Rethink how you use 3D printer infill!

Summary

In this video, the host explores the complexities of 3D printer infill, testing various patterns for speed, strength, and top surface support. Using PETG filament from sponsor VOXELPLA, the experiment compares 2D and 3D patterns, nozzle sizes, and the balance between infill and shell thickness. The results show cubic infill as the strongest and fastest, with aligned rectilinear excelling in surface support. The conclusion favors thicker shells over high infill for structural strength, offering insights for 3D printing enthusiasts.

Takeaways

• 😀 The video discusses the complexities of 3D printer infill, acknowledging the lack of a single 'best' answer due to varying needs and preferences.
• 🔍 The script explores three main aspects of infill: the best infill pattern, the use of thicker nozzles for infill, and the balance between infill and shell thickness.
• 📏 It compares infill patterns based on print speed, strength, and their ability to support the top surface of prints, using the same amount of material for each pattern.
• 🏗️ The video categorizes infill patterns into '2D', '3D', 'specialty', and 'dubious', highlighting their unique characteristics and applications.
• 🚀 The fastest infill pattern tested was concentric, which does a single continuous line, while the slowest was Lightning, due to its minimal material use and specific application.
• 💪 The strongest infill pattern in terms of bend load was cubic, which also printed quickly and supported top layers well.
• 🧩 The script notes that for structural prints, a thicker shell generally provides more strength than additional infill, except in specific part geometries that benefit from infill.
• 🌀 The video mentions that 3D and specialty infill patterns like cubic and lightning infill can provide better support for top surfaces compared to static 2D patterns.
• 🔧 The test used PETG filament from VOXELPLA, chosen for its balance of affordability, reliability, and suitability for mechanical applications.
• 🛠️ The methodology for testing involved adjusting infill percentages to ensure equal material usage across different shell thicknesses and infill densities.
• 📉 The results consistently showed that a thicker shell provided better strength than additional infill, suggesting a rule of thumb for part printing.

Q & A

What are the three main aspects of infill that the video aims to test?

The video aims to test the 'best' infill pattern in terms of print speed, strength, and support for the top surface of the print; whether using a thicker nozzle for infill is beneficial; and whether more infill or a thicker shell provides better structural support.

Why did the author decide to use PETG for the tests instead of PLA or other materials?

The author chose PETG because it's a good compromise material that is suitable for mechanical applications and provides reliable data, unlike PLA which is rigid but tends to creep, or polycarbonates and ABS which require a controlled environment for optimal printing.

What are the four categories of infill patterns mentioned in the script?

The four categories of infill patterns are '2D', '3D', 'specialty', and 'dubious'.

Why is honeycomb considered an odd one out among the 2D infill patterns?

Honeycomb is considered an odd one out because it is the only pattern that avoids crossing over itself, instead creating double-width walls in some spots.

What is the fastest infill pattern tested in the video?

The fastest infill pattern tested is concentric, which does one single, continuous line.

Which infill pattern was found to be the strongest in the video's tests?

Cubic infill pattern was found to be the strongest in the tests.

What is the general recommendation for infill percentage when printing structural parts?

The general recommendation is to use just enough infill, around 15-20%, to ensure the part prints cleanly, and then use the rest of the material to increase the shell thickness.

What was the result of testing different shell thicknesses versus infill percentages for strength?

The test results showed that a thicker shell always provided better strength than more infill, regardless of the starting infill percentage.

What is the significance of aligned rectilinear infill pattern in supporting the top solid layers?

Aligned rectilinear provides almost perfect support for the top solid layers because its aligned pattern allows the first solid layer to bridge over cleanly at a 90° angle.

What is the author's suggestion for the default infill pattern in most cases?

The author suggests that the default infill pattern should be cubic, or adaptive cubic, as it provides a good balance of strength, print speed, and support for the top surfaces.

Outlines

00:00

🤔 Exploring 3D Printer Infill Controversies

The script introduces the complexities and debates surrounding 3D printer infill, with the narrator aiming to test three aspects: the 'best' infill pattern, the impact of nozzle size on infill, and the balance between infill and shell thickness. The narrator will compare print speed, strength, and top surface support, using the same amount of material for each pattern. The testing will be conducted on an XL printer with PETG filament from VOXELPLA, chosen for its affordability and reliability, and the narrator mentions other products from the sponsor.

05:00

🔍 Categorizing Infill Patterns for Testing

The narrator categorizes infill patterns into '2D', '3D', 'specialty', and 'dubious', detailing the characteristics and potential issues of each. The '2D' patterns like grid and honeycomb are compared, with honeycomb noted for its slower print speed. '3D' patterns are highlighted for their support and strength, while 'specialty' patterns are discussed for their specific uses. 'Dubious' patterns are questioned for their practicality, with the Hilbert curve noted for its aesthetic appeal despite questionable mechanical benefits. The narrator also discusses the methodology for testing these patterns, including scaling down parts and using a smaller nozzle for consistency.

10:02

⏱️ Print Time and Strength Analysis of Infill Patterns

The script presents the results of print time tests for various infill patterns, showing a clear division between 'fast' and 'slow' patterns, with concentric being the fastest due to its continuous line. The narrator discusses the strength testing of these patterns, with cubic emerging as the strongest, followed by concentric. The results are qualified with the acknowledgment of testing limitations, such as orientation and load type, and the narrator emphasizes that while cubic performed well, other patterns may be suitable for different applications.

15:03

🏗️ Material Distribution: Infill vs. Shell Thickness

The narrator explores the distribution of material between infill and shell thickness, testing various configurations to maintain consistent filament usage. The results consistently favor a thicker shell over additional infill for strength, suggesting that for typical part geometries, material is best used in the shell. However, the narrator notes exceptions for certain part shapes that could benefit from infill. The script concludes with a recommendation to use a default infill pattern like cubic or adaptive cubic for most prints, adjusting based on specific needs and part geometries.

Keywords

💡3D Printer Infill

3D Printer Infill refers to the internal structure of a 3D printed object, which is filled in to provide strength and stability while reducing the amount of material used. In the video, the concept is central to the discussion of various infill patterns and their impact on print speed, strength, and surface support. The script explores the 'best' infill pattern, considering factors like print speed, strength, and the quality of the top surface support.

💡Infill Pattern

An Infill Pattern is a specific arrangement of material within a 3D printed object that determines its internal structure. The script categorizes these patterns into '2D', '3D', 'specialty', and 'dubious', each with different characteristics and performance in terms of print speed, strength, and top surface support. The video aims to identify the optimal infill pattern by comparing these categories.

💡Material Efficiency

Material Efficiency in 3D printing is the measure of how effectively the filament is used to create a part with the desired strength and minimal waste. The script discusses the use of the same amount of material for different infill patterns to ensure a fair comparison, highlighting the importance of material efficiency in the context of infill patterns.

💡Strength

In the context of the video, Strength refers to the mechanical resilience and load-bearing capacity of a 3D printed object. The script investigates how different infill patterns affect the strength of the prints, with tests conducted to determine which pattern provides the best balance between material usage and structural integrity.

💡Print Speed

Print Speed is the rate at which a 3D printer can create an object, and it is a critical factor in the efficiency of the printing process. The script compares the print speeds of various infill patterns, noting that some patterns, like honeycomb, are slower due to their complexity, while others like concentric are faster due to their simplicity.

💡Top Surface Support

Top Surface Support is the ability of the infill pattern to provide a stable base for the top layers of a 3D printed object. The script evaluates how well different infill patterns support the top surface, which is crucial for the aesthetics and structural integrity of the print, especially when the top surface is visible.

💡Nozzle Size

Nozzle Size on a 3D printer refers to the diameter of the nozzle through which the filament is extruded. The script discusses the argument for using a thicker nozzle for infill to increase print speed, while acknowledging that it may result in a coarser infill structure, thus affecting the trade-off between speed and quality.

💡Shell Thickness

Shell Thickness is the measure of the outer perimeter's density in a 3D printed object, which contributes significantly to its strength. The video explores the engineering logic of preferring material in the shell over infill and tests the strength of parts with varying shell thicknesses and infill percentages.

💡PETG

PETG is a type of thermoplastic polymer that is used as a material in 3D printing. It is chosen for the tests in the video due to its balance of rigidity and flexibility, making it suitable for mechanical applications where strength is a factor. The script mentions PETG as the filament used for all the tests.

💡VOXELPLA

VOXELPLA is mentioned in the script as the sponsor of the PETG filament used in the video. The company is highlighted for providing affordable and reliable filament choices, which are used in their print farm and recommended for their performance in the video.

Highlights

The video explores the best infill pattern for 3D printing, considering speed, strength, and support for the top surface.

Different infill patterns are tested with the same amount of material to ensure a fair comparison.

The impact of nozzle size on infill structure coarseness and print speed is examined.

The debate on whether to prioritize more infill or a thicker shell for part strength is discussed.

The testing is conducted on the XL 3D printer, allowing for different nozzle sizes in a single print.

PETG filament is chosen for testing due to its balance between rigidity and flexibility.

Infill patterns are categorized into '2D', '3D', 'specialty', and 'dubious' for systematic analysis.

Honeycomb pattern is noted for its slow printing speed due to non-overlapping and double-width walls.

3D patterns like cubic, 3D honeycomb, and gyroid are praised for their consistent top surface support.

Lightning infill and support cubic are identified as specialty patterns for minimal material use and good part appearance.

Dubious patterns such as Hilbert curve are recognized for their mathematical interest but questioned for practical strength.

Cubic pattern wins in strength tests, followed by concentric, despite its inconsistent pattern.

Aligned rectilinear pattern shows exceptional support for top solid layers due to its alignment.

The test results indicate that a thicker shell consistently outperforms additional infill for strength.

The recommendation is made to use the default cubic pattern for most prints, considering strength and print time.

For parts requiring high strength, a thicker shell with minimal infill is suggested.

The video concludes with a call to action for viewers to share their experiences with structural part printing.

Transcripts

Ah, 3D printer infill. A topic that’s so full of  polarized points of views, personal preferences  

and passionate presumptions that I thought, well  this is something that I can jump into and surely  

not get wrapped up in any controversies. Perfect. But on a serious note, there are still plenty  

of things that don’t have a  definitive answer yet, so today,  

I want to test three different aspects to infill: First, what is the “best” infill pattern? And yes,  

“best” almost never has one single answer, so  this breaks down into a couple of sub-sections.  

I’ll be comparing both how fast they print, how  strong they are, and how good of a job they do  

supporting the print’s top surface, because yes,  sometimes all you care about is your print’s  

looks, and not how rigid or strong they are. And I’ll be doing all of this with the same amount  

of material used for each pattern, not just with  the same infill percentage - because turns out,  

you can’t trust the infill percentage  number at all when changing patterns. 

Second, should you be printing your infill  with a thicker nozzle? This keeps coming up  

as an argument for dual-extruder or toolchanger  printers, basically saying you can speed up your  

prints by just using a fatter nozzle for the  infill when you won’t be seeing it anyway.  

But that also makes the infill structure  coarser, so is it worth the speed gain? 

And third, more infill or a thicker shell?  The engineering logic is that you should  

always prefer putting more material into the  shell of your parts, because that’s where the  

majority of the strain is happening, but there  has got to be a crossover point where there’s  

simply not enough infill to support the  shells, so we’ll find that point, again,  

keeping the amount of filament used constant. I’ll be printing all this on the XL,  

because that’s the only printer where I can chuck  up different nozzle sizes and use them in the same  

print. For filament, I thought about materials  I would actually use when strength matters. PLA  

is very rigid and strong, but it also likes  to creep and when you really need strength in  

mechanical applications, you quite often also  have at least some amount of heat involved,  

so while it may make for some easy testing, PLA  just seemed a bit pointless. The other end of the  

spectrum with polycarbonates, ABS or ASA are  good candidates for mechanical applications,  

but because I don’t have the enclosure set  up yet and even then, I don’t think it would  

be controlled to a consistent temperature, so  I compromised and used PETG. It’s the softest  

of materials and might sometimes bend instead  of snapping off, but that’s still good data.

And what a coincidence - all the PETG I’ll  be using is from today’s sponsor, VOXELPLA! 

Their PETG Plus and PLA Pro are among the most  affordable filament choices you can print with  

at just $16.99 per spool or even less with bulk  discounts. VOXEL filaments are exclusively used  

in their 150-machine print farm in Southern  California - and I only have good things to  

report about them as well. They print great  with default profiles and no tweaking,  

they’re suitable for high-flow printing and  have been a perfectly reliable choice for me. 

Also check out their printer upgrades  like the Bento Box Air Filter,  

HULA Vibration Damper, and the Python  AMS Dryer Upgrade - at the link below.

Let’s get started with infill patterns. I’m  going to group these into four categories:  

“2D”, “3D”, “specialty”, and “dubious”. In the  basic 2D camp, we’ve got old favorites like grid,  

triangles, stars and honeycomb. The odd one out  here is honeycomb, because it’s the only one that  

avoids crossing over itself and instead creates  double-width walls in some spots. Crossing over  

already printed paths can be an issue, especially  when going fast, because you’ll often see the  

extruded line rip and tear at those points, which  can weaken the infill structure as a whole. But  

honeycomb, being a hexagonal pattern, has tons  of corners that the printer has to slow down  

for, so it’s a rather slow pattern to print.  We’ll get to the exact print speeds in a bit,  

but as a rough estimate, for the same amount  of material, honeycomb takes about 20% longer  

to print, and that difference only goes up  the faster your maximum print speeds are. 

Then, the 3D group, the cool kids of the  bunch: cubic and its varieties, 3D honeycomb,  

and gyroid. 3D honeycomb and gyroid are  both no-cross patterns too, but again,  

they’re both on the slower side. The gyroid  pattern is explicitly meant to have even strength  

in all directions and uses a very organic  pattern, while 3D honeycomb is more of an  

octagonal pattern that changes print direction  every layer. Cubic is actually just cubes stacked  

on their corners, hence the name, so it looks a  lot fancier in the slicer than it actually is,  

and essentially, it’s just a tilted version  of grid if it were to print a solid layer  

every couple of layers. I do like the 3D  patterns because I feel like they do a better job  

of consistently providing some support for top  surfaces and tying together perimeters that may  

not ever get crossed by the static 2D patterns. Then, “specialty”. These are circumstantially  

useful, and that’s lightning infill, which is  designed to use as little material as possible  

while still holding up the top solid surface,  and support cubic, which… does the same thing,  

but with the cubic pattern that prints tighter  and tighter cubes the closer you get to the top  

surface. Neither one of these is designed for  strength, but just to give you good-looking  

parts. I’ve printed some samples with lightning  infill anyway, but since its strength literally  

depends on which way you hold it, this  is more for completeness than anything. 

And then the “dubious” patterns. I mean, I see  why they’re in here, and that’s because they are,  

by their mathematical definition, patterns  that fill in a surface, with an adjustable  

amount of fill density. Yay! These all happen to  be non-crossing patterns by the way, but honestly,  

I don’t think these will provide any value at all,  but hey, I’m very open to be convinced otherwise. 

The most striking one certainly is the  Hilbert curve. It’s more of a mathematical  

phenomenon than an actually mechanically sound  concept, but I have to admit, it does look  

cool! I’d also put concentric, Archimedian  Chords, and Octagram Spiral in that camp. 

Rectangular looks similar to grid, only that each  layer is exclusively printed in one direction, and  

it alternates every layer. So this is a pattern  that only has point contact between the layers and  

uses most of its material in unsupported bridges. Aligned rectilinear is the same pattern,  

just with all the layers aligned in the  same direction. Makes sense. And lastly,  

the line infill once again is the same  pattern as rectilinear, but this time, drunk.

I still printed all of the patterns as test parts,  and because my intuition would be that the effect  

of the different infill patterns would be more  pronounced the more space it has to work with,  

but printing samples large enough where  especially the 3D patterns don’t just turn  

into mush would mean I’d samples that would end  up breaking me instead of me breaking them. So  

I simply scaled everything down and used a  0.25mm nozzle for the parts. The parts all  

printed perfectly with the smaller nozzle, so  all I’m doing is scaling down the strength of  

all the parts evenly. This, of course, also  saved me a bunch of filament and print time.

Speaking of time, here’s how the  patterns stacked up for print times: 

Basically, there is a fast group and a slow group,  but within each group, you’re probably not going  

to notice a dramatic difference in print times.  But when going from a “fast” pattern to a “slow”  

one, print times increased on average by a third,  and that is with the same amount of material laid  

down in each of these prints. As expected,  patterns that use many short moves instead  

of longer continuous ones do take significantly  longer; with the fastest one being concentric,  

which does one single, continuous line, making  it very hard to beat. The default grid pattern is  

tied for second place with the three rectangular  varieties that also just print straight lines,  

followed by Stars, Cubic and Triangles. The slowest pattern overall is Lightning,  

but it’s an odd one out, because a) I couldn’t get  it to lay down so much material that it would use  

as much as the others, and b) it’s not meant  to be used at such high infill ratios anyway,  

all it does is make the very top structure denser,  which, at a certain point, just ends up being  

material that doesn’t really help the print. Over in the “slow” group, gyroid is the fastest  

pattern, and while it didn’t make much difference  for print times back when the pattern was first  

introduced before input shaping had become a  thing, with printers moving much faster now, it  

means that they have to slow down to accurately  print the swirly goodness that is gyroid. 

But maybe it makes up for it with its strength?  Well, sort of. It takes third place. Second  

place is actually the fastest-printing pattern,  concentric. Though take this with a grain of salt,  

because concentric doesn’t have  a consistent pattern throughout,  

and I think really, we just got lucky here  and managed to get a spot that was perfectly  

oriented for the bend load I was applying. Most of the other patterns form a surprisingly  

tight middle group, with the only outliers  being lightning, again, not meant for strength,  

and Hilbertcurve, which falls into the same  camp as Concentric, Archimedian Chords,  

Octagram Spiral, of not being a consistent  pattern, which I think disqualifies all of  

them from being used for structural prints. And if you’ve been counting cards,  

you’ll know what the top spot is - it’s  cubic! With a significant lead, actually! 

Now, caveats. I tested these patterns printed  flat and on their side, but not in any other  

orientation, so some patterns might behave  differently in slightly different alignments;  

and I only tested for bend load, as it’s  the easiest one for me to test, but also,  

most real-life loads end up inducing a bend  load of at least some amount of significance. 

Also, while these results are consistent for this  geometry with this combination of print profile,  

machine and material, things might  slightly change with different part  

geometries, and with filament that’s  more or less rigid or has higher or  

lower material strength. But I think the  general trends should still transfer.

We’re going to dive a bit deeper  on strength in a bit, but first,  

let’s look at top solid layer support.  The test prints for these were done  

with only three top solid layers  and roughly 10% infill, again,  

I had to adjust each pattern individually to make  sure they all used the same amount of material. 

And all these prints look about the same. They  all have some areas where they covered well,  

other bits where they didn’t do so  well, except… for aligned rectilinear.  

That one is almost perfect, and it makes total  sense! All the other patterns have sections where  

that first solid layer has to span a distance  that’s too large to bridge over cleanly,  

but because aligned rectangular is, well, aligned,  it ends up being perfectly at a 90° angle, which  

gives that first solid layer the perfect geometry  to bridge over. Even lightning isn’t this good! 

One interesting thing here is that between  the regular cubic and the support cubic print,  

the support cubic one does print a coarser  structure down low, as it should, but because  

it then wastes material on printing double walls  as it transitions to the full-density pattern,  

if you actually give it the same total amount of  material to use, it has the exact same density  

of pattern when it gets to the top where it  supports the top solid layers. With larger parts,  

there is an actual benefit to using support cubic,  but keep in mind that if you just give the support  

and adaptive cubic patterns the same infill  percentage, without even doing anything adaptive,  

they will by default create a coarser structure  and use less material than standard cubic.

I know I’m talking a lot about cubic, because  that’s the pattern that I think so far comes out  

as the overall winner. It’s very strong, prints  quickly and doesn’t show issues with its ability  

to support material printed on top of it. So  it’s the pattern I’m moving forward with for the  

next test, and that is figuring out whether  you can just print your infill thicker. Now,  

this was all done on the XL because I could mix  and match nozzle sizes. But as good as these parts  

look, the alignment issues struck once again and  while one side is perfectly bonded between the  

shell done on one nozzle and the infill done on  another, the other side was completely loose, and  

this isn’t exactly good for strength. Maybe I’ll  come back in the future and explore this topic  

more, but for this video, I had to compromise  and just print everything with one nozzle and  

different extrusion widths, which worked really  well, too, but it’s not the cool two-color look  

I was going for. The results with what  I tested here, though, are promising,  

and there doesn’t seem to be any significant  loss in strength with printing the infill wider  

and faster. But again, this was fairly limited  testing and more exploration is required here.

And lastly, and this was actually the biggest  chunk of printing, where should you put your  

material - into the infill or into the perimeter?  I need to explain my methodology here real quick.  

I wanted to test 1, 2, 3, 4 and 5 perimeters,  so I started with a 30% infill part for each  

one. I then looked at the weight of each of those  samples and for each series, adjusted the infill  

percentage for all the other perimeter counts  until I had a set of parts that all used the same  

amount of filament, just distributed differently.  And of course, I did that for all the other other  

starting points as well, I also used 5 perimeters  and 50% infill as a high-fill starting point,  

and a single 100% print. By the way, when I say  “perimeters”, I actually mean “shell thickness”, I  

did increase the top and bottom minimum thickness  to be identical to the actual perimeters.

And these ended up being quite interesting,  or boring, depending on which way you look  

at it. There was not a single instance where  more infill ended up being the better choice  

over a thicker shell. This is the result that  one should expect, but I definitely thought we  

would be running into issues with things like  wall buckling which would reduce strength, but  

it looks like those might only start becoming an  issue once you go into the extremes with almost no  

infill and very thin shells, but since I’m testing  for strength, I wanted to use settings that you’d  

typically for functional parts, so those sort  of featherweight prints aren’t included here,  

but they might still hold some interesting data. Now, while these trends would suggest that the  

best setting to use for strength would be as  thick of a shell as you can get and zero infill,  

I wouldn’t say that that’s universally true.  Again, it’s true for this one part shape,  

but I can easily think of a bunch of shapes that  would profit from at least some amount of infill.  

Let’s say you have a large flat part, that would  not just be unprintable without infill, it would  

also be pretty bad at supporting any amount of  weight. Or something that has, like, a corrugated  

or baffle-shaped outer wall, even just a small  amount of infill would help with the strength and  

rigidity of that part much more than extra shells. So with typical prints, which are most often  

compact parts with walls that are a couple of  millimeters thick, your material will still be  

best used in the shell and not in the infill.  I guess as a rule of thumb - I’d say use just  

enough infill, 15, 20% so that your part prints  cleanly, and then use whatever you would have put  

into the infill to increase the shell  thickness. And even in high-infill situations,  

you’re probably not going to need to go above 30%. And for patterns, honestly, I think your and your  

slicer’s default should be cubic. Maybe even  adaptive cubic, because that will conveniently  

save some material with really chunky parts while  behaving like regular cubic otherwise as long as  

you account for the difference in fill density at  the same percentage. And if you don’t care about  

strength and just want fast, clean prints, maybe  even give aligned rectilinear a try! Just don’t  

forget to add a solid layer every now and then. Let me know what your experiences have been  

when printing structural parts - do you  have a favorite infill pattern? I’d love  

to hear from you in the comments below. As always, I hope you learned something,  

thanks for watching, keep on making,  and I’ll see you in the next one.