H2D Fan Flow Duct (Coandă Effect)

New design with different approach and excellent result here.(click)

 

 

When the H2D was first announced, I had doubts about the location of the FAN DUCT in that model.

For H2D, as you can see in the picture, the fan ducts on both sides are quite far apart due to the two nozzles.

Of course, it may be possible to compensate for this to some extent by equipping it with a high-performance fan, but it is clearly at a disadvantage compared to other printers with only one nozzle.

 

I finally got my hands on an H2D recently (thanks to your support, of course).
The H2D performed exceptionally well when printing most common models. However, it occasionally failed on models requiring high tree support.

The thought that occurred to me at that moment was, 'Could it possibly have something to do with the performance of the fan duct?'

 

So I ran some tests to see how well the H2D would cool.

The model used in the test is one of the models available on MakerWorld above.

This model features a 1.4mm thick bridging pattern, resulting in seven overlapping layers when sliced at 0.2mm. The better the bridging, the cleaner the top print.

 

I have test results using the same models of P1S and K1MAX that I used previously.

As you can see in the picture, the printing result of the top layer of P1S is slightly better than that of K1MAX.

 

The photo below shows the same model printed one by one using both nozzles of the H2D.

You can see that the print quality is significantly lower than that of other printers. Prints using the left nozzle are particularly poor. Several possible reasons are: The left nozzle extends further down the print path, increasing the distance from the duct hole to the print. Another possibility is that the left duct directs air further downward than the right duct, which can cause the bridge to sag more.

 

Some of my subscribers may remember my Coanda fan duct designs. I've previously showcased three models (for the P1, X1, and K1MAX) utilizing the Coandă effect here. 

 

https://makerworld.com/en/models/773580-p1s-p1p-fan-flow-duct-coanda-effect#profileId-767208

While it's difficult to say there's a significant difference, these models did show some improvement in cooling performance.

 

I decided to make a duct for H2D using this Coanda effect.

 

First, I analyzed the structure of the existing fan duct using various methods, including 3D scanning.

The part where the air is divided into two inside is slightly wider on the left.

The duct hole size is slightly wider on the right (strictly speaking, it is a longer hole with the same width).

The intent of the two designs above is likely to be to direct slightly more air through the left hole, creating a narrower opening and thus faster airflow. As mentioned above, the left nozzle is positioned further down for printing, which structurally appears to be more disadvantageous for cooling, so this design is likely intended to compensate for this.

 

I believe that these designs are the result of considerable research, so I decided not to make any major changes to this part.

However, I decided to just apply my Coanda design to the exhaust port where the air is discharged.

The overall length and width of the exhaust port are maintained, while the fan quickly exhausts the air through a narrow hole on the outside, and additional air is drawn into the center.

 

After several revisions, I have completed a design that fits perfectly as shown in the photos below.

 

Below are the results of the first experiment.

The left is the result using the existing duct, and the right is the result using the new Coanda duct.

Overall, there wasn't a significant difference, but some changes were evident. In some areas, the existing duct seemed superior, while in others, the opposite was true.

This is encouraging, as it demonstrates that even with identical fan performance, cooling performance can vary depending on the duct outlet design.

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One advantage the H2D's fan duct has over the P1S's is its ease of disassembly and assembly. While disassembling the P1S's fan duct and installing a new one requires the tedious process of removing the glued parts and preparing magnets, the H2D's fan duct can be easily replaced by removing four screws. So, it's worth a try.

 

I considered releasing this after achieving better results, but I'm releasing it in advance to continue this project and gather feedback.

The above is simply the result of printing a test model. If you let me know what the results are when printing actual models, I will use it to improve future designs. Thank you.

 

When printing, I recommend using ABS or higher temperature resistant filament.

 

For those of you who would like to try your hand at designing your own FAN DUCT, I have also attached the 3D SCAN file of the original FAN DUCT.

 

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https://makerworld.com/ko/models/1991417-h2d-poop-bucket-system-no-magnets-modular#profileId-2143144