Hi im Trevor Brooks from a First Robotics team in Dover NH USA http://gwrobotics.net . i have been looking at a lot of great 3D printers and some of them do not have a heated bed to provide better large abs prints. Since i have no physical experience with either ABS or PLA i dont know which material would be best to use on our robots. i know that pla smells good, non toxic, renewable, and doesn’t require a hot heated bed, it is also more brittle and less flexible. ABS is flexible, toxic smelly fumes, non environmentally friendly, and needs a hot heated bed to print well. the thing im struggling with is weather being flexible is a good thing to have on a robot (worrying of warping parts under pressure/lots of weight) but at the same time i know PLA is more rigid and resistant to warping (providing cool temperature) but i don’t really know how tough it is (how much force can we put on it before the part snaps) im just worried that during a competition if we get hit to hard some parts may snap. THANKS IN ADVANCE FOR YOUR HELP!!
-Trevor http://gwrobotics.net
Abs shrinks when it cools(slightly) the heated bed prevents problems. I think abs or polycarbonate would be best for mechanical parts.
Agree with Camerin. ABS is tougher than PLA in my experience. Polycarb and nylon are also good options. Polycarb requires an all metal hotend due to its higher melting point. The nylon product is pretty new but people seem to be liking it, it can also be dyed 
http://reprap.org/wiki/Taulman3D_618_Nylon
http://reprap.org/wiki/Polycarbonate
You can add compounds to most plastics to improve their toughness. So you can get Impact Modified and High Impact PLA. Does make them harder to extrude though.
http://www.diamondage.geekofarm.com/?page_id=150
It’s one of those things I think that you need to get a few types of filament and give them a test. Remember though, that any material in a filament will be different to that same material once it’s been extruded into a part.
Thank you, so much help!!
It is accually the other way around.
ABS is hard and brittle. While it is not mechanicly forced in any way, it is tougher that PLA.
PLA is softer than ABS but is very flexible and therefor stronger than ABS when mechanicle or vibrating forces are being applied.
Also keep in mind that for example motor mounts, should be printed in ABS anyway. If the motors get warm, PLA will bend en warp.
I have looked at this video again and am doubting if he is right. Do you see that the green parts look translucent? That can only be done with pla. Also i wonder if the “green” part was printed solid. The blue one seems to be…
Yeah… I’ll just have to try and experiment myself. Sounds like the best option
Sorry to contradict you @Mano_Biletsky_Open_M but PLA is the brittle one. A quick Google will confirm this.
I have heard that PLA is in general more finicky than ABS. All in all it does depend on the actual PLA and ABS samples that you use. It the ABS is recycled it could be more brittle. But just so you know, PLA is technically compostable, but you need to use an industrial composter, it does not break down quickly under normal circumstances.
I agree.
Of you just take. Look at the fillament, wich type breaks and wich type bends?
@Mano_Biletsky_Open_M It isn’t that simple, you would need to measure strain. If it deforms at a higher strain, it would still be “stronger” than a material that breaks at a lower strain. and the same would be true in reverse. Just because it is brittle doesn’t mean it is weak/strong. Just because it is deformable doesn’t mean it is weak/strong. Depending upon the structure of your print, both could bend. but I am sure someone has performed these tests, I am just not aware of where that data is.
Does pla or abs have any issues with supeglue?
Both fine as I recall. You can ‘weld’ ABS with acetone as well.
k, thanks… just making sure it wont melt or anything like foam.