Introduction: INNER WALL SPEED Effects on OUTSIDE PRINT QUALITY (Close-Up COMPARISON)

By youtube.com/@DIYPERSPECTIVE
About: For anyone wondering I fully transitioned to producing 3D printing content only on YouTube. Old videos are no longer available but all full detailed Instructables are still here if you want to make any of my p…

In this instructable/video, I am testing how much inner wall speed affects the outside 3D print quality. As always, I will provide many close-up comparisons so you can easily spot the difference.

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Step 1: Lighting Is KEY

The first question when making a comparison always is which test prints to use, so I designed one with all types of shapes.

From my experience, prints with vertical walls and top to down lighting will show the inconsistent outside layers the most. And I can't stress this enough - the lighting is the key here. Because with the correct angle you can easily expose or hide the imperfections of the prints.

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Step 2: The Acceleration

So without further ado let's go straight to the test print results with PLA filament. And when I checked them under the microscope the results looked basically the same. And if you have a lot of experience with 3D printing, I can already hear the correct answer why.

The main reason for that is the 3D printer’s acceleration. You see, same as racing on multi-turn tracks, speed is nothing without adequate acceleration. To help you visualize things, check picture (2) and how printing speeds look with 1k compared to a 3k acceleration value. As you see, even at 30mm/s we only manage to maintain 69% (1k acc) vs 85% (3k acc) of the set target speed.

And if we compare when printing inner walls at twice the speed of 60mm/s (picture 3), the drop is even more drastic from the set target speeds.

So the first very important point, before we start further testing, is that wall speed almost doesn’t even matter for most printers on the market when printing very detailed objects (last picture).

Step 3: First Test Results

Well then, let’s increase acceleration to 3k and repeat the prints. And here are the results.

The difference is subtle, but when you know where to look it is not very hard to spot it. The increase in speed with this print will result in around 20% lower print times. And I would say these are pretty good results considering that we running the printer with 3 times higher acceleration than default and stock firmware.

Step 4: More Testing

So with that in mind, this is how the print looks when we use 3k acceleration and 60mm/s speed on all walls.

And now the ghosting and all vibrations are way more pronounced. It will result in a further 10% print time reduction but in my opinion, this is not worth it at all, if you search for the settings with the fastest print times and minimal quality loss.

Step 5: Effects on Small Prints

And what about small object prints? Like this Cali-dragon that became one of my favorites.

Just keep in mind that at 3K acceleration we actually get the set speeds.

But can you spot the difference? Even when I looked at them directly it was really hard to tell which one is which. The only place that gave it away was this sharp corner (last picture) that had noticeable ghosting. Otherwise, there was no difference whatsoever.

Step 6: Angles and Overhangs

Another important scenario is the overhangs and angles. For that, I made this spaceship-looking part with 45, 55, and 65-degree angles. And with this print even if we would set the acceleration to quite a low value like 500mm/s, we would still reach the set speed on the curves.

So can we see any difference in this scenario? This is a pretty hard one to spot as both parts look extremely similar. Also, this speed increase helps us to reduce the print time by around 15%.

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Step 7: Worst Case Scenario?

But previous prints were printed on Kingroon KP3S - a small and lightweight printer on linear rails with a 0.4mm nozzle. So what about the worst-case scenario? A big printer with a bigger nozzle (0.6mm), heavy glass bed, and POM wheels - Longer LK5. Well, the results here are a little bit less impressive.

I would say that most spots of the print still look on par despite the twice faster inner wall speed. The only bad thing is the overhangs in the sharp corner where the seams meet and at the low radius corner.

But this problem is amplified because bigger nozzles also print worse overhangs as Thomas already showed in his recent video.

Step 8: LK5 Results 2

And if you own a larger-scale printer you probably will print bigger things. Then it will potentially spend more time at higher speeds. So for that comparison, I made the shape with straight walls, overhangs, and angles.

And just like before we are seeing worse overhangs at higher angles and at sharp corners. But there is so little difference elsewhere. So considering that is close to a worst-case scenario I would say it is not that bad at all.

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Step 9: PETG?

But what about PETG prints? This time I will use Prusa style Anycubic Mega S 3D printer.

And here are the results. So do they look any different? Well, not by a lot. There is more ghosting in some corners but rather than that, both test parts look very similar. Exactly the same I can say about the result of the smaller spaceship print.

Step 10: More Forgiving Conditions

And the most important thing to take into account is that we are trying to expose the problems, either with print files or with the lighting. In more regular conditions like you see in these photos, the imperfections will be way harder to spot with the naked eye.

Step 11: We GOTTA GO FAST

And I left best for the last. The 90 versus 30 mm/s inner wall speed with my final design test part. It incorporates all the most important features from previous designs. Here we are chopping almost one-third of the total printing time. And considering that I would say the results are very acceptable. Yes, there will be prints where you see very little improvement in print time, but there also will be ones that result in huge time cuts.

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Step 12: The Summary

So in summary, how much inner wall speed affects outside print quality? Well, in most cases not by a lot and we can get significant print time reduction on some prints. The most visible defect that was most common in all the prints was ghosting in spots where the printer had to slow down very fast and then continue accelerating.

Small and light printers will see the most benefit. Same with the nozzles as smaller ones will print overhangs more cleanly, especially at higher speeds.

Step 13: Nozzle Quality

And the last important thing is the nozzle quality. As I tested in my previous instructable/video, the big downside of cheap nozzles was the thermal conductivity.

And it is important because the more drastic difference in speeds we have the better heat transfer we must have to get consistent filament temperature. And if we need to crank the printing temperature by 7C degrees even at 30mm/s, it would be hard to imagine what we need for three times (or more) the printing speed.

But as we still need to print the outer wall at a way slower rate, this combo could lead to a horrible stringing. So this is why the nozzle quality is important in this specific scenario.

So yeah, I hope this helped you to see more in-depth on this specific topic.

Step 14: Thanks for Support

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