UM3: Bad quality only at support surface

[Technofrikus 0]

Hello,

 

in general the UM3 works fine for us, but the print quality of the surface where the support connects to the print is really bad.

Picture1: bad print quality where the support used to be, 0.8mm nozzle, with support roof

Picture2: rest of the same print, quality is fine

Picture3: another part, same problem, nozzle 0.4mm, without support roof, just normal support.

 

Material: PLA

 

Is this common with Ultimaker/Cura? Or is something wrong?

[SandervG 1,521]

Hi, what kind of support are you using? Is it PLA-PLA or do you use BreakAway or PVA?

[Technofrikus 0]

PLA-PLA, havent tried PVA yet, because it is pretty expensive and often not necessary for us. We dont need perfect print quality because most things we print are only for functional tests. But this is so bad, it even makes some problems for the function.

 

I would guess this has something to do with bridging? Should I do a bridging test print? Maybe one of the part cooling fans are broken? But this would cause an error message I suppose?

Edited June 13, 2018 by Technofrikus

[peggyb 171]

Would advise to use the PVA for overhangs more than 45 degrees though, your prints don't look huge, so the amount of PVA will be that much.. and the print will be much better.

For normal support the distance between the model and the support is bigger than the support for PVA, as the PLA/PLA wil fuse together without a gap.

You can play with the z distance of the support, preferably one layer height, so one layer nothing in between.

[Technofrikus 0]

I may try PVA but I still think there is something wrong with the normal support somehow, it shouldnt be that bad. I checked the part cooling fans and they do work fine.

 

I will test some prints with different z distances, thanks for the suggestion.

[ultiarjan 1,223]

I agree you should try to solve the issue without PVA first. I've had much better results with PLA support and support roof, though only with 0.4 I believe the 0.8 profiles really needs some work still. If I look at the side of the last picture it looks a bit like underextrusion to me. Do you use default cura pla profiles and default temperature? what print speeds? some of the profiles have strange print speed variations, like super fast infill vs walls, I like to normalise speeds a bit more. 

 

If you want to use the 0.8 I think it's good do do a few similar test prints and vary the support roof settings to find the optimum.