Cura builds useless support 'towers' in my print

[ronvanvliet 0]

Afternoon gents, and ladies

 

Cura tends to place useless support towers in my prints that I don't want to have in there. They have no function. 

 

I can't support block them out of the print. Also, 'use towers' option is disabled. 

 

see some pics attached.

 

Any ideas how to get rid of them? Thx

[ronvanvliet 0]

to add to the above. Cura seems to want to print a support structure for an overhang above it, but it's not functional as there's a large gap between the two support placements. Even if there wasn't, I wouldn't want it to be there. See the pic attached. 

[Slashee_the_Cow 283]

It would be really helpful if you could provide a .3mf copy of the project file (in Cura, go to File > Save Project). You could also look at changing Support > Support Overhang Angle. The higher the angle, the less support it will generate, but too high and it won't support parts which really need support. The best angle (which isn't the highest one you can get away with, it's a bit below that just to give you a margin of error) really depends on your material and print settings (mainly line width) - usually printing PLA+ with a line width of 0.4mm I set it at about 55°.

[ronvanvliet 0]

Thanks for the reply

 

I'm currently printing with a 60 degree angle, Tough pla and BVOH combo. Works great, expect for Cura that creates these towers. Tried to increase the angle, but the towers remain.

 

I don't want to share the file unfortunately due to it being a new product for my company. 

 

Perhaps Ultimaker should update Cura so that the support blockers always override any type of support placement- which it doesn't do now. 

 

 

[Dadkitess 19]

I second that, there is a LOT of useless / not continuous / not homogeneous / not relevant support, just like the overhang rule is actually not really followed. The OP has good examples : some conic continuous slope having some support at some point, but not everywhere else while it's the exact same overhang, the exact same geometry, etc.

 

And it's missing a lot of required overhang area too, unfortunately.

 

And... well, the support strategy tends to be very lacking, not built to be used properly with PVA for instance : lot of very short path, lot of quick retractation, it's totally not PVA friendly and it would be "good" either for normal material. Supports needs to be as continuous as possible, and most of the time the geometry totally allow for it but computation won't achieve to something practical, even using the whole palete of experts / custom settings.

[Slashee_the_Cow 283]

First important thing to remember: a support blocker doesn't stop support being generated where the blocker is. It marks parts of the model which don't need to be supported.

 

If you have Support Structure set to Everywhere you need to make sure a support blocker bisects any part of your model above where you want support blocked - i.e. here the parts I've crudely painted yellow are there to support the parts above the blocker:

(The diagonal the blocker is on doesn't require support because it's at a suitably shallow angle).

 

Using two blockers here is just an example, it's easier if you just make one:

Every part of that section which would require support is inside a blocker, so no support is being generated.

 

Here support is still being generated because only the bottom bar has a support blocker on it, so support needs to be generated for the top bar:

But if I move it to block the top bar, it's not just the blocker where there's no support - because none of it needs support, it doesn't generate any from the bottom bar upwards:

 

So what do you do if you need an area supported above areas that don't need support? Be environmentally friendly and use trees!

Trees won't go through a support blocker, even if it means they can't properly support a surface above it. But notice how they're also growing from the ground underneath the blocker

 

Is there a way to do this with regular support? I wouldn't be surprised if there is, but I don't know how off the top of my head. But I ❤️ tree support anyway (generally uses less filament, easier to remove) so it doesn't bother me too much.