small blobs on corners / bubbles between layers

[nihilianth]

Hi guys,

lately (no idea when it started) I've noticed that the corners of my ABS prints seem to have some little blobs on them. I have tried printing with different settings, but nothing seemed to help, so I'm getting a little bit desperate here now >.<.
Also, since the day I had used ABS for the first time I always had some small bubbles between / on my layers, however I've ignored that until now.

My printer is Makerfarm Prusa i3v with hexagon hot end (0.4 nozzle). I am using Cura as my slicing software

There are the settings I've tried when printing the cubes:
1:

• Hot End: 225°C
• Bed: 110°C
• Print fan: on
• retraction: 4 mm

3:

• Hot End: 220°C
• Bed: 110°C
• Print fan: off
• retraction: 2 mm

3:

• Hot End: 215°C
• Bed: 110°C
• Print fan: off
• retraction: 2 mm

here are the photos of those 3 prints, as you can see the corner blobs are present on all three:
2014-10-02 00.21.12.jpg

Bubbles between layers:
2014-10-02 00.20.47.jpg

I hope anyone can give me some advice on how to fix this

[Geoff]

Hi mate,

I cannot say this is definitely your issue but when my prints look like that, with little bits everywhere, either 1 of 2 things was wrong...

1. The filament clicked every now and again (or the stepper motor did) and every time it clicks and skips due to whatever reason, it forms one of those blobs.

2. There was some old crap in my extruder. I heat up my extruder , take my cleaning tool (which is a very thin string of metal, like a super thin guitar string) and then I push it up inside the nozzle to clear whatever is blocking it.


One question tho, when you extrude (without printing... just let it extrude like you are changing filament) ...
Does it come out straight down? as in a clean line of filament leading to the loops of extruded filament on the hotbed? like making a slinky?

A good extrusion will feel smooth along the extruded plastic, feel it with your fingers. It also should come out of the nozzle and go straight down.. not shoot out to the left or right, this indicates other filament possible stuck in there, needs flushing.

OR does it extrude funny, like curly bits coming out?

[nihilianth]

Hm just checked those 2 possible reasons. The filament starts curling a bit but then extrudes in a straight line (due to gravity I guess :P) I will try to clean it with some string today.
Do you think it's a good idea to soak the hot end (or just the nozzle) in acetone before trying to clean it with the string? Or is it better to just warm it up to say 200°C.

Also, is it possible that the bubbles started to form due to ABS filament getting moist over time? I am not using any air-tight containers or dessicant for my spools atm.

P.S. the filament doesn't click, but there is some steam (or mb water vapor? ) coming out of the nozzle when trying to extrude at 220°C

[Geoff]

Hm just checked those 2 possible reasons. The filament starts curling a bit but then extrudes in a straight line (due to gravity I guess :P) I will try to clean it with some string today.
Do you think it's a good idea to soak the hot end (or just the nozzle) in acetone before trying to clean it with the string? Or is it better to just warm it up to say 200°C.

Also, is it possible that the bubbles started to form due to ABS filament getting moist over time? I am not using any air-tight containers or dessicant for my spools atm.

P.S. the filament doesn't click, but there is some steam (or mb water vapor? ) coming out of the nozzle when trying to extrude at 220°C

That could be something in your nozzle then. If it curls to a side and forms a ball, and when gravity takes over the ball drops and it forms another ball etc... this is a blockage.

No, no acetone really required, 200c is too low to flush any residual ABS. Warm it up to 250c and cook the gunk out. Mixing ABS and PLA will cause this or just PLA itself has a habit I find of getting clogged in the nozzle. If you don't have something to poke it out, just heat it up and let it get really hot and linger at 250, then feed a tonne of filament through.

[nihilianth]

So I've tried cleaning the nozzle at 250°C with a string and pushing a lot of filament through it, however that didn't help: The surface was just as bad as the 3 prints earlier.

But then I've decided to check the moisture "theory". I've baked the filament in an oven at 70°C for about an hour and the magic happened .


Here are the first 3 prints again:
3_prints.jpg

And here is the same object printed with "baked" ABS:
baked_print.jpg

I guess next thing I will buy is some tupperware container and kitty litter to keep it dry

However, the other issue I've had, with corners not being square but having a small blob on them still remains :\ Any idea what might cause that?

[Geoff]

Do you have any other colours you can test with? for me, black has always been a notoriously funny filament to print in.. check this thread out...

http://3dprintboard.com/showthread.php?2584-Black-ABS

[nihilianth]

I only have orange PLA as an alternative, don't have any bubbles or weird corners when printing with it tho :\
Hm I didn't think the filament color would matter that much Just ordered a spool of blue ABS, I hope it will make a difference.
Thanks for your tips Geoff^^

[Geoff]

I only have orange PLA as an alternative, don't have any bubbles or weird corners when printing with it tho :\
Hm I didn't think the filament color would matter that much Just ordered a spool of blue ABS, I hope it will make a difference.
Thanks for your tips Geoff^^

No problems,

The colour and material does always differ I find. When I find the magic setting for each filament I write it down! I have nearly 60 rolls here (I sell lots of colour options with my parts) so I have to keep on top of it all.

I have about 5 rolls of black left here, ABS/HIPSABS and PLA, and I'll be honest the only one I like the quality from is the black PLA, the rest to me are only used for parts that will be painted or sanded. For absolute smashing quality in prints, the natural PLA (which does look bland as there is no colour in it) is still for me the bees knees. A 0.2mm print looks more like a 0.1mm print, and an 0.1mm layer height print just looks so smooth it could have almost been an SLA printer.