How To Succeed When 3D Printing With PLA Filament
For years PLA 3D filament has been the top dog in the 3D printing industry; it prints easily, is available in a huge variety of colors and effects, and can be printed on virtually any 3D printer. Being successful with PLA is an essential skill to develop as you are likely to stick with PLA for most of you're projects until you find yourself working on more demanding use cases. PLA is great for demonstration models, jigs, fixtures, your average around-the-office 3D print, or even full-body costumes, so let's jump into what you need to know to perform at your best.
Table of Contents - Jump to PLA 3D Filament Help Topic You Need
- What is PLA Plastic?
- Hardware Requirements To 3D Print With PLA
- Hotend Requirements To 3D Print With PLA
- Bed Requirements To 3D Print With PLA
- Changing PLA Filament
- Getting the First Layer Right
- What to do When Things go Wrong - PLA Filament Troubleshooting
PLA or Polylactic acid is a thermoplastic polyester. It is commonly derived from renewable resources, such as corn starch, tapioca roots or sugarcane. One of the most attractive things about PLA plastic is that it is industrially compostable, which means it can be broken down back into its base elements through industrial means, and not through a ten thousand year lifespan (note, composting in a compost bin is not the same as industrially compostable). It is important to point out that although PLA is compostable it is very robust when used in any normal application such as a 3D printed jig or a manufacturing prototype.
PLA plastic is used in many industries from food packaging to biodegradable medical implants such as sutures, tissue screws, and tacks. When used as a 3D printing material, it is almost always the introductory material as its printing properties make it well suited for a complete beginner. A majority of 3D printer users will have experience with PLA in one way or another, from end-use products to general prototyping.
PLA filament is an attractive material for newcomers as it's tough, available in a huge variety of colors, and be easy to print on basically an 3D printer. PLA is less thermally contractive which means it hardly ever warps and is very dimensionally stable, making it much easier to print big parts with and rely on the print being as close to the 3D model's dimensions as possible. The thing to consider is that being stiffer and harder also means that it is more brittle; if the part you're printing will be used where it might receive a lot of sudden impacts or sharp collisions, PLA has a tendency to shatter during failure.
The other important consideration when printing parts with PLA filament is knowing what sorts of temperatures the part will be subjected to. PLA plastic becomes soft as low as 50°C and will deform rather quickly in this rather limited heat. This is why you should avoid PLA when you have a design that will be exposed to heat, even as little as the heat inside a car on a summer day. At MatterHackers we generally use PLA filament for all our educational models, test-pieces, and quick-turnaround prototypes, as they aren't going to face any stressful scenarios, they just need to look beautiful.
As PLA is a rather undemanding filament, there isn't a lot you need to consider for your 3D printer to get it up and running and printing PLA. On average, 200°C is an excellent place to start printing PLA, but some brands and even colors may need you to adjust this hotter or cooler, depending on their individual makeup. Wood-filled PLA tends to clog easier when you have the temperature too high, so dropping it even as low as 180°C is a rational decision. Some black or white filaments use additives that take a bit more heat to flow nicely and may need as much as 220°C to print well. Essentially, start with 200°C and play around with 5°C higher or lower to find the ideal print quality for you.
With such a (relatively) low printing temperature, PLA does not require an all-metal hotend (a hotend that uses a thin walled heatbreak to keep heat in the heater block and away from the heatsink) and will work just fine with a PTFE-lined hotend (where the PTFE tube passes all the way through the heatsink and butts up against the nozzle). However, if your printer already has an all-metal hotend, don't worry as it's still perfectly compatible with PLA.
In general, PLA is non-abrasive, but once you start playing with additives it becomes a case-by-case basis. Sparkly filament isn't abrasive despite having non-PLA material in it, but glow-in-the-dark filament is abrasive as the additive that glows will wear away at your nozzle before you're through even one spool. Wood-filled PLA doesn't tend to abrade brass nozzles, but often a 0.6mm is necessary to prevent the wood particles from clogging the nozzle. An easy way to avoid these concerns is to swap over to an Olsson Ruby nozzle or a Nozzle X when you want to use these materials.
Layer cooling is a must for PLA, in fact, there's no such thing as "too much" cooling when it comes to PLA. Many other filaments' only requirement for the cooling fan is for it to be turned on for very short layers, but can stay off the rest of the time. PLA stays soft considerably longer than other materials so your fan will spend most of its time at 100% power, and even then some models print better when printed in pairs so there is enough time for the extruder to move away from the part and give it time to cool.
Right off the bat, PLA doesn't actually need a heated bed. Of course, having a heated bed will only makes things easier, but you can get by without one as long as you have the right bed surface. If you do have a heated bed, around 60°C is a good place to start and then you can adjust by 5°C in either direction to get the adhesion you need. Some bed materials need more heat than others for PLA to stick, so experiment until you feel happy with your results.
As for the bed surface itself, you have quite a few options to work with: glass, Buildtak, Buildtak PEI, GeckoTek, Wham Bam PEX, or LayerLock Powder-Coated PEI are all viable options for your 3D printer's bed surface, and keep in mind that's not an exhaustive list, just the big players. Let's take a look at each surface individually:
- Glass - If you want a glossy smooth bottom to your 3D prints, this is the way to go. Often you don't even need adhesive to get PLA to adhere to bare glass but a little bit of adhesive solution can help lock the print down.
- BuildTak - An adhesive sheet you can apply directly to your 3D printer's bed or on top of a Flexplate. No adhesive solution necessary, simply wait for your bed to cool and use a BuildTak spatula or twist the Flexplate to remove your print.
- LayerLock Powder-Coated PEI - A textured, flexible build surface that can add a unique look to your 3D prints. Make sure you already have a magnetic system in place for this to work properly and consider a quick smear of glue stick to help the PLA stick down solidly.
- BuildTak PEI - An adhesive sheet you can apply directly to your 3D printer's bed or on top of a Flexplate. Basically magic. Sticks solid when hot and pops off with a gentle tap when cool. You may need to bump the temperature up slightly to get enough adhesion to stick (near 70°C should be plenty).
- GeckoTek - An adhesive sheet you can apply directly to your 3D printer's bed or on top of a Flexplate. Available in both a hot and cold variant to better suit the capabilities that your 3D printer has.
- Wham Bam PEX - An entire flexible bed system adhered to the 3D printer's bed. A strong magnet keeps the spring steel with an adhesive sheet of PEX applied to it secured to the printer's bed during the print, but can be easily removed and flexed to pop your print off.
There are always new and exciting methods for bed adhesion being developed, so it's important to have a good grasp on what each method is best used for. You can check out our 3D Printing Essentials article about bed surfaces to fully understand the pros and cons of every bed surface you might come across while 3D printing.
In addition to build surface upgrades, there are also a wide variety of 3D printer adhesives that you can apply to your 3D printer's bed to get a great first layer. These adhesives are specifically developed for the 3D printing industry, so you can trust they have been tested to be tried and true 3D printer adhesives. Here are the best 3D printer adhesives that you can use to get the best first layer for PLA filament:
Most 3D printer bed adhesives have the same instructions for use: apply a thin layer to the build surface where your actively 3D printing. Then, wait for your part to cool before removing - waiting for your 3D printed part to cool makes it much easier to remove, and certain adhesives will sometimes even "pop" the part of the bed once cooled.
When switching between two PLA spools and colors:
- While the extruder is cold set the heat to 120°C and wait for it to heat up.
- When you reach 90°C, start pulling on the filament until it finally gives out and pulls all of the filament from the nozzle in one long, stringy strand
- If you are having trouble removing the filament, it's okay to raise it to 200°C and deal with purging more filament to compensate.
- Increase the heat and load the new filament normally.
- Run the new color through the extruder until it runs clean and the new color is all that is coming out of the extruder. If you are switching from a dark color (such as black) to a light color (like white or natural) run a while longer to be sure you don't have any dark contamination. Without this step it's possible to be a couple layers in and have the last bit of filament finally purge out.
The first layer is the most important part of any print - it sets the foundation that the entire print builds on. You can check out the in-depth article on how to get a perfect first layer here, or for a brief summary of what to consider below are the few things you need to do to get the first layer to stick well.
- You need the print bed to be level.
- You need the nozzle to be the correct distance from the bed at the start of the 3D print.
- You need a good base material for your PLA to adhere to.
Below is a video from MatterHackers' 3D Printing Essentials series that will help guide you in the right direction for getting a stellar first layer. In this video, we'll walk you through the steps mentioned above in detail so you can succeed when 3D printing with PLA filament.
There are a few key things to check when your prints aren't working. But before we look at solutions we need to have a brief description of your symptoms.
"I can't tell if my printing temperature is right"What to Look for if you are having trouble getting your PLA filament temperature right:
- If the temperature is too high
It's hard to say there is truly a "too high." The biggest thing you may notice is that your overhangs droop considerably and that you have some extra stringing between the separate parts of your print as the extruder leaks out a little bit of plastic while moving between separate areas of the print. Improving the ability of the 3D printer's layer cooling can help with your overhangs, and adjusting the retraction settings can remove the stringing. Additionally, in general the hotter you print PLA the glossier the 3D print becomes. If you have the best layer cooling and you know your retraction settings are well tuned but you still have issues, then it's time to try bringing the printing temperature down 5°C at a time.
If the temperature is too cold
You will either see that the filament is not sticking to the previous layer and you are getting a rough surface (like the picture below), or you will get a part that is not strong and can be pulled apart easily. In either case, you should increase the temperature by 5°C and try again until you get consistent extrusion and layers that fully adhere to each other. In contrast to printing too hot, the colder you print PLA the more matte it will be.
"I can't get the first layer to stick."
- Make sure the nozzle is at the right height.
Check out the 3D printing Essentials: Bed Leveling for what to look for in an ideal first layer.
- Make sure the print bed is level.
Check out the 3D printing Essentials: Bed Leveling for best practices when leveling your bed. If part of the bed is too far from the nozzle and the other part of the bed is too close, filament can drag around and create compounding problems.
"The part has bad internal layers and top surfaces."
- Check the temperatures.
Make sure you’re printing at the right temperature and that your bed is the right temperature. Too cold on either of these and there won't be enough adhesion between the two surfaces.
- Check the filament tension.
Too loose and the extruder gears won't have the bite they need to push the filament around, too tight and filament can be deformed and not extrude reliably.
- Clean the filament drive gear (if it looks clogged).
If you had a print fail where the job continued but no filament was being extruded, then the drive gear likely chewed a spot in the filament and filled its teeth with filament, reducing its overall grip.
"The outside edges of my parts have lots of little bumps on them."
- Make sure your printer is getting enough data.
If printing from a computer, ensure that the computer is not too busy to feed the printer commands. If the printer is pausing it is usually due to the printer being too busy.
- Print from SD card.
You can get around this by printing from an SD card. Sometimes this means you lose the ability to control the printer from your PC, but its a guaranteed way to remove your PC's hardware capabilities from the equation.
- Source better PLA.
We have found that the quality of your print material can have a big impact on the quality of your part. Getting better PLA can help you get better parts. However, don't be too quick to assume the problem is in your PLA. With the right settings and patience hobbyists have succeeded in printing all sorts of materials many of which have very low viscosity and inconsistency. You should be able to get at least usable parts even with some lower quality filament.
- Your retraction settings need tuning.
If your retractions settings aren't set right, your printer could be overextruding after each retraction leaving little bumps at the location where it started extruding again. Play with the "extra restart distance" and see if that helps.
"Tall sections of my prints look melted or squished together."
- Turn on "Cooling".
If your printer has a fan you should enable "cooling" in the print settings. With PLA this should be at 100% at all times except the first layer
- Print more than one part at a time.
By adding more parts to the build plate you are increasing the overall cross sectional area of each layer, giving more time for the separate objects to cool than if they were printed on their own.
"My printer will not put out any material."
- Make sure your hot end is getting hot.
Check that the hot end is heating at all. If it is not you need to have your printer serviced. It is likely that you have a loose connection or your electronics have been fried (assuming the printer is still connected and responding to your host software :).
- Clean the drive gear and adjust tension.
The first thing we are going to do is clean the filament touching drive gear and ensure that we have proper tension against the filament. Usually improper tension or a clogged drive gear will make the print look more like the picture we have for low temperature filament, but it sometimes does prevent extrusion all together. Clean the pinch wheel with a wire brush, and make sure your tension is good and solid (too much can also prevent extrusion and is more common with direct drives [the motor is directly connected to the drive gear] but less common with geared drives).
- Remove the current filament.
It may be that you have a small particle in your extruder tip jamming the plastic. Use the change filament technique described above to pull out any particles that are in the extruder tip.
- Check for and remove jams between the extruder and hot end.
This is the most extreme type of problem because now it is time to take things apart. Sometimes heat can creep up the filament in the extruder and cause a bulge that then cools and prevents any further extrusion. This is usually at the junction between the extruder and hot end. Take off the extruder and remove all the PLA you can (you may need the hot end hot (80c-100c) to get all the material out. If you can't get out all the filament by pulling it out you may need to try and drive it down through the hot end. We usually use a small allen wrench. If this fails you can try and drill out the extruder or hot end but you may need to replace parts. Be sure to take precautions against being shocked or burned. If you are not qualified to do this work find someone who is, rather than risk injury.
Thank you for reading How To Succeed When Printing In PLA.
If you have any comments or contributions, please drop us an email or give us a call. We are always looking for tips, and best practices - and would love to hear from you. Feel free to reach out with any specific questions on the MatterHackers Forum.
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