Supports trouble.

[BarraVox 0]

Hi

 

What is up with Supports in Cura? They seem broken.

 

I've been struggling to get it to generate sensible supports for a fairly complex model, the STL is attached.

 

With Support Horizontal Expansion at the default it tries to start some part of supports in midair and adds support where none is required if there is support further up in the model ,

 

with it zero it's better but still with some support started in midair:

 

This is sliced in fine, only because I was messing about to see if the greater over lap on walls with thinner layers might help reduce need for support I could reduce need for support. 

InnerBodyTest1.stl InnerBodyTest1.gcode

Edited May 7 by BarraVox

[Torgeir 262]

Hi @BarraVox,

 

to be honest, I cant see that any support starting mid air.

I'll see you're using tree support "everywhere", and as far as I'll see -this all is good..

 

However, we do not know what printer you're using, -but you're using Cura 5.71

 

Here's the overview picture of your gcode file.

 

 

Thanks

Torgeir

 

 

[GregValiant 1,346]

 Wow.  That is a seriously complex model.

Those little slots (~2mm wide) need to be printed vertically so I think the way you have it orientated is the only way it can be.

I tried with normal supports and yes, there were two spots that wanted to rest on the part, but the angle was really steep and I don't think they would grow successfully.  But as Torgeir points out, Tree supports look pretty good, and would be a lot easier to remove.

This is with normal supports, towers at 6mm dia., and Support Horizontal Expansion at 1.0.  Tower supports just look to be easier from the round holes.

 

Whatever you decide, it's going to be a nervous 21 hours.

 

[BarraVox 0]

Hi @ Torgeir

 

Thanks for your attention and help.

 

My printer is an Ender 2 clone

 

I attached the Tree support gcode file by mistake - I normally use tree supports but I'd sort of given up with tree supports on this partly because my printer sometimes struggles with tree supports -( I think maybe I  need to increase extruder temp or flow rate ), but the main reason was that with the standard 50 deg max branch angle and 0.2mm layer thickness the layers of the supports don't seem to be enough on top of each other to print properly:

and hoping to avoid the extra time for 0.1mm layers that helps that 

just tried with a reduced max branch angle (40deg) and that looks better from that point of view

but  still has weirdness and printing in midair going on

Below shows roughly the same section of layers 461 and 462 with straight bits of support printed in midair in layer 462  (this is with branch angle at 30 deg but same happens at 40 deg)

 

And also at layers 456 and 457 more weirdness and printing in midair:

[BarraVox 0]

@GregValiant

 

Thanks also to you for your attention and help.

 

My printer is an Ender 2 clone.  Obviously I'd like a better one like an UltiMaker, but this one was cheap and does OK, l printed this marble run and the tall thin spiral at its centre: 

had a bit of an adhesion issue partway trough the main body and have now resorted to raft for almost any print to avoid adhesion issues

 

[BarraVox 0]

@GregValiant

 

I'm not too worried about removing supports - it's going to be a replacement battery pack for a 10 year old cordless SDS drill which I want to  convert from the useless Nicads it had to Li-Ion.

 

But the normal supports was at one point putting support in the long thin holes (these are just for m2.5 through bolts so not worried about their finish, or the teardrop shape which I added to avoid any need for support.

 

Oh my! It's all gone to sh!t with a couple of changes! WTF!:

Support Horizontal Expansion set to 1mm and tower diameter to 6mm has resulted in a complete  mess 😞 :

 

I seem to have messed up some settings when I changed profile from draft to fine earlier and saved changes - TBH I didn't realize that is a permanent save.

Changing  Support X/Y (back?) distance from 0.7 to 0.5 has mostly fixed the above:

though I'm a bit concerned about how tall and thin the supports are

and still a little weirdness going on here though probable not fatal:

 

Phew! sorry for long past and thanks again for your help.

 

As long as the raft goes down ok and the first few layers are OK I've never had a real spaghetti monster failure, had a few fluffy super light massively under extruded weak prints a while back and still not sure my layer adhesion is as good as it could be but mostly good. 

[GregValiant 1,346]

Good luck with it.  It's an ambitious project.  Remember though that all this thought and experimentation up front can save a lot of time by avoiding having to reprint it, and reprint it, ad nauseum

 

Going back to a previous set of images, the tops of the support structure in your photos are cyan colored and so all of that is support.  It gets wormy like that because you did not enable "Support Interfaces" which would be a darker blue.  How "odd" the support tops look is a function of other settings.

 

I generally run the support interfaces at 50 to 60% density and "Grid" pattern with a "Top Distance" of 1 layer height.  It can still be a pain to remove.  I've stabbed myself with the hobby knife a few times trying to get it out of tight places.

 

[Slashee_the_Cow 421]

4 hours ago, BarraVox said:

but the main reason was that with the standard 50 deg max branch angle and 0.2mm layer thickness the layers of the supports don't seem to be enough on top of each other to print properly:

Try increasing Quality > Support Line Width. The general guideline for line width is 60-150% of your nozzle width, so if you're using a (relatively common) 0.4mm nozzle, set it to 0.6mm.

Okay, not the clearest example ever (I just opened a model I use for testing little things).

 

If you want to stop support creeping into extremely tiny areas that can probably be bridged easily, then increase Support > Minimum Support Area (I can't really give you a value, just start with like 1mm² and play around with it).

 

1 hour ago, GregValiant said:

I've stabbed myself with the hobby knife a few times trying to get it out of tight places.

Everything is a competition, at least to me. Have you managed to cut yourself with a craft hobby knife through cut resistant gloves?

[BarraVox 0]

9 hours ago, GregValiant said:

I've stabbed myself with the hobby knife a few times trying to get it out of tight places.

Haha! haven't we all 🤣 and the same stupid mistake every time you promise to be more careful and not do it again! 🙄

 

Thanks, you've been very helpful, I'm going to start the print tomorrow when I'm WFH, I'll comeback and say how it went.

Edited May 8 by BarraVox

[BarraVox 0]

Hi again.

 

My first attempt to print this ran out of filament part way through, that's no problem because as usual I realized  the model needed some tweaks anyway. But it convinced me to go back to tree supports because the support was basically impossible to remove without destroying the print

:

 

Second attempt with tree supports and settings adjusted (with gratitude to yourselves for the advice) is OK ish. Supports were still a PIA to remove but at least possible. The raft was also difficult to remove from the print. Anyway this print is useable because the only part that will be visible when assembled is the 2 plain faces , one flat & one curved (or it would be if I didn't need to make more tweaks to some features!)

Regarding the over adhesion to the support or raft is there a way to change the cooling fan speed for any part of the model printed onto support (or raft), to get best layer adhesion I have to reduce fan speed down to 50 or 60% but that has very noticeable increase in adhesion to the raft or to supports.

[Torgeir 262]

Hi @BarraVox,

 

Great improvement.

Sure there is, @GregValiant have made a plugin that can adjust the fan at the line level you want.

I'm not sure if this plugin work with the newest Cura versions, but he'll answer.

Just checked and sure it works with all of the latest..  (OFC 😉)

You find it at the "Marked Place in Cura", named: "Advanced Cooling Fan Control".

 

Torgeir

Edited May 23 by Torgeir
More text.

[GregValiant 1,346]

"Advanced Cooling Fan Control" can be set to "By Feature" or "By Layer".  It is also possible to have multiple instances of it running.  For example you could have one instance set to adjust the fan "By Feature" and have that run from layer 5 to layer 100.  Then another instance could make adjustments "By Layer" from layer 101 to layer 200, and then a third instance could go back to "By Feature" from layer 201 to layer "-1" which indicates the end of the print.

The script also includes a setting for "Raft Cooling" and you can shut the fan off during long travel moves.  Torgeir was off a bit as the script is now included with Cura and can be found under "Extensions \ Post Processing \ Modify Gcode" and then "Add Script".