Printing ABS curling without fan on

for some strange reason, I was unable to print abs without it curling from 3rd or 4th layers up, first layer is perfectly flat and stuck to the bed, so I went on and print with PET for a day, with cooling at 100% from 3rd layer on, hoping to keep more transparent finish but didn't make much different, print was perfect, with 0% infill it managed to do skin fill without dropping thanks to the fan duct.

so I decided to try with ABS, same setting as I printed the PET except 240c instead of 230c, surprisingly I got no curl, perfect all the way, except when I try the calibration cube, not perfect but no curl, only effected side is on the opposite side of the fan duct, I'm going to swap out the duct with a ring one to cover the other side and see how that turns out.
I been reading everywhere all suggested to turn off cooling, but in my case, 100% from 3rd layer up works for me. no curl, strange.... the only perfect wall on the cube is the right side where it gets blown directly, and the smaller the object I try to print the worst it was for me, tried various speed and settings but no luck, this is the first no curl abs I have had in a week, before that, I was able to print all size and shape without fan no problem, nothing changed, anyone have any clue??

here the pics

printed a 20mm cube again all same settings but with a different duct, maybe 0.6 is a little too thing for its size but no curl, going to try tackle the cracking by lower to 230c and thicker walls

raise your heated bed temp to 80 deg celsius if your heated bed can go that high. the convection of heat rising will help keep heat on the abs and it will cool slower. this will reduce curling effect. you can also skirt layers around the object as it prints, this protective skirt can also help keep plastic warm until print finishes. also with abs you want to reduce air flow from fan.


you want part to cool to below glass transition for abs that is around 80c-100c, but you don't want it much cooler than that until it finishes print. this will be an issue without a skirt and when room weather is cooler.


this is abs the rules are a bit different , with pla you really need to cool it fast because its glass transition is a lot lower (about 60C), and it does not shrink as much, so you can really cool it down and not worry about warping.


the most ironic thing is if you could cool down the abs with warm air at about 70-75c then you could cool it quickly and print quite quickly without cracking or warping . since you are using room air temp, you will need to slow down your fan speed. you can do this in software settings of your slicer. i would have at least 1/3 the fan speeds as with pla. or even try a print without fan to see how it turns out. (not for pla)



the only other way is to print part really slow. what i think this does is allow for the previous layer to heat back up tp glass transition state and reform/reshape its bond relieving stress.




open to ideas people. I don't know it all.

Edited 1 time(s). Last edit at 09/26/2015 02:44AM by jamesdanielv.

I print with 100c plus on the bed, it can get up to 112c. I used to print without fan on and was perfect. Suddenly that had changed for no reason. Now I have to use cooling... or it curl everywhere. ...

Don't use a fan for printing ABS, and do enclose the printer, preferably in a way that the heat will be retained inside the enclosure.

It was working fine before and now it doesn't? Are you using old filament? I have found that old ABS behaves differently from freshly unwrapped filament. Try some fresh filament.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Yes they about 2 months in the box with silica gel. I do have the printer enclosed. Haven't got any new abs layer around. I printed with the silver abs and that doesn't needs cooling just like I used to print. No fan and enclosed. Only the yellow is having trouble which was perfect when freshly opened. Both were opened the same day 2 months ago.

Edited 1 time(s). Last edit at 09/26/2015 07:39AM by deaconfrost.

For 'hot air' cooling, I made a "recycling" fan duct, that fits on the opposite side of an E3D v6 - it 'clips on' to the exhaust for the E3D cooling fan, and blows it onto the layer.

[github.com]

(OpenSCAD version is up one directory, in the same GitHub repo)

Maybe this concept would be applicable for your ABS projects?

thats a very good idea, but I think I need a little more than that, I'm using the big fan duct now that blows around the model, at 50% fan speed, seem to be working one well

maybe I could make a fan duct to suck from behind the heat sink actually

I printed this with 40% fan speed, it is impossible for me to print with no fan on at all, everything will curl like mad from 3rd layer on regardless of layer height. bed at 110c and hotend at 230c, printer inside encloser