Support not reaching edge

[MaartenO159 0]

Hello,

I'm trying to print a rapid prototype of a dash replacement that I have been drawing. 
For some reason cura decides that the last support layer needs to be smaller then whatever it is supporting. This causes the inner shell to not be supported and of course causing a failed print. I have tried a bunch of the support settings, including the support guide and settings list, but I can't seem to figure out why this is the way it is.

I'm printing with a 0.8mm nozzle on 0.6mm layer height and 0.8mm line width with E-sun PLA+ at 210°C. Aldoh I don't think this matters allot.

(color scheme is line type. Blue = support, red = shell, yellow = top/bottom)
Second to last support layer:


Last support layer is smaller and doesn't reach all the way to the edge.

 

This causes the inner shell to not stick to the support because it's printing in mid air.

[GregValiant 1,248]

I could ask a lot of questions but it would be easier to see if you would use File | Save Project and post the 3mf file here if you can.

The first question would be - Do you happen to have Coasting turned on?

[MaartenO159 0]

Hello,

Coasting is not turned on. I've attached the 3mf file. I'm printing this face down with a Z-2mm offset so the outer edge is not printed.

I believe I found the "issue" myself. The support leaves 1 layer empty between the support and the part. Probably to make separation easier. Even when I set support Z-distance to 0 and with Z overrides X/Y it doesn't change.
With a layer height of 0.6mm this is obviously a large gap and too large to make the part stick to the support.
The support being smaller on the second picture is due to the little edge I have around the lower cut-out because that is 1 layer high, the support gets smaller by the size of the edge. (if that makes sense)

Nonetheless I'm wondering if there is no solution to this. Besides splitting up the design in a back and front side. Or printing it face up because that would take waay too much support


Like so:

Dash print test.3MF

[GregValiant 1,248]

Have you tried setting the Support Top Distance to 0?  That gets rid of the gap but I think you're right that removing the supports won't be easy.

That 3mf file is the model.  If you use "File | Save Project" it will also produce a 3mf file but it will have your printer and settings in it.

[MaartenO159 0]

 

I'll try the support top distance next time, I must have missed that one, thinking "support Z-distance" to 0 would do just that.

I don't have the cura project saved anymore. But I'm basically using the standard ender 5 profile with standard PLA and 0.8mm nozzle. Only thing changed is layer height to 0.6mm as cura only gives 0.32 as standard.
I don't think I'll be printing at 0.6mm anymore as it gave more issues then just the supports not working. But also the part warping allot. The original part is also bend, but sadly the warp is the wrong way around 😅

 

Anyway, I'll try the "support top distance" and 0.32 mm layer height and see if that fixes things. I'm going to be printing allot of tests for this part to get the dimensions as close as possible to the original anyway.

I'll keep this updated. Thanks for the help.

Edited April 13, 2021 by MaartenO159

[GregValiant 1,248]

That's a fussy part.  If I had to print things like that all the time I do believe I'd get a second extruder so the supports could be PVA (or something easier to remove).

[MaartenO159 0]

Haha wel it stuck alright.... 🙂 I bet the finish is awesome, if i could get there. Managed to get most of it off, only the last support layer is near impossible to get off. At least not without damaging anything around it.
Guess I'll have to split the part and print the inner part separately. 

[GregValiant 1,248]

I guess I called that one pretty good.  It's odd how some times the support will come off like a zipper and leave a decent finish, and other times it's welded on so good that removing it would destroy the part.  It's one of the reasons why even though right side up would use a lot of support - it would all be on the backside.

 

Designing parts for FDM involves different realities, or alternate universes, or something.