PLA!
Everyone knows it, everyone loves it, right?
Kinda?
Talking to filament manufacturers, it’s obvious that PLA is the number one most-used
filament by quite a margin.
For many people, it’s the only material they’ll ever print - and that’s ok!
Let’s talk about the best practices when printing PLA, how you can use and process
the parts and what choices you have when buying it!
[Intro] So PLA is a really good standard choice for
our maker-level 3D printers mostly because, well everyone else is using it, too.
Most machines are optimized specifically for PLA and the profiles for PLA are usually the
best-tuned ones.
Still, PLA is easy to print with relatively low temperatures, it will stick well enough
to most bed surfaces except maybe raw aluminum or bare PCBs, and it’s actually mechanically
quite strong!
Especially with PLA, though, I would recommend oversizing mechanical parts by a bit because
some grades of PLA like to develop stress cracks over time, just like laser-cut acrylic
does, and it will also deform under continuous pressure like under a tight screw head and
basically very slowly flow out of the way.
It’s also probably the material with the lowest usable temperature, so PLA is definitely
not dishwasher or even sunshine-safe, but that’s also what keeps it from warping during
a print.
And that same property is also what practically requires you to use a part cooling fan when
printing it to get crispy and clean prints - you can get away without a fan, but there’s
even still a visible difference between an okay fan shroud and a really good one that
gets cool air onto your freshly printed layers from every side.
It’s actually pretty hard to get too much cooling onto your PLA prints, short of using
an air compressor and blowing the print off your bed.
With enough cooling, it’s possible to print PLA at pretty mind-boggling speeds by slightly
increasing the hotend temperature or using a high-flow hotend, but typically, your printer’s
mechanics are going to run into issues like ringing and step loss before you get limited
by the melt rate of PLA.
Bowden setups help tremendously here!
Ok, so here’s how you can tune in PLA for best results: Starting with the print temperature,
which PLA is actually quite lenient about.
Smack middle in the manufacturer’s recommended temperature range is a good starting point,
and while most PLAs will print well at 210°C, there are some significant differences between
different grades of PLA.
Some print best at 180°C, others can easily be pushed up to 230°C without any major downsides!
Always keep in mind here that no two temperature measurements between two printers are going
to be identical - printers can easily have an offset of 10° or more even if they display
the exact same temperature, so what works for another user doesn’t necessarily have
to work for you as well.
If you’re seeing curling or melting artifacts, first try increasing the fan speed to full
blast after the first layer - if it’s already at full speed, you’ll need to either slow
down the print or reduce temperatures.
By the way, slowing down a print is almost a universal guarantee for better prints, and
it’s no shame to drop down all the way to 40mm/s.
Most printers claiming much faster speeds won’t reach them anyways because they can’t
accelerate fast enough, so, yeah, what is even the point in trying.
Though the bigger impact will be print and bed temperatures.
If you see curling artifacts like these in the first few centimeters of your print, chances
are all you need to do is drop the bed temperature by 5° to keep them at bay.
You don’t want to melt your print with the bed, you just want to keep it at a comfortable
temperature to keep it from warping too much!
As long as larger prints still stick, there’s no reason to use your heated bed at higher
temperatures.
The good thing is, the default print profiles you get for your specific machine will usually
be pretty good already - unless, of course, you cheaped out and went for a manufacturer
that doesn’t even know how to use their own machines.
In that case, the best thing to do is to start with a “known-good” profile meant for
a similar machine and start making small corrections from there.
PLA is a great choice for accurate parts, but also decorative stuff, props, really,
anything.
It’s quite easy to work with, since almost all adhesives will work well, ranging from
superglue over epoxy to hot glue - but be careful with hot glue, as using too large
of a dab in one spot will soften and deform the PLA underneath.
What also works really well is solvent-welding with acetone, it creates an incredibly strong
bond between two parts and doesn’t add any extra thickness to the part.
You can also easily drill, file, saw and mill PLA parts, but again, be careful that you
don’t melt the part, so go slow and use water, alcohol, WD-40 or proper cutting fluid
to keep your tools cold.
For drilling or tapping, simply let your tool cool off between holes and you should be good
to go.
PLA is also super easy to paint and you don’t need any specialty paints for it, the standard
automotive rattlecans or modelmaking paints work perfectly.
Just make sure your part is clean before applying primer or filler, and if you need to sand
it, go for wet sanding as, again, it will keep your part nice and cool.
Now, you might have read that some PLA colors will always have their own printing properties,
so like “yellow PLA will always droop more than blue one”, but that’s not really
the case.
If a manufacturer used the same base resin for all colors, the differences should be
marginal between each one.
But if e.g. the yellow colorant does influence properties, for example because the colorant
itself absorbs more moisture than others, you might be able to observe that same behavior
across many different filament brands.
Why?
Well, there are only like three or four “big” manufacturers that supply most of the smaller
brands with white-label products, so it is actually the same stuff you’re using with
a different sticker on it.
I’ll say don’t worry about the exact filament color too much and just get ones that you
like - and you can never go wrong with a bright, screaming pink, right?
PLA has an enormous range of colors available from translucent ones to fully neon vibrant
ones to glow in the dark and even some fiber-filled types.
Though for the last two you’ll definitely want to use a wear-resistant nozzle.
Most PLAs can be even be printed to a glossy or matte finish just by changing the temperature
or print speed!
The newer “PLA+” types are a PLA blend with a modifier mixed in, and they behave
drastically different from normal PLA.
Except for the shiny look - which I absolutely adore - there are no true real-world advantages
to them, since PLA+ typically prints worse than standard PLA and parts come out weaker
overall.
Alright, that should cover PLA pretty well!
if you have any tips to share, leave them in the comments below or discuss them in the
forum!
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