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Layer splitting with ABS

Posted: May 12th, 2018, 5:06 am
by Lez0
Hi all
I have a problem with ABS that I can't seem to solve.
The layers are splitting when I print ABS with a z height of more than about 10mm, see photo.
I have a Folger FT5 and am printing with a heated bed at 100°C and a 0.4mm nozzle at 240°C (up from 230°C) and layers at 0.25mm
Print speed is 60mm/sec. with the initial layer at 30mm/sec.
I use a brim of 8mm.
I have tried 2 different makes of ABS, both with the same result.
It is in an enclosure, although a bit crude, so it is not affected by drafts etc.
Does anybody have any suggestions, it's driving me mad having to repair every print.

Thanks
Lez0

Re: Layer splitting with ABS

Posted: May 13th, 2018, 8:33 pm
by LePaul
I'd be curious how well that enclosure is maintaining the temp needed to print ABS Maybe a thermometer inside?

Re: Layer splitting with ABS

Posted: May 14th, 2018, 3:11 am
by Lez0
I have put a thermometer inside and it get's up to the high 30's, perhaps I need to plug the small gaps.

Re: Layer splitting with ABS

Posted: May 14th, 2018, 7:57 am
by shurik
IMHO, 240C is on the lower edge for ABS. Try to up it to 260C and make thicker walls if possible.
Lower the speed to see if it makes an impact.

Re: Layer splitting with ABS

Posted: May 15th, 2018, 3:21 am
by Lez0
Hi thanks for the reply.
The Folger FT5 can only go to 240°C also the manufacture recommends 220-240 so I am working at the top end.
The walls are 1mm thick with infill, do you think this is thick enough?

Re: Layer splitting with ABS

Posted: May 15th, 2018, 6:35 am
by shurik
Hi,
Hmm, I would still up the temp, since there is a problem. Maybe, you can try some other printer, capable of higher temperatures?
The thickness of the walls - how many outside layers(shells) do you have? Make sure you have at least two, more is better. Infill is secondary to that. IMHO, again.

Re: Layer splitting with ABS

Posted: May 15th, 2018, 7:46 am
by jonnybischof
In my own short experience with ABS I also noticed that I had to print at very high temperatures (255 °C for a material rated for 230-240 °C), and no print cooling, good enclosure with 15+ minutes pre-heating, and very slow print speeds around 30 mm/s. Oh, and ridiculously high bed temperatures.

Even then I had problems with very bad inter-layer adhesion compared to PLA, so I never got any useful results out of it,

Short story: I would ditch ABS and look into the newer products like ASA or Colorfabbs Ngen. Maybe the good old XT, but this also needs more than 240°C for mechanically strong prints.

Re: Layer splitting with ABS

Posted: May 15th, 2018, 10:07 am
by Lez0
I tried to set the FT5 to 250°C but it kept stopping with MAX TEMP, so I had to reset it, Like I said the FT5 can only go to 240.
I have tried various wall sections but the layers still split.
I am thinking of getting another printer anyway, possible a smaller one.

I'll also look at these materials: ASA Colorfabbs Ngen.

Thanks
Lez0

Re: Layer splitting with ABS

Posted: May 15th, 2018, 11:00 am
by LePaul
nGen is quite good, you'll have to play with retractions a bit since it can get hairy/stringy

Re: Layer splitting with ABS

Posted: May 16th, 2018, 1:49 am
by jonnybischof
Colorfabb really likes their stringy filaments :lol:

Re: Layer splitting with ABS

Posted: May 16th, 2018, 7:03 am
by nilrog
jonnybischof wrote: May 15th, 2018, 7:46 am Short story: I would ditch ABS and look into the newer products like ASA or Colorfabbs Ngen. Maybe the good old XT, but this also needs more than 240°C for mechanically strong prints.
I tried ASA once, based on reading that it was like ABS, but easier to print with and not as toxic.
But if you do not have an enclosure I would not recommend it. The parts I printed on my UMO+, with side panels, had bad layer adhesion, and some of the supports were wavy.

So I opted to use PETG instead and, although it's a bit tricker to print that PLA, i'm quite happy with the result, on the same printer setup as I tried ASA on.

Re: Layer splitting with ABS

Posted: May 23rd, 2018, 12:51 pm
by Anders Olsson
I have printed a lot in ABS though the years and there are simply certain things you do and certain things you don't do with pure ABS in a printer which doesn't have an actively heated chamber.

I always print with the bed at 90-95 C, with a thin layer of Tesa Easy Stick glue on the bed and always with the fans off, those are the most crucial thing of them all!
An enclosure certainly helps and the larger the nozzle diameter is and the thicker the layers are, the more likely it is that you get good layer adhesion.

For cheap/old ABS filaments i generally need to keep the nozzle at 255-260 C for them to print properly.
Some of the more modern ABS or ABS blends can print fine already at 235-240 C though, so what can be done at 240 C depends hugely on the specific type of ABS you are using.

Square boxes are fundamentally very difficult or often even impossible with ABS when you don't have an actively heated chamber, just as the picture you posted shows.
I had this result too a few times and it is simply about that the stress from the relatively large shrinking when ABS cools will be concentrated in the corners of a square object.
Cylindrical objects of the same size generally prints fine, so if I for some reason want to print a large box with sharp corners I simply don't use ABS, while for cylindrical objects ABS is just fine.

Here is an example of an object I made recently that prints excellent in some dirt cheap ABS (at 50 mm/s, 0.25 mm layer height, 255 C / 90 C with 0.6 mm nozzle)
2018-05-17-4712.jpg
Here is another one, even larger, printed with 0.8 mm nozzle and 0.3 mm layer height if I remember correctly.
2015-01-08-4803.jpg
As you can see the objects above have in common that they are cylindrical which gives an even distribution of the stress from the shrinking.

Re: Layer splitting with ABS

Posted: May 23rd, 2018, 6:05 pm
by LePaul
@Anders Olsson is alive! :)

Re: Layer splitting with ABS

Posted: May 24th, 2018, 2:37 am
by Lez0
Thanks Anders Olsson
What you say makes sense. I have bought another make of ABS and it prints a lot better at the same settings 100°C bed 240°C nozzle.
I have no problem with the ABS sticking to the bed as I have a plastic type mat that works, sometimes too well as I can have great difficulty getting the parts off the bed.
So as you say some makes are better than others. One problem with the better printing ABS is it's not pure black it has a slight blue tint to it. I can live with this tint if the prints are strong and good.
I have just bought some PETG and will be trying that.
As I design my own parts I'll keep in mind what you said about corners etc.

Thanks again and I'll keep you posted.
Lez0

Re: Layer splitting with ABS

Posted: May 30th, 2018, 11:28 am
by Lez0
Well I have done a few parts in PETG, some aren't perfect but better than ABS.
This part below is 180mm tall. As you can see at the top it started to print better for some reason. I'll have to play with the settings to get a better part but the first results look good, at 240 nozzle 80 bed 0.25 layers at 60mm/sec, no supports, retraction 6.5.

Lez0