A difficult subtraction in Part Design

[kisolre]

What is the "fanduct".

Fanducts
.

Why should I make in single body? I will need to print these parts with a printer.

How will you later connect them as a single body? You can design as a single part and then cut to pieces for easy printing. Or design separate pieces with means to fit/connect them together.
Here is what I did with your file to ilustrate my method. Sketches were duplicated (without dependencies) from one body to the other and moved to proper places (changing attachment valued). I deleted the external geometry links first and fully constrained them before moving. Then changed internal contours to reference geometry and sweep to create outer solid. For ease of placement I duplicated the sketch inside the body, removed all geometry from it and Carboncopied the original sketch to link the dimensions to one sketch. Then created the substractive features to hollow the solid.

air_pipe_2_kiss.JPG (109.73 KiB) Viewed 755 times

[koluna]

How will you later connect them as a single body?

Why should I do so? I insert this into another project with A2Plus.

[kisolre]

Why should I do so?

It will be a real detail for a real printer.

I will need to print these parts with a printer.

My bad for not being clear. How will you connect the 3D printed parts if they are created and printed as separate bodies? Glue those 1mm walls against each other? When designing something for the real world you should consider the process of the actual production. For 3D printing where will you need supports, will the bridges actually work, are the walls thick enough to be properly printed with the specific printer,... Just a general "measure twice, cut once" thoughts

[koluna]

How will you connect the 3D printed parts if they are created and printed as separate bodies?

I have some ABS juice

Glue those 1mm walls against each other?

Yes, I will Is it a wrong way? Are the walls very thin?

When designing something for the real world you should consider the process of the actual production.

I have thought about it... I do not any airflow on my printer: I am making it now. The bridges will be bad... And how will I remove supports from a long and not straight tube?
I am printing an ABS now.

For 3D printing where will you need supports, will the bridges actually work, are the walls thick enough to be properly printed with the specific printer,...

https://3deshnik.ru/forum/viewtopic.php ... 315#p41916
Welcome

[kisolre]

Are the walls very thin?

With ABS it might just barely work. But the walls are unnecessary thin. It is plastic. Weight and material cost is not a concern.

And how will I remove supports from a long and not straight tube?

You dont remove them. You design it to not need them. It is an air pipe. Do you need the circular cross section? No. Make it paralelogram, print it flat on the side. Do you need fancy cylindrical holes at the exit (complex bridges on top) - no. Make it square. Do you need perfect qualiy for your first fan duct - no. Print it, seal problems with nail polish, install it, design and print better version based on problems you encountered with the previous one

[koluna]

Do you need the circular cross section? No. Make it paralelogram, print it flat on the side.

Ok. Did You mean a parallelogram? Did not You mean a rectangle?

Do you need fancy cylindrical holes at the exit (complex bridges on top) - no. Make it square.

Ok. But if I will make them square I have also the bridges

Do you need perfect qualiy for your first fan duct - no. Print it, seal problems with nail polish, install it, design and print better version based on problems you encountered with the previous one

Ok. Did You advice the nail polish instead a paint?

[koluna]

It is the second variant of the head

[kisolre]

Did not You mean a rectangle?

Yes, sometimes proper words dont come to mind

I have also the bridges

Bridges-yes. Steep overhangs - no.

Did You advice the nail polish instead a paint?

Usually easer to find at home instead of paint. My first fanduct turned out crappy as hell (thin walls, no layer cooling, not realy sure what the hell was I doing ) so I covered the holes with nail polish, installed it and printed a better one
Your second design looks ok but it would have been better as one piece, printed on the left side, steep angle towards the exit. And no need for fancy curves. Now when you have some layer cooling bridges will work better.

[koluna]

Bridges-yes. Steep overhangs - no.

Are bridges printed better than steep overhangs all time?

Usually easer to find at home instead of paint. My first fanduct turned out crappy as hell (thin walls, no layer cooling, not realy sure what the hell was I doing ) so I covered the holes with nail polish, installed it and printed a better one

Do You have some pictures? Could You show it?

Your second design looks ok but it would have been better as one piece, printed on the left side, steep angle towards the exit. And no need for fancy curves.

Did You say the ONE PEACE?
Could You show how, If it is not difficult for You?
Did You mean a left side of the duct at the last photo?

[kisolre]

We are getting quite offtopic here but...
Steep overhangs dont have anything to support the other end of extruded material - it stays in the air and so easily falls (and fails). Bridges are from material to material and if they catch on both ends (sometimes slicers might not ensure that properly) they can be quite stable and so be able to support subsequent layers. There are a lot of 3d printing tutorials, examples, better explanations,... Just google and read

Did You mean a left side of the duct at the last photo?

Yes. This way the exit will point up and if the angle is more than 40-45 deg it should print ok without any supports. I made an single body (no treasure there )model of your duct:
.

air_pipe_5_kiss.JPG (85.77 KiB) Viewed 647 times

.
Here it is sliced with Slic3r in the suggested orientation:
.

air_pipe_5_kiss_sliced.JPG (53.51 KiB) Viewed 647 times

.
Notice that at the first bridge layer it might fail because the slicer tries to connect bridge to bridge:
.

air_pipe_5_kiss_sliced might fail.JPG (129.25 KiB) Viewed 647 times

.
So before printing allways check your generated g-code and if you think that it might fail somewhere think what to modify in the model/slicer settings/supports included in model,... to fix it before printing.