Things you should know about PLA

Things you should know about PLA

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!

 

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 anyway 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! Make sure to get subscribed and to enable the bell notifications so you don’t miss the rest of this series, click like if you liked this one, and if you want to support this channel directly, check out the affiliate links in the video description or donate directly on Patreon.

Thanks for watching and I’ll see you in the next one!

 

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