Consistent material flow is one of the most common issues with getting consistent 3D prints, and we have some real practical suggestions and an overview of several things that can affect your print quality. What can you do to maintain that? It’s tough because there are so many variables that it is sometimes hard to identify what it is. If you have material flow that is too low, you end up with little gaps around the perimeter of your part.
I would say consistent material flow is one of the most significant problems, and it’s also one of the hardest as a new user to identify that that is the problem. People may be too quick to say it’s bad material, but it could be bad settings, right? Settings is part of it, but it also comes down to things you can affect in how you operate your machine and how you insert your filament. There are a number of things we are going to go over quickly.
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Maintenance Tips for Consistent Material Flow
One of the most basic things that I learned early on—because I change colors a lot for different parts, I don’t just put one spool of filament up there and let it go—if you are a new user, you want to pay attention to this—is to take a spool that you started using out of your printer and store it. You have to make sure that the end of that filament is properly captured and it doesn’t unwind a little bit. What you find happens all too often is if it unwinds a little bit and you tighten it up and fix it in place, oftentimes the end of the filament will have gone underneath the loop of another piece of filament, and then it gets tangled. Then it’s like pulling back on it. It’s resisting the filament drive gear feeding that filament. It can impede your filament flow for sure. It’s basically counteracting what your motor is trying to do. It’s expecting some natural resistance due to gravity, but not much more.
I have even talked to people that have had such a tangle on there that they didn’t realize, and they have a bigger shop, they will be across the room, and the filament drive motor is so strong it actually rips the filament down from whatever spool holder it’s on and throws it wherever gravity takes it. I hope you’re not in the way! It can cause some significant damage to your printer. We have our printer on a holder, so it’s within it, threaded through it. That is something else I am going to talk about, too.
If you change filament a lot, I find that it’s better to have more consistency from one to another and have ease of changing that filament; it reduces some problems you can have. Build a little rack. Ours is a bit ugly. It’s not a design. It was an engineered functional thing. I 3D printed some parts that are working really well, and it has some electrical conduit that I got at Home Depot. I can fit ten spools of filament on it above the printer, and then I just pull down the one I need. When I’m done, I take it off and put it back on the rack. I’m not really doing a lot of installation or removal within the machine. I’m not using their little holders if they have them; not all printers do. I find that helps with some consistency as well if you are doing a lot of changing of colors.
Being able to decrease resistance by making sure that you have not caught the ends of your filament in anything and how you hold or change out your filament can be a factor. You want to develop a system that is consistent. If you do things differently all the time, then different things will happen, and that will throw you off.
Getting down to that filament feeding into your extruder: There are a lot more contaminants in your environment than you may realize. Dust is the biggest one. It’s a really simple thing you can do yourself to take a sponge and cut a slit into it and then mount that somewhere that won’t interfere with the operation of the machine but is as close to the filament feeding into the tube as possible. What that sponge will do is as the filament is pulling through it, it’s not enough resistance to hurt the flow, but any dust will come off and remain on that sponge and not go in and be a contaminant.
If you are getting some inconsistent material flow, one of the things you need to do is when the nozzle is hot, remove it from your extruder and clean it out and double-check that there are no contaminants in there. I was surprised once that I had my filament rubbed so low on the build plate that it picked up a piece of blue tape, which got stuck inside that nozzle. I didn’t realize it for a long time. I kept getting restricted filament flow, and I couldn’t understand. But when I picked up that nozzle, I found there was something in there. You may not think it’s possible for something to have gotten inside your nozzle, but it can happen. So check your nozzle if all else fails.
Here’s the biggie. If you are using a lot of different filaments, different filaments melt and flow at different rates. You might think, It’s all PLA from the same manufacturer, so it should flow the same way. Guess what? Different colors have different materials in them.
That’s the same case with every single product that has a color. Think about this in terms of your clothing. When you buy black jeans, they are always slightly smaller in size, and they are shrunk slightly more. Women know this, and maybe some of you men experience the same thing. You buy the same size in blue and black, and you think they are going to fit the same, so you always think your black fits snugly. There is a reason for that. The types of dyes and things in them require a higher level of heat to cure them, so they shrink more in the process so that they don’t leave black dye all over you.
There are characteristics involved in any time a color is applied to something: more fillers in something. A lighter color requires less dye, which requires less curing, so the processing is different. It’s the same in filament. Some brighter chroma colors have a heavier amount of the chromatic feature that is in there and fewer fillers. More fillers might make the product more brittle. There are a bunch of characteristic differences that happen just because the color is different. To think that just because it’s PLA it’s the same, that’s not true.
On top of that, just because you think you’re getting it from the same manufacturer and that it’s going to be the same, it’s also different from lot to lot. It’s not even unfortunately going to be consistent from one spool to another. We have experienced this ourselves repeatedly buying colors from the same supplier and having them be different.
You may need to affect your temperature differently in order to get the material to continue to flow, or change your feed rate, essentially what is called your extrusion multiplier. You may need to raise or lower that. You have to go through some trial and error. Another day we will go into how you can actually test that extrusion multiplier for each material and how you can dial that in before you have failed prints and have to figure that out the hard way.
I remember early on when we were talking to someone about how 3D Simplify has profiles on filaments as well. They had different profiles for different colors they had created for the Max Filament, back when we were using the Leapfrog. If you chose the profile for their filament and chose the color you were using, it would adjust for that. Not everybody does that. People get lazy, and they’re like, “I just choose this general filament,” but if there is a choice in there of the various colors of the filament, do it because it should dial you in closer.
Not only that, but if you also learn through trial and error, your own differences for some of the filaments you buy, that this color filament requires different settings than this other one, you can save your own profiles for your materials that you have experienced. That will help you out.
This is just a tip. If you bought it on Amazon or some other place, send the information back in so other people can know who are buying it. People read the reviews. If you say, “Hey, this works great but only if you use it at this temperature,” that’s useful for other people. Please put that in.
When we review new filaments from manufacturers, I always get the specs of their recommended temperature settings and other settings to make sure I am starting as close as I can. We have some filament reviews coming up. If you find it’s different, we always post what we found as being different for our particular machine so that those who also use the same machine and same filament will benefit from that.
One last thing for consistent flow is the filament drive gear itself. That gear over time, especially if you are a heavy user, gets tiny pieces of plastic caught in the teeth of the gear. The more that is there, the less effective that gear is at grabbing, pushing, or pulling that filament. You need to learn how to take apart your 3D printer; they can all be taken apart. Even the smart extruder that I talked about last week can be taken apart so I can get at its filament drive gear. You want to get in there, take a toothbrush you use for this, and brush out all of those little particles on a regular basis. You want to keep that clean. That is a very frustrating thing for me over time. When I have had some of my biggest problems, it’s come down to my not having cleaned that gear enough.
Some good maintenance and some basic practices overall will help you. There are things to check if you are having feed problems. You want consistent flow, not too much, not too little. Unfortunately, it’s not all simple. Every material is different, and every 3D printer is different. That’s part of why you need to spend some hours getting to know your material and your machine.
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