Issues with overhang/underside of prints.

Hi everyone,

I have been trying to learn 3D printing since I got my Robo C2 earlier this year (as my work schedule permits) but I seem to be constantly having an issue no matter what settings I try. It started to become frustrating so I figured I must be missing something fundamental. Hoping someone here can help me with it.

I'm having issues on the underside of overhangs with or without using supports. Basically almost all the sides that are facing bottom come out very rough and most of the time the supports weld to the model because of this too. Please see the picture, this is what the bottom looks like after cutting the supports with an xacto knife.

Other than that, the prints seems to come out fine, may be with the occasional exception of very top layers. (See top of vertical stabilizer for example)

Here is another one, but printed without supports this time. Again, sides that are facing bottom are rough especially on the left leg, hands, arms, face etc. I think this would be great if I was printing a zombie 'thinker', but that wasn't my goal here.

I'm using Cura 2.3.1 and these were my settings for the Viper MkII model. (The spaceship above for those of you who are not a fan of Battlestar Galactica ) All other settings that are not pictured were left at default. All help is much appreciated!




This is my first post and I'm still a newbie at 3D printing so please bear with me if I'm not following any proper etiquette. I did, however search through the forums but haven't been able to find an answer to my question. Thanks in advance.

 

Hi Mark, thanks a lot for the replies.

1) I'm using the filament from Robo. Had similar results in 190, I thought maybe it is not enough so tried 195, apparently it is the opposite. Is it ok to go lower than 190? How much lower can I go with PLA without risking breaking or clogging anything?

2) Is there a way I can increase this beside Cura? Right now Regular Fan Speed is already set at 100% and it is not letting me go any higher.

3) I don't know how to do this in Cura. Is this the Flow setting? Right now it is set at 100%

Thanks again for your replies.

 

Ok tried the Viper model again with 185 degrees and 90% flow. Supports were a little easier to break this time but underneath the model is still as rough if not worse than before. It also warped a little more on detail areas on top and created couple tiny holes in the model as well. I don't know what I'm doing wrong Maybe I'll try to go as low as 170 degrees tomorrow and see what happens.

 

This might be a Cura thing... When it's printing a 1st layer (like after the raft), it seems to want to almost "air print" the first layer with the diagonal filling lines. It's like the author hopes that those lines will bound to the line next to it and not even touch the floor, if you will. This means that you have to dial in the temperature perfectly or you end up with some slight form of fail. (It's a wonder that it succeeds using this strategy.)

I note that the white or blue Robo PLA filament works perfectly at 190C and their own black is a little too plastic at this temperature. (The net result is that 1st layer will get very wavy on those lines rather than nice & ordered.) If you ignore and let it then print the second layer, the weight of that can tend to try to squash things down but by this point, you have a slightly uneven plane when then is exaggerated slightly in subsequent layers.

It's not horrible but this is probably Cura's attempt to make raft separation easy. Another slicer may be worth testing.

 

I actually had this issue when I upgraded Cura to 2.5. Overhangs were horrible, rafts overly stuck to the prints, and under prints looked terrible. I reverted back to 2.3.1 and it cleared it up. Maybe try the opposite for you? Cura isn't the greatest software from what I am seeing. It takes some playing with.

 

I know you've tried this with multiple models, but try something other than the viper. I get great prints and I have never been able to print that mode right. It has issues.


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