What's stronger? PLA or ABS?

[Elbot]

4043D as the standard PLA grade, and PA-747 as the standard ABS grade; which is the stronger material? I want to 3d print a bicycle like in the Youtube video:  http://youtu.be/hmxjLpu2BvY

The strongest ABS is stronger than the strongest PLA, but what about the grades commonly used in 3d printers such as makerbot replicator sold by makerbot and octave, etc?

I just found out from tbuser's blog that you can't use ABS with PVA so I may have to either;
1. print with ABS and ABS support and do extensive post print clean-up.
2. print with PLA with PVA water soluble support and do no extensive post print clean-up.

There's a 3rd options but it deals with extremely toxic chemicals that I'd rather not deal with:
3. print with ABS with PLA as support and do post print dissolution of PLA using toxic industrial strength solvents that selectively dissolve PLA but leaves ABS alone.

So, the deciding factor is the strength of ABS vs PLA because ABS is already 66% the strength of nylon, what the guys in the youtube video used and their bike barely worked. The first prototype suffered a broken spoke. they had to reprint the wheel. I already have to compensate with 50% thicker parts to compensate for ABS being weaker than nylon, so if PLA is even weaker than ABS then I don't think it would work.

Please advise. Thanks!

[c f]

ABS is much less brittle than PLA, so a bike made of ABS is probably less likely to fracture/shatter than a bike made of PLA.

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[Zip Zap]

Try Polycarbonate from Ultimachine.com

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From: Elbot <tomas...@gmail.com>
To: make...@googlegroups.com
Sent: Saturday, September 29, 2012 4:19 PM
Subject: [MakerBot] What's stronger? PLA or ABS?

[Elbot]

So that means polycarbonate will stick to PVA water soluble plastic so I can print ball bearings, bike chains, and interlocking gears in situ with no assembly?

[Chuck Joga]

I choose ABS for it's strength over PLA.  I would love to avoid the warpage/shrinkage problems of ABS.  I compensate a lot to make ABS work, but my tolerances are not very tight so I have a lot of leeway.  However, you assessment of the relative strengths of ABS or PLA parts vs. molded nylon is an apples to oranges comparison.  I agree that an injection molded ABS part is about 66% the strength of Nylon.  But using the relative strength of a 3D printed ABS compared to nylon doesn't make sense unless you are printing with nylon also.  Since nylon is toxic to print with, I don't see this is a viable option either.

I would not use any 3D print that must be load bearing that is larger than my fist.  This stuff will de-laminate under vibration or load.  The strength of a 3D printed part is not equal along all axis.  So you may be OK as long as you orient the direction of the layers properly to resist the forces. But, IMHO this technology can only be safely used in load bearing applications that are very small scale.  Generally smaller is stronger and larger is weaker.

As an aside, I am a cyclist and there is no way that an ABS 3D printed bike can safely be used as anything more than a novelty under very controlled conditions.  A bike coming apart at even a walking pace can send your head to the ground in an instant.  Wear pads and a full face helmet!

-Chuck

[Joseph Chiu]

+1.

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[BilbyCNC]

Does anyone know of a study or stats on pla verses abs strength? or on pla life and degrading rates?

Cheers

Lee

BilbyCNC

[Michael Overstreet]

I think printing with ABS is the only way to go for printing out robot servo brackets. The major problem that I have found is that the servos on my robot will run hot. That heat is then transferred from the servos to the PLA brackets connected to them. The heating and cooling of the PLA brackets will start causing structural issues with the brackets: warping, bending and structural failure. I have not notice this issue with ABS brackets. 

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[RocketSled]

I would not use any 3D print that must be load bearing that is larger than my fist.  This stuff will de-laminate under vibration or load.  The strength of a 3D printed part is not equal along all axis.  So you may be OK as long as you orient the direction of the layers properly to resist the forces. But, IMHO this technology can only be safely used in load bearing applications that are very small scale.  Generally smaller is stronger and larger is weaker.

As an aside, I am a cyclist and there is no way that an ABS 3D printed bike can safely be used as anything more than a novelty under very controlled conditions.  A bike coming apart at even a walking pace can send your head to the ground in an instant.  Wear pads and a full face helmet!

I agree that the prints we get from our printers are of limited value as structural components, and that smaller is better. But there's a Kickstart (or similar) with a guy who is making bicycles out of cardboard.  I wouldn't have thought it possible, and I still don't believe it can be all that safe, but the final product is compelling!  There's a pretty high production value video.  Just do a google search for "cardboard bicycle" and check it out.  8*)

 

 

[Elbot]

Thanks for that video: http://youtu.be/txSboSNQINs
It was inspiring. I noticed the thickness of the parts and the lack of multiple speeds. It is a one speed bike. Bike was also made of CORRUGATED cardboard and the cardboard was folded and coated for strength. I would also have to print out the parts carefully orienting it so as not to have delamination. I think I'll print out the parts diagonally.

[Chuck Joga]

I was going to refer to the cardboard bike too, but thought it off topic.  Paper is very strong when laminated.  In the video I saw, the rider of the cardboard bike was taking it very easy.  :)  A cardboard bike is pointless IMHO.  The labor involved will far exceed the old fashioned way of welding metal tubes together to make a frame.

A commercially available 3D printed bike is in the future.  Maybe not with a 3D "plastic" printer but using some high-tech bomb-proof resin/fiber.  This should put and end to the current methods of laying up carbon fiber/resin in molds.  I'm looking forward this technology maturing and changing the world!

-Chuck

[Elbot]

of course, it will be open source, too. I want everyone to enjoy this. why didn't the guys on the youtube video post their bike on thingiverse? I mean, it's not like they're going to manufacture and sell a nylon bike with no brakes anyways? I would love to get my hands on their CAD files! It's much easier to improve than start from scratch, which is what I'm doing.....

[Zip Zap]

There is an ABS filament that blends in carbon fiber.  Not sure how strong it is:

http://www.repraper.com/goods.php?id=173

As far as replacing carbon fiber cloth/resin molding would be a stretch. An extruder just pumps out pieces of material v.s a weaved material combined with resin.  It's like comparing sawdust to wood boards cut out from a tree trunk.

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From: Chuck Joga <chuc...@yahoo.com>
To: make...@googlegroups.com
Sent: Wednesday, October 3, 2012 7:04 AM
Subject: [MakerBot] Re: What's stronger? PLA or ABS?

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[Jack Coats]

The strands of carbon fiber must be pretty short, so I would not think
that it would add much/any strength. It also mentioned that carbon
black is added in addition to assist in the black coloring.

[Chuck Joga]

I was hoping for some "unobtanium" kind of futuristic nano assembled material that would make all currently manufactured materials obsolete. :)  One of these days......

-Chuck

[Justin M]

I find that ABS will survive the dishwasher while PLA will not.

[Cymon]

On Thursday, January 10, 2013 6:08:09 PM UTC-7, Justin M wrote:

I find that ABS will survive the dishwasher while PLA will not.

 Just when I'm considering a switch to PLA to resolve my cracking issue you have to say this?

[Joseph Chiu]

FWIW, I know a guy who had a reprap using PLA-printed parts.  He was taking his machine around to do demos and he left it in the car mid-day once.  It melted the parts enough that prints were coming out very poorly even after his best effort at recalibrating the machine.

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[whpthomas]

I don't think I would want to leave my 3D printer in a hot car regardless. That goes for iPads, Notebooks and windsurfers - non of them like getting baked.

[Big-E]

I am fascinated by the folks printing in nylon. that would be pretty strong. strong enough to print a bike. Before kevlar, they used to make bullet proof vests from layers of nylon. just a thought. http://www.taulman3d.com/index.html

[Clinton Hoines]

Probelm with nylon as of right now till someone figures it out is the warping. It is far worse than ABS for warping unless your printing small parts.

And large object while super strong are very flexible, so if you need rigid parts nylon might not be the way to go unless it's a fairly solid part. This is

just my opinion with the limited number of pieces I have printed though.

 

Clinton

[Elbot]

3d printed bullet proof vests.... hmmm......

[Elbot]

with dual extruders, you could print a nylon abs matrix. That would solve the problem!

However, the real problem is the toxic fumes that nylon printing produces.

[John Driggers]

The "toxic fumes" are why most everyone I know playing with Nylon are 1] Printing Tauman 618 which has been tested and 2] Ventilating the printer to the outside.  I vented mine outside and put a bowl of birdseed so I'd have early warning - so far, evidently I'm safe.

[whpthomas]

I vented mine outside and put a bowl of birdseed so I'd have early warning - so far, evidently I'm safe.

I was wondering where all those birds had gone - looked out the window and they are all taking a nap - maybe I should stop printing now.