Solved Weird surfaces on certain angles

Hi all, I've had my Robo for about two weeks now and have had pretty good luck with it so far. The only thing I haven't been able to figure out yet is the weird blotches on the surface of certain angles and certain prints. Attached is what I'm talking about, 99% of my angled prints are good, even steeper angles than this, it just seems to be this certain one it struggles with and i don't know why (happens with different models, all around this angle). I've watched as it struggles with these, and the edge seems to curl up causing the extruder head drag through it slightly.

Settings:
Tried 200-220 degrees
Happens at .1 and .3 resolutions
Happens with multiple files, not just charmander

Any help is appreciated, ill be around to reply with any sort of info I left out.

Edit: The chin part of him

 

Just switched to repetier with similar settings but used slic3r instead of matterslice, same result.

I watched it print the problem areas again, and it's definitely curling up at the outer edge of the angle it's making causing the print head to drag through it and do weird things. Could be the fan I have pointed directly at it maybe?

 

Are you using support material? I can tell you i use to have the same results... then i switched to Simplify 3D and problems dissapeared

 

Do this for me. Change the Z Offset to 0.8 and re-print charmander

 

Did the .8 Z offset (side note, I print on painter's tape) and that made my prints stick better! But! The original problem remains, no one else has had this problem??

 

Flip the model 180 degrees so the chin portion is under the fan. Does that improve results?

Consider adding a dual parts fan mod to your printer

 

Sounds to me like the layers on the chin are not cooling enough between passes. I would try slowing the print speed down a little so each layer has more time to cool before the next layer is printed.

I had this issue when printing with abs on small areas. I would watch for when the layer seemed to curl up and turn the fan on for a couple layers at a time (the fan typically doesn't run when cooking abs because it needs a higher temp for the layer to stick, otherwise the layers may split apart)... You have to sit there and watch it, but it worked for me.

I have even resorted to blowing on the print as it was printing ( and even using the spatula to flatten out the section that was curling up while it was printing)... It was not my proudest 3d printing moment, but it came out ok after.

 

That would probably help! I will give that a try myself next time.

 

That's a great idea! Sounds similar to my issue so I'll give that one a try!

 

Alright, I've tried a few more things now. I looked at a thread from 2014 and they recommended everything from increasing/decreasing extruder temp, lowering/turning off bed heating, extra fans, adding more parts to increase time for cooling on the previous layer. I tried all of em: turned off bed heating; I already have dual extruder fans but added a desk fan as well; lowered temp all the way to 185 and worked back up to 200 in 5* increments; aaaand added a duplicate part to increase layer times and allow cooling.

These angles are so weird, the edges of overhang start to curl up more and more (not the edges on the bed), the extruder starts to rub through them, but eventually they work themselves out when they've gone up approx 50 layers, or the angle changes to a non-negative overhang.

Plus, only certain overhangs even do this. But if one does, it does it repeatably on multiple prints.

Lots of attached pictures of what I'm talking about. My next plan is to whip out my ABS enclosure to see if evening of heat helps or not, and maybe turn off cooling fans too.

 

That is pretty bizarre. Does it do that on objects without an outward slope?

 

Nope, the bottom layers of objects without outward slopes come out perfectly. But, as seen with charmander in the OP, layers up to 2 inches off of the print bed that have this angle are susceptible to the effect as well.

 

It might be over extrusion. I know you said you have a lot of fans so I'm surprised it looks like that, usually more cooling resolves what you have

 

I haven't bothered tuning the E axis yet, it's still default settings. Maybe I'll do that real quick-like.

 

Alright, whipped out my calipers and a sharpie. Extruded exactly 100mm at a normal rate of flow and got exactly 100mm of travel, at a surprising level of accuracy. Measured filament diameter at 1.69-1.73 (yes I have a decent pair of calipers, not $10 made in china stuff), so if anything I would be under-extruding slightly with default settings?