How I tune in new filaments

How I tune in new filaments!
Got a new filament and don’t quite know where to start with getting it printing right? This one’s for you!

A couple of weeks ago I asked which topic you all would like to see covered on the channel. Clear winner – how to tune in a filament you’ve never printed with before. So, let’s go over the steps of getting practically any PLA, PETG, ABS, ASA, PC, PMMA, PA, etc filament to work and to print well, but keep in mind that specialty filaments like fiber- or wood-filled ones, super-flexibles ones or stuff like Colorfabb’s lightweight PLA will need a bit of extra attention. But honestly, once you have a good profile for something like PLA or PETG, you’ll be able to use that with basically any other brand of the same material type. Of course, unless it’s some weird modified material or just downright bad filament.

Let’s start with the most important bit when it comes to getting good print: Make sure your filament is in good condition. Maybe not so much for simple PLA, but at the very least for PETG, and higher temperature materials like ABS, and especially for Nylons, make sure your filament is dry to start with. If you’ve had it out of the original sealed package for a while or you’re unsure if it was ever properly dry out of the package, get it dry before use.

I like to toss it into the oven at about 50°C, a bit lower for PLA and similar materials, or some people also use food dehydrators with good results. If your filament isn’t dry, you might get anything from bad layer adhesion and stringing, to the filament snapping in your extruder or giving you tons of tiny little bubbles on the print.

So when you’re sure that you’ve got that sorted out, here’s the regions that we’ll be looking at, and that’s also the order that you should prioritize your efforts in finding good settings.


Bed Adhesion

First, bed adhesion. If your prints don’t stick, there’s no point tuning anything else. Then, print temperature, next, flow rate, and lastly, retractions.

After that, and that’s really a bonus, you can maybe look at eeking out a bit more print speed, but personally, I’ll always prefer a reliable, repeatable, and high-quality profile over one that just prints faster. But even though I’m putting speed last, if you’re trying to get a flexible material to work, speed should be one of the first things to consider. Especially when your printer has a very “open” extruder design or uses a bowden, before you do any other tuning, you’re better off cutting your usual print speeds in half or more before you do anything else. And printing a bit slower is usually also a very easy way of increasing reliability and quality.

Okay, so first off, bed adhesion. As with anything, you can have too much or too little, but usually, you’ll find usable best practices for your material either recommended by the manufacturer or by the community.

I still use a glue stick for a lot of prints, for a few reasons actually: It will stick well to almost any type of filament, PLA, PETG, ABS, flexibles, and even Nylons, it’s easy to get, it’s cheap, and it usually errs on the high adhesion side, so while it might be a bit of a pain to get print off a non-flex bed at times, at least you’ll have a decent print to start with. It also works great to protect PEI and glass surfaces when printing flexibles and PETGs, those can sometimes bond excessively well to smooth PEI film and bare glass. So in case of doubt, just throw down a thin layer of glue stick. And the same tips about increasing the first layer extrusion width and height and slowing down the first layer of course also apply.


Bed Temperature

The other factor to adhesion is bed temperature and I’d say, as long as you can trust the temperature reading on your printer, meaning the top of the bed is actually as hot as the printer is telling you, you should get good adhesion based on temperatures for a similar material type.

So 50 to 60°C for PLA and flexibles, 80 to 90°C for PETG and 100, 110°C and up for ABS, ASA, and polycarbonate. And of course, if it doesn’t stick and the print comes loose, go higher, or if the bottom of the part is significantly curling in, go lower in temperature. 5°C can make quite a big difference already.

So on the topic of using “similar materials” as a starting point – I most often just start off the presets in PrusaSlicer that are actually built for Prusa’s MK3, but you can use the exact profiles for any printer or at least base your starting point for a new profile on some of these values. Here’s what you’ve got to do: In the configuration wizard, choose the MK3 or MK3S with the standard nozzle size, then jump to filament settings and hit “All”. Now you have all presets available, but only for the MK3. So to make those available for any printer that you’ve set up in PrusaSlicer, first make sure you’re in the “Expert” view mode, then in the “Dependencies” tab, hit the checkboxes on “All” compatible printer and profiles and remove the dependency line. Finally, save the profile with a new name, and then it’ll be available to use on your own machine.

Now, most of the time, almost always, actually, these profiles will give you very close to perfect prints, but sometimes, you might still need to tune a few things. Starting with temperature. And when you’re talking about temperature, you’ll always have to consider the effect of the part cooling fan as well.

As you increase temperature, you’ll get better layer adhesion, but you will also start to introduce effects like curling where overhangs start to curl inwards.

There is a minimum temperature below which the filament just won’t extrude properly anymore, but that temperature is way below what you want to be printing at to get parts that are at least usable strength-wise. On the other hand, there’s not really a true maximum temperature, like, you could be printing PLA at 280°C and the prints would still be, I mean, not the prettiest, but they’d still work. Of course, filaments like ABS will start to decompose when you push them past certain temperatures, which is neither great for the print nor particularly healthy for you.

The temperature I like to print at is just high enough to get properly strong parts, and stuff like curling I can look past a bit more because usually when you hit that “strength maximum” temperature, curling will still only appear in the most extreme spots. Finding the right temperature is simply running a few test prints at various temperatures and seeing which ones work for you and which ones don’t.


Part Cooling Fan

But, of course, the other part to temperature is the part cooling fan. And the effect there is the opposite of what your temperature setting does – more cooling means less layer adhesion and less curling. You might need to bump temperature up by 5 or 10°C when you add a fan to the mix, but it’s a similar experimental process as with temperature itself. Many filaments react really strongly to an added fan, especially the higher-temperature ones, in general, full fan for PLA after the first few layers, moderate fan settings for PETG and other polyester-based filaments, and no fan for ABS, ASA, polycarbonate. But there are exceptions to the rules, for example, I’ve found some ASA actually really benefits from a bit of fan added.


Flow Rate

So once you’ve found your temperature and rough speed settings, it’s time to fine-tune flow rate. Because most extruders are always ever so slightly slipping on the filament, and the teeth of the drive gear dig in different amounts depending on how soft the filament is, the exact amount of filament extruded varies a bit between filaments and on based on how much resistance the hotend is putting up.

The way I like to tune flow rate is by looking at the top solid layer of a print – if there are still gaps between the individual lines of filament, your printer is underextruding, on the other hand, if the nozzle starts digging through the top layer and that effect gets worse as you add more solid layers on top, you’re overextruding. Anything between those two goal posts is generally deemed acceptable, it’s almost a 10% extrusion multiplier range between those two, but you can still choose whether you want significantly stronger or slightly prettier prints by adding or removing 5% multiplier.

You might also still find tips from the 3mm filament era like measuring your filament diameter to get a baseline to start with, but with 1.75mm filament, not only do you get a much larger measurement error with for example being off half a tenth of a millimeter on 1.75 vs 3mm but today, filaments are also generally much better quality and are extruded much more consistently that, really, the only tuning that actually improves things is going to be by eye.


Retractions

So the last thing to look at is retractions. From a part functionality standpoint, a bit of stringing rarely is much of an issue.

The two extremes you can tune to is either no retraction and getting more stringing or too much retraction and ending up with blobs at the start point of every new extrusion line. And before you start to change settings like the retraction distance and speed, the following things might already help you get rid of some of the furries. Fuzzies. First, make sure the filament is dry. Just wanted to reiterate on that. Then, try increasing the travel speed between extrusions. Just don’t give the hotend time to leak and ooze. And lastly, try a bit of z-hop.

Now, for some combinations of hotend and filament, you’ll have a hard time finding that sweetspot where you have no stringing but also no blobs, but for most materials, there is that point where it will print fairly nicely. I would suggest that you start with a low or almost zero retraction length and a normal retraction speed and then work your way up in retraction length to the point where you have stringing under control. If you then still have blobs on your parts, you can experiment with retraction and deretraction speeds and the “extra length on restart” setting, where you can use a negative value to suck up that bit of material that might have dropped while the filament was retracted.

But be careful with that setting since it’s very easy to overcompensate and create holes on your part instead.

So that’s really all that’s needed for a basic tune or setup of new material. Of course, that assumes that the rest of your printer is set up in a way that’s not going to impact print quality and that any changes you see are caused just by the settings you’ve just changed. But like I said, snatching a preset from another printer has worked really well for me before, and is probably going to get you very close already. 

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But for now, thanks for watching, keep on making and I’ll see you all in the next one!


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