PLA vs ABS tough or not ?!

Source: http://forums.reprap.org/read.php?1,420767

Rigor_M [ PM ]
PLA vs ABS tough or not ?!
October 17, 2014 07:32AM Registered: 1 year ago
Posts: 86
Ok, So I guess this topic was discussed multiple times on this forum but still, I can’t wrap my head around it confused smiley

Here is the scenario : If I print a thin wall (lets say 2mm think) horizontal layers going up. One in PLA and the other in ABS.

the ABS is so easy to break between layers when the PLA is much harder (will eventually break).

Everywhere i read that if you need something solid, print it in ABS.. but, personal experience, says to do it in PLA.

Am I missing something ? printing ABS at a to high temprature, to fast ?

Is there a rule a thumb ? or am i right is saying that ABS is not that tough ?!

ask away if i forgot to mention something πŸ˜‰

Thanks for any feedback..

J-F
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cdru [ PM ]
Re: PLA vs ABS tough or not ?!
October 17, 2014 08:48AM Registered: 8 months ago
Posts: 302
Different materials have different physical characteristics. It’s difficult to say without physical examination to determine why you had structural failure. It’s possible your temperature extruder wasn’t hot enough, your extrusion rate not suitable for your actual layer height, moving too fast, too rapid of cooling etc. IOW, poor bonding between layers.

Generally speaking, ABS is suppose to be tougher, more impact resistant (less brittle) with easier flexing. However if there’s poor adhesion between layers then that becomes the weak link in the print.
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Rigor_M [ PM ]
Re: PLA vs ABS tough or not ?!
October 17, 2014 09:10AM Registered: 1 year ago
Posts: 86
For the example that I gave above, I was using a 0.2mm layer height, 230c hotend, (I does the same thing if I set it to 240c), print speed is 40mm/sec

Hope this help define my settings

J-F
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ggherbaz [ PM ]
Re: PLA vs ABS tough or not ?!
October 17, 2014 09:19AM Registered: 8 months ago
Posts: 79
Which is your bed temperature and it’s your printer open or enclosed? Inter layer adhesion has more to do with those two factors than hotend temperature (within ABS acceptable temperatures).

PLA will be more solid but brittle. ABS will flex before it brakes.

Edited 2 time(s). Last edit at 10/17/2014 09:21AM by ggherbaz.
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Rigor_M [ PM ]
Re: PLA vs ABS tough or not ?!
October 17, 2014 09:42AM Registered: 1 year ago
Posts: 86
I set the bed at 110C with capton tape on it and a layer of hairspray.. I get minimal shrinkage on that side.

And, like alot of printer, mine is opened.. I do plan on building a printer with Plexiglas surrounding it..
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Ralph.Hilton [ PM ]
Re: PLA vs ABS tough or not ?!
October 17, 2014 01:50PM Registered: 10 months ago
Posts: 300
I would use white dibond for the enclosure except the front. That way light is reflected inside for better viewing of prints.
s1361.photobucket.com
s1361.photobucket.com

Edited 1 time(s). Last edit at 10/17/2014 01:52PM by Ralph.Hilton.
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sheepdog43 [ PM ]
Re: PLA vs ABS tough or not ?!
October 17, 2014 05:39PM Registered: 8 months ago
Posts: 199
If you get ABS right, it will be stronger than PLA, get it wrong and it’s brittle as heck.

The problem is that ABS is VERY fickle about how it’s printed:
Too little airflow and you lose definition, too high of airflow and it becomes brittle.
Allow the previous layer to cool too much before the next layer, and it won’t stick. Allow it to stay heated too much and it will sag.
Heat your bed too little and it won’t stick, too much and it effects layer cooling and gives your print an hourglass shape.

Higher speed, makes this an even bigger problem.

PLA… you can’t over-cool it and as long as it’s not burning, it’s fine, making it very hard to mess up.
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ggherbaz [ PM ]
Re: PLA vs ABS tough or not ?!
October 17, 2014 06:25PM Registered: 8 months ago
Posts: 79
Ok, since it is an open frame, do the following experiment:

1.- use a ceramic space heater in front of printer an set it to at least 75 to 80 degrees and slow fan setting.
2.- use a 200 watts incandescent bulb and put it close to the part you are printing (this method is the one I used all the time) be sure that the socket for the bulb is ceramic. The heat from the bulb keeps the small area in front really warm and moves the air around too.

Attached you can see a white ABS part I printed for a customer.
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Attachments:
open | download – IMG_2014101754356.jpg (37.3 KB)
Rigor_M [ PM ]
Re: PLA vs ABS tough or not ?!
October 18, 2014 07:15AM Registered: 1 year ago
Posts: 86
Thank you all for the hands-on knowledge.

I did try one with 2x 100W bulbs, (one in front and the other in back). I wasn’t sure it helped.

@sheepdog43:
Got any good values you use that I could play around with ?

@ggherbaz:
1. Do you have to shine the bulb at the current layer being printed or the part in general ?
2. Also, do I need both steps or just one ? (cause I don’t have a ceramic heater).
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Lepes [ PM ]
Re: PLA vs ABS tough or not ?!
October 18, 2014 09:39AM Registered: 16 days ago
Posts: 6
ehhhhhmmmmm, Don’t you play with extrusion width parameter on Slic3r?

For example, I have a 0.6 nozzle, while I have 0.9 extrusion width, that ensures more surface to stick one layer on top of another one… maybe it helps.

Cheers
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ggherbaz [ PM ]
Re: PLA vs ABS tough or not ?!
October 18, 2014 02:26PM Registered: 8 months ago
Posts: 79
Either or, if you have a heater used it, the bulb is cheap and a ceramic socket too. You only put it facing the part you are printing within 6 inches. My printer is semi enclosed and the bulb is enough for the job, with an open frame you want to prevent from cold air to move around the printed part that’s why a heater will be useful because will move hot air around the part.
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ggherbaz [ PM ]
Re: PLA vs ABS tough or not ?!
October 18, 2014 02:31PM Registered: 8 months ago
Posts: 79
Commercial printer used this principle to keep the built chamber at temperature. With an open frame most of the heat will be lost, but might be sufficient, you will have to play with the fan settings to find the one that works best for you.
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ggherbaz [ PM ]
Re: PLA vs ABS tough or not ?!
October 18, 2014 02:36PM Registered: 8 months ago
Posts: 79
One last thing, if you understand a little of thermal dynamics you will understand that it most be unidirectional, or by vectors. Don’t put the bulbs facing each other, you need flow.
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Rigor_M [ PM ]
Re: PLA vs ABS tough or not ?!
October 18, 2014 08:07PM Registered: 1 year ago
Posts: 86
Would a forced air heater do the trick ? Ive seen some cheap ones at my ocal big box store.

I could get one tomorrow if you say its ok.

Thanks
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Rigor_M [ PM ]
Re: PLA vs ABS tough or not ?!
October 18, 2014 08:10PM Registered: 1 year ago
Posts: 86
Also, i have some cardboard here that i could use to close off the sides and top. Temporary for the time being. What do you think ?

Edited 1 time(s). Last edit at 10/18/2014 08:11PM by Rigor_M.
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ggherbaz [ PM ]
Re: PLA vs ABS tough or not ?!
October 19, 2014 10:10AM Registered: 8 months ago
Posts: 79
Yes it will work, I prefer ceramic for it’s safety. Slow air flow. At any dollar store you can get the foam boards. Get the white ones and just hot glue them to make a 3 side box.(foam works as added insulation)

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