Considering a 3D printer

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ABS is more flexible/resilient where PLA is brittle and hard. (There are some newer formulations of PLA that are less brittle.) ABS also tends to be a a little more forgiving of ambient conditions (PLA will absorb humidity like nobody’s business and the resulting prints will suffer serious quality problems. So you have to keep it in a sealed container next to silica gel or else print only during the winter :unamused:)

ABS stinks and warps, but it also captures detail in ways that PLA won’t, because ABS solidifies very quickly after extrusion while PLA stays softish unless aggressively cooled (which can cause other issues). Also the temperature resistance thing can be a big deal: most PLA softens around 60C (which is useful for shaping with hot water but a pain if you leave it in the sun). I’ve got an ABS spoon handle that’s gone through the dishwasher countless times and still looks as good as it did when I made it.

ABS can also be smoothed with acetone for some cool results.

As @Jules and @markevans36301 have said, PETG is seldom mentioned but really pretty wonderful. Durable, flexible, easy to extrude, blah blah.

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I can’t agree with that. PLA simply become very runny at ABS temperatures and is flushed out well before it can carbonize. Even if you had some very sensitive PLA, the minimum temperature you can extrude ABS at overlaps PLA extrusion temperature. E.g. ABS can be extruded at 220C (it won’t bond well but it will pass through the nozzle easily enough) and PLA can make objects at 220C but tends to be a bit too liquid to bridge well, etc.

Having said that, PLA is the easiest material to cold pull and that leaves the nozzle empty.

ABS is fundamentally different in that it doesn’t really melt. It is extruded above its glass transition temperature and is more paste like than liquid. The upside is it is very well behaved while it being laid down but the downside is it doesn’t bond as well as PLA.

And some natural white ABS doesn’t stink, although most does.

Another downside of PLA is it creeps. I.e. if you tighten a screw down on it then it won’t stay tight because it slowly deforms under pressure. It is great for aesthetic objects but doesn’t have very good mechanical properties.

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PLA (which is nothing more than sugar) carbonizes at higher temps and burns onto the nozzle. Just like burnt sugar on a baking sheet is impossible to remove without physical force. As it does, it gradually reduces the ID of the nozzle.

Some few people print ABS at the lower ranges…most of the folks I know print it at 245°C or so, which does carbonize PLA. We tell folks to run some cleaning filament through between filament types to keep them from having to replace their nozzles every few months, because they switch back and forth between temperature ranges a lot with a single nozzle. We have fewer problems with PLA when we print it at the lower end of the range as well - anywhere from 190°C to 210°C. Fewer warping and slump problems on overhangs.

But your mileage may vary… lots of ways to use a 3D printer.

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Such a cute groot!

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I agree with most here. I don’t find ABS to be too stinky when printing and I do like the way it can be vapor smoothed - some acetone in the bottom of a crockpot and the printed piece on a stand above the liquid lets the vapor smooth out the layer striations. You can get nice shiny & smooth parts that way.

PLA is non-toxic (ABS is said to be toxic when extruded but safe when solidified) so some people prefer it for things kids might eat (even if they’re not supposed to). ABS is stronger and as others have noted, more temperature resistant (PLA can soften not just in the sun but in a hot car in the summer).

If you get an ABS capable printer you can print PLA too but not always vice versa. ABS requires a heated bed, higher temps and an enclosure. PLA can be (and usually is) printed on an unheated bed without an enclosure so it solidifies faster and doesn’t droop while it cools. You can add a cooling fan to the the extruder head so it cools quicker.

I make prosthetic hands out of ABS or nylon for adults but PLA for younger children due to the toxicity fears (they’re not founded but it’s not something that you can change) and since the kids switch out of them pretty fast, its durability isn’t a problem.

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I use a glass bed wiped with an Acetone/ABS wash. The same mix I use for gluing parts together. It works so much better than Kapton tape I can’t even tell you. The only adhesion problems I have had since switching over are because I failed to level the bed, or missed an are when reapplying fresh wash. Another advantage is a glass smooth bottom print.

When the print is finished you cannot pull the part off of the glass, but as soon as the glass cools it pops right off. It almost sounds like the glass is breaking sometimes.

Has anyone mentioned that printing ABS requires a heated bed?

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Certainly does. I print ABS at 255C and PLA at 185C and use 220C to switch between them. PLA gets flushed through long before it carbonizes. It becomes very liquid, so the much more viscous ABS flushes it easily. It is more difficult going the other way.

Both ABS and PLA will carbonize if left at their extrusion temperature for long enough. They glaze the nozzle and can reduce its orifice over time. I check the diameter of the extrudate from time to time and ream the nozzle if it is too small because bridges start to sag.

And it is an oversimplification to say PLA is simply sugar. It starts as starch and is converted to lactic acid before it is polymerized. At the end of the day it is a hydrocarbon with some oxygen and ABS is a hydrocarbon with some nitrogen. They both leave a hard black residue when the more volatile components boil off.

There are big differences in hot ends and filament from different manufactures, which is why people’s experiences vary so much. I prefer PTFE lined hot ends for PLA and that probably makes them easier to flush. And most of my experience is with the original type of PLA from Natureworks.

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Most beginners do not want to have to ream nozzles, do cold pulls, and have to continue to re-configure their extrusion rates as the nozzle diameter is reduced. (Much less hit a nozzle with a blowtorch.)

It’s obvious you’ve been doing it for a while and have a process that works for you. We found that if you run the cleaning filament through it, (which takes about a minute or two between filaments), you don’t get that glazing build-up over time. Making it unnecessary to do all those clean-up operations, which required disassembly and re-assembly of the hotend, and re-calibration of the Z-gap at the end of that to boot. (PITA)

I used the same nozzle for over a year before eventually switching to a dual, (for other reasons), switched filament types practically every other day (testing) and never had a clog, never had a build-up, and the extrusion rate remained perfectly consistent. We were trying to find the easiest method for beginners to use. (Experts who don’t mind taking the machine apart might prefer to do something else if they have a higher technical skill level.)

You know that filament (and nozzles, and machines) can vary quite a bit between manufacturers, and that there is no “one-size-fits-all” procedure for 3D printing. But most beginners don’t realize that before they buy, so we wanted to give them the easiest way to prevent problems.

Actually, nowadays the nozzles are so cheap it’s probably best to just replace them. (Make it a disposable item and get on down the road.) :slight_smile:

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Is that only between two types of filament, or between spools of the same type?

At peak kit production I was getting through a 2.2kg spool of filament per machine every five days. That meant I was changing spools on at least one machine most days. It would have been a PITA to run cleaning filament through. Probably not a bad idea when changing filament types. Large commercial extruders do that, but I have got away without doing it for nine years and never blocked a nozzle by changing filament types.

In fact, I don’t suffer from blocked nozzles at all nowadays, touch wood. The last time was when I got a faulty batch of filament with particles in it a few years ago. That is very rare these days from reputable suppliers.

Usually I can fix a jam with several cold pulls and pushing a drill shank up the nozzle. If that doesn’t fix it it means the PTFE liner is damaged. Sometimes the massive over-pressure bursts through the side of it.

I don’t dismantle them and certainly don’t attack them with a blow torch. It is so rare a problem that I would simply replace the whole hot end as I figure it owes me nothing after continuous use for some years.

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No, not between spools…just when you switch from one filament that prints at a really low temp like PLA (or the wood derivatives, PVA, etc.) to something that melts at a high temp like PETG, ABS, Polycarbs, etc.

Everyone tends to start with PLA, and there is always some filament left in the nozzle when you switch filaments. (Usually a purge before starting a new print with a different color shows a little bit of the previous color left in the nozzle that comes out first.)

If you’ve left some low temp filament in there and suddenly up the temps really high for a different kind of filament, yes some of it runs out, and some of it bakes onto the inside of the nozzle. Those little flakes of carbon can either build up if you keep doing it, or they can sometimes flake off and get stuck in that absolutely minuscule nozzle opening, causing a full or partial clog.

Cleaning filament has the unique property of being able to melt at both low temps, and at high temps without charring. So we push the remnant of the low temp filament out with a short length of cleaning filament, (which pushes out that leftover bit), then raise the temp to the second filament printing temp and feed in the high temperature filament, and push out the remainder of the cleaning filament, which took the place of the low temp filament in the nozzle.

Just another way of doing it. I’ve only ever had one actual clog, and that was early in, before I started using the cleaning filament. (That was on a V3B nozzle too - the newer V4s and V5s make it a lot easier to just switch the nozzle out, so if I were still printing with a single, I might not mess with it either.) :relieved:

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You seem to assume that because a filament needs a high temperature to extrude, you cant extrude it a lower temperature. I have not found that to be true as the high temperature is needed for bonding, not to get the viscosity low enough to extrude. Perhaps something like PEEK or PTFE filament would have no common ground with PLA but most things will melt enough to extrude at 220C and PLA is fine at that temperature.

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Usually I have different colors of different filament types, so it’s pretty clear when the old stuff is all out of the nozzle. (And then you go for a while longer.) I’m also using a PLA that claims to extrude at 230 (I go 220-225), so there’s less of a difference in temp between that and ABS or PETG.

PETG is fascinating because it behaves quite differently depending on temp and extrusion speed. If you extrude into free air very quickly at low speed the filament will shrink linearly and expand in diameter while becoming seriously translucent. (E.g. a 0.4mm nozzle produces a 1mmcooled filament.) It bonds OK that way. If you crank the temp up and slow down, you get something very nearly transparent and very strong. (I’ve had fun doing vase mode with a 0.75mm nozzle.)

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Ok writing all this stuff down…when I’m done printing, do you have to run cleaning filament at the end too. Or when changing colors, does the color bleed into the previous or should I clean it out first…so much stuff to learn…lol
Weird not having to figure all this stuff out on my own like I had to do with my first laser

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Okay, apparently I don’t clean my nozzle as often as I should.The only time I use cleaning filament is when I have symptoms of clogging.

When I change types I just run the temp. up to 200c and push through the new until I just have the new flowing.

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I used to run it before putting the next type of filament on. With PLA, (esp.if you live in a humid area), you will want to retract the remnant when you are done printing and store the spool in a bucket with desiccant when you’re not using it. (To keep it from getting brittle over time.)

I would remember what I printed last, so that worked. If you just finished printing PLA, and are going to print PLA again the next time, you don’t need to run cleaning filament. Most of the time, unless you are specifically testing for something, you’ll tend to print with the same type of filament anyway.

If you’re going to be around when the print finishes, and you don’t mind doing it then, and you know you’ll be printing something different the next time, you can run it after you finish a print. But I wasn’t always sure what I’d be printing next, so I tended to wait until I knew I needed to run it.

Just once between each set of filament “types” is fine, either after finishing the last or before starting the next.

And you’ll want to learn to print just one type of filament first…every type has it’s own quirks and vastly different print settings. If you only print PLA, you don’t need to worry about cleaning filament. (Or only ABS.)

Yes, there will be a little bleeding of colors…you can purge a little (just shoot a little melted filament into thin air, then remove it, before beginning the main print), to clear the remnant in the nozzle.

Or you can get some really neat multiple color effects by just feeding one color in after another and let the print continue uninterrupted.

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Or you can pause the print and switch colors but that is a little trickier if you are shooting for accuracy. (Might require getting into the code and making a change depending on the printer you are using. I’ve got a write-up for the process on the M2, but I’m not sure it would work on other printers. You’d be able to get a lot closer than chasing filament though.)

Both of the multi-color prints shown above were done with a single nozzle printer. The second method is much more accurate, but a bit more of a hassle to pull off.

Anyway, you’ll have lots of time to get into things like that once you get the machine. And it’s different for every printer, so you don’t have to write all of this down right now. :slight_smile:

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This thread has convinced me that I don’t have the time to learn 3D printing right now and should hold off on even thinking about getting one for a while.

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I love my dual nozzle dual material Robox printers for dual color or complex models. I use PolySupport with the second nozzle and it just peels off most of the time. I also don’t have to worry about all that cleaning stuff. I bought cleaning filament about a year ago and haven’t touched it since. If I want to clean out a hot end, I just run a little Taulman Bridge and it seems to take care of it.
@cdw You may want to look into one of the more advanced printers like the Robox. A lot of the daily tasks are automated and as along as you are willing to give up a little control for the convenience it is worth it. I use four of them on a daily basis. If I had to worry about clogged nozzles, cold pulls, blown liners, and the like I wouldn’t be able to keep up enough throughput to keep my customers happy.

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You don’t pick up all of this stuff at once…it’s like anything else…the more you play with it, the more fun it gets. Don’t let it put you off…they’re a stone-cold blast. :relaxed:

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Agreed! PLA+ is an amazing easy filament to work with, and eSun has the advantage of being really inexpensive. I just ordered two more spools from Amazon for my next e-NABLE hand recipient. Well worth the extra $3 per roll over standard PLA.

Have you used PLA/PHA blends? I’m curious about printability as well as the durability of the prints.

Btw, checked the logs on my freshly-upgraded UM2+ printer this morning – it’s used just over 2.6km of filament in about 2,200 hours of printing since December of '14. :sunglasses:

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Something was lost in translation. Get a Lulzbot or several other reliable printers and you can have useful prints the first day! Like every smart tool you learn from there.

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