I am Switching from ABS to PLA for tall items
September 14, 2014 07:37PM
I have been printing with ABS for over 3 years now and I have a new (month old) TAZ 4 printer. I have not built an enclosure yet for it and I am having a heck of a time with tall thin items cracking and warping. Small items or low profile items are no issue but in the past 4 days I have tried to print a power supply hanger I designed that is 3mm wide and 60mm tall (5 hour print) and every attempt has failed. It either pulls off the glass and even pulled off a raft (the raft stayed stuck down fine) or last night I finally got it to stick all the way through the print only to find 3 cracks all the way through it that made it fall apart.

Now, I have only printed a few small items from PLA and I have a 1lb roll of it. So I did a test print of another small item last night with that just to see if it was going to work at all (it's a year old and in a bag but the bag has cuts in it so I was worried about moisture). Well the first layer looked a little sloppy but it actually printed fine. I use the Purple glue stick and it worked even better with PLA, in fact I had to use a little bit of force to remove the print but not overly so.

So, today I re sliced the power supply hanger for PLA and it's printing now (still over 4 hours to go) but seems fine so far. I got so enthused about PLA that I ordered 2 rolls last night (ruby red translucent, I love the way it looks, and gold).

I always want to make some translucent stuff for vases and lamp shades.

Just wanted to share.

Thanks!

Edited 1 time(s). Last edit at 09/14/2014 07:39PM by tmorris9.
Re: I am Switching from ABS to PLA for tall items
September 14, 2014 11:22PM
I love printing in PLA - I find it much more forgiving. The ONLY gripe I have is it's low melting point. That makes it useful for printing, but limits where the final object can be used. The only time I print in ABS is when the part needs to withstand higher temps.
Re: I am Switching from ABS to PLA for tall items
September 14, 2014 11:36PM
im also one of those people who prefer PLA..
I hate the smell of abs.. i prefer to print at higher temps to ensure each layer is bonder.. but there is that fine line when to hi will cause warping if used without a chamber
I remember once printing in nylon... It was a model of a head.. zombie hunter if my memory serves right..
Woke up in the morning..the print split right down the center, this happened at the end of the print... I should of taken a picture because its like someone sliced it cleanly with a blade..
looked cool but ruined

if i want to print like a model.. or something that just needs to look good.. i love how shiny pla is when you print it at low temps

Edited 2 time(s). Last edit at 09/14/2014 11:37PM by nechaus.
Re: I am Switching from ABS to PLA for tall items
September 15, 2014 02:56AM
The two are simply to different to make a general decision. For mechanical stuff i will always prefer ABS, for many other things PLA is ok.
You should decide according to need not personal preference.


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Re: I am Switching from ABS to PLA for tall items
September 15, 2014 06:03AM
Quote
Srek
The two are simply to different to make a general decision. For mechanical stuff i will always prefer ABS, for many other things PLA is ok.
You should decide according to need not personal preference.

Exactly. And that is how I am going to treat them. I make parts for machines I sell and those need to me more mechanical and need strength so I will continue to use ABS for those. I will use PLA for more decorative items or tall thin prints.

I am going to build another heat chamber for this printer when I can find some time.

Interesting note: Tonight after the PS mount (printed perfect by the way) I decided to print a little loose filament spool (I bought the PLA 1lb loose roll in a bag) and the fork ends started to lift about 1/4 way through the print. I think I forgot to put the glue stick in the spot or something. I just decided to let it finish and figured I could print a new fork when it was done with the rest of it. Well an hour later I checked on it and the for was stuck back down and looked perfect beside a small flashing that can be easily removed. I think the nozzle just kept pushing it down and so it kept printing it and as it got thicker it got stiffer so it stayed straight. That's my theory anyway.
Re: I am Switching from ABS to PLA for tall items
September 15, 2014 03:57PM
I'm curious - many people talk about using ABS for stronger parts, but PLA is actually stronger than ABS. PLA is also stiffer and has less shrinkage (for better accuracy), so aside from the lower operating temperature, it would seem that PLA is better for most low-temp mechanical applications. ABS does have a higher impact strength (better for a phone case that gets dropped), but many (most?) mechanical things don't get beat on with a hammer. It's also easier to get higher strength layer-to-layer adhesion with PLA. I get the feeling that ABS is popular because it has the aura of being an "engineering" plastic.

If I need something that's tougher (greater deformation before breaking) and has a higher operating temperature, I'd rather use nylon. The Taulman Bridge filament I tried prints up pretty easily and has excellent layer-layer adhesion.
Re: I am Switching from ABS to PLA for tall items
September 16, 2014 07:25AM
Quote
LoboCNC
I'm curious - many people talk about using ABS for stronger parts, but PLA is actually stronger than ABS. PLA is also stiffer and has less shrinkage (for better accuracy), so aside from the lower operating temperature, it would seem that PLA is better for most low-temp mechanical applications. ABS does have a higher impact strength (better for a phone case that gets dropped), but many (most?) mechanical things don't get beat on with a hammer. It's also easier to get higher strength layer-to-layer adhesion with PLA. I get the feeling that ABS is popular because it has the aura of being an "engineering" plastic.

If I need something that's tougher (greater deformation before breaking) and has a higher operating temperature, I'd rather use nylon. The Taulman Bridge filament I tried prints up pretty easily and has excellent layer-layer adhesion.


id have to disagree, PLA is more stiff and rigid, but overall tensile strength ABS is stronger..
PLA is easier to get each layer bonded well at lower temps which also help with less warping..
ABS printed at hi temps with a heated bed and chamber with zero warp makes stronger parts..

This is based on my personal experiences...

I just love printing with PLA, lower energy foot print, less toxicity, easy to print with, Strong enough for most of my projects including full PLA multi rotors that hold up well...
Re: I am Switching from ABS to PLA for tall items
September 16, 2014 10:45AM
As a lover of all things PLA, and for my first year of printing being exclusively PLA, I can also attest to PLA's lack of real robustness compared to ABS. There's a real reason that ABS is an "engineering plastic."
I'm hoping on PETG coming into my favorite supplier's line, as I trust them to set extremely high quality standards on everything, without the hefty price. PETG is superior in both the printing and the strength aspect, each better than PLA and ABS respectively [from what I've read from others]. When the price isn't twice that of PLA it should become more common and in more colors than white and translucent.

To keep with OP, PLA does seem to be much better at printing tall objects, it works consistently all the way up where the furthur you get from the first few layers with ABS whatever lack of compensations you have will be exaggerated beyond the initial warping/peeling.


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Re: I am Switching from ABS to PLA for tall items
September 16, 2014 11:47AM
One thing that might be getting lost in the mix is the difference between yield strength and tensile strength - yield strength being how much force can be applied before the material is permanently deformed, vs. tensile strength being how much force can be applied before the material breaks altogether. Most casual tests of 3D printing materials have all been a breaking strength tests - usually in bending. But if you look at the piece of material that "wins" the test (whether it's ABS, Nylon, PET, etc.) it is hopelessly deformed. Not breaking altogether is certainly important for lots of applications, but when I'm designing most mechanical parts, I'm looking at the yield strength because I don't want any permanent deformation.

One important plus for ABS, which is a large part of why it makes a good engineering plastic, is that it machines nicely. PLA is pretty horrible for machining. Outside of maybe cleaning up holes with a drill or tapping holes, modifying 3D printed PLA is usually a mess.

EDIT: Here's some interesting data on PLA and ABS:
ABS data
PLA data
One thing to note is that PLA seems to have more variability in its properties than ABS. That would be another cause for differing opinions about the two materials.

Edited 1 time(s). Last edit at 09/16/2014 01:34PM by LoboCNC.
Re: I am Switching from ABS to PLA for tall items
November 15, 2014 08:50AM
I'd like to know the machining ability of the PET's too. Here other PET info:

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