low temperature and then you get that "turn white" effect.

Alternatively you can add a few drops of baby oil (or any oil but baby oil smells better) and then wipe the oil off and it will return to it's normal beautiful look.