Overhang layers curling

We are all familiar with curling of the first layer and how to deal with it. But what can I do about curling of the overhang layers? I'm printing PLA (colorFabb) at 190C and have two 40mm fans blowing at the tip of the nozzle (E3Dv5 hotend). Is there enough cooling? Is there something else I'm missing? Thanks for suggestions and recommendations.

 

Everyone's experience is different and what works for one person may not work for you. That being said, I have never really had an issue with PLA curling or deforming. That mostly happened with ABS. Either way, are you using anything as a binding agent(Hairspray, Glue Stick, etc?) on the print bed? I use Hairspray and all my PLA prints come out flat and even. I do not think the cooling on the tip is as important. I only have one 40mm fan on mine and it prints just fine. Try a few layers of hairspray. On a clean bed, I will spray a layer of hairspray and let it dry for about 15 minutes. I add a second and let it dry and after the third dries, I will start printing. Never had any PLA warp. Don;t know if it makes a difference, but I just upgraded to the E3D v6 and had to up the hot end temp to 210. I read somewhere that you may have to up the temp if you are using an all metal hot end. You may want to try setting the temp to 200 to see if you get any better prints.

 

@Doug1 thank you for your reply. But please read the original question - it's NOT about the first layer curling or not sticking! That I can handle myself just fine. It's about other layers, that overhang, when the edge of the next layer is not on top of the previous layer, but rather slightly in the air - that portion tends to curl up while still warm. For excessive overhang, when it starts to sag down, I can add support structures. But in this case, when it curls up, the support is not really helping...

 

Not sure if this applies to your situation. I think I saw in other posts that when it curls in the air, that means your nozzle may be a little bit too hot.

I see that you're printing PLA @ 190C and E3DV5, so not sure if lowering the temp a little bit would help or not.

 

Thanks, @Paul Yeh! I can definitely play with the temperature. Unfortunately, last time I tried lowering it down to 180C, I had other issues, such as layer delamination...

 

Maybe you can try lowering your temp a little bit to 185C (to reduce the curling), and also reduce your fan speed a little (to reduce delamination) as well.

 

Well, any curling that I have read about tends to be due to temp differences but that is mainly with ABS. The PLA I use really does not have any issues with curling on overhang layers or any layers for that matter. Are there any AC vents that are blowing directly on the printer? Do you keep your house cooler than normal? Personally, I would try to heat up the nozzle a bit. Maybe to 200 or 205. I have never experienced curling at higher temps, only more stringy-ness and plastic threads as the nozzle moves around. That is when I know I need to drop the temps back down some.

 

I'm printing with the new hot end at 210 and getting excellent results. I also vote on lowering your fan speed and checking for drafts. Cooling too fast can cause curling.

I apologize for not staying on topic, but I was surprised to hear your method of using the hairspray. I used to clean the bed and spray once everytime I printed. Then, I'd spray after a few prints. The last time I sprayed was a week ago, and I've printed probably 20 pieces. No problem sticking, and I still have to use a scraper to get the flat pieces off and they pop right off. I think you're overusing the hair spray, but I guess whatever works for you.

 

Well, originally, I only used one layer of hair spray but I was still having problems with the prints not sticking. Then, I read the multi layer method on another website and that seemed to work for me. I will put on a new coat before every print as well because the previous print seems to leave an "imprint" of itself when you remove the piece from the bed. The imprint sometimes feels like there is a lip at the edge where the part was. A new coat seems to smooth it back out.

 

Isn't it funny (strange, frustrating, etc.) how what works for one person, doesn't work for another. Maybe it's bed temperature (mine is 50c). I see why you would spray again to fill in the imprint, but maybe that means you using too much to begin with? I've seen the imprint you mention, but it's more of a shadow with no edge. I give mine two quick sprays to cover the width and length of the plate, but very little thickness. Like I said, whatever works is all that matters.

 

I had the same issue... kept messing with lower temperatures... had my buddy come over he said the temp was too low (which is what someone on here has previously stated).... i thought he was full of it, but he convinced me to do a test print and much to my surprise he was right.... seemed counter intuitive to me, but do a test print at 210 and see what happens.... worked for me

 

Does anyone else have ANY other ideas. I am in the same boat as Denys here. I have tried all sorts of settings from low temp low speed to high temp high speed with variations of layer thickness and fan settings and nothing I do seems to stop this overhang curling which inevitably fails the print due to head crashing. For what it's worth I have seen this on slicer and Cura. I really sick and tired of wasting time and filament and from what I've seen of other printers they are more than capable of printing overhangs without this issue. Please help! Additionally after going through a whole spool attempting real prints I've been testing with the customizable overhang test print on thingiverse attempting 15,25,35 and 45 until I can get this resolved. All with the same overhang curl and eventual head crash.

 

I just point a big fu**n fan at my printer when i use pla. thats what does it for me.

 

My original duct design above is quite tall and requires the E3D v5, I'm not sure if the v6 is as tall. Use my new low profile design which has plenty of clearance, even for the Hexagon hotend and also has screwless attachment to the X carriage for either the fron or back.
http://www.thingiverse.com/thing:431160

 

I can confirm that was has almost completely eliminated the problem was to increase my filament temp by 10C to 205C, removing bed heat after first layer, apply 100% fan and sometimes adding additional prints to ensure each layer has a chance to completely cool. Thanks Printed Solid and Littlecricket!