How to Print Complex S-Shaped Tube Without Internal Support?

[4Dprinting]

Hi everyone,

I’m using a Bambu Lab P1S, and I recently printed a complex part with an S-shaped internal tube. As shown in the picture below, the print has a lot of filament overhang inside the tube—especially at the top.
The problem is that removing internal support is nearly impossible due to the curved and enclosed geometry.

Has anyone here successfully printed curved internal tubes like this without using support?

Are there slicing strategies, orientation tips, or design modifications that might help reduce or eliminate the need for internal support?

Any advice would be greatly appreciated!

Thanks in advance!

Slicer settings= 0.2mm
Type of filament =esun PLA

[EnoTheThracian]

I am afraid that this looks like a case for soluble support (interfaces).
If it were smaller, bridging would have worked better. But at this size, you may need to look at PVA or BVOH.

[user_3026326371]

There is support materials that dissolve in water…
Without that finding a suitable angle so the top of the tube won’t be one single area should help a lot.
If printing flat try to reduce the layer height for that area AND check the orientation of the bridging in the preview.
You want any bridging that closes the tube gap to go at a different angle so it won’t run parallel.

[grizewald]

You have to print tubes vertically.

Putting support in a tube will give you PTSD.

[flabbyorca]

if you have an ams you can still use supports, just use another material (like pla if you’re using petg or vice-versa) and increase the top z distance by like .1 (so if default’s .2 then .21). the second material doesn’t like clinging to the first.

that said if its just extracting it id just use chopsticks or get one of those reusable pipe cleaners and slap it around the inside.

you could try making a tear-drop shape as well.